The aim was to assess the relationships between cardiovascular activity, corneal pulse characteristics, and corneal biomechanics in rabbits. Seventeen rabbits were randomly assigned to one of two anesthetic regimens to induce differences in arterial blood pressure and heart rate. Experimental protocol included measuring blood flow parameters in the ophthalmic artery by color Doppler imaging, corneal biomechanical parameters using a non-contact tonometer Corvis ST, and the corneal pulse (CP) signal using a non-contact ultrasonic technique. Statistically significantly lower mean values of normalized amplitudes of higher CP harmonics and changes in eight of the twelve corneal biomechanical parameters were observed in the rabbit group with lower arterial blood pressure and higher heart rate, intraocular pressure, and resistive index. The results of partial correlations showed that the CP signal energy and amplitude of its first harmonic correlate with the resistive index, diastolic and mean arterial pressures, whereas no statistically significant correlation was found between any of the CP parameters and intraocular pressure. Our pilot study indicates, for the first time, that non-contact and continuous measuring of corneal pulse allows indirectly assessing changes in cardiovascular activity when the confounding effect of intraocular pressure is eliminated. The OP signal characteristics have been found to be highly influenced by cardiovascular activity9. In particular, Trew et al.9 showed that ocular pulse volume, derived from the pulse amplitude and the duration of its waveform, decrease with increasing heart rate (HR). Further, the waveform of the corneal indentation pulse has been shown to correspond to the alteration in ocular blood supply related to several pathologies10. Correlation between the ocular pulse amplitude and the degree of carotid stenosis has been found in animal studies11. Recently, characteristic changes in a shape of corneal pulsation, named as an ocular dicrotic pulse, have been observed in healthy elderly subjects6 and glaucoma patients7. It is speculated that both vascular and biomechanical factors have contribution to these changes, however, explaining a mechanism of its formation without controlling those factors is difficult. Evaluating the relationship between cardiovascular parameters and corneal biomechanics and pulsation is difficult in in-vivo studies because it requires controlled levels of blood pressure and heart rate. To ease such an evaluation animal model are presented14.With each heartbeat, blood pressure wave is propagated to the eye resulting in choroidal volume changes, pulsatile ocular tissue movements and intraocular pressure (IOP) variations. This phenomenon is known as the ocular pulse (OP)14. For example, Marcus et al. analyzed factors that determine the decrease of IOP in animal model triggering an increase of arterial blood pressure through acute exercise14. Another way of changing the ABP and HR is pharmacological induction. There are several medications influencing cardiovascular activity including, among others, sedative and anesthetic drugs. The specifics of examination of the anterior segment of the eye requires stable measurement conditions. In the case of an animal model, stable conditions are usually associated with sedation or general anesthesia. Hence, pharmacologically induced changes in heart activity with sedatives and/or anesthetics seem to be appropriate to evaluate the relationship between these changes and corneal pulsation and biomechanics. Furthermore, the advantage of this method is the ability to simultaneously perform hemodynamic and ocular measurements under controlled conditions.Arterial blood pressure (ABP) and HR are cardiovascular variables that can be easily modified in an animal model. Several approaches, in which these parameters are modified, have been proposed to understand mechanisms of ocular physiology and pathologyThe purpose of this study, in which control levels of cardiovascular activity is achieved pharmacologically, is to investigate the relationships between blood pressure, heart rate, corneal pulse characteristics, and corneal biomechanics in rabbits.The study protocol for the experimental use of the animals was approved by the Animal Care and Ethics Committee of the Wroclaw University of Environmental and Life Sciences (No. 82/2017) and adhered to the ARRIVE guidelines and the EU Directive 2010/63/EU for animal experiments. Seventeen White New Zealand rabbits, aged 6 months and weighing from 2.9 to 3.8 kg without sex restrictions were used in this study. The rabbits were acclimatized for 2 weeks after shipment. Animals were kept individually in a stainless-steel cages under standard environmental conditions . The rabbits were fed a commercial diet (Labofeed KH Standard) and had ad libitum access to water via 1-L water bottles with stainless steel ball-bearing sipper tubes (bottles were changed daily). Food and water were not withdrawn before treatment.16, whereas ketamine was used as only anesthetic agent that leads to an increase blood pressure and heart rate by activation of sympathetic nervous system17.The animals were randomly assigned one of two different anesthetic regimens: Group I  and 0.5 mg/kg midazolam  intramuscularly as a premedication. To induce general anesthesia propofol  at initial dose of 0.5 mg/kg was injected. After local anesthesia of larynx with diluted 1:1 2% lidocaine  rabbits were intubated with uncuffed endotracheal tube  and general anesthesia was maintained with oxygen-volatilized isoflurane .In Group II, rabbits were given medetomidine  and ketamine  intramuscularly. Animals were intubated with uncuffed endotracheal tube  and received pure oxygen. Rabbits from both groups were breathing spontaneously.2) was monitored using a pulse oximeter with a probe placed on the tongue . Sidestream capnometry was used to measure end tidal carbon dioxide and respiratory rate . Since full animals’ instrumentation to the end of all measurements, all the above parameters were monitored every 5 min and recorded every 20 min. Heating pad was used to maintain normal body temperature.After obtaining surgical plane of anesthesia the left ear of each rabbit was clipped and the skin cleaned with alcohol, a 22 G catheter was placed in the marginal ear vein for anesthetics and fluid injections. Right ear was used to central auricular artery catheterization (20 G catheter). Catheter was connected via saline-filled non-compliant tubing (regularly flushed) to a calibrated pressure transducer (zeroed level with the thoracic inlet) to obtain direct measurement of the heart rate, systolic, diastolic and mean arterial blood pressure , . Arterial oxygen saturation  color Doppler imaging of the external ophthalmic artery, (2) measurement of the corneal biomechanical parameters, (3) measurement of the corneal pulse (CP) signal.Blood flow measurement was performed in both groups using an ultrasound system (ESAOTE MyLab ClassC) equipped with a 4–13 MHz linear ultrasound transducer. After achieving anesthesia plan, a layer of sterile aqueous gel was applied to the corneal surface of left eye, and the transducer was gently positioned with minimal pressure in the horizontal plane. The long axis of the transducer was held horizontally between the lateral and medial canthus with the marker pointing nasally. The external ophthalmic artery was identified near the optic nerve by color Doppler imaging. The peak systolic velocity (PSV) and end diastolic velocity (EDV) were measured and mean values of PSV and EDV from three pulse waveforms were calculated. Arterial resistive index (RI) of the blood flow was calculated using the formula Following the external ophthalmic artery imaging, measurements of the corneal biomechanical parameters of the left eye were acquired in both groups using a non-contact tonometer Corvis ST . Initially, the rabbit’s head, held by an anesthesiologist, was positioned such that the cornea surface was facing the tonometer horizontally. This guaranteed successful records of deformation profiles of the cornea under the effect of air pressure with a high-speed Scheimpflug camera and provided 12 parameters stemming from the imaging analysis. Those parameters included: uncorrected intraocular pressure (IOP), central corneal thickness (CCT), the time from the start until the first and second applanation , the length of the flattened cornea during the first and second applanation (A1L and A2L), the corneal velocity at the two applanation events (A1V and A2V), the time from the start till the highest concavity of cornea (HCT), the maximum deformation amplitude (DA), the distance between the corneal bending points (PD), and the radius of the curvature at the corneal apex (R) at the time of the highest concavity. The measurement was repeated three times for each eye at inter-measurement intervals of at least 2 min.18. An ultrasonic transducer was mounted in a specially constructed holder and placed in front of the central cornea within its working distance (around 12–15 mm), as performed in our recent animal study19. Five 30-s CP signals were measured for each eye with the sampling frequency of 400 Hz. Due to the ocular surface expansion1, the CP signal measured at its central area was chosen as a representative signal of the ocular pulse phenomenon.After the corneal biomechanics measurements, when the animal stayed laid, the pediatric size wire speculum was used in the left eye, in a manner preventing direct pressure on the cornea and the eye globe, to retract the eyelids and nictitating membrane, as well as to enhance the exposure of the conjunctiva, cornea, and eye globe during the measurements of the corneal pulse (CP) signal. Then, the CP signal was registered in both groups using a non-contact ultrasonic technique 19. However, the lower bound was now adjusted to the lower mean of the heart rate frequency in Group II. After visual inspection of the signals performed by a signal-processing expert, three 30-s artefact-free CP signals were chosen from each rabbit for further analysis. In the time domain, the CP signal energy was computed as a root mean squared (RMS) value, whereas in the frequency domain, amplitudes of the first four harmonics of the CP signal  were calculated using the Fourier transform. The first CP harmonic corresponds to the frequency of the rabbit’s heart rate. The amplitudes of the higher harmonics were normalized to that of the first one, resulting in To compute time and spectral parameters of the CP signal, the raw signal data were preprocessed numerically using a custom-made algorithm in MATLAB . This procedure included linear detrending and filtering in the range from 1.3 to 30 Hz. This range was similar to that from our earlier workAll experimental data are included in the t-test was used either with the assumption of unequal variances (in the case of the aforementioned five parameters) or equal variances (for the remaining parameters). To compute the mutual relationship between any two parameters, partial correlation was performed, with Group set as a control variable. Additionally, we have performed partial correlation analysis with Group and IOP set as control variables to compute those relationships, when the confounding factor of IOP was also removed. The significance level Statistical analysis included standard descriptive statistics and normality testing using the Kolmogorov–Smirnov test with the Lilliefors correction. The null hypothesis of normality was not rejected for any of the considered parameters in both groups of rabbits  were tested using the one-way repeated measures analysis of variance (ANOVA) with Bonferroni corrected Calculations were performed using SPSS 22.0 .Time from induction of general anesthesia to the end of all measurements did not exceed 40 min in both groups. Hemodynamic parameters were stable throughout the experiment Fig. . In Grout-test are given in Table Mean values, standard deviations and ranges of all considered parameters together with the results of Levene’s test and unpaired Group II is characterized by statistically significantly higher values of SBP, DBP, and MBP  and the heart rate (HR) was controlled pharmacologically, contributes to those findings and reveals the relationships between parameters of corneal pulsation and biomechanics and those of cardiovascular activity.Alterations in cardiovascular activity is of interest in studying many systemic and ocular diseases16 and animals15, whereas ketamine showed to exert opposite effect increasing blood pressure17. In this study, to induce differences in ABP and HR between two rabbit groups different anesthetic protocols were used with acepromazine and isoflurane in Group I and ketamine and medetomidine in Group II. Mean values of systolic, diastolic and mean arterial pressures were found to be statistically significantly lower in Group I than those in Group II. This was expected according to the previous results29. The purpose of the selected drugs was solely to differentiate the two groups in terms of cardiovascular parameters.Acepromazine and isoflurane have been known to reduce ABP in human23, dogs24, cats13, rats12 and rabbits21. However, different methodologies used in the studies of other authors may resulted in different correlation between ABP and IOP  than in rabbits with higher ABP (Group II). These findings can be explained by the employed anesthetic protocols. The drugs have been selected to emphasize the differences in blood pressure and heart rate parameters between the two groups. However, apart from the desired events, drugs directly affect IOP and exert additional effects like myorelaxation or aqueous humor production and outflow which also affect IOP.14, it can be claimed that after anesthesia, the mean IOP in Group I might not have changed or slightly decreased, whereas in Group II it might have significantly decreased. Volatile anaesthetics, like isoflurane used in Group I, either slightly reduce or have no effect on IOP31. Moreover, additionally used midazolam and acepromazine has been shown to have no significant effect on IOP30. On the other hand, it has been reported that medetomidine, used in Group II, reduces IOP32, as well as combination of alfa-2 agonist and ketamine has the same effect on IOP33.Assuming an average value of natural IOP in rabbits in the range of 15–23 mmHg34. Furthermore, the intravenous administration of medetomidine has been shown to cause miosis in dogs35. Miosis is known to reduce IOP by increasing the outflow of aqueous humour36, hence, pupil size is an another important factor that can affect IOP. Additionally, medetomidine effects are decreasing the central venous pressure and miorelaxation, including relaxation of extraocular and retrobulbar muscles. These effects can also contribute to reduction of IOP. In addition, an influence of ketamine on the IOP values in Group II should be also considered. Some reports suggested that ketamine elevates IOP37, whereas others that there is no effect30. The latter are further supported by animal studies, which have shown that IOP tends to be stable after ketamine administration30. Based on aforementioned findings and assuming a negligible influence of volatile anesthetics (Group I) and ketamine (Group II) on the IOP, it can be concluded that observed lower mean value of IOP in Group II results mainly from the use of medetomidine.Three possible mechanisms behind the reduction in IOP mediated by a2-adrenoceptor agonists have been previously suggested: (1) a reduction in aqueous humor production caused by the activation of pre-junctional a2-adrenoceptors, (2) vasoconstriction in the ciliary body triggered by activation of post-junctional a2-adrenoceptors, and (3) inhibition of adenylyl cyclase by the activation of epithelial a2-adrenoceptors to suppress the production of aqueous humor40. Changes in intraocular volume, caused by pulsatile arterial inflow and steady venous outflow41, are accompanied by changes in parameters and signals of the ocular pulse, ocular pulse amplitude40, pulsatile ocular blood flow42, fundus pulse amplitude43, cornea, sclera and retina movements44. Ocular rigidity, expressing elastic properties of the eye coat (cornea plus sclera), influences all abovementioned characteristics45. In our study, the corneal pulse (CP) signal was measured as a representative signal of the ocular pulse. The applied non-contact ultrasonic technique enabled to register the CP signal as a natural pulsatile corneal expansion without disturbing its natural biomechanical properties. Differences in ABP and HR in both considered rabbit groups did not implicate corresponding differences in the energy of the CP signals , but implicate differences in their spectral content. Specifically, significantly higher mean amplitudes of the second (A2n), third (A3n), and fourth (A4n) frequency harmonics of the CP signals were observed in Group I characterized by higher IOP and HR, and lower SBP, DBP, and MBP, than those in Group II.Mean arterial pressure, ocular circulation, specifically pressure within the choroid, and absolute IOP are the main determinants of the ocular pressure-volume relationship46, and it was also reflected in spectral changes of the CP signals in glaucoma patients after the period of washout from antiglaucoma medications47. Taking the above findings into account, we conclude that in this study rabbits in Group I have higher ocular rigidity than that in Group II. Also, higher ocular stiffness can lead to lower internal damping, which, in turn, reflects in higher CP harmonic vibrations as a corneal response to pulsatile component of IOP. The results of corneal biomechanical properties, additionally measured with Corvis ST, are consistent with aforementioned mechanism. In particular, in Group I statistically significantly higher value of the first applanation length (A1L) and lower value of deformation amplitude (DA) were obtained, where both parameters correspond to higher IOP level in this group in comparison to those achieved in Group II. It has been shown that DA depends strongly on IOP46, whereas A1L is mostly affected by central corneal thickness and age of the subjects rather by a change in IOP. Therefore, A1L can be used to describe corneal stiffness. In this study, partial correlation analysis revealed that the normalized amplitude of the second CP harmonic, A2n, statistically significantly positively correlate with A1L, even when the IOP was removed as a confounding factor. So, our findings clearly demonstrate that the second harmonic of the CP signal could be utilized for estimating measures of corneal stiffness in an indirect manner. Further, according to our previous study with glaucoma patients who underwent canaloplasty combined with phacoemulsification47, changes in the amplitude of the third CP harmonic reflected alterations in corneoscleral stiffness caused by the surgery. Hence, the proposed analysis of the higher harmonics of the CP signal might be useful in the future to indirectly predict biomechanical alterations that appear in compromised corneas, such as those affected by keratoconus49, refractive surgery50, or diabetes51, and separate them from the changes in cardiovascular activity expressed mainly in the first harmonic of the CP signal corresponding to the heart rate.Earlier studies showed that the elevation in IOP increases ocular rigidity, expressed in higher mechanical resistance of ocular walls52 dependent also on the degree of arterial stiffness. In our study, we found lower RI in Group II, when compared to Group I. These results are in agreement with a number of previous experiments which have shown that despite the ketamine raising the arterial blood pressure, RI is reduced55. The RI reduction was observed after combination of ketamine/alpha-2 agonist administration in large arteries in rabbits53. Similar effect of ketamine in smaller ocular vessels was obtained in cats55 and dogs54. This effect was supposed to be caused by direct acting of ketamine on the vascular smooth muscle layer causing its relaxation by decreasing et al.56 measured a marked cerebral vasodilatation in rabbits using ketamine alone. This effect was associated with ketamine-mediated inhibition of tension-dependent 57. Furthermore, in this study, based on partial correlation analysis, RI was found to correlate significantly only with two of the CP parameters—energy computed as a root mean squared (RMS) value and amplitude of the first harmonic (A1) related to the heart rate. With increasing RI the RMS and A1 increase, whereas there were negative correlations between RMS and DBP or MBP, as well as between A1 and DBP or MBP. Hence, RMS and A1 may indirectly reflect ocular volumetric changes and they are shown to depend on retrobulbar ocular hemodynamic parameter (RI). Several animal and human studies have shown that ocular volume changes, in the form of ocular pulse amplitude is directly related to the rigidity of the ocular coat45. Higher ocular pulse amplitude has been found in eyes with increased ocular rigidity, corresponding to a higher rigidity coefficient or a higher IOP level45 and in eyes with increased RI in retrobulbar vessels58. Here, significant association between RI and RMS or A1 parameters is consistent with aforementioned studies, underlying the role the CP signal characteristic may have in estimating variations in ocular volume related to changes in vascular resistance and cardiovascular activity, when the IOP was eliminated as a confounding factor. Hence, the proposed analysis of the CP signal measured using a non-contact technique could offer in the future additional supportive parameters to standard cardiovascular parameters having potential physiological and clinical utility in systemic diseases. However, further research including a larger number of patients with systemic diseases should be performed to form any guidelines for clinical care.Furthermore, difference in ABP and IOP values obtained between both rabbit groups resulted also in different values of the resistive index (RI) in ophthalmic artery as assessed by color Doppler imaging. The RI is considered to reflect vascular resistance peripheral to the measuring location59. Some concerns have been raised on RI as a good measure for peripheral vascular resistance. In the case of central retinal artery, RI was found not to be a valid indicator of vascular resistance52. Notice that RI was found to alter not by vascular resistance alone but by the combination of vascular resistance and vascular compliance60.Limitations of this study are the small number of animals and lack of possibility to compare relative values of ocular and cardiovascular parameters before and after anesthesia within the groups. Thus, there is a need to confirm the obtained results in a larger study population. In that sense, our study has a pilot character. All measurements of IOP should not be treated in their absolute terms, because no calibration curve is available for quantifying IOP measurements in rabbits using Corvis ST. Further, results obtained with RI should be interpreted with caution, because the CDI technique does not reflect volumetric blood flow (no information about vessel diameter is available), but blood flow velocityin-vivo animal experiment, for the first time, results of partial correlations clearly demonstrate that the RMS and A1 of the CP signal correlate with the resistive index, diastolic and mean arterial pressures, whereas no statistically significant correlation was found between any of the CP parameters and intraocular pressure. The main conclusion of this study is that changes in the energy and amplitude of the first harmonic of the CP signal show stronger dependence on the parameters of arterial blood pressure than intraocular pressure. This study indicates that by using the contactless and continuous method for measuring corneal pulse, one could indirectly assess changes in cardiovascular activity regardless of intraocular pressure.The proposed methodology might be helpful in exploring the significance of characteristics of the eye dynamics in the diagnosis of cardiovascular diseases.Since arterial blood pressure is inherently related to intraocular pressure, it may be difficult to disentangle the influence of the two pressures on changes in the CP signal. However, in this Supplementary Information.


Introduction: Sensitisation of the nervous system in a patient with migraine is supposed to be associated with calcitonin gene-related peptide (CGRP) activity. Therefore, the vascular response to human αCGRP (hαCGRP) could be a surrogate marker for the sensitization. We hypothesize that vascular response to hαCGRP is augmented in a patient with migraine.Methods: Twenty healthy subjects and 20 patients with migraine participated in our study. TCD was used to monitor mean arterial velocity in the middle cerebral artery (vm MCA). Simultaneously, end-tidal CO2 (Et-CO2), mean arterial pressure (MAP), and heart rate (HR) were measured. The reconstruction of the signals was made for basal conditions, during and after CGRP infusion which were compared using statistics.Results: In both groups, we found significant decrease between measurement points of vm MCA and Et-CO2 during and after hαCGRP infusion. MAP did not show significant trends during the infusion, but it was significantly increased after the infusion in migraine patients only. Responses to hαCGRP, defined as differences between two measurement points, were significantly higher for vm MCA and Et-CO2 in patients with migraine. A significant difference between groups was found in MAP response. Significant relationships were found between migraine and vm MCA, Et-CO2, and MAP.Conclusion: In patients with migraine, vm MCA responses to hαCGRP are significantly higher and are associated with CGRP-induced headache which indicates that patients with migraine are more prone to sensitization. Migraine is recognized as an episodic or chronic state of nervous system sensitization involving a CGRP-dependent process . It is wUntil now, only a few studies have investigated exogenous hαCGRP response of cerebral circulation. In two previous studies, they monitored the vascular responses in healthy subjects using TCD  and magnSeveral studies on cerebrovascular reactivity in migraine observed consistently increased responses to visual stimuli, but inconsistent responses to systemic stimuli such as hypo- or hypercapnia . This sup = 0.105) and in age (p = 0.066) between the groups. The inclusion criteria for the group of healthy participants were age 18 years or more, without migraine history, normal somatic and neurological status, and normal carotid and vertebral arteries ultrasound examination. The exclusion criteria for the group of healthy subjects were pregnancy and breastfeeding. The inclusion criteria for the group of migraineurs were age 18 years or more, history of migraine with or without aura in accordance to the ICHD-3 criteria of the International Headache Society, normal somatic and neurological status and without any hemodynamically significant atherosclerotic processes of the carotid and vertebral arteries. The exclusion criteria for this group were current or previous cerebrovascular, renal or liver diseases, uncontrolled hypertension, pregnancy and breast-feeding. The subjects with migraine were free of migraine headache at least 24 h before the experiment.In our study we included 20 healthy subjects , which represented the control group, and 20 patients with migraine , which represented the study group. We did not find statistically significant differences in sex  was given and a 10 min period after the end of the application of hαCGRP. The hαCGRP dose was chosen based on the finding of previous studies so as not to induce pronounced hypotension .2 was measured by a ventilation mask and an infrared capnograph  using the standard protocol. The capnograph was connected to a computer. Et-CO2 signals were recorded on the same time scale as other variables.Transcranial Doppler (TCD) sonography with 2 MHz ultrasound probes was applied to measure mean flow velocity (vm) in left MCA through the left transtemporal acoustic window. The signals of the MCA were defined according to the direction of the blood flow and typical depth of the signal. A mechanical probe holder was used to ensure a constant probe position. During the entire experiment mean blood pressure (MAP) and heart rate (HR) were continuously measured using non-invasive plethysmography . The Et-CO2 during 5 min intervals: one interval during the baseline period (5–10 min of the experiment-measurement point 1), two intervals during the hαCGRP infusion (15–20 min-point 2 and 25–30 min-point 3 of the experiment), and one interval after the end of hαCGRP infusion (35–40 min of the experiment-point 4). The mean vm MCA was calculated for each 5-min interval using the following equation: vm = ∫ vdt/ (t0 – t5).The mean values of other variables  were also calculated for the same time intervals as vm MCA using TCD software.TCD Multi-Dop X4 software  was used to define mean values of vm MCA, MAP, HR, and Et-CO2, MAP, and HR, respectively. The response 1 represented the difference between points 1 and 2, the response 2 between points 1 and 3 and the response 3 between the measurement points 1 and 4.We determined responses to hαCGRP as the differences between measuring points for vm MCA, Et-COThe incidence of CGRP-induced headaches was recorded within 1 h of the experiment (immediate CGRP-induced headache) and within the next 12 h after the experiment (delayed CGRP-induced headache).t-test was used to test the significance of differences between two measurement points in the same group and ANOVA for responses between the groups. Linear and logistic regressions were used to test the correlations between the variables. Chi-square was used to test the difference among the frequencies. A p-value < 0.05 was considered to represent a statistically significant difference or relationship. We used a multivariate model, which includes migraine as the covariate to test the relationship between the responses of all previously mentioned parameters.The number of the subjects enrolled in the study was driven from previous studies –5. For sp = 0.010) while delayed headaches appeared in 13 migraine patients (65%) and one healthy person (5%) (p < 0.01). Migraine was significantly related to immediate CGRP-induced headaches  and delayed CGRP-induced headaches  as well.First, we analyzed the occurrence of the immediate and delayed CGRP-induced headache in healthy and migraine patients. An immediate headache was found in seven migraine patients (35%) and in three healthy participants (15%) with a statistically significant difference between the groups  but not in MCA response 1 (p = 0.085) and MCA response 3 (p = 0.103), although the probabilities were borderline. The response of Et-CO2 was significant for response 1 (p = 0.012) and response 2 (p = 0.007) but borderline for response 3 (p = 0.057). MAP showed significant differences in response 1 (p = 0.034) and response 3 (p = 0.018) and borderline in response 2 (p = 0.086). HR between the groups was not significantly different for any response; response 1 (p = 0.375), response 2 (p = 0.520), and response 3 (p = 0.741).In the next step, we tested the responses between the measuring points 1–2 (response 1), 1–3 (response 2), and 1–4 (response 3) between the control group and patients with migraine. The results are presented in 2 response could directly affect vasodilatation and the increase of CBF, we tested the relationship between Et-CO2 and vm MCA responses. Linear regression showed significant associations between the variables .The relationship between vm MCA, Et-CO2, MAP, HR, and migraine was tested using logistic regression. We found significant associations between migraine and vm MCA , Et-CO2 , MAP  but not for HR .Since the Et-COp = 0.002) but not between delayed headache and vm MCA response . Interestingly, we found a statistically significant relationship between Et-CO2 response and delayed CGRP-induced headache  but not immediate CGRP-induced headache .Finally, we tested the relationships between CGRP-induced headache and physiologic variables using logistic regression. The CGRP-induced headache represented the dependent and vm MCA presented the independent variable. We predicted that CGRP-induced headache refereed to vasodilatatory response and vm MCA changes. Logistic regression showed the association between immediate CGRP-induced headache and vm MCA response  . It is a2 could be a putative factor counteracting the CGRP vasodilatory effect. This is a well-known phenomenon named vasomotor reactivity to hyper/hypocapnia, and it is one of several mechanisms to ensure a constant level of CBF (2 in migraine could be attributed to the hypersensitivity neurological state that is associated with migraine. In our study we found that Et-CO2 responses were associated with delayed CGRP headaches but not to immediate ones. On the contrary, vm MCA was associated with immediate CGRP headaches. It seems that CGRP itself, with immediate vasodilatation, is responsible for immediate CGRP-induced headaches, while delayed headaches are associated with the compensatory processes in cerebral circulation. It is known that in migraine patients elevated CGRP levels are normalized after sumatriptan administration (Since CBF under the constant conditions is an imperative of cerebral hemodynamics, the Et-COl of CBF , which cstration , which cIn addition, we monitored systemic variables in both groups and found significant differences in some MAP responses but not in HR responses between the groups, as well as differences in baseline hemodynamic parameters. We believe the latter not to be important to our study since we focused on the changes of hemodynamic parameters during CGRP stimulation and not on their absolute baseline values. In two previous studies, a decrease of MAP was found in migraine patients  but not The distinction in systemic effects might be linked to the endothelial dysfunction in migraine which is still a debatable issue, but could explain the association between migraine and the risk of vascular disease .Nevertheless, in the present study we found a significant positive chronotropic effect of CGRP, which has already been recognized in previous studies .The main limitation of our study was the lack of data on blood CGRP concentrations in the study subjects during the experiment. In addition, we did not test placebo effects on CGRP headaches. In our study we did not explore the difference in hemodynamic responses between migraine with and without aura. However, previous studies demonstrated that patients with migraine with aura might have excessive response to several stimuli , 21. Furvia activation of TVR. Decrease of Et-CO2 might reflect a compensatory decrease in arterial partial pressure of CO2, which underlies the normalization of CBF during CGRP activity. It seems that immediate CGRP-induced headaches are caused by the direct CGRP effects on neurovascular structures, while delayed CGRP-induced headaches are an indirect CGRP phenomenon due to compensatory processes. CGRP had chronotropic effects in both the migraine patients and the control group, while systemic hemodynamic was not importantly affected in either group.In conclusion, hαCGRP could induce vasodilatation of MCA probably The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by National Medical Ethics Committee of Republic of Slovenia. The patients/participants provided their written informed consent to participate in this study.All authors made a substantial intellectual contribution to the study. DV, BŽ, and MZ made conception and design. MZ made analysis and interpretation of the data. All authors approved the final version of the article.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


This study investigated whether ECCO2R therapy could affect RV function.Right ventricular (RV) failure is a common complication in moderate-to-severe acute respiratory distress syndrome (ARDS). RV failure is exacerbated by hypercapnic acidosis and overdistension induced by mechanical ventilation. Veno-venous extracorporeal CO2/FiO2 ratio between 80 and 150 mmHg were enrolled. An ultraprotective ventilation strategy was used with VT at 4 mL/kg of predicted body weight during the 24 h following the start of a low-flow ECCO2R device. RV function was assessed by transthoracic echocardiography (TTE) during the study protocol.This was a quasi-experimental prospective observational pilot study performed in a French medical ICU. Patients with moderate-to-severe ARDS with PaO2R facilitated an ultraprotective strategy in all 18 patients included. We observed a significant improvement in RV systolic function parameters. Tricuspid annular plane systolic excursion (TAPSE) increased significantly under ultraprotective ventilation compared to baseline . Systolic excursion velocity (S’ wave) also increased after the 1-day protocol . A significant improvement in the aortic velocity time integral (VTIAo) under ultraprotective ventilation settings was observed (p = 0.05). There were no significant differences in the values of systolic pulmonary arterial pressure (sPAP) and RV preload.The efficacy of ECCO2R facilitates an ultraprotective ventilation strategy thatwould improve RV function in moderate-to-severe ARDS patients. Improvement in RV contractility appears to be mainly due to a decrease in intrathoracic pressure allowed by ultraprotective ventilation, rather than a reduction of PaCO2.Low-flow ECCO Although the current guidelines recommend a protective ventilation strategy  and adjuVT) on the right ventricle is well demonstrated. A study showed that the incidence of RV failure was related to plateau pressure (PPlat) [VT and Pplat could decrease driving pressure, which was recently identified as a risk factor for mortality in ARDS [PPlat, titrate PEEP, and ultimately limit hypercapnia. This theoretical approach to preserving RV function in ARDS patients is sometimes difficult to implement in clinical practice. Additional measures as prone positioning could improve RV function [2 removal (ECCO2R) is actually used to facilitate ultraprotective ventilation while avoiding risks of hypercapnia, acidosis and injurious ventilator settings [2R in French intensive care units are ultraprotective ventilation for ARDS patients, shortening the duration of invasive mechanical ventilation in chronic obstructive pulmonary disease (COPD) patients, preventing intubation in COPD patients, and controlling hypercapnia and dynamic hyperinflation in mechanically ventilated patients with severe acute asthma [Many studies have shown that respiratory settings in ARDS patients are associated with RV function by several pathophysiological mechanisms. First, the deleterious effect of positive pressure correlated with tidal volume ( (PPlat) . Second, (PPlat) , 15. Thi in ARDS . However in ARDS . Therefofunction . While nsettings –23. Curre asthma , 25.2R in RV function. Therefore, the aim of the current quasi-experimental pilot study was to assess the impact of an ultraprotective ventilation strategy facilitated by low-flow veno-venous ECCO2R on RV function in patients with moderate-to-severe ARDS.Despite an interesting physiological approach, no study has investigated the potentially beneficial role of ECCOThis quasi-experimental observational prospective pilot study was conducted between January 2017 and March 2019 in a French intensive care unit (ICU) of an academic hospital. The protocol was approved by appropriate legal and ethics authorities . Informed consent was obtained from patients or legally authorized surrogates.2/FiO2 between 80–150 mmHg with fraction of inspired oxygen (FiO2) ≥ 60%; under protective invasive mechanical ventilation and sedation; and ARDS of pulmonary origin to have a homogeneous patient cohort. Exclusion criteria were age < 18 years, pregnancy, contraindication for systemic anticoagulation, platelet count < 50 Giga/L, moribund patients or those with treatment-limitation decisions, pre-existing severe treated pulmonary arterial hypertension, significant mitral valvulopathy, ARDS from extra-pulmonary cause and poor echogenicity, making the echocardiography assessment impossible.The inclusion criteria were as follows: severe-to-moderate ARDS with PaO2R was provided by a low-flow CO2-removal device  integrated into the renal replacement therapy (RRT) platform . Of note, this device is currently unavailable, pending the new Prismalung Plus device (Gambro-Baxter). The polymethylpentene, hollow fiber, and gas-exchanger membrane (surface area 0.32 m2) was connected to the extracorporeal circuit. When RRT was required, both techniques were performed simultaneously. A 13 or 14-Fr double-lumen hemodialysis catheter  was aseptically and percutaneously inserted under ultrasonography guidance into the internal jugular or femoral vein. Systemic anticoagulation was started after catheter insertion. We performed a priming with unfractionated heparin, and maintained systemic continued heparinization with the goal of anti-Xa between 0.3 and 0.7 UI/mL.ECCOVT at 6 mL/kg of predicted body weight (PBW) and PEEP set to achieve a Pplat of 28–30 cm H2O. Transthoracic echocardiography (TTE) and blood gas were performed at inclusion. Then, after priming anticoagulation, the ECCO2R device was connected to the patient, and extracorporeal blood flow was progressively increased to 400 mL/min with sweep-gas flow through maintenance with 100% oxygen at 10 L/min during the entire protocol. After 1 h with ECCO2R, TTE and blood gas were performed simultaneously. Then, VT was reduced from 6 to 4 mL/kg PBW under the ECCO2R device. After 1 h with these settings, TTE and blood gas were performed again. Then, the ECCO2R device was maintained for 24 h with ultraprotective ventilation parameters (4 mL/kg PBW). During the protocol, severe hypercapnia, acidosis and/or hypoxemia could be managed at the attending clinician’s discretion with changes in respiratory rate (RR) and VT and with prone positioning and/or switching to ECMO if necessary. After 24 h under VT 4 mL/kg PBW and ECCO2R, we also performed TTE and blood gas. After measurement, VT was returned back to 6 mL/kg PBW with other settings adjusted according to the recommendations of protective ventilation. One hour later, under these standard conditions for the ventilatory management of patients with ARDS, TTE and blood gas were also performed. This last step allows the patient to be his or her own control in a quasi-experimental design. If, under these conditions, the patient remained stable, the ECCO2R device could be maintained after the protocol. The manufacturer determined the Prismalung® membrane’s maximum duration to be 72 h.The study protocol is described in Fig. VT, minute ventilation (VM), RR, PEEP, PPlat, FiO2, and driving pressure calculated as PPlat minus PEEP [2), partial alveolar carbon dioxide pressure (PaCO2), bicarbonate (HCO3−), pH, lactate) were also collected. All TTE exams were made by two experienced physicians with specialized diploma in echocardiography to reduce the inter- and intra-observer variability. The TTE parameters evaluated were left ventricular ejection fraction (LVEF) at baseline, aortic velocity time integral (VTIAo), early diastolic mitral inflow velocity (E), atrial contraction mitral inflow velocity (A), E/A ratio, early diastolic mitral annular velocity (E’), RV systolic excursion velocity (S’), tricuspid annular plane systolic excursion (TAPSE), systolic pulmonary arterial pressure (sPAP), right/left ventricular end-diastolic diameter (RV/LV) ratio, and right atrial (RA) pressure estimation [2R parameters  were collected at baseline and then at the different times described previously. During the 24-h protocol, the need for prone positioning, nitric oxide, ECMO, and association with continuous RRT were recorded. Blood chemistry data and urine volume were collected daily. Physiologic data collected during and after the end of the protocol included the need for renal replacement therapy, ICU mortality, length of ICU stay, length of mechanical ventilation and duration under the ECCO2R system.Demographic data collected included age, gender, primary admission diagnosis, cause of ARDS, comorbidities and documented microorganisms during ARDS. Ventilator settings .E velocity, E/A ratio, E’ velocity, E/E’ ratio) were evaluated. The number of subjects required for the study was not calculated because of a pilot study design. Qualitative variables were expressed as numbers and percentages. Quantitative variables were expressed as the median and interquartile range . Changes in values are expressed as the percentage with the median and IQR. Comparisons between data over time during the protocol were performed using analysis of variance (ANOVA) for repeated measures. Missing data were integrated in the calculation. The comparison of one variable in 2 groups, taking into account (or correcting for) the variability of other variables , was performed using analysis of covariance (ANCOVA). Values obtained at different times were compared with those obtained at baseline by using paired Student’s t-tests. The significance level was fixed at p < 0.05. Statistical analyses were performed using MedCalc Software (version 15.11.4).The primary end point of the study was RV systolic function, assessed first by contractility parameters with TAPSE and S’ wave. Second, RV afterload (sPAP estimation), RV preload parameters , VTIAo (to assess cardiac output), and LV function . Neuromuscular blockade and prone positioning were applied before inclusion in 17 and 8 patients, respectively. In the 24 h following ECCO2R initiation, 6 patients received prone positioning. Four patients were under RRT at inclusion without additional patients thereafter. Two patients required vvECMO for worsening hypoxemia after the 24-h protocol. The operational characteristics of ECCO2R are summarized in Additional file Eighteen patients with moderate-to-severe ARDS were included in the study. The baseline characteristics of the patients at inclusion are shown in Table VT was significant in all 18 patients at a mean of 4.04 (4–4.19) mL/kg PBW one hour after CO2 removal began (p < 0.001). Initiation of ECCO2R resulted in a reduction in PaCO2 from 43.1 to 37.7 mmHg, a change of 13% from baseline . Twenty-four hours after the ultraprotective ventilation strategy with ECCO2R, PaCO2 and pH were maintained at 52.5 mmHg (44.2–64) and 7.31 (7.27–7.33), respectively. The reduction in VT was associated with a significant reduction in PPlat from 25.5 (24–28) at baseline to 21.5 (20–25.8) cm H2O (D0 ECCO2R 4 ml/kg). The evolution of PPlat remained significant throughout the study protocol (p = 0.04). VT and PPlat reduction with ECCO2R were not associated with a significant change in the PaO2/FiO2 ratio. All the renal and hemodynamic parameters did not differ significantly during ECCO2R therapy , as illustrated in Fig. 2R at day 0 (25.4 mm) compared to baseline (22.9 mm) (p = 0.02)  and a non-significant  inverse correlation for VT and PaCO2, respectively. When we separated all 18 patients in two groups with normocapnia  and hypercapnia  at baseline, we observed a poorer TAPSE value in the hypercapnic patients than in the normocapnic patients but a significant improvement in TAPSE in both groups associated with low VT at 4 mL/kg PBW  . There was no significant difference in the other echocardiographic parameters reflecting RV function and RV preload. Regarding left ventricular systolic and diastolic function, parameters did not differ significantly throughout the study, whereas interestingly, we observed a significant increase in VTIAo values from 18.3 cm at baseline to 22.1 cm at day 1 ECCO2R 4 ml/kg (p = 0.05). Of note, RV variables of interest (TAPSE and S’ wave velocity) returned at day 1 to a value close to the baseline value of day 0, after recovering standard conditions of ventilation with 6 mL/Kg VT.Echocardiographic characteristics are described in Table day 0 25. mm compa2R-related adverse events, we observed 5 (28%) membrane lung clotting events  could explain the observed variation of TAPSE, S’ wave velocity and VTIAo in our study.The results of this quasi-experimental pilot study showed that a low-flow ECCOfterload . On the fterload ), withouConcerning the other RV parameters, we failed to highlight a significant modification of RV preload including RV/LV ratio, and afterload (sPAP) measures during the protocol period. RV function depends on preload, contractility and afterload, in particular through ventricular interdependence. No changes in RV preload  reflect constant and adequate volaemia. Consequently, our results support that RV preload did not affect directly change in TAPSE and VTIAo under ultraprotective ventilation, despite the lack of power of the study. Furthermore, no changes in RV afterload parameters suggest an improvement in RV contractility that arises with an ultraprotective ventilation strategy. However, our results for sPAP values should be treated with caution. Indeed, there is no specific agreement regarding the definition of pulmonary hypertension in ARDS. Using echocardiography, it is currently considered that a sPAP higher than 40 mmHg defines the presence of moderate pulmonary hypertension in ARDS . The lit2/FiO2 ratio remained consistent, and we did not have to increase the PEEP level. Some studies have suggested that lowering VT may be associated with derecruitment [Allardet-Servent et al. using the same RRT platform with an ECCO2R membrane [2O were probably sufficient to prevent alveolar collapse.In our study, we demonstrated the efficacy of a low-flow device to implement an ultraprotective ventilation strategy in ARDS patients, as previously described . During ruitment . Similarmembrane , this wa2 reduction during the primary phase was lower than that observed in other studies [2 during the VT reduction phase at 4 mL/kg PBW. This statement is related to the low-flow device that we used compared with the high-flow devices which provide with higher CO2 extraction. However, in accordance with the recent literature, the VT reduction phase at 4 ml/kg PBW was achievable in all cases [2R, we were unable to decrease respiratory rate with the risk of worsen PaCO2 level and acidosis. Interestingly, we observed a deleterious effect of hypercapnia on RV function when we separated patients into normocapnic and hypercapnic patients with PaCO2 > 50 mmHg at baseline. However, early ultraprotective ventilation allowed by the ECCO2R device remains efficient on TAPSE in both groups.The magnitude of the 13% PaCO studies , 35, whill cases , and hyp2R associated with ultraprotective ventilation on RV function despite a strong pathophysiological rationale. In ARDS, single-center or multicentre studies have examined the feasibility of ultraprotective ventilation facilitated by ECCO2R [2R in a severe ARDS patient with an acute cor pulmonale [2R in a porcine model with experimental ARDS. The authors found a significant reduction in pulmonary arterial pressure [2R to allow ultraprotective ventilation in the improvement of RV function and to what extent its potential benefits lead to improved prognosis in ARDS patients. Focusing on the same purpose, further larger studies will be necessary to specifically assess the safety and the benefit–cost ratio of the ECCO2R in the ARDS population.The strengths of this study were its originality and design. To the best of our knowledge, no research has focused on the potential role of low-flow ECCOy ECCO2R , 37, 38.ulmonale . Regardipressure . HoweverS’ velocity were 22.9 mm and 13.8 cm/s, respectively, which were much higher than the threshold values under which RV systolic dysfunction is usually defined  [2R in ARDS patients with RV dysfunction are now warranted. Moreover, our evaluation of RV function was not exhaustive. Other parameters, such as the right ventricular–vascular coupling (TAPSE/sPAP), or RV area, and RV wall thickness and RV outflow tract acceleration time, could also be measured. Similarly, for ventilator parameters, mean airway pressure was not monitored throughout the study protocol. Indeed, in accordance with the literature about ventilator factors influencing RV dysfunction, we focused our data collection on PPlat, driving pressure, VT and PEEP. Fourth, concerning our population study, we made the choice to exclude extra-pulmonary ARDS in order to have a small homogeneous group of ARDS patients. Our choice could be discussed because of in contrast to previous study [Several limitations should be addressed in our study. First, because of the monocentric design and our small sample size 18 patients) which results in a lack of power, inferences from this quasi-experimental pilot study may be limited. Second, RV assessment with TTE could cause problems with reproducibility. The interrater reliability was not evaluated in our study, but previous studies found excellent results for right function valuation in echocardiography with low interobserver variability, particularly for the TAPSE . Transoectively) . In addius study , recent us study , 45. Fin patients2R device could improve RV systolic function in moderate-to-severe ARDS patients. Similarly to prone positioning, ECCO2R could become a strategy that enables the reconciliation of a lung protective approach with an RV-protective approach in ARDS patients. Large-scale clinical studies, including patients with severe RV dysfunction, are warranted to confirm these preliminary results and to assess the overall benefits of ECCO2R ARDS patients.This quasi-experimental study demonstrated that ultraprotective ventilation strategy facilitated by a low-flow ECCOAdditional file 1: Table S1. Operational characteristics of extracorporeal CO2 removal during the study period for the 18 patients. Table S2. Adverse events and outcomes of the 18 patients receiving ECCO2R. Figure S1. Individual changes in TAPSE between baseline and 1-hour after reduction of VT at 4 mL/kg PBW with ECCO2R. Tricuspid annular plane systolic excursion (TAPSE) increased from 22.9 mm (19.2–24.3) to 25.4 mm (21.4–27.9) (p=0.02). Figure S2. Time course of TAPSE in two groups of patients with PaCO2 < 50 mmHg (n=11) and PaCO2 > 50 mmHg (n = 7) at baseline .


Increasing EGF concentration was a statistically significant predictor of the presence of microangiopathy in multivariate logistic regression analysis (p < 0.0001). Additionally, a higher GDF-15 level was associated with diabetic kidney disease, peripheral neuropathy, and proliferative retinopathy vs. nonproliferative retinopathy. GDF-15 concentration correlated negatively with estimated glomerular filtration rate (eGFR) . To conclude, higher EGF concentration is an independent predictor of the presence of microvascular complications in T1DM patients. Besides the relation between GDF-15 and diabetic kidney disease, it may be also associated with peripheral neuropathy and retinopathy.Type 1 diabetes mellitus (T1DM) is associated with chronic complications, which are the result of neurovascular changes. There is still a lack of universal biochemical markers of microvascular damage. The present study aimed to investigate whether selected inflammatory proteins are related to the prevalence of microvascular complications in adult T1DM patients. The following markers were determined in a group of 100 T1DM participants: epidermal growth factor (EGF), metalloproteinase 2 (MMP-2), growth/differentiation factor 15 (GDF-15), and interleukin 29 (IL-29). Screening for microvascular complications, such as autonomic and peripheral neuropathy, diabetic kidney disease, and retinopathy, was conducted. The group was divided according to the occurrence of microvascular complications. At least one complication was required for the patient to be included in the microangiopathy group. The median EGF concentration in the microangiopathy group was higher than in the group without microangiopathy ( Type 1 diabetes is an autoimmune disease frequently associated with microangiopathic complications .Every participant underwent a basic physical examination that included blood pressure assessment and anthropometric measurements. Hypertension was assessed as present if the patient reported so or used antihypertensive medications or was newly diagnosed (by aneroid sphygmomanometer after at least 10 min rest in a sitting position). Arterial hypertension was defined as a mean value of systolic blood pressure (SBP) ≥ 140 mmHg and/or diastolic blood pressure (DBP) ≥ 90 mmHg. Body mass index (BMI) was calculated using the following formula: BMI = weight/heightData on sociodemographic characteristics and medical history were collected via questionnaire.http://www.statsoft.com). First, a Shapiro–Wilk test was applied to assess whether qualitative variables were normally distributed. The distributions of all the qualitative variables were not normal, thus nonparametric statistical tests were applied. Qualitative variables are expressed as median and interquartile range (IQR), and categorical variables as number (%) of subjects. EGF concentration is also presented as Log10EGF (decadic logarithm) because of the normality required in multivariate linear regression analysis. In descriptive characteristics, comparisons of parameters on dichotomous scales were prepared using a chi-square test, and for the remaining variables, which were continuous, a Mann–Whitney U test was applied. The Spearman’s rank correlation coefficients were calculated to estimate the correlations between selected parameters. A multivariate logistic regression model was built to examine the relationships between EGF and the prevalence of neurovascular complications. Additionally, EGF was also evaluated in terms of receiver operating characteristic (ROC) curve with the Youden index to determine the cut-off. The p-value threshold was set at <0.05 for statistical significance.The acquired data were analyzed using Statistica V13 software  years, and median T1DM duration was 12.5 (IQR: 9–16) years. Full baseline characteristics are presented in p < 0.001) and higher abnormal creatinine/albumin ratio prevalence . We found no differences in Il-29, GDF-15, and MMP-2 concentrations between these two subgroups.Participants in the subgroup with microangiopathy as compared with the subgroup free of these complications had longer disease duration (16 (14–18.5) vs. 11 (7–13.5) years; p = 0.032).Participants in the subgroup with microangiopathy as compared with subgroup free of these complications had higher EGF concentration (57.5 (IQR: 28.5–100.5) vs. 28.5 (IQR: 15–76) pg/mL; p = 0.035) and GDF-15 concentration  were found.Correlations between selected proteins and other parameters are presented in p = 0.04) after an adjustment for T1DM duration, HbA1c, BMI, LDL, and SBP (p < 0.0001).In multivariate logistic regression analysis , increasp = 0.019). A similar value for the crossing proportion point  was estimated.The ROC analysis for EGF at microangiopathy diagnosis revealed an EGF cut-off of 40 pg/mL  0.78 and negative likelihood ratio (LR−) 0.27) as the best value that significantly indicated the presence of neurovascular complications (area under the ROC curve (AUC): 0.636; 95% confidence interval (CI): 0.522–0.749; p = 0.002). As expected, the concentration of GDF-15 was also higher within the group of patients with diabetic kidney disease vs. patients free from this complication (59 (42–66) vs. 25.5 (15.6–41.5) pg/mL; p = 0.004). Similar to the above, patients with peripheral neuropathy had higher concentrations of GDF-15 vs. patients without it (62 (42–73) vs. 28.5 (15.6–43) pg/mL; p = 0.045). Moreover, patients with proliferative retinopathy had higher GDF-15 concentrations vs. patients with nonproliferative retinopathy (55 (30–66) vs. 15.6 (15.6–23) pg/mL; p = 0.023). Unfortunately, we found no statistically significant difference in GDF-15 concentration between patients with and without retinopathy, as well as with and without microangiopathy altogether.Patients with abnormal creatinine/albumin ratios had higher GDF-15 concentrations vs. patients with normal ratios (57 (43.5–64) vs. 23 (15.6–41) pg/mL; p = 0.027) and MMP-2 , and negatively with eGFR .GDF-15 concentration correlated positively with concentrations of hsCRP  after an adjustment for T1DM duration, HbA1c, BMI, and smoking (p = 0.0002).In multivariate logistic regression analysis , increasThe present study was conducted with the aim of searching for new determinants of neurovascular complications among selected novel inflammatory markers: EGF, MMP-2, GDF-15, and IL-29. The most valuable result of the current study is the revealed relationship between EGF and microangiopathy. In multivariate logistic regression analysis, this factor turned out to be a significant and independent predictor of neurovascular complications in T1DM patients. ROC analysis showed that EGF measurement can be especially used as a tool to exclude microangiopathic complications (LR− = 0.27). The value of EGF to affirm diagnosis of microangiopathy is low (LR+ = 0.78). Hence, it probably cannot be used to detect affected individuals, but it can be useful do detect individuals without microangiopathy.2 and urinary albuminuria > 300 mg/24 h, revealed a lower concentration of urine EGF per gram of urine creatinine [Although it was previously revealed that blood concentration of EGF is higher among T1DM patients vs. healthy controls, further analyses were not conducted . Urinaryeatinine . A studyeatinine . Lower ueatinine . Only oneatinine . Howevereatinine . It is peatinine . Althougeatinine . It is veatinine . SummariIn our study, GDF-15 turned out to be a statistically significant marker of diabetic kidney disease occurrence. It also correlated with eGFR. The most important study to compare with this result is a large and meticulously prepared prospective project named EURAGEDIC, conducted on T1DM patients . In thisIn our study, we did not obtain any relation between MMP-2 and diabetic microangiopathy. This lack of relation between MMP-2 and microvascular changes is consistent with the available literature. MMP-2 was previously an object of several studies in T1DM patients. The most important study in this matter was conducted by Peeters et al. in a cohort of 493 T1DM subjects . In thisAnother protein investigated in the current study was Il-29. Unfortunately, it turned out not to be associated with the clinical parameters and prevalence of neurovascular complications. Probably, it is associated with an acute autoimmune process that is not present in patients with a disease duration of longer than 5 years, as was the case in our cohort. Moreover, inflammation within the small vessels in the course of diabetes is very subtle and does not affect the whole organism as it does during acute viral infections. Thus, although other interleukins such as IL-6 were found to be related to diabetes, Il-29 seems not to take part in microvessel damage in the course of diabetes.We must also address the mutual correlations between the pairs EGF/GDF-15 and GDF-15/MMP-2. As they are inflammation-related proteins, even local and chronic inflammation can result in low correlation. GDF-15 and EGF are probably associated with microangiopathy. MMP-2 is also described as related to diabetic kidney disease, which was not reflected in the current study. However, it was correlated with GDF-15 concentrations, which are related to diabetic kidney disease, so it can be a reflection of such evidence.Finally, several limitations of our study must be emphasized, including the fact that it was a single-center trial and the limited size of the studied group. Another limitation is measurement of GDF-15, MMP-2, and IL-29 not on all subjects. The whole group of 100 patients had EGF assessed. Moreover, this study does not establish any causal link between the dysregulation of the investigated proteins and the development of diabetic complications, as the conclusions on the relation were made only on the basis of single-point measurements. We also cannot indicate tissue sources of examined proteins. Our observation may become a useful background to plan a prospective study evaluating the relationship between proteins such as EGF and GDF-15 and the prevalence of microvascular disease within a population of patients with T1DM.To conclude, impacts of EGF and GDF-15 on the prevalence of neurovascular complications in the course of T1DM are very possible. The results strongly indicate that in T1DM, serum EGF concentration might serve as a useful marker to detect microangiopathy, while GDF-15 may probably be engaged to some extent in microvascular damage as a marker of diabetic kidney disease, peripheral neuropathy, and retinopathy. However, further and prospective studies on larger groups of patients should be conducted in the future to assess the full clinical utility of these markers.


The difference between CNBP and arm SBP was significantly smaller : −6.03 ) compared to that between ankle and arm SBP (least squares mean (95% CI): −15.32 , p = 0.019). However, this significant difference was not observed in DBP and MBP . Ankle SBP measurements showed larger differences from arm SBP measurements than did CNBP SBP measurements in patients undergoing breast cancer surgery. CNBP could serve as a useful alternative to ankle BP when standard arm BP measurements cannot be obtained.Measuring blood pressure (BP) via a pneumatic cuff placed around the arm has long been the standard method. However, in clinical situations where BP monitoring at the arm is difficult, the ankle is frequently used instead. We compared continuous non-invasive blood pressure (CNBP) measurements obtained at the finger, ankle BP and arm BP in patients undergoing breast cancer surgery. Arm BP, ankle BP  and CNBP measurements were obtained every 2.5 min during surgery. Correlation and Bland–Altman analyses were performed and differences among measurements were analyzed using a linear mixed model. A total of 245 sets of BP measurements were obtained from 10 patients. All systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean blood pressure (MBP) measurements of ankle BP and CNBP were positively correlated with the arm BP measurements (Spearman rho 0.688–0.836,  Blood pressure (BP) is an essential hemodynamic parameter . The golHowever, leg BP readings can be higher than those of standard arm BP ,6. This TM system  allows for continuous non-invasive blood pressure (CNBP) measurements to be obtained at the finger. The system uses the volume-clamp method where the changes in cuff pressures to maintain constant arterial transmural pressure are converted to brachial arterial pressure [The ClearSightpressure . These ppressure . The Clepressure ,12,13,14pressure ,16.The finger arteries are closer to the brachial arteries than the arteries of lower extremities and the ClearSight system has an intrinsic algorithm to reconstruct brachial pressure . AdditioThe study complied with the Declaration of Helsinki and the study protocol was approved by the Institutional Review Board of Seoul National University Hospital (No. 1906-113-1041). After obtaining informed consent, we enrolled patients with an American Society of Anesthesiologists physical status of 1–2 who were undergoing elective breast surgery under general anesthesia. The exclusion criteria were as follows: no palpable radial artery pulse, arteriovenous shunt, cardiac arrhythmia , peripheral vascular disease, trauma or skin disease in the arm or leg designated for BP measurement and requiring invasive arterial pressure monitoring.The patients were anesthetized according to our institutional protocol. Standard monitoring included electrocardiogram, pulse oximetry, temperature probe, bispectral index monitoring, end-tidal carbon dioxide monitoring and a non-invasive BP cuff was applied. Anesthesia was induced with 1.5–2 mg/kg propofol, 1–2 µg/kg fentanyl and 0.6–0.8 mg/kg rocuronium. The supraglottic airway was intubated and the lungs were ventilated with volume-controlled ventilation at a tidal volume of 6–8 mL/kg and respiration rate of 10–20/min, to titrate the end-tidal carbon dioxide pressure to 35–45 mmHg with a fraction of inspired oxygen of 0.5. Anesthetic agents were adjusted with 2.0–2.5 vol/% sevoflurane to maintain the bispectral index between 40 and 60. During surgery, the patients were positioned in a supine position with the surgical-side arm in an arm-positioning device.®; Welch Allyn Inc., Skaneateles Falls, NY, USA) was fitted. The bladder of the cuff was at least 40% of the circumference of the arm or ankle. The cuff was attached to the arm contralateral to the operation site, where a venous catheter was inserted. The middle of the bladder was placed over the brachial artery.After measuring the circumference of the arm or ankle, an appropriately sized non-invasive BP cuff , diastolic blood pressure (DBP) and mean blood pressure (MBP) were recorded every 2.5 min during surgery at the arm, ankle and finger.The sample size of 225 pairs of values was required to compare CNBP and arm BP with a power of 90% and an alpha level of 0.05, based on the expected mean bias of 2 mmHg and standard deviation (SD) of 9 mmHg reported by the previous review on the accuracy of the finger cuff  and the To compare the relationship between each method, correlation coefficients were obtained considering the repeated measurement data . We calcTen patients were enrolled in, and completed, the study. Among the patients, nine received breast-conserving surgery (three right and six left), while the remaining patient received a total mastectomy. The demographic data of the enrolled patients are summarized in p < 0.001; 0.744, p < 0.001; and 0.755, p < 0.001, respectively). The CNBP SBP, DBP and MBP measurements were positively correlated with the arm BP measurements  between arm and ankle BP measurements was −15.3 ± 12.4 mmHg (39.7 to 9.2) for SBP, 1.8 ± 6.8 mmHg (−11.6 to 15.2) for DBP and −2.6 ± 8.5 mmHg (−19.3 to 14.1) for MBP a,c,e; thp = 0.019) . The differences between the arm BP, ankle BP and CNBP values for each of the 10 subjects are presented in The difference between CNBP and arm SBP was significantly smaller : −6.03 (−11.40 to −0.67)) compared to that between ankle and arm SBP (LS mean (95% CI): −15.32 (−20.69 to −9.96), = 0.019) . HoweverNo adverse events were observed during the study, including any signs of pressure-induced damage from the finger cuff.In this study, CNBP (ClearSight system) and ankle BP measurements were both correlated with arm BP measurements in patients undergoing breast cancer surgery. However, the difference between ankle and arm SBP was significantly greater than that between CNBP and arm SBP. No such significant differences were observed for MBP or DBP.Arm BP obtained with a pneumatic cuff has been the gold standard BP measurement method in clinical practice . Most guBP measurements obtained at the lower extremities, including ankle BP, have been well studied ,26,28,29A false high SBP may have clinical implications. During surgery under general anesthesia, patient management based on ankle BP could lead to hypotensive events due to unnecessary attempts to lower SBP using anti-hypertensive drugs or increasing the dosage of anesthetic agents. Although MBP has been regarded as a better indicator of perfusion of vital organs , a high Many studies have reported devices that can be used to obtain BP measurements as an alternative to conventional pneumatic cuff BP measurements, including the ClearSight system ,13,15,16Several limitations of this study should be discussed. Firstly, the study was only performed on women undergoing breast surgery with a limited number of patients. Therefore, the results might not apply to other clinical settings, such as male patients or very old and dehydrated patients. Secondly, we enrolled only American Society of Anesthesiologists physical status 1–2 patients who were undergoing breast cancer surgery under general anesthesia. Additionally, we excluded patients with peripheral vascular diseases, such as peripheral atherosclerosis and autoimmune diseases affecting peripheral vessels. Thus, our results may not be applicable to patients under local anesthesia, awake patients or patients with comorbidities. Therefore, further studies may be needed to validate our results in other clinical populations. Thirdly, CNBP readings obtained using the ClearSight system could be a useful alternative to ankle SBP. In addition, the ClearSight system is less invasive compared to arterial catheter BP monitoring. Therefore, CNBP seems to be an attractive and feasible alternative to arm BP. However, compared to conventional pneumatic cuff BP monitoring systems, the ClearSight system is costly. Further studies should conduct cost-benefit analyses of the ClearSight system.In conclusion, ankle BP and CNBP measurements were correlated with standard arm BP measurements in patients undergoing breast cancer surgery. Furthermore, ankle SBP measurements showed larger differences from standard arm BP measurements than did CNBP measurements. CNBP could serve as a useful alternative to ankle BP when standard arm BP measurements cannot be obtained.


Background: Diabetic nephropathy (DNP) is a type 2 diabetes mellitus (T2DM) chronic complication, which is the largest single cause of end-stage kidney disease. There is an increasing evidence of the role of inflammation and Toll-like receptors (TLRs) as part of innate immune system in its development and progression. In addition, Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) downward signaling causes the production of proinflammatory cytokines, which can induce insulin (INS) resistance in T2DM.Objective: The goal of this study was to estimate the expression of TLRs (TLR2 and TLR4) in relation to inflammation and INS resistance in nephrotic type 2 diabetic patients with or without renal failure and to discuss the role of these TLRs in DNP progression.Patients and Methods: In this study, blood samples were obtained from type 2 diabetic patients with or without renal failure, and patients with non-diabetic renal failure were compared to healthy controls. All participants were tested for analysis of fasting plasma glucose and serum insulin, kidney function tests, C-reactive protein (CRP), and proinflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), and interleukin 6 (IL-6) as well as expression of TLR2 and TLR4 in peripheral blood (PB). Statistical analysis of data was done by using SPSS.Results: Diabetic patients with renal failure exhibited significant increase in TLR2, TLR4 mRNA expression in PB in comparison with normal subjects, diabetic patients without renal failure and non-diabetic patients with renal failure. Both diabetic patients with or without kidney failure and non-diabetic patients with renal failure had increased TLR2 and TLR4 mRNA expression in association with increased levels of proinflammatory cytokines  compared to normal subjects. The diabetic patients with kidney failure exhibited the highest elevation of TLRs, Th1 cytokines and CRP in association the highest record of insulin resistance.Conclusion: Toll-like receptor 2 and Toll-like receptor 4 increased expression and Th2 cytokines may have an important role in the progression of DNP and deteriorations in insulin resistance in type 2 diabetic patients. Therefore, TLR2 and TLR4 may be a promising therapeutic target to prevent or retard DNP in type 2 diabetic patients. Type 2 DM (T2DM) is the most common form of DM . T2DM be disease . The inc disease . Emergin disease . Innate  disease . Inflamm disease . Proinfl disease . Such ch disease . During  disease . In this disease . AGEs ar disease  and play disease . Inflamm disease . In case disease . This si disease .via TLRs is implicated in the pathogenesis of insulin (INS) resistance, DM, and atherosclerosis .The target population of this study comprises DNP patients with or without renal impairment either on hemodialysis (HD) or not, from Beni-Suef University Hospital and other local hospitals. The sample was classified into four groups (each of 20 patients). Group 1  includes healthy individuals. Group 2 (non-DM + HD) consists of non-diabetic patients that have renal failure and are subjected to HD. Group 3 (DM + HD) consists of diabetic patients that have renal failure and are subjected to HD. Group 4 (DM) consists of diabetic patients that have no renal failure and are not subjected to HD.Patients having autoimmune diseases or recently hospitalized for infectious disease.After obtaining a full history from all participants, 6 mL of the peripheral blood (PB) from all the study participants were obtained aseptically by venipuncture.Obtained blood samples from overnight-fasted subjects were divided into 2 mL in a plain tube for biochemical studies and detection of proinflammatory cytokines, 2 mL in sodium fluoride tube for the determination of plasma glucose level, and 2 mL in dipotassium ethylenediaminetetraacetic acid (EDTA) for TLR2 and TLR4 expression examination.Plasma glucose level was determined with glucose oxidase, and 4-aminoan using reagent kit purchased from Vitro Scient in Egypt . Serum iHOMA-IR = fasting insulin level (μIU/mL) × fasting blood glucose (mmol/L)/22.5.HOMA-IS = 10,000/fasting insulin × fasting glucose.HOMA-β cell function = [20 × fasting insulin (μIU/mL)] ÷ {[fasting glucose (mg/dL) ÷ 18] − 3.5}.Serum urea level was detected according to the method modified Berthelot reaction using reagent kit obtained from Vitro Scient in Egypt . Serum cSandwich ELISA was applied for quantitative detection of serum TNF-α, IFN-γ, and IL-6 levels using kits obtained from MyBioSource, San Diego, California, United States; the catalog numbers for these kits were MBS015648, MBS824507, and MBS261259, respectively.Total RNA was extracted from whole blood by using a Trizol kit obtained from Ambion, Life Technologies, Carlsbad, CA . Cloned Quantitative real-time PCR technique carried out to detect mRNA expression of TLR2 and TLR4 in PB by using a universal Taqman master mix and a gene expression ready-made assay . A volume of 2.4 μl of cDNA was used as a template in 20 μl reaction containing 10 μl of TaqMan Universal Master Mix II, 1.0 μl of TaqMan Assay and 9.0 μl of cDNA/DNA template + RNase-free water. Holding stage includes two cycles, cycle 1 (50°C/2 min) and cycle 2 (95°C/10 min). Amplification stage includes 40 cycles; each cycle includes (95/15 s and 60/1 min). All data were presented compared with control after normalization to GAPDH (housekeeping gene). The Taqman(R) Gene Expression Assay ID of TLR2 is Hs00610101_m1 and Taqman(R) Gene Expression Assay ID of TLR4 is Hs00152939_m1.p > 0.05 were considered not significantly different, while those of values of p < 0.05 were significantly different. Correlation analysis was also performed by IBM SPSS, version 20.0 to assess correlations between different variables.Gene expression was calculated using ∆ ∆ Ct method. Data were analyzed by using one-way ANOVA and Duncan’s test using the statistical package for the social sciences . Results were expressed as mean ± SE. Data of values of Demography of the studied groups in Biochemical analysis and comparison between the studied groups are shown in Analysis between the four groups regarding the level of TNF-α showed that there was statistically significant difference between group 1 and the other three groups as indicated in TLR2 mRNA expression of exhibited a marked increase in group 2 (Non-DM + HD), group 3 (DM + HD), and group 4 (DM) recording percentage changes of 392.7, 3363.9, and 260.8%, respectively as compared to normal; the most potent effect was attained in group 3 (DM + HD). While the effect was significant in group 3 (DM + HD), it was non-significant in group 2 (Non-DM + HD) and group 4 (DM) as compared with normal. TLR2 mRNA expression was found to be significant in diabetic patients with kidney failure when compared with patients with either DM or kidney failure as indicated in TLR4 mRNA expression markedly increased in all patient groups including group 2 (non-DM + HD), group 3 (DM + HD), and group 4 (DM) groups recording percentage changes of3.13.4, 920.6, and 60.8%, respectively as compared to normal; the most potent deleterious effect was attained in DM + HD group. While the effect was significant in groups Non-DM + HD and DM + HD, while it was non-significant in DM group as compared with normal. TLR4 mRNA expression was found to be significant in diabetic patients with kidney failure when compared with patients with either DM or kidney failure .The correlations between the inflammatory indictor (CRP), inflammatory cytokines, and TLR2 and TLR4 on one hand, and HOMA-IR, HOMIS, and kidney function parameters on the other, were represented in Most patients with T2DM suffer from serious complications of chronic hyperglycemia including nephropathy, retinopathy, neuropathy, and accelerated development of cardiovascular diseases . DNP is In this study, the serum levels of proinflammatory Th1 cytokines TNF-α, IFN-γ, and IL-6 were higher in patient groups than the control group. Moreover, the serum levels of these cytokines were higher in diabetic patients with kidney failure than in diabetic patients without kidney failure and non-diabetic subjects with kidney failure. These higher levels of these inflammatory cytokines in diabetic patients with kidney failure reflects the important roles of these cytokines and inflammation in the progress of DN and the advanced disease state to reach end-stage renal disease and kidney failure. In parallel with the present study, As indicated in the present study, in the diabetic patients with renal failure, the expression of TLRs was significantly higher than normal group and other groups. The expressions of TLR2 and TLR4 remarkably increased in nephrotic diabetic patients with or without kidney failure and in non-diabetic nephrotic patients (with kidney failure) in comparison with normal subjects. The effect on TLRs expression was highest in diabetic nephrotic patients with end disease state and kidney failure. The higher expression of TLR2 and TLR4 in nephrotic diabetic patients with kidney failure than in nephrotic diabetic patients without kidney failure reflects their important roles in the progress of DNP to reach the end disease state subjected to HD. In support with this elucidation, the present study revealed a positive significant correlation between TLR2 and TLR4 expression and serum levels of kidney dysfunction biomarkers including cystatin C, creatinine, urea, and uric acid in diabetic patients with and without end-stage renal disease and kidney failure.In agreement with our study, In the present study, higher expression of TLR2 and TLR4 in diabetic patients with kidney failure than in diabetic patients without kidney failure was associated with higher values of HOMA-IR (as indicator of insulin resistance) and lower values of HOMA-IS (as indicator of insulin sensitivity). In concomitance, the diabetic patients with end-stage renal disease also showed higher levels of serum inflammatory cytokines TNF-α, IL-6, and IFN-γ. These associations reflect the roles of TLR2 and TLR4 in the progress of insulin resistance and inflammation which in turn may lead the advance of nephrotic disease to the end-renal disease stage and renal failure . This suκB, which is transferred to the nucleus and cleaved to p50 and p665 to induce inflammatory response and release of inflammatory cytokines and chemokines. The stimulation of TLR2 and TLR4 also leads to activation of activator protein-1 (AP-1), which also aggravates the inflammatory response through AP-1 target gene. The persistent increase in chemokines and inflammatory cytokines such as TNF-α, INF-γ, and IL-6 leads to progression of insulin resistance in one hand and of DNP to end-stage renal disease and kidney failure on the other.As represented in schematic In conclusion, TLR2 and TLR4 expressions are elevated in nephrotic diabetic patients with renal failure or without renal failure compared to normal individuals. TLR2 and TLR4 expressions are much more elevated in nephrotic diabetic patients with renal failure compared to nephrotic diabetic patients without renal failure. Moreover, TLR2 and TLR4 activity was markedly increased in association with elevated TNF-α, IL-6, and IFN-γ expressions, increased insulin resistance in response to inflammation; the changes were more prominent in diabetic patients with end-stage renal disease and renal failure. These observations significantly add to the emerging role of TLRs and Th1 inflammatory cytokines in the development and progress of DNP in type 2 diabetic patients. Moreover, it can be suggested that TLR2 and TLR4 may be a promising therapeutic targets to prevent or retard the DNP in type 2 diabetic patients.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Ethics Committee of Faculty of Post-graduate studies for Advanced Science, Beni-Suef University, Egypt. The patients/participants provided their written informed consent to participate in this study.RA, AAh, WH, and OA designed the experiments. RA, AAh, WH, AR, TA, AAs, and OA conducted the experiments, analyzed the data, and edited and approved the final version of the manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Cardiac rehabilitation after percutaneous coronary intervention decreases recurrence and mortality but has a high dropout rate. The aim of this study is to identify dropout predictors by comparing the characteristics of complete and dropout patients in cardiac rehabilitation. The study included 593 patients (455 men and 138 women) who received percutaneous coronary intervention and were enrolled in a 1-year cardiac rehabilitation program consisting of home-based cardiac rehabilitation with three center visits. Dropout was defined as participation in the first center visit but not the second or third center visits. Blood lipids, quality of life, socioeconomic status, and 6-minute walk distance measurements at the first visit were compared between participants who completed and dropped out of cardiac rehabilitation. For both men and women, the dropout rate significantly correlated with a low 6-minute walk distance and low muscle mass ratio. The dropout rate was significantly higher for men, but not women, with low education and low income. However, the dropout rate was decreased for women, but not men, with low blood pressure and triglycerides. An improved understanding of the characteristics of participants and the cardiac rehabilitation dropout rate are expected to contribute to the development of cardiac rehabilitation strategies that decrease patient dropout. Cardiovascular disease is a major cause of death worldwide . The mosFitness and body composition have been studied as predictors of cardiovascular disease and mortality. Even among individuals with normal weight, those with low fitness have a 2.7-fold increase in cardiovascular mortality compared to those with high fitness . AdditioThere were 650 patients who underwent PCI in our cardiology department. However, depending on the patient’s choice, there were patients who did not participate in CR or had incomplete test data. Therefore, 57 of these patients were excluded from the analysis. The criteria for inclusion in the study were participation in the CR program at least once and completion of physical fitness tests, body composition analysis, and SES surveys. A total of 593 patients (455 men and 138 women) were finally included in the analysis.The CR program was presented by a cardiologist, and only patients who agreed to participate in the program were included. Patients who underwent PCI were instructed to participate in the CR program at 4 weeks following discharge. Patients were encouraged to participate in CR through home-based exercise for 10–12 months. A dropout patient was defined as one who did not continue with follow-up CR after the first visit. A complete patient was defined as one who continued follow-up CR for 1 year. This study complies with the Helsinki Declaration and was approved by the institutional review board (AMC 2015-0594). The CR team consisted of cardiologists, exercise specialists, nutritionists, and nurses. The nurse explained to patients how to deal with precautions such as the Valsalva maneuver, how to use nitroglycerin, and how to monitor heart rate. Dietitians consulted on how to make a balanced diet, including low-sodium and low-fat diets, and menu choices when eating out. The exercise program was prescribed based on the American College of Sports Medicine guidelines . Based oQoL was assessed with the short Form Health Survey (SF-36), and SES was assessed through a questionnaire. Physical fitness was evaluated based on grip strength, flexibility, balance, and a 6-minute walking test (6MWT). Fasting with limited water was requested for 8 h prior to the analysis of blood lipids. The study measurements were performed in the following order: (1) questionnaire, (2) body composition and anthropometric measurements, (3) blood pressure measurement, and (4) physical fitness tests.Body weight, BMI, and muscle mass were measured using the Inbody 770 , per the manufacturer’s instructions. Waist circumference was measured twice horizontally using a tape measure at the thickest part of the navel level. If the measurements differed by more than 0.5 cm, the waist circumference was measured again. Grip force was measured using a Takei 5401 handle force dynamometer . The patient stood upright with the elbows in line with the waist and chest and the hand being examined extended. The hand was placed next to the thigh, and the patient was instructed not to touch the thigh. Then, the mechanical handle was placed on the second metacarpal bone. When the patient was ready, the examiner gave the signal “go,” and the patient exerted maximum strength. The posture was not disturbed during the test ,18. The For the balance test, the patient stood on a foot-shaped examination table, and both hands were placed on the waist. Then, the patient closed his eyes and stood on one leg. The opposite leg was bent back 90 degrees at the examiner’s “go.” The test ended when the patient opened his eyes, removed his hands from his waist, and placed both feet on the ground ,19. BothA 6MWD test was administered, in which the participant was allowed to walk as fast as possible for 6 min on a 60-m track. Cones were installed at both ends of the track, and the test was conducted in a safe space with a flat floor and no obstacles. The examiner started the test after the test had been fully explained and the patient understood the test method. The test started with the inspector’s “go” signal, and the patient was informed of the time in 1-minute increments. The walking pace was self-regulated, and running was prohibited ,21. Socioeconomic variables were based on monthly income and education level. Household income was divided by tertiles, and the survey was conducted in Korean Won (KRW), with low , middle , and high  groups. The education level was also divided into three groups: low, middle school graduation; middle, high school graduation; and high, college or higher.A participant’s general health and QoL were measured using the Korean version of the SF-36 in a self-administered manner. In the analysis, mental, physical, and total scores were calculated using the standard calculation formula. As a result of structural equation modeling, the Comparative Fit Index was 0.984, the root mean square error of approximation was 0.039, and the standardized root mean square residual was 0.038, indicating this was a valid questionnaire .t-tests were performed to compare medical and fitness test results at the first visit. The categorical variable SES went through the process of setting it as a dummy variable. Monthly income and education level were classified as high, meddle, and low through the tertile. Comparison of complete and dropout patient was performed by chi-square test. Variables with significant differences in the comparison between complete and dropout patients were selected as the odds ratio. As a result, it was the 6MWD and muscle ratio, monthly income and education level in men, while it was the 6-MWD, muscle ratio, systolic blood pressure (SBP), and triglyceride (TG) in women. In order to convert these variables into dummy variables, a tertile was performed and classified into high, middle and low. Odds ratio was calculated by logistic regression analysis. These variables were also used as adjustment variables. The significance level was at p < 0.05. SPSS 25.0  was used for data analysis. For complete and dropout patient characteristics, independent Comparisons of variables measured at the initial visits of the complete and dropout groups are shown in p = 0.016). In the high education group, 47.9% were complete patients, whereas in the middle and low education groups, only 36.7% and 15.4% were complete patients, respectively (p = 0.034).p = 0.036) and 1.573 times for the low 6MWD group as compared to the high 6MWD group . Moreover, dropout for men increased by 2.102 times for the low income group as compared to the high income group  and 1.980 times for the low education group as compared to the high education group . For women, dropout increased by 2.538 times for the low muscle ratio group as compared to the high muscle ratio group  and 1.800 times for the low 6MWD group as compared to the high 6MWD group . In addition, the dropout for women in the low SBP and TG groups increased by 3.000 and 1.708 times, respectively, compared to the high SBP and TG groups  than men 29%) failed to complete 12 months of CR % failed . HoweverA main finding of this study was that the relationship between SES and CR dropout was significant for men but not for women. According to a cross-sectional study, participation in CR was significantly reduced for patients with a low level of education, those living in rural areas rather than cities, and those with a low SES . SimilarAnother main finding of this study is that exercise capacity, as evaluated by the 6MWT, affects the dropout rate. The 6MWT, which measures the distance that a person can walk in 6 minutes or the 6MWD, is a simple method to measure cardiopulmonary endurance without complicated equipment and is mainly used with cardiac or pulmonary patients or the elderly . One stuOne of the main findings of this study was that people with low muscle mass had a high CR dropout rate. While there reports that physical fitness affects adherence to cardiac rehabilitation, studies on muscle mass are very rare ,39. HoweThe SF-36 measures general health and well-being and is largely divided into sections on mental and physical health. In this study, there were no significant differences in mental health based on completion of CR. However, previous studies have suggested that psychological or mental factors such as depression and low QoL negatively affect adherence to CR ,43. TherThe main strength of this study is that muscle mass and 6-minute walking, which are often measured for health evaluation, are expanded usability as tools to predict cardiac rehabilitation adherence. This result can be used as information to prevent dropout during cardiac rehabilitation. Because, patients with low walking capacity and muscle mass have a high CR dropout rate, various CR adherence strategies are needed for these patients. Ultimately, increasing the participation rate of cardiac rehabilitation will contribute to the prevention of heart disease recurrence and psychological relaxation. Nevertheless, our research has the following limitations: The individual reasons for dropout were not specifically investigated. In addition, the results of the exercise performance evaluation and the nutrition evaluation were not analyzed. Even if the patient did not come to the CR center, it cannot be excluded that the patient is engaging in healthy behavior. Additionally, this study did not assess the severity of the patient’s cardiovascular disease, and there were multiple medical staff and physical fitness testers. Therefore, the difference between therapists and examiners was an uncontrollable variable. In the future, it will be important to identify and compare relapse in complete and dropout patients. Additionally, as the elderly may have low physical activity , future This study was conducted to analyze predictors affecting cardiac rehabilitation program dropout in patients undergoing PCI. People with high 6-min walking distance and muscle mass had a high rate of participation in cardiac rehabilitation. Furthermore, a low level of education and economic status was increased the dropout rate in cardiac rehabilitation in men.