This study aimed to assess patients' preferences of nonsurgical treatments for chronic low back pain (CLBP).We conducted a discrete choice experiment (DCE) in Quebec, Canada, in 2018. Seven attributes were included: treatment modality, pain reduction, the onset of treatment efficacy, duration effectiveness, difficulties with daily activities, sleep problems, and knowledge of the patient's body and pain location. Treatment modalities were corticosteroid injections, supervised body‐mind physical activities, supervised sports physical activities, physical manipulations, self‐management courses, and psychotherapy. Utility levels were estimated using a logit model, a latent class model and a Bayesian hierarchical model.424 individuals. According to the Bayesian hierarchical model, the conditional relative importance weights of attributes were as follows: (1) treatment modality (34.79%), (2) pain reduction (18.73%), (3) difficulties with daily activities (11.71%), (4) duration effectiveness (10.06%), (5) sleep problems (10.05%), (6) onset of treatment efficacy (8.60%) and (7) knowledge of the patient's body and pain location (6.06%). According to the latent class model that found six classes of respondents with different behaviours (using Akaike and Bayesian criteria), the treatment modality was the most important attribute for all classes, except for class 4 for which pain reduction was the most important. In addition, classes 2 and 5 refused corticosteroid injections, while psychotherapy was preferred only in class 3.Analyses were conducted on Given the preference heterogeneity found in the analysis, it is important that patient preferences are discussed and considered by the physicians. This will help to improve the patient care pathway in a context of a patient‐centred model for a disease with growing prevalence.A small group of patients was involved in the conception, design and interpretation of data. Participants in the DCE were all CLBP patients. As recommended by the guideline of the Institute of Health Economics ,Patients' decisions and beliefs are taking a growing place in their care pathways.However, patients' preferences on CLBP treatments are not well known. The present study was the result of a request from an academic healthcare institution in Quebec  to improve the organization of care and provision of CLBP treatments, especially nonsurgical treatments. Consequently, we conducted a discrete choice experiment (DCE) to assess patients' preferences for nonsurgical treatments for CLBP. DCE is a stated preference method that aims to elicit preferences throughout a set of choice tasks on the basis of a finite set of alternatives. This method relies on the random utility theory and on the ability of individuals to make choices between treatments with the same characteristics (attributes) but different modalities (levels).To our knowledge, only 7 DCEs on patients' preferences specifically refer to back pain treatments with mean samples of about 337 individuals using between 5 and 8 attributes. Different treatments were studied such as pharmaceutical treatmentsThe main difference in our study is that we only considered first‐line treatments  and put emphasis on corticosteroid injections  versus five other first‐line treatments that have shown effectiveness in the scientific literature.22.1An online questionnaire was conducted in Quebec, Canada, at the end of 2018 among members of a provincial support group for patients with chronic pain, the Association Québécoise de la Douleur Chronique (AQDC). Respondents had to suffer from LBP for at least 3 months to be included in the survey . The study was conducted in both French and English, using the online survey platform provided by Sawtooth Software (Sawtooth Software Inc.).200–300 respondents was thus expected, which is in line with the usual recommendation for a DCEAmong the members of the AQDC, it was estimated that about 1,500 suffered from CLBP and it was expected to recruit 15%–20% of them through an invitation letter sent by the president of the AQDC. A minimal sample of 0 (no pain) to 10 (worst pain). Three scales ranging from 0 to 10 measured personal health and life satisfaction and willingness to take risks. The second part was the DCE itself followed by choice certainty scales from 0  to 10 (absolutely certain). The third part included follow‐up questions  and four health‐related quality of life questionnaires  and numeric pain rating scales (NPRS)2.2n = 4) and discussions with two patients and experts  as well as with a health technology assessment (HTA) consultative committee.The DCE was constructed following the ISPOR recommendations.34,006,392 pairs. An orthogonal selection procedure allowed us to generate 600 scenarios combined into 300 pairs. These pairs were divided into 30 blocks. Each respondent had to answer to one block of 10 pairs plus one pair for the rationality test  and one pair for the temporal consistency test . The blocks' distribution was run randomly among participants. An illustration of a choice card is given in Supporting Information: Appendix About 5832 different scenarios were possible resulting from all combinations of attributes and levels, yielding a possibility of 2.3The Conditional Logit (CL) modelA dual‐response none opt‐out option (named ‘none’) was allowed in all models . The LC model considers interclass homogeneity and intraclass heterogeneity while the HB model considers that all individuals have different preferences. In the HB model, all parameters were specified as normally distributed. We also performed cross‐tabulation between latent classes clusters  were performed to assess differences between classes. The bivariate results are presented in terms of column frequencies. A p‐value <.1 was considered significant.For purposes of descriptive analysis, relevant tests  did not achieve any of the choice tasks, 6 (0.98%) declared not responding as well as possible to the choice exercises, 6 (0.98%) declared ‘poor’ or ‘very poor’ quality of answers, 6 (0.98%) had low back pain for less than 3 months, 31 (5.08%) never chose a treatment (opt‐out), 2 (0.33%) always chose the first treatment and 1 (0.16%) always chose the second treatment. This yielded a total of 424 (69.51%) individuals included for analysis.Among a total of 3.255 years (±12.62) and was in majority composed of women (F/M ratio of 4.15). About 36.08% were married, 36.56% were retired and 43.40% had a higher education with an average household income of 57,883 CAD . Almost all individuals reported having LBP for more than 1 year (98.11%) and the principal diagnoses were lumbar disc herniation (37.74%), facet arthritis (34.91%) and fibromyalgia (35.14%). When answering the survey, individuals had an average level of CLBP of 5.39 (±2.03) over 10. The worst pain and the average level of CLBP in the past 2 weeks were 7.53 (±1.85) over 10 and 5.53 (±1.88) over 10, respectively. Almost one‐third used painkillers every day. Other treatments used were massage therapy sessions (41.98%), infiltrations of corticosteroid products (36.08%) and physiotherapy sessions (34.20%). The average amount of treatment expenditure was 1542 CAD  per year and 10.38% were not covered by insurance (public or private one). More than two third of respondents reported having a health problem affecting their quality of life  and half declared having a fair or poor health status. Both satisfactions with health and life, and the willingness to take risks were 4.12 (±2.42), 5.53 (±2.42) and 4.31 (±2.50) over 10, respectively. Finally, the RMDQ, the ODI, the health utilities of the SF‐6Dv2 and the EQ‐5D‐5L and the EQ‐5D VAS were, respectively, 10.02 (±5.18) over 24 (14 or more indicates a poor outcome), 42.49 (±15.36) over 100 (41–60 indicates severe disability), 0.33 (±0.23) and 0.58 (±0.23) over 1, and 52 (±22.39) over 100.All descriptive statistics presented here are available in Table 3.3The ranking of the attributes' conditional relative importance was the same in two models (HB and LC). It was as follows: (1) treatment modality, (2) pain reduction, 3) difficulties with daily activities, (4) duration effectiveness, (5) sleep problems, (6) onset of treatment effectiveness and (7) knowledge of his/her body and pain location (Table  difficul±11.94) to 6.06% (±3.17) whereas it was from 36.06% to 5.43% in the LC model, showing little difference (Table −52.18 (±121.81) for corticosteroid injections, 23.30 (±61.09) for supervised body‐mind physical activities, 6.15 (±89.92) for supervised sports physical activities, 52.57 (±49.66) for physical manipulations, 21.47 (±59.66) self‐management courses and −51.31 (±76.19) for psychotherapy, thus showing on average a high disutility for corticosteroid injections and psychotherapy.According to the HB model, the conditional relative importance of these attributes ranged from 34.79%  expressed a high utility for corticosteroid injections, and only class 3  expressed a utility for psychotherapy Table  Support classes.6–12 months until their preferred treatment started to be effective and wanted an effectiveness duration of at least 6 months. An improvement from ‘fewer difficulties as before’ to ‘no difficulties’ in their daily life activities, as well as an improvement to ‘fewer problems than before’ in their sleep problems were appreciated whereas the attribute ‘knowledge of his/her body and pain location’ had a minor effect, that is, its improvement had to be high to influence the preference.With regard to other attributes, the HB model  indicated that respondents were able to wait up to H0:μ=0).From these results, we can observe that the treatment modality had a great importance beside the other attributes. All attributes were always ranked at the same position. Among the treatment modality, corticosteroid injections and psychotherapy were generally rejected whereas physical manipulations were preferred followed by the supervised body‐mind physical activities and the self‐management courses. Supervised sports physical activities had a positive but slight effect, and its weight was smaller in the HB model than in the logit and CL models. Graphical representations of part worth utilities are given in Supporting Information: Appendix 3.4p < .10) in the sociodemographic characteristics of the six classes , benefited more from injections of corticosteroid products , spent more money to treat CLBP  and had more other problems affecting quality of life . Class 2 benefited less from corticosteroid injections  and spent less money to treat their CLBP . Class 3 was made up of more men , although the ratio of men over women remained very unbalanced (1 man for 2.8 women against 1 man for 4.1 women in the full sample), more individuals with pain lasting from 3 months to 1 year at the time of the survey , more often benefited from corticosteroid injections , did less yoga , presented more diseases or physical or mental problems affecting their quality of life , and reported having a better self‐reported health state . Class 4 was more feminine , less in pain when responding to the survey  and spent more money to treat CLBP . It was also the class with the most cancer  and respiratory problems reported . Class 5 was slightly younger  and more educated (p = .046). Finally, class 6 was the oldest , the one with the most of men , the least educated (p = .046), more diagnosed with vertebral arthritis or spondylarthrosis  and the one being the most in pain when answering the survey , but also having the fewest other problems affecting their quality of life . Respondent's personal ranking of attributes and treatment modalities are presented in Supporting Information: Appendix The LC model estimated preferences that are heterogeneous between classes and homogeneous within classes. It allowed us to examine significant statistical differences (at es Table . Comparep = .102), individuals in class 1 being more annoyed compared to other classes (39.13%). Only the number of dimensions/attributes considered by individuals for the choice exercises was significant (p = .004), with classes 1, 3 and 6 who considered less dimensions than the average. Class 6 rejected more than other classes the treatments offered in the choice‐based exercise , whereas classes 1 and 5 strongly accepted them . About 13.68% and 34.67% failed to the rationality test and to the temporal consistency test, respectively, and differences between latent classes were significant . Bivariate analyses of the hierarchical clustering derived from the HB model are provided in Supporting Information: Appendix No significant difference was found among classes on the choice certainty score, the difficulty and the quality of responses , class 2 preferred supervised body‐mind physical activities and self‐management courses and classes 4 and 5 preferred physical manipulations. More generally, patients (as a whole) expressed a disutility for corticosteroid injections and psychotherapy. They all differed in their sociodemographic status, health conditions and in their experiences with CLBP, although in a multivariate analysis this was not a predictor for class membership. These results were somewhat corroborated with a simple question of attributes self‐ranking and with the four‐item questionnaire of Dima et al.We found seven DCEs on LBP treatments conducted in the United States,n=4) from an LC model with their own preferences and sociodemographic characteristics. For instance, the primer found that the elderly and men with lower socioeconomic status preferred exercise less whereas all other classes preferred this programme. Individuals already doing exercise also had a preference for a programme with higher frequency and lower cost. Walsh et al. found that improvement in symptom control and risk of physical dependency were of utmost importance in patients suffering from osteoarthritis and CLPB and defined four distinct groups as ‘efficacy‐focused’, ‘cost‐averse’, ‘physical‐dependence‐averse’ and ‘needle‐averse’. Yi et al.,Differences between the six classes from the LC model could explain some preferences for the treatment choices, in particular why classes 1, 3 and 6 expressed a strong preference for corticosteroid injections. Including heterogeneity in the analysis, the LC model allowed us to consider heterogeneity between classes. We described six classes and found relevant discriminant preferences and sociodemographic characteristics. Ferreira et al.7.30 over 11, ±2.91), which could lead to estimation issues, and (2) they reported higher CLBP according to the NPRS, higher frequency of use of painkillers, as well as a low satisfaction with life, which could induce a poor understanding about the choice‐based exercise although it was not reflected by the follow‐up questions  and all participants gave their informed consent before starting the survey. All responses were anonymous.Supporting information.Click here for additional data file.Supporting information.Click here for additional data file.Supporting information.Click here for additional data file.


Currently, there is neither a standardized mode for the documentation of phantom sensations and phantom limb pain, nor for their visualization as perceived by patients. We have therefore created a tool that allows for both, as well as for the quantification of the patient's visible and invisible body image. A first version provides the principal functions: (1) Adapting a 3D avatar for self-identification of the patient; (2) modeling the shape of the phantom limb; (3) adjusting the position of the phantom limb; (4) drawing pain and cramps directly onto the avatar; and (5) quantifying their respective intensities. Our tool (C.A.L.A.) was evaluated with 33 occupational therapists, physiotherapists, and other medical staff. Participants were presented with two cases in which the appearance and the position of the phantom had to be modeled and pain and cramps had to be drawn. The usability of the software was evaluated using the System Usability Scale and its functional range was evaluated using a self-developed questionnaire and semi-structured interview. In addition, our tool was evaluated on 22 patients with limb amputations. For each patient, body image as well as phantom sensation and pain were modeled to evaluate the software's functional scope. The accuracy of the created body image was evaluated using a self-developed questionnaire and semi-structured interview. Additionally, pain sensation was assessed using the SF-McGill Pain Questionnaire. The System Usability Scale reached a level of 81%, indicating high usability. Observing the participants, though, identified several operational difficulties. While the provided functions were considered useful by most participants, the semi-structured interviews revealed the need for an improved pain documentation component. In conclusion, our tool allows for an accurate visualization of phantom limbs and phantom limb sensations. It can be used as both a descriptive and quantitative documentation tool for analyzing and monitoring phantom limbs. Thus, it can help to bridge the gap between the therapist's conception and the patient's perception. Based on the collected requirements, an improved version with extended functionality will be developed. After the amputation of a limb, up to 90% of the patients report a feeling of the missing body part still being present . This efPLP usually manifests itself 24 h to 1 week after amputation and decreases in intensity and frequency over time in most patients . EspeciaPLP, defined as painful sensation in the missing part of the limb, is to be distinguished from pain in the residual limb , and in PLP is an elusive entity, which makes it hard to track the progress of these patients over the course of treatment. Currently, there is no standardized mode of documenting PLP and PLS. The guidelines of the German Society of Neurology for the diagnosis of neuropathic pain recommend to document the onset and duration, the temporal course, pain qualities, localization and intensity as well as factors triggering pain . In geneThis still does not allow for the illustration of the patients' altered body image, in particular the phantom. Although several software tools do exist that can be used to illustrate an altered body image, these have been developed primarily in the context of eating disorders –19. TherSince we could not find any suitable software, we decided to develop such a tool ourselves. In the present study we describe the functionality of the first version of C.A.L.A. (Computer Assisted Limb Assessment) and the results of its evaluation with therapists and patients in terms of usability and functionality.The basic idea of C.A.L.A. is the customization of a virtual human 3D avatar in such a way that it represents the patient's body image including their PLS. A prototype  and a fiThe process of documenting a patient over the course of treatment was as follows: Initially, a basic model is created by adjusting the 3D avatar to fit the patient's (perceived) body dimensions. This model then serves as a baseline to be built on in the following sessions. Over the course of treatment, the phantom limb can then be adjusted in terms of deformation, position, and pain, thus visualizing the changes in perception by the patient.These functions are explained in detail in the following:To increase the patient's identification with the 3D avatar, we used some of the original functions provided by MakeHuman, which allow for the adjustment of the avatar in terms of gender, age, muscles, weight, and proportions. These adjustments have no further purpose in the documentation process apart from cosmetic ones. The avatar can additionally be clothed with underwear.The patient's body measurements can be transferred to the avatar. The body height as well as circumference and length of upper arm, forearm, upper and lower leg, fingers, and toes as well as the length and width of hands and feet can be entered and form the basis for the subsequent measurements of the phantom limb.The length and circumference of the upper arm, forearm, thigh, and lower leg can be increased or decreased. Hands and feet can be enlarged or shrunk. Fingers and toes can be adjusted in length and circumference, the thumb and long fingers can be adjusted separately. The telescoping effect can be represented using this feature see .The sensation of the phantom limb being fixed in one or more, twisted or unnatural positions is captured by moving the respective joints of the 3D avatar into the position reported by the patient. Based on the original MakeHuman 3D model, it is possible to rotate the shoulder, elbow, and wrist joints as well as the individual finger joints of the 3D avatar, the same applies to the joints of the lower extremities. All joints can be rotated along their natural axes in steps of ±10° and even beyond the limits that are anatomically possible. As a result, all conceivable positions of the upper and lower extremities can be represented see .Pain is drawn directly onto the 3D avatar by using the mouse cursor as a brush, similar as it is done in 2D paint software. Currently C.A.L.A. distinguishes between pain in general and cramps in the phantom, these two aspects can be drawn independently of each other and with their respective intensity see , which iAll data that were entered during the documentation process can be quantified and contain informative value about the phantom's constitution at the respective time. This allows for the analysis of the recorded aspects, namely deformation, position, and pain, and for their observation over the course of treatment. The quantification of these three aspects is briefly described as follows: Quantification of deformation reflects the percentage change in length and circumference of the respective limbs compared to the base model. Based on the originally collected dimensions of the patient's body, these changes can also be expressed absolutely in centimeters. The quantification of the position results from the deviation of each rotation axis of each joint from the basic position of the 3D avatar. Pain and cramps are quantified as the percentage of the body surface that is covered by the respective intensity.C.A.L.A. was evaluated with 33 professionals . Of these, 22 were female and 11 were male with an age range of 25–58 and a mean age of 41. The inclusion criteria for all participants were to actively work with amputees and document their phantom limb in a clinical context.Each participant was initially provided with a brief introduction to the operation of C.A.L.A. Subsequently, participants were given the task to perform the entire documentation process (see Section C.A.L.A.) on two given, fictional patients see . These tSubsequently, all participants were questioned with the System Usability Scale  to deterTo test the scope of the currently implemented functionality regarding real-world cases of PLS and PLP, we evaluated C.A.L.A. on 22 patients with the following amputations: 1 × transhumeral, 1 × transradial, 12 × transfemoral, and 5 × transtibial, thereof one patient with a transfemoral and one with a transtibial amputation of both legs, 3 × finger amputation. Eight of the patients were female and 14 were male with an age range of 21–73 and a mean age of 52. The inclusion criterion for all patients was the amputation of at least one limb.For each patient, the entire C.A.L.A. documentation process was performed (see Section C.A.L.A.) by the investigators. The therapists who took part in our study did not evaluate the patients. Subsequently, the patients were questioned about their phantom pain with the German version of the Short Form McGill Pain Questionnaire (SF-MPQ-D)  to assesAll 33 participants completed the documentations of two given fictional patients. The average duration needed to complete a task decreased from 15.2 (±3.5) min for the first task (T1) to 10.8 (±1.7) min for the second (T2), the assistance provided by the investigator, measured on a 1–5 Likert scale (“very little help” to “very much help”), decreased from 2.4 (±1.0) to 1.5 (±0.8). Broken down by age group, the duration was very similar through all groups, however the amount of help provided was the highest for the oldest age group and the lowest for the youngest age group see .The evaluation with the System Usability Scale resulted in an average score of 81.7% (±11.2), placing in the 4th quartile which represents high usability. The values are similar across age groups and professions. Additionally, we evaluated the usability of C.A.L.A. by user observation and semi-structured interviews, in which we asked about the difficulties in using C.A.L.A. Several users mentioned that the controls were too small and too cluttered. We also observed operational errors (such as modifying the wrong side of the body), problems understanding the user interface and difficulties navigating the 3D avatar.With a separate, self-developed questionnaire and semi-structured interview we prompted the participants about their own documentation methods during therapy. Regarding the use of templates or specific questionnaires, 45% of the participants reported to use body charts to draw pain and 27% use validated questionnaires to assess pain, PLS, or body image. Besides questionnaires, the documentation was usually mostly handwritten and in a self-defined form.We asked the participants to rate various aspects of the therapeutic finding by their importance on a scale from 1 to 5 (“not important” to “very important”). The results see  show theRegarding the documentation of pain, most of the participants (76%) used the Numeric Rating Scale (NRS) and 51% used the Visual Analog Scale (VAS)  to assesSubsequently, we asked the participants to evaluate the functionality of the C.A.L.A. features. Using a Likert scale from 1 to 5 (“very low” to “very high”), participants were asked to rate the usability of the functionalities regarding the documentation of phantom limbs on a 1–5 scale (“not helpful” to “very helpful”), which resulted in high acceptance of the functions, rated least was the function to quantify the deformation of the phantom with 3.6 (±1.2) see .In the semi-structured interview, we asked about additional functionalities for C.A.L.A., the most frequently mentioned ones are listed as follows: The documentation of pain qualities and the temporal aspects of pain  were mentioned very frequently, not only in relation to phantom pain but also to residual limb pain. Another request concerned the modeling and positioning of the body parts, here a more differentiated adjustment, especially of the fingers and toes, was asked for. Regarding the positioning of the phantom, it was suggested to use a standardized diagnostic specification to describe the rotation of the joints, e.g., the deviation from the neutral zero position .Finally, we compared the quantifiable aspects of the documentations that have been created in the first respective second task by all participants, namely the shape and position of the phantom, and the drawing of pain and cramps. Analyzing the data revealed that during the documentation of both tasks, 3—always different—participants mixed up the side of the body and worked on the wrong arm or foot. The data of these six documentations were corrected by the side of the body and added to the evaluation. We determined the coefficient of variance for all parameters of the respective documentation aspects  and calculated their mean values see . This shSeventeen of the 22 patients were experiencing PLP, five of them reported a deformed phantom and five reported a twisted position of the phantom. Thirteen patients reported suffering from stump pain.All 17 patients with PLP or a deformed or twisted phantom were asked how well their phantom and their body image could be mapped, rated on a 1–5 Likert scale (“very inaccurate” to “very accurate”). The other five patients, who only reported stump pain were just asked about the accuracy of their body image representation. The phantom was rated with an average of 4.6 (±0.7), the body image with 4.2 (±1.0). We also asked the patients, how important the aspects of gender, age, and physical shape were for them regarding the accurate representation of body image, which revealed that these aspects were not of primary concern.Regarding the functional range, it was often remarked that the body image was inaccurate due to the missing visualization of the residual limb. Modeling of the individual fingers was required in greater detail than provided, both in terms of deformation and position. It was also not possible to visualize, that some parts of the amputated limb were still present as phantom sensation while other parts were no longer perceived.The documentation of pain revealed the missing option of documenting different qualities of pain. Here, especially the pain quality “stabbing” was mentioned several times. Another functional absence was the description of the temporal aspects of pain, such as long, short, or periodic pain. In addition, patients mentioned various other aspects when describing their pain, such as the course of the pain experience, the time of day, whether the patient was resting or moving, or even the influence of weather.Subsequently, all 22 patients were interviewed with the SF-MPQ-D to measure number of pain qualities mentioned per patient and the frequency of each pain quality. For the patients without phantom pain, stump pain was queried instead. On average, 4.8 (±2.8) of 15 qualities were mentioned per patient, the most frequently mentioned were “shooting,” “stabbing” and “hurting.” During the interview as well as during the documentation of pain in C.A.L.A., it became apparent that the distinction between stump and phantom pain was not clear for many patients and therefore a mixture of both pain sensations was sometimes described.The evaluation of C.A.L.A. with the System Usability Scale and the survey have shown that the vast majority of the participants considered C.A.L.A. user-friendly and feasible. To our knowledge, there is currently no software tool for therapists that allows for the visualization of phantom limbs, especially considering deformation, position, and pain. Therefore, rendering a comparison of C.A.L.A. to any existing standard regarding the documentation of phantom limbs is practically impossible. In a clinical setting time is of the essence. The duration of the documentation averages at 10 min, reducing the time by about one third in the second documentation trial, indicating that more training will likely reduce the time further.During the evaluation with patients, they reported of never having given this amount of thought to the exact nature of their phantom limb. This fact was especially observable in localizing PLP. It was stated in only one case that the process of visualizing the phantom had a negative impact on the patient's body image. No patient indicated that phantom pain had increased because of the documentation process.In this study we emphasized validity and did not specifically test for reliability, due to the nature of the modeling and positioning of the phantom limb and pain, which is dependent on the accuracy of the patient's report. We have provided different levels of detail in the tasks for position, deformation and pain, which is supported by the documentation differences shown in Since all body image data are available in digital form, they can be easily quantified. This allows for a much more precise and simpler quantification than it would be possible with the conventional, mainly analog, methods. The amount of pain drawn onto a 2D human outline as well as joint angles of the phantom could possibly be estimated as could the circumference and the length. However, to our knowledge no one has ever calculated such values, especially regarding position and deformation, nor have their changes been evaluated over the course of treatment. To the best of our knowledge, no tools exist, yet, which can be used to document phantom limbs and PLP. C.A.L.A. offers a convenient tool to document just that.In addition to evaluating usability, an essential aspect of our study was to identify possible extensions and adaptations of the functional scope. These will be discussed as follows.When documenting PLP and PLS, pain is clearly the most important issue. Pain affects the patients' quality of life, and its reduction usually is the primary goal of therapy. The importance of pain was also evident in the qualitative surveys with patients, in which it was described by far the most frequently and in the greatest detail. In the therapist survey, too, there was the most feedback on the topic of pain documentation.In this context, the topic of pain qualities was most frequently mentioned by both patients and therapists. This is not surprising since using these pain qualities for describing PLP had been established almost 50 years ago . CurrentIn addition to the localization, intensity and the qualities of pain, the guidelines of the German Society of Neurology  recommenBesides the issue of pain, C.A.L.A. should include means of clearly visualizing the stump to make it easier to distinguish it from the phantom. Several patients stated during the qualitative interviews that the visualization of their body image was not complete due to the missing visualization of the stump, even if the sensation of the phantom limb was present in the patients.When drawing PLP based on the patients' descriptions, it became obvious that the strict distinction between phantom pain (exclusively in the missing part of the limb) and stump pain (exclusively in the part still present)  was not The distinction between PLP and residual limb pain could be simplified in a future version of C.A.L.A. by a clear visual differentiation between residual limb and phantom limb in the representation of the 3D avatar see . This woAs described in the literature , 20 and In addition to these two main topics, we have identified several other contexts in which C.A.L.A. could be improved to increase its usability and validity. The most relevant ones are listed below.When adjusting the position of the phantom limb, the 3D avatar is initially in a position where arms and fingers are slightly spread and bent. While this body position is advantageous for painting and deforming the phantom, we think that a more standardized body position, such as the neutral-zero position , would bAnother feature that has been mentioned several times was the desire for a visual representation of the progress of the phantom over the course of treatment; or, in other words, over the course of several documentations. This could especially help both to clearly demonstrate the progress of therapy and to motivate the patients to continue.Finally, participants also considered other possible application scenarios in which C.A.L.A. could be used with modified functionality. Often mentioned was the application in Complex Regional Pain Syndrome (CRPS) or stroke patients, as well as for all other situations in which patients experience an altered body image.We have created a tool that allows for the visualization and documentation of PLP and PLS. Thus, it provides a standardized form for their presentation and can be used as a descriptive and quantitative documentation method.Based on the evaluation with the therapists, a great demand for our tool could be determined, therefore a further development of C.A.L.A. is reasonable and can contribute to increase its usability and efficiency in operation. For such an improved version, the most important additional features in our point of view are briefly listed here again: (1) introduction of pain qualities; (2) clear distinction between phantom and residual limb; (3) additional documentation of residual limb pain; (4) more precise adjustment of shape and position of individual fingers; and (5) a visualization of the course of treatment over several sessions.C.A.L.A. can help to bridge the gap between the therapist's conception and the patient's perception of the phantom limb. The possibility to quantify the representation of the phantom offers a previously unavailable option to monitor and analyze its change over the course of treatment and can help to create insights into the correlation between certain forms of treatment and PLS or PLP. Finally, C.A.L.A. enables a more integrated representation of the phantom than is possible with conventional visualization methods with little effort regarding time and other resources, increasing feasibility regarding clinical context.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 the Medical Faculty of the Eberhard-Karls-University Tuebingen. The patients/participants provided their written informed consent to participate in this study.MB designed and implemented the first version of C.A.L.A., conceived and performed the evaluation, analyzed the data, and wrote the manuscript. JM contributed to the design of C.A.L.A., contributed to planning and performing of the evaluation, and revised the manuscript. JH provided feedback on and verified the data analysis and revised the manuscript. MVB contributed to the interpretation of the results and revised the manuscript. AD and JK contributed to critical revision of the intellectual content and approved the final version. CP conceived the original idea of the project, contributed to the design of C.A.L.A., contributed to data acquisition, revised the manuscript, and was in charge of overall direction and planning. All authors provided critical feedback and helped shape the research, analysis, and manuscript. All authors contributed to the article and approved the submitted version.We acknowledge support by the Open Access Publishing Fund of the University of Tuebingen.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.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Postoperative pain remains a common problem in gynecologic laparoscopy, especially in head zone-related regions, triggered by intra-abdominal pressure during capnoperitoneum. Humidified and prewarmed insufflation gas may ameliorate pain and be beneficial.2 with forced air warming blanket (“AIR”), humidified warm gas without forced air warming blanket (“HUMI”), or humidified warm gas with forced air warming blanket (“HUMI +”). We hypothesized that using humidified warm gas resulted in lower pain scores and less analgesic consumption. The primary endpoint postoperative pain was assessed for different pain localizations every 12 h during 7 days after surgery. Secondary endpoints were demand for painkillers and epidural anesthetics, length of stay in recovery room, and hospital stay. .This prospective randomized controlled parallel group multi-arm single-center study investigated the effects of temperature and humidity of insufflation gas on postoperative pain during gynecologic laparoscopy with a duration ≥ 60 min. Female participants (18—70 years) were blinded and randomly assigned—computer generated—to either insufflation with dry cold COn = 48), there was significantly less pain in group “HUMI +” (n = 48) in the recovery room , as well as significantly less ibuprofen use at day two . Other variables did not change significantly. Stratification for presence of endometriosis or non-previous abdominal surgery in patient history revealed significantly less pain in both groups “HUMI” (n = 50) and “HUMI +” versus group “AIR.” Related side effects were not noted.150 participants were randomized. Compared to group “AIR” (In the overall population, the use of warm, humidified insufflation gas did not yield clinically relevant effects; however, in predisposed patients with endometriosis and who could otherwise expect high pain levels, warm and humidified gas may be beneficial.The online version contains supplementary material available at 10.1007/s00464-021-08742-1. Since its invention, laparoscopic surgery became the gold standard in various surgical disciplines with a wide range of indications : the majDespite these benefits and the rising numbers of laparoscopic procedures, postoperative pain remains a common problem . Gerbers2 compared with WHCD [There are several approaches proposed to reduce postoperative pain, especially shoulder tip pain, in gynecological laparoscopy. One of the proposed methods is the use of warmed and humidified carbon dioxide (WHCD) for establishing the capnoperitoneum. Animal studies have shown that the use of WHCD during laparoscopy results in less desiccation and cell alteration and therefore less peritoneal damage and inflammation as compared to cold and dry gas –13. Dry ith WHCD .Consequently, Binda concluded in her review that both pain and tissue damage can be prevented using humidified gas . However2 on intraoperative hypothermia compared to room temperature and dry gas in laparoscopy that lasted at least 60 min [We therefore decided to investigate the impact of WHCD on postoperative pain course following gynecological laparoscopic procedures with a duration of more than 60 min in a prospective, randomized, controlled monocentric multi-arm trial ). This article describes parts of this TePaLa trial (the effects on body temperature have not been published yet). The TePaLa trial is based on a retrospective pilot study showing the preventive effect of body temperature and humidified COt 60 min . As percWe hypothesized that using WHCD compared to cold and dry carbon dioxide resulted in lower pain scores, especially shoulder pain, and less analgesic consumption. Since patients suffering from endometriosis are more prone to having severe postoperative pain, we suggested that they could profit more from this kind of insufflation technique as compared to women who underwent surgery because of other gynecological diseases. In a combined three-arm study design investigating pain and temperature management, patients were either warmed with a forced air warming blanket, with the use of WHCD, or with a combination of both.The aim of this section of the study was to assess the impact of forced air warming or WHCD on postoperative pain course following gynecological laparoscopic procedures with a duration of more than 60 min.The study was designed as a monocentric, prospective, randomized, double-blinded controlled trial with three parallel intervention arms. Before trial commencement, the study design was changed to be a single-blinded trial because the surgeons and study staff could not be effectively blinded with respect to the devices used during the laparoscopic procedure. All patients and ward staff were not aware of the method used during laparoscopy.The methods and trial are described in detail in supplement 2.The study included 150 participants with an indication to a laparoscopic gynecological surgery. It was conducted at the Department of Anesthesiology and the Department of Gynecology and Obstetrics, University Hospital Aachen, Germany between July 2016 and September 2018.The participants were randomized in 3 groups of 50 subjects each. In group “AIR” (control group “AIR”), a forced air warming blanket and cold and dry insufflation gas was used during surgery. In group “HUMI”, insufflation was performed with warm and humidified insufflation gas and no warming blanket was used (“HUMI”). Group “HUMI +” was treated with a combination of a forced air warming blanket and warm, humidified gas (“HUMI +”).Eligible patients were female, aged between 18 and 69 years with a body mass index under 35, admitted to the hospital for laparoscopic surgery with a planned duration of more than 60 min.Exclusion criteria were patients who were pregnant or not using sufficient contraception, who were breastfeeding, who were engaged in alcohol or drug abuse, who were either expected not to comply with instructions or with limited ability to comply with instructions for this study, who were unwilling or unable to give informed consent, who participated in another interventional study within the last 3 months, who are committed to an institution and/ or penitentiary by judicial or official order, and who are employees of the investigator cooperation companies.2 (21.0 °C room temperature/ 0% humidity) in group “AIR” or with warm and humidified CO2 (depending on flow rate > 38.6 °C/ > 98%) [If epidural anesthesia was indicated and desired by the patient, an epidural catheter was placed according to standard operating procedures. All patients received general anesthesia as total intravenous anesthesia or low flow (< 1 l/ min)-balanced anesthesia. After the induction of anesthesia, patients of group “AIR” and group “HUMI +” received forced air warming and patients of group “HUMI” were only covered with cotton sheets. According to randomization, capnoperitoneum was established and maintained either with cold and dry CO/ > 98%)  in group/ > 98%) .After the patient’s arrival in PACU, the pain score was determined with the visual analogue scale (VAS) for pain from the abdominal area, pain in the shoulder, pain upon movement, and pain upon coughing. Pain scores were also recorded before transfer to the ward, on the day of surgery at 8 p.m., and on postoperative days 1 to 7 at 8 a.m. and 8 p.m. until the day of the patient’s dismissal from the hospital. All patients were instructed to use VAS on the day before surgery, and the pain questionnaire was filled out by the patient alone to avoid observer bias. Postoperative pain management was standardized and followed a three-step analgesic ladder, based on the WHO guidelines for the pharmacological and radiotherapeutic management of cancer pain in adults and adolescents .The primary endpoint was postoperative pain recorded by the visual analogue scale upon arrival in the recovery room, before transfer to the ward, at 8 p.m. on the day of surgery, at 8 a.m. and 8 p.m. on postoperative days 1 to 7 specifically for abdominal pain, pain in the shoulders, pain upon movement, and pain upon coughing. Secondary endpoints were analgesic consumption, the duration of epidural anesthesia, postoperative nausea and vomiting, differences in activities of daily living (ADL), the length of stay in post-anesthesia care unit (PACU), and the total length of the hospital stay.This study was designed to address heating capabilities and pain reduction. Three groups were constructed, and sample size and statistical power were calculated to detect a difference in core body temperature. In a Cohen's delta effect size power analysis, a sample size of 50 in each of the treatment groups would give a power of 0.8 to detect a difference of at least 0.2 °C between groups in a balanced design. The effects on body temperature have not been published yet.After patients were enrolled by the study team and written informed consent was obtained, study participants were randomized with equal allocation ratios to the three interventions using permuted block randomization (block size 6) stratified by endometriosis (Yes/No). Computer-generated sequences were used. To maintain allocation concealment, the randomization sequence and the block size were concealed from the investigators and the study team until database lock and the assignment to study participants was carried out with a web-based application maintained by the Institute of Medical Informatics, RWTH Aachen University.Outcome variables were described within each treatment group using standard descriptive statistics . Descriptive statistics for pain scores were also calculated separately for each measurement timepoint. Analyses of pain scores were performed on the maximum pain score calculated as the maximum of the abdominal-, movement-, upon coughing-, and shoulder pain scores for each subject at each measurement occasion. A linear mixed effects model was used to model the pain score , 26. EstA total of 208 patients with an indication to a laparoscopic gynecologic surgery were assessed for eligibility between July 2016 and September 2018. The trial ended after the planned 150 interventions were completed. 58 subjects were not included, as they did not meet inclusion criteria, declined to participate, participated in another study, or for other reasons. The 150 patients who were included in the study were randomized either to the control group or to one of the two intervention groups, stratified by endometriosis. Seventy-four women declared to suffer from endometriosis and 76 did not have a diagnosis of endometriosis. Four of these patients were newly diagnosed with endometriosis during this study.One patient randomized to the control group accidently received no warming blanket, but warm humidified insufflation gas instead of the allocated intervention with forced air warming blanket alone. One patient randomized into group “HUMI” did not receive surgery and consequently the allocated intervention, because of a preoperative spontaneous rupture of the ovarian cyst that was the indication for laparoscopy. Three patients randomized into group “HUMI +” did not receive the allocated intervention: in two cases because the planned surgery was not performed due to different reasons and the other because the patient received a forced air warming blanket only instead of the allocated intervention.In two cases the intervention was discontinued: one patient from group “AIR” because of the intraoperative indication to a conversion of the laparoscopic procedure into laparotomy and one patient from group “HUMI” because of the lowering of core body temperature below 35 °C during the intervention with the necessity to use in addition a forced air warming blanket.Follow-up data were available for 146 of the 150 randomized patients. In one case from group “AIR” and one case from group “HUMI +”, follow-up data were missing, because the VAS questionnaires were not available. There were also no follow-up data from the two patients without surgery after randomization.Primary intention-to-treat analysis was performed on the full set of follow-up data Fig. .Fig. 1CO2, as well as the type and length of operative procedures were recorded. Significant differences between the groups were seen in ASA classification and intraoperative use of paracetamol. No other differences were recorded.Table Descriptive statistics of pain perceived on each postoperative day specific for the abdominal area, shoulder pain, and pain caused by movement or coughing is shown in Table Figure p-value = 0.0471)  or on discharge day . ADL scores were the same in each treatment group separately on day 1  and on discharge day .Table Additionally, exploratory post hoc analysis of postoperative pain scores was performed. We analyzed the treatment effect on postoperative pain scores of the two intervention groups combined, both received warm and humidified gas, and in comparison to the control group, which received cold and dry gas: no significant differences in this model were detected.Results stratified by endometriosis are shown in Fig. Analysis of data stratified by abdominal surgery showed significantly less pain scores in patients who did not undergo previous abdominal surgery in both groups “HUMI” and “HUMI +” compared to group “AIR” at different timepoints Fig. A and B.FA total of 109 (74%) study objects experienced adverse events during study intervention. All adverse events were classified as mild and they were not, or highly unlikely to be, related to the study .In the present study, we investigated the effect of three different intraoperative management regimens using either standard conditions with a heating blanket with forced air warming and dry insufflation gas at room temperature (group “AIR”), no heating blanket, but warm and humidified insufflation gas (group “HUMI”) or both a heating blanket with forced air warming and warm and humidified insufflation gas (group “HUMI +”). Importantly, we could not detect clinically relevant differences over the whole patient population. We could work out that patients suffering from endometriosis and patients without previous abdominal surgery profited from the use of humidified insufflation gas.Although reduced in comparison to open surgery, pain after laparoscopic surgery is a common phenomenon exceeding the pure nociception by wounds, drains, or sore intra-abdominal tissue. Knowledge about “head zones” is well described in several pathologies, and the occurrence of shoulder pain after laparoscopic surgery is common. Some studies have indicated that the use of dry insufflation gas to establish the capnoperitoneum might increase the nociception or, in fact, induce an inflammatory reaction of the peritoneal tissue –15.In our study, we could not detect differences in postoperative pain in groups “HUMI” and “HUMI +” versus group “AIR” besides the timepoint “arrival at PACU” between group “HUMI +” and group “AIR.” The actual VAS score for abdominal pain in group “HUMI +” was 0  and 1.5  in group “AIR” at this timepoint; therefore, we interpret this significant difference as an effect of direct individual anesthesia but not of the intervention. Interestingly, there is no difference in the amount of postoperative analgesic medication  which could explain this difference. Moreover, the use of analgesics on the day of surgery did not differ significantly, which could have been expected, if pain was higher in groups “AIR” and “HUMI.” Additionally, the effects were not altered when combining the groups receiving warm and humidified gas with and without the intraoperative use of a heating blanket (group “HUMI” and “HUMI +”) versus the control group, where cold and dry insufflation gas was applied (group “AIR”).At day 2, we measured less consumption of Ibuprofen in group “HUMI +” compared to group “AIR,” while the effect did not occur in group “HUMI” versus group “AIR”; no other non-opioid was used differently that could have replaced ibuprofen in the other group. This difference may simply be due to the preferences of the treating physician or nurse on this day and, in our opinion, should not lead to the conclusion that group “HUMI +” really experienced less pain: in fact, in all patient groups, the VAS at day 2 was moderate with a VAS of 3 at rest and not significantly different.These findings are in line with Matsuzaki and her colleagues’ work that could not find differences between the likelihood of higher pain intensity (VAS > 3) in the PACU and a significantly higher use of opioid analgesics . This stConsidering that epidural anesthesia in some patients may have influenced our results, we performed the exploratory analysis to correct for this effect without major influence on the results: in fact, group “HUMI +” had less pain in PACU, but this effect did not extend through the next hours or days. Epidural anesthesia is a standard in a wide field of indications, even in laparoscopic surgery, and yields impressive results . HoweverOur post hoc analysis revealed two important results. First, patients suffering from endometriosis showed higher pain score levels than non-endometriosis patients nearly over the whole period during our observation Fig. A. HoweveWhen grouping our patients according to prior or non-prior abdominal surgery, we measured a higher pain level in patients without pre-existent surgery Fig. A, which Our study has several strengths and limitations that need to be addressed. First, the study design had a clear randomization, single blinding, a pre-defined surgical team, and a variety of measures to assess “pain” in a well-defined homogeneous population.Since the study was designed to address heating capabilities and pain reduction, three groups were constructed, although for the research question, if humidified and warm insufflation gas reduces postoperative pain, a two-sided model would have been sufficient. In our analysis, we remained in the group “HUMI”/ “AIR” and “HUMI +”/ “AIR” design; one model was calculated with both groups pooled against group “AIR” without changing significance levels and under consideration of statistical balancing. Because we did not see any differences, we remained in the three-group model to follow the investigation plan properly.This study was powered to detect a difference in intraoperative core body temperature. As a limitation, we must mention that no power was calculated for questioning pain score differences.The unequal distribution of patients stratified by previous abdominal surgery is worth mentioning. While the endometriosis/ non-endometriosis patients are nearly equally distributed, there are 66% with previous abdominal surgery and only 1/3 without. Therefore, we must assume that the results stratified by previous abdominal surgery are perhaps less meaningful.It is of interest whether the results of this monocentric study can be extrapolated to other patient populations  or reproduced in other hospital settings.Further studies on the pathogenetic mechanisms of the observed differences, involving inflammatory pathways and HIF-1α, especially in the subgroup of patients with endometriosis, are needed.The adverse events we recorded were overall mild and not related to the study and unlikely explainable simply by the use of differently warm and humid insufflation gas.Application of prewarmed and humidified insufflation gas during laparoscopic surgery was not clinically relevant in reducing post-surgical pain in a mixed gynecological patient population. However, patients suffering from endometriosis or patients with expected high pain levels, in our study patients without a history of abdominal surgery, showed less pain up to several days. Therefore, in predisposed patients the use of preheated and humidified insufflation gas may be beneficial.Supplementary file1 (DOCX 103 kb)Below is the link to the electronic supplementary material.


Percutaneous nephrolithotomy (PCNL) is a minimally invasive procedure for removing renal calculi, while a large number of patients experience acute moderate-to-severe pain despite the analgesia provided. This study aimed to explore the risk factors for postoperative pain after PCNL, which may provide a novel perspective to refine the enhanced recovery after surgery (ERAS) program and to improve clinical outcomes. The clinical data of 331 patients who underwent PCNL in our hospital from September 2020 to February 2021 were retrospectively analyzed. The pain intensity was assessed every 4 h until 24 h post-surgery. According to the visual analog scale (VAS) score, patients were divided into two groups: mild or no pain group  and moderate-to-severe pain group . The pre-, peri-, and post-operative data were collected and analyzed. The indicators with statistically significant differences were selected, and multivariate logistic regression analysis was employed to determine the risk factors for postoperative pain after PCNL. Among 331 patients, 221 patients had moderate-to-severe pain and the incidence rate was 66.77%. Multivariate logistic regression analysis showed that the independent risk factors for moderate-to-severe pain after PCNL were the diameter of the renal calculus (odds ratio (OR) = 6.23, 95% confidence interval (CI) 2.50–15.56, P = 0.001), the number of renal calculi , the presence of residual calculi , and operation time . The diameter of the renal calculus, the number of renal calculi, the presence of residual calculi, and operation time were significant predictors of postoperative pain after PCNL. According to the European Association of Urology guidelines, percutaneous nephrolithotomy (PCNL) is the first-line treatment for large (> 2 cm), multiple, and inferior calyx renal stones2.Over the past two decades, open surgery has been almost completely replaced by minimally invasive procedures for patients with kidney stones5. It may originate from the renal capsule, muscle, subcutaneous tissues, and skin6.However, to date, few studies have concentrated on the postoperative pain after PCNL. Minimally invasive surgery is not painless, and postoperative pain after PCNL includes creation of a percutaneous access tract through the parenchyma and parenchymal shearing, renal pelvic pressure, renal tissues, visceral pain mainly accompanied by autonomic nerve reaction, and low back pain caused by indwelling nephrostomy tube7. Since the urinary system is innervated by the same autonomic nerve as the gastrointestinal system, pain may cause reflexive nausea and vomiting4.Anatomical studies showed that the main sources of acute postoperative pain after PCNL were visceral pain from kidneys and ureters and body surface pain from incisions. Renal pain originates from the T10-L1 spinal nerve, and ureteral pain originates from the T10-L2 spinal nerve. However, the incisions and pathways are typically formed under the 12th rib or between the 10th and 11th ribs, where a cutaneous innervation is mainly undertaken by T10–11. Indwelling of renal fistula, peritubular compression of renal cortex, and dilation of renal capsule may also aggravate postoperative pain. However, discomfort, stress, and pain associated with nephrostomy highlight the importance of postoperative analgesia. Additionally, stones were discharged from the ureter due to changes in body position when residual stones or large stones (4–5 mm) were directly flushed into the ureter due to fluid flow intraoperatively and moved into the ureter. Because calculi stimulate mucous membrane of the ureter and cause ureteral spasm,ache typically lasts longer8. If postoperative pain is not timely alleviated, it may result in adverse consequences, such as delay of activity, pulmonary dysfunction, prolonged hospitalization, and even septic shock and renal failure in some severe cases9. More importantly, transition of acute pain to chronic pain may occur, seriously influencing patients’ quality of life.The pain is mainly associated with severe postoperative somatosensory and visceral pain, necessitating a substantial action for postoperative opioid consumptionThe present study aimed to identify the predictors for the postoperative pain after PCNL, which may provide a novel perspective to refine the enhanced recovery after surgery (ERAS) program and to improve clinical outcomes.The study protocol was approved by the Ethics Committee of Beijing Tsinghua Changgung Hospital , and the study was conducted in accordance with the tenets of the Declaration of Helsinki. Written informed consent was obtained from all eligible subjects or their entrusted representatives before enrollment.2; and (5) signing the written informed consent form. The exclusion criteria were as follows: (1) history of surgery for ipsilateral renal stones; (2) severe urinary tract infection; (3) severe cardiac and pulmonary insufficiency and coagulation disorders; (4) a spinal deformity, an underlying pathology, or history of surgery for prior spinal cord injury; (5) neurological disorders, psychiatric disorders or experience of substance abuse.The clinical data of 331 patients who underwent PCNL in Beijing Tsinghua Changgung Hospital from September 2020 to February 2021 were retrospectively analyzed. In conformity with the occurrence of postoperative pain, patients were divided into mild or no pain group and moderate-to-severe pain group. The inclusion criteria were as follows: (1) patients undergoing elective PCNL under general anesthesia; (2) patients aged 18–70 years old; (3) American Society of Anesthesiologists (ASA) grade I–III; (4) body mass index (BMI) of 18–35 kg/m2) were routinely monitored.According to the ordinary preoperative fasting guidelines, patients were prohibited from both food and fluids for at least 8 h prior to surgery. A preventive antibiotic  was given 30 min before surgery. Venous access was established in the upper extremities, and the blood pressure (BP), electrocardiogram (ECG), heart rate (HR), and pulse oxygen saturation  at 40–60%, and these parameters were measured every 5 min throughout the procedures. After proper padding of eyes, patients were kept in prone position, and all pressure points were secured.All patients underwent general anesthesia using the same type of medication. General anesthesia was induced with intravenous propofol (2 mg/kg) plus sufentanil (0.4 µg/kg), and neuromuscular blockade was achieved with rocuronium (0.6 mg/kg) and maintained with combined intravenous–inhalation anesthesia. After endotracheal intubation, the mechanical ventilation was performed with tidal volume of 6–8 mL/kg, 12 breaths/min. Anesthesia was maintained with a minimum alveolar concentration (MAC) of sevoflurane (1.5–2.5%) in a 60% oxygen and air. Nitrous oxide was not used. Remifentanil infusions (0.1–0.2 μg/kg/min) were used for analgesia. Expiratory CO10.Under the guidance of B-mode ultrasound, the area between the posterior axillary line and the scapular line was selected as the puncture point under 12 ribs or between 11 ribs according to the distribution of calculi. After puncturing the target calyx, a guide wire was placed to dilate. Two-step or balloon dilation can be used to establish a standard channel  for recovery. Neostigmine and tropine were used to antagonize residual neuromuscular block when necessary. Endotracheal tube was removed if patients were awake with absence of respiratory failure, residual paralysis, and overdose of opioids. All patients were extubated in PACU, and were then sent to the ward when their modified Aldrete score was more than 13.Participants’ pain was assessed using the visual analog scale (VAS) scoring system. It is a standard and verified 10-point scale for pain self-report, where a score of 0 represents no pain and a score of 10 represents the highest pain level. VAS scores were assessed by a well-trained doctor at 30 min immediately after extubation, followed by every other 4 h until 24 h post-surgery in the ward.All patients did not receive patient-controlled intravenous analgesia (PCIA) postoperatively. The pain intensity was assessed using the VAS scoring system during rest and cough every 4 h thereafter until 24 h post-surgery. Patients were divided into two groups based on VAS pain score: mild or no pain  and moderate-to-severe pain . Rescue analgesia was intravenously administered according to the protocol, and patients were treated with parecoxib sodium (40 mg IV) when they complained of moderate-to-severe pain and two injections should be given at least four hours apart.Data collection was performed by urologists and anesthesiologists for age, gender, BMI, ASA grade, diameter of the renal calculus, degree of hydronephrosis, preoperative urine culture, expansion method, tract diameter, the presence of residual calculi, preoperative analgesia, underlying disease, puncture time, number of expanded channels, operation time, postoperative complications (Clavien–Dindo classification), number of renal calculi, and VAS pain score. Postoperative adverse events included postoperative nausea and vomiting (PONV), high and low BP, bradycardia, pruritus, and respiratory depression.t-test or χ2 test. The Kolmogorov-Smirnoff single-sample test was used to assess the normal distribution of continuous variables before further comparisons. The Chi-square test was utilized for comparison of the two groups. When P was < 0.05, the difference was regarded as statistically significant. Multivariate logistic regression analysis was used to analyze the statistical significance of the indicators.SPSS 25.0 software  was used to perform statistical analysis. Measurement data were expressed as mean ± standard deviation and were analyzed by the This study was approved by the Ethics Committee of Beijing Tsinghua Changgung Hospital. All patients signed the informed consent form. The procedures did not require any additional intervention, and all data were analyzed anonymously. All methods were carried out in accordance with relevant guidelines and regulations.P < 0.01), the diameter of the renal calculus (P < 0.01), the presence of residual calculi (P = 0.017), and operation time (P < 0.01) were significantly different between the two groups  renal stones and/or staghorn renal stones. However, it is difficult to perform PCNL, which is greatly affected by the composition, size, and location of the stones. Severe cases are mainly complicated by septic shock and renal failure13. At present, there are few reports on the causes and risk factors of postoperative pain after PCNL. Haotian et al. showed that the incidence of moderate-to-severe postoperative pain after PCNL was about 60%14. It was revealed that our results were similar to Ahmet et al.’s findings which showed that the issue of PCNL-pain during postoperation period has not yet been completely solved15. In the present study, the clinical data of 331 patients were analyzed to identify risk factors and provide a reliable reference for clinicians to alleviate moderate-to-severe postoperative pain after PCNL.There is a global increase in the incidence of renal calculi in all age groups owing to changed dietary habits and global warmingIn the present study, it was found that there were no significant differences in age, gender, BMI, ASA grade, degree of hydronephrosis, preoperative urine, culture, expansion method, tract diameter, preoperative analgesia, underlying disease, puncture time, number of expanded channels, and postoperative complications (Clavien–Dindo classification) between the two groups (P > 0.05). Multivariate logistic regression analysis showed that the independent risk factors for postoperative pain after PCNL included the diameter of the renal calculus, the number of renal calculi, the presence of residual calculi, and operation time.16.Before surgery, all patients received plain computed tomography (CT) scan of the urinary system, accompanied by a high-resolution spatial presentation, and it possessed significant advantages in indicating the size, number, and location of calculi. Large calculi or large stone burdens may expand the surgical scope and prolong operation time, which can cause perfusion fluid imbalance and lead to the increase of internal pressure of the renal pelvis. The higher internal pressure of the renal pelvis, stone crushing after the release of bacteria and toxins associated with lavage by renal pelvis renal sinus, peripheral vascular and lymphatic vessels of the renal pelvis and renal pelvis venous reflux into the blood, thus, increase the risk of infection, and this leads to the release of cellular mediators, causing pain13. More time and greater intensity of lithotripsy are needed intraoperatively, aggravating the postoperative pain. It is noteworthy that partial or complete staghorn stones will have a longer operation time, a larger volume of blood loss, and more severe postoperative pain.Due to the high-resolution CT, stones containing calcium, phosphorus, and magnesium (positive stones) or uric acid stones (negative stones) can be displayed on CT images, which shows the shadow of stones with an increased density, and highlights a "calcification point". The greater the CT value (Hounsfield Units), the greater the stone hardness17. Inadequate analgesia can result in an increased morbidity, delayed or impaired ventilation, and prolonged hospitalization, which may increase the medical costs.Postoperative pain after PCNL has important negative effects on patients’ postoperative rehabilitation, daily activities, quality of life, and social and economic conditions26. They can play a role after the onset of postoperative pain, at the same time different analgesic drugs have different adverse reactions27. Poorly managed acute pain has the potential to progress to chronic pain28, which remains a significant burden to the rehabilitation of patients. Thus, a clearer understanding of acute pain can help minimize the occurrence of acute-to-chronic pain transition.An effective management of postoperative pain is essential to reduce the morbidity of PCNL. There are several methods for reducing postoperative pain, including control of local anesthetic pressure during surgery, use of paravertebral block (T11-L1), application of erector spinae plane block, use of thoracic paravertebral block, application of quadratus lumborum block III, use of intercostal nerve block, opioid analgesia using intravenous patient-controlled analgesia, reduced size of nephrostomy tube, and no placement of a nephrostomy tube29. It aims at accelerating postoperative recovery, improving patient outcomes, and reducing medical costs30. An effective perioperative pain management is a crucial part of the ERAS program31. If we can predict and manage the risk factors for preoperative pain, perioperative pain may be reduced, thus accelerating patients’ recovery.The ERAS program has been applied to a variety of surgical procedures in recent yearsOur study has some limitations. Firstly, the pain intensity was examined using a self-reported scale, and as the threshold of tolerance varied from person to person, the results might be affected. Secondly, this was not a prospective, randomized controlled trial. We expected that there would be a certain correlation between Clavien–Dindo surgical complications and pain score, while it was not found. This may be related to the small sample size that influenced our results. Further multi-center studies with large sample size and long-term follow-up are therefore required to obtain more accurate clinical data for in-depth analysis. Thirdly, the high incidence of postoperation pain was found within three days after surgery. Our clinical observations showed that PCNL-pain occurred more frequently in the first 24 h, so we only evaluated the VAS pain score within 24 h after surgery not within three days. Last but not least, the pathophysiology of postoperative pain after PCNL was not explored.In summary, the diameter of the renal calculus, the number of renal calculi, the presenceof residual calculi, and operation time were significant predictors of postoperative pain after PCNL. Early identification of the risk factors for moderate-to-severe postoperative pain after PCNL and formulation of reasonable preventive measures are essential to control the onset of pain and to improve patients’ quality of life.


Health‐related quality of life (HRQoL) of orofacial pain patients is lower than that of the general population and impaired in multiple dimensions. The aim of the present study was to investigate HRQoL of orofacial pain patients in comparison with patients suffering from other chronic pain disorders.t test, χ2 test, or analysis of covariance. Multivariate linear regression analysis was used to study whether pain‐related aspects influencing HRQoL are similar between the patient groups.One hundred and fifty‐one tertiary care facial pain patients , were compared with 312 other non‐cancer chronic pain patients , recruited from three multidisciplinary pain clinics in Finland. The groups were compared using the 15D, and pain‐related measures such as pain interference, pain acceptance, anxiety, depression, and sleep. Statistical comparisons between groups were done using p < .001). The 15D profiles of studied populations resembled each other but orofacial pain patients showed significantly higher scores for most individual 15D dimensions. Dimensions regarding discomfort and symptoms and sleep were most affected in both groups. Orofacial pain patients showed less psychosocial disability and better acceptance of their pain. Pain acceptance was a weaker explanatory factor of HRQoL in orofacial pain patients.The 15D score was significantly higher in facial pain patients  indicating better HRQoL in comparison with other chronic pain patients  (Compared to other non‐cancer chronic pain, chronic pain in the orofacial area causes less impairment in HRQoL. Orofacial pain patients showed less psychosocial disability and better pain acceptance. An informed consent was obtained from all participants.Among the recruited consecutive 164 orofacial pain patients, four patients refused to participate and nine patients did not return questionnaires or answered them incompletely. Finally, 151 orofacial pain patients were included in the study. For patients suffering from other pain conditions, formation of the study data set is described in previous studies reporting on the KROKIETA study . It consists of 15 dimensions: mobility, vision, hearing, breathing, sleeping, eating, speech, excretion, usual activities, mental function, discomfort and symptoms, depression, distress, vitality, and sexual activity. For each dimension, the respondent chooses a statement about the severity of problems that best reflects his or her health state in that dimension. The valuation of the 15D is based on an application of the multi‐attribute utility theory, including a three‐stage valuation procedure performed in the general population. An overall single index score (the 15D score) and separate scores for individual dimensions are calculated based on mean dimension values. The maximum overall 15D score as well as the scores in individual dimensions are 1 (indicating no problems) and the minimum score is 0 .Health‐related quality of life (HRQoL) was measured using the 15D instrument. It is a self‐administered, standardized, generic, HRQoL instrument with 15 dimensions. It can be used both as a profile and a single index utility measure      was set at .05 for all tests. All analyses were performed using STATA software, version 16.1 .Data are expressed as the mean and standard deviation (SD) and counts with percentages. Statistical comparisons between groups were done using y Cohen, . In the 3The two studied patient populations were similar with regard to age, education, and other socioeconomic factors. Facial pain patients were more often female than the other pain patients. Duration of pain in the patient populations was found to be very similar, the majority of patients in both groups had suffered from pain disorders for more than 2 years Table .Lifestyle of the facial pain patients was generally more favorable compared with patients suffering from other chronic pain conditions. Facial pain patients smoked less, consumed less alcohol, and were somewhat more physically active at leisure time. The household income level did not differ between the groups. When compared with the other pain patients, facial pain patients had less problems related to sleep, they reported less depressive and pain‐related anxiety symptoms and showed better acceptance of pain. Pain intensity and interference scores were also lower in the group of patients with facial pain. Comparison of demographic and socioeconomic data, lifestyle factors, and pain‐related measures are presented in detail in Table p < .001), indicating a better HRQoL for patients with orofacial pain in comparison with the other chronic pain patients  compared with the other chronic pain patients (0.732)  of chronic orofacial pain patients in comparison with patients suffering from other chronic non‐cancer pain conditions. In addition to HRQoL, pain‐related measures, such as pain intensity and interference, pain acceptance, pain‐related anxiety, depression, and sleep, were investigated. On the whole, orofacial pain patients were found to perceive their HRQoL better than other chronic non‐cancer pain patients. The studied patient groups demonstrated similar profiles of the 15D, but the scores of orofacial pain patients were statistically significantly higher regarding almost all dimensions of HRQoL. Only for the dimension regarding eating, did orofacial pain patients report significantly lower scores. When compared with the other pain patients, the facial pain patients reported lower pain intensity and interference, less depressive and pain‐related anxiety symptoms, and had less problems related to sleep, but showed better acceptance of pain. No significant differences were noted in the influence of these pain‐related aspects on quality of life except for pain acceptance that seemed to be a stronger explanatory factor of HRQoL in patients with other chronic pain problems compared to orofacial pain patients.Based on the findings of the present study, chronic pain in the orofacial region seems to cause less burden as regards quality of life and psychosocial wellbeing than other chronic pain conditions. An explanation behind this difference may be that bodily pains are likely to have a more severe effect on for example, mobility and usual activities, compared with those caused by orofacial pain conditions. Health‐related quality of life of chronic pain patients is found to be more impaired in patients suffering from widespread pain compared with patients with only few pain locations (Lamé et al., Using the 15D instrument to measure HRQoL enables comparison of different patient populations with regard to quality of life and its different dimensions. In the present study orofacial pain patients received a higher score for both the 15D score and for nearly all individual dimensions of the 15D instrument. In general, the 15D profiles of the two studied patient groups resembled each other, with both populations showing their lowest scores for discomfort and symptoms, which is in line with previous findings (Dick et al., The studied patient populations did not differ with regard to sociodemographic variables, except that facial pain patients were more often females. Instead, differences were seen in health habits and psychological symptoms. Orofacial pain patients lead a generally more active and healthy lifestyle. In addition to a more favorable health behavior, such as low consumption of tobacco and alcohol, orofacial pain patients were more physically active at leisure time. Healthier lifestyle is often linked to better socioeconomic position, though here the household income levels were identical in studied patient groups. Previous studies have associated higher pain interference to lower recreational activity (Karoly & Ruehlman, Chronic pain and psychological problems often occur simultaneously and overlap. In the present study orofacial pain patients showed lower psychosocial disability and better acceptance of their pain compared to other chronic pain patients. Acceptance of pain is generally viewed as willingness to experience continuing pain without the need to control it (McCracken, β coefficients might indicate that pain acceptance is more important for the overall well‐being in other chronic pain than in orofacial pain, or that the relationship of pain acceptance and HRQoL is not linear, that is, the interdependency is stronger in more severe symptoms. Since facial pain patients had more favorable results in most of the measured aspects, their perceived better HRQoL is likely to be a net effect of several of these or other factors not covered in this study.Results of the regression analysis indicated that all studied pain‐related measures had a strong impact on HRQoL. The two patient groups were similar regarding the impact of these factors except for pain acceptance, which was a stronger explanatory factor for the HRQoL outcome of patients with other chronic pain. These patients showed poorer acceptance of pain and their HRQoL was more impaired. This difference in 4.1The groups of patients were similar with regard to pain duration. In both groups over 70% of patients had experienced pain for more than 2 years, indicating that both patient groups represented patients with long‐lasting chronic pain problems. A limitation of the study was that information on comorbid pain conditions or other medical comorbidities were not assessed. Many chronic medical conditions are associated with chronic pain and the number of comorbidities has been shown to correlate with HRQoL of chronic noncancer pain patients (Dick et al., The 15D instrument was chosen to be used in this study because its validity in the study of chronic pain has been demonstrated in previous research (Vartiainen et al., A possible disadvantage of the present study is the use of a generic HRQoL instrument. It is known to be less sensitive than a condition‐specific instrument and may thus not distinguish all relevant features of the disease. However, using a generic instrument enabled us to make comparisons of HRQoL with a patient population suffering from other pain conditions.5Chronic pain in the orofacial area causes less impairment in HRQoL than does other chronic non‐cancer pain. Furthermore, the patients have a lower pain burden in general; they suffer less from psychosocial disability, show better pain acceptance and engage a healthier lifestyle. There are no differences in the pain‐related factors influencing HRQoL in the two patient groups except for pain acceptance; pain acceptance explains the HRQoL more strongly in patients with other chronic pain problems compared to orofacial pain patients. Despite the findings of better HRQoL and psychosocial functioning in orofacial pain patients in comparison with other chronic pain patients, the results of this study are in line with earlier studies in showing that orofacial pain affects a broad spectrum of health dimensions. This emphasizes the importance of comprehensive assessment and care in chronic orofacial pain. The present results might, however, indicate that not all patients with chronic orofacial pain need as comprehensive and as multidimensional care as is often indicated for patients with other non‐cancer pain problems, but this needs corroboration.Johanna Tanner drafted and edited the manuscript and participated in the analysis of the data. Tuija Teerijoki‐Oksa collected the data and participated in manuscript editing. Hannu Kautiainen analyzed the data and participated in drafting and editing the manuscript. Pekka Vartiainen participated in manuscript editing. Eija Kalso and Heli Forssell conceptualized the study, defined the methodology, and participated in data analysis and manuscript editing.The authors declare no conflicts of interest.


To investigate the effect of thoracolumbar interfacial plane block (TLIP) on analgesic consumption and pain score in vertebral surgery.All patients  were randomly allocated as Group T  and Group C . After surgery, patient-controlled analgesia using tramadol was administered to all patients. Pain intensity was evaluated with visual analogue scale , and as rescue analgesia, morphine was administered to patients with VAS scores of >4. In this study, total tramadol consumption, the number of patients requiring morphine, VAS score, and Quality of Recovery-40 of all patients questionnaire was evaluated.p=0.001) and the number of patients requiring additional analgesia . There were important differences between the 2 groups according to the postoperative VAS pain score (p=0.000).There were important differences between the 2 groups according to mean postoperative tramadol consumption (Group T and Group C; 180 mg [100-260] vs. 210 mg [100-300]; Ultrasound-TLIP reduces analgesic consumption and pain severity after vertebral surgery. Therefore, it is an important regional analgesia technique.NCT04548076 Vertebral surgeries are common surgical procedures, and lumbar instrumentation surgery is especially associated with significant pain and immobility. Pain in vertebral surgery may arise from the skin, muscle, tissue trauma, and surgical incision. Insufficient pain control can reduce patient satisfaction, chronic pain, and prolong hospital stays. Therefore, efficient and safe methods of administering postoperative analgesia for the achievement of early recovery and better outcomes is essential. Nonsteroidal anti-inflammatory drugs, paracetamol and opioids are used for pain. In addition, regional anaesthesia techniques  are used to reduce the nausea, vomiting, and constipation associated with opioids and also for pain control. This block can be easily applied with a low risk of complications. Thoracolumbar interfascial plane block can be carried out via 2 different approaches; the classical (cTLIP) technique and the modified (mTLIP) technique with ultrasound guidance. The cTLIP technique involves the administration of local anaesthetic between the multifudus and longisumus muscles, and the mTLIP technique administers it between the longisumus and iliocastalis muscles.Thoracolumbar interfascial plane (TLIP) block has been used in recent years.In this study, the effect of TLIP block on analgesic consumption and pain score in vertebral surgery was investigated.It is a study carried out as a prospective, randomized in patients planned vertebral surgery between September 2020 and August 2021 at Tokat Gaziosmanpasa University Hospitals, Tokat, Turkey. Local Ethics Committee of Tokat Gaziosmanpasa University, Tokat, Turkey, (20-KAEK-076) approval was obtained. All patients provided written informed consent for this study and the Declaration of Helsinki was complied with. The inclusion criteria were a total of 64 patients (18-65 years), that were scheduled for lumbar disc, and 2-, 3- or 4-levels of posterior lumbar instrumentation surgery, with a physical status American Society of Anesthesiologists I-III. Patients with chronic pain, preoperative analgesic consumption, bleeding diathesis, anticoagulant, or corticosteroid use with patients who canceled the procedure and refused further participation were excluded. The study was completed with 64 patients  1 μg/kg fentanyl  and 0.6 mg/kg rocuronium bromide . Anesthesia was continued with sevoflurane  (1 MAC) and 50/50 oxygen/air. After general anesthesia in the group TLIP(+), a 20 mL mixture of 0.25% bupivacaine  and 1% lidocaine  was injected bilaterally between the longissimus and multifidus muscles at the third lumbar vertebra (L3) in the prone position with a 100 mm - 20-G needle (Vygon) under the guidance of a high linear probe of the ultrasound system  and the device was set up such that there was a 20 mg bolus dose, a 10-minute lock time, and a maximum of 3 doses per hour. Again, 10 mg/kg paracetamol  every 8 hours was routinely prescribed to all patients. The VAS score for pain was evaluated in the recovery room at 1, 2, 6, 12, and 24 hours. For patients with a VAS score of >4, a rescue analgesic  was administered. The Quality of Recovery-40 (QoR-40) questionnaire was completed to evaluate patient satisfaction at the 24A pilot study revealed that the total tramadol consumption of patients who did not undergo TLIP was found to be 240±50 mg. Assuming a 15% reduction in tramadol consumption in patients undergoing TLIP (a power of 80% [beta=0.2]) with a 5% significance level , 60 patients were required to detect a statistically significant difference.p-value of <0.05 was considered significant.The Statistical Package for the Social Sciences, version 20.0  was used. The normality was evaluated using the Kolmogorov-Smirnov test. The Mann-Whitney-U test, Pearson’s chi-squared test, or independent samples t-test were carried out to compare the data. A A total of 64 patients  were analysed in this study. From the Group T, 2 patients refused to fill out the questionnaire and from the Group C one patient re-operated and they were excluded. The data regarding the patients and surgery are presented in p=0.000; p=0.532; The postoperative VAS pain score was statistically lower in Group T p=0.000; . The quap=0.001, 12.5% vs. 75%; p=0.000; Postoperative tramadol consumption and the number of additional analgesia were found to be lower in Group T  and vomiting (p=0.545; There was not difference between the groups according to postoperative nausea (p=0.545; .Thoracolumbar interfascial plane block significantly reduces postoperative tramadol consumption, morphine requirement for rescue analgesia, and VAS pain score within 24 hours following vertebral surgery. It is hence an important regional analgesia technique for vertebral surgery. The standard analgesia protocols for spine surgery usually include opioids for adequate pain management. High-dose opioids can be used in these patients, but they can result in side effects such as nausea, vomiting, and constipation. Therefore, alternatives analgesic methods are important for both reducing opioid requirements and promoting the early mobilization of patients.Vertebral surgeries are common surgical procedures that are being carried out increasingly frequently. Patients undergoing such surgeries may suffer from moderate to severe pain. In this study, we found that the TLIP block decreased patient consumption of opioids and provided adequate analgesia. There are similar prospective studies that reported similar results. Ammar et al used a 20 mL mixture of 0.25% bupivacaine and 1% lidocaine on each side, and Ueshima et al used 20 mL of 0.375% levobupivacaine on each side. According to these study, TLIP block provided effective analgesia after vertebral surgery.Thoracolumbar interfascial plane block is a type of interfascial block and at the L3 level have an analgesia that spreads from L1-S1.We found that the requirement for morphine for rescue analgesia was reduced in the TLIP group. In a study of lumbar fusion surgery patients, an average of 23 mg of morphine was administered in patients who did not undergo TLIP, but not required in patients who underwent TLIP. The same differences in VAS pain scores were also noted in a different study involving lumbar disc surgery.The VAS pain scores in the postoperative period were significantly lower in the TLIP group, which is in line with other studies showing similar results. In patients who underwent lumbar spine fusion surgery, the VAS pain scores for patients at movement and at rest were significantly lower compared to patients who did not receive TLIP block. This could be explained by the fact that VAS pain values were generally ≤4 in both groups and that there were no differences in nausea and vomiting between the groups.The Quality of Recovery-40 is used to evaluate the quality of healing. In one of these studies, the quality of recovery and the patient’s postoperative health status were better in the TLIP group, but we failed to see such a difference in our study.First, groups has heterogeneous patient scheduled lumbar disc and lumbar instrumentation surgery. Thus, planning a study for only one indication might be beneficial. Second, this prospective study has a relatively small sample size. Finally, because of general anesthesia, it was not detected whether or not there was a lost sensory area after the block procedures.In conclusion, bilateral TLIP block could provide sufficient analgesia and significantly reduce patient opioid consumption after vertebral surgery. Therefore, it is an important regional anesthesia technique that can be used for multimodal analgesia.