Video-assisted cardiopulmonary resuscitation (V-CPR) describes an advanced telephone-assisted CPR (T-CPR), in which emergency medical service (EMS) dispatchers view a live video steam of the resuscitation. Dispatchers ‘ general attitudes toward and self-assessment in V-CPR have not been previously investigated.We conducted this quantitative analysis along with a pilot study on V-CPR. After conducting V-CPR with laypersons in a simulation, EMS dispatchers were given questionnaires with 21 items concerning their personal attitude toward V-CPR and their self-assessment in providing instructions. The actual CPR performance achieved was recorded and compared to the dispatchers’ self-assessments.Dispatchers completed 49 questionnaires, and the data is presented descriptively. Over 80% strongly agreed that V-CPR was helpful in guiding and that their feedback improved CPR quality. Fifty-one percent agreed that video images supported them in making a diagnosis, while 44.9% disagreed. A vast majority (80–90% each) strongly agreed that V-CPR helped them recognize CPR issues such as compression point, compression rate, and deterioration. In contrast, data for improved compression depth and release were weaker. Thirty percent found V-CPR to be more stressful or exhausting than T-CPR. A majority stated they would prefer V-CPR as an addition to T-CPR in the future. There was a huge gap between dispatchers’ own view of CPR effort and measured CPR quality.Dispatchers generally embrace V-CPR and praise the abilities it provides. Our results indicate that the use of V-CPR did not automatically result in an overall improvement in guideline-compliant CPR quality. Telephone assistance by emergency medical service (EMS) dispatchers during cardiopulmonary resuscitation (CPR) has proven to improve patient outcome and is strongly endorsed by international guidelines.To overcome this uncertainty and improve patient outcome in cardiac arrest, novel technologies now enable the dispatcher to see a live video stream from the caller’s smartphone of the actual CPR effort. This facilitates video-assisted CPR (V-CPR). Research on the effectiveness of V-CPR has been focused primarily on resuscitation quality and recognition of typical mistakes.The Ethics Committee of the University of Cologne approved the study , which was conducted in accordance with CONSORT guidelines specifically under the pilot and feasibility statement.ClinicalTrials.gov (Identifier: NCT03527771).The study was registered at This quantitative analysis was conducted in a subgroup of a pilot study on V-CPR from July–August 2018 in the facilities of the University Hospital of Cologne.Fifty healthy adult volunteers with no medical background were recruited from passersby at the study location. Volunteers were blinded to the study objective. They were told that they would be confronted with a medical emergency situation and were instructed to handle it to the best of their ability. They were given a study smartphone to “call EMS if necessary.” After giving written and informed consent, these participants were accompanied into the simulation room by a study assistant who was equipped with a smartphone . Participants were instructed to provide “appropriate first aid according to their own best knowledge and skills.” During the CPR scenario, using the phone for an emergency call automatically established a video connection from the caller’s phone to the dispatch center. The study assistant operated the phone and placed himself with the camera facing participants and manikin in a predefined position.What do we already know about this issue?Telephone assistance by Emergency Medical Services (EMS) dispatchers during CPR improves patient outcomes. Video-assisted CPR (V-CPR) could be a consistent further development of the current Telephone-CPR (T-CPR).What was the research question?We evaluated dispatchers’ attitude toward V-CPR using a post–interventional questionnaire after a simulated V-CPR situation.What was the major finding of the study?Although dispatchers embrace the abilities of V-CPR, there is a discrepancy between the assessment and actual quality of CPR.How does this improve population health?While V-CPR has the potential to strongly improve resuscitation quality, it is important to train and guide EMS dispatchers in V-CPR to sustain the best results.The dispatcher followed a standardized, structured dispatching protocol, quickly guiding the caller through the most important questions and toward the correct diagnosis. After detection of cardiac arrest, the dispatcher informed the participants that the patient was in cardiac arrest and needed resuscitation. The dispatcher then activated the video livestream and started standardized, video-guided compression-only CPR according to the 2015 European Resuscitation Council Guidelines for Resuscitation.After each V-CPR, the dispatcher was given a questionnaire we developed, which consisted of 21 items focusing on the dispatcher’s personal attitude toward V-CPR and its usefulness in providing CPR instructions. For each question, answers could be given on a four-point Likert scale. These questionnaires were then descriptively and quantitatively analyzed. We conducted descriptive analysis using SPSS version 25 . Results are presented as absolute and relative frequencies.Fifty V-CPR sequences were eligible to be analyzed in this study. In one case, due to technical problems no video was transmitted, and hence no questionnaire could be completed. All remaining 49 attempts were successful and resulted in instructed V-CPR for eight minutes. In all these cases, a questionnaire was completed by the dispatcher in charge. Thus, 49 complete questionnaires were obtained for further analysis.In this study the mean age of the dispatchers was 54 years ± 6.9 years. All participating dispatchers were male, and all had more than 10 years experience as EMS dispatchers.When asked whether the video image irritated them while instructing CPR, 95.9% of the dispatchers strongly disagreed (Item 1). Over 80% strongly agreed that V-CPR was helpful in guiding subjects in CPR (Item 2) and 75.5% strongly agreed, while the rest agreed that the video image offered a new quality in the emergency call inquiry (Item 3). Regarding the question of whether the video image helped with the emergency call inquiry, only 55.1% strongly agreed and 38.8% agreed, while 6.1% disagreed (Item 4).Fifty-one percent agreed that video streaming supported them in making a diagnosis, while 44.9% disagreed with that statement (Item 5). In contrast, 85.7% strongly agreed that the video showed them errors in the resuscitation effort of the subject (Item 6), while 14.3% disagreed. Regarding certain CPR issues, such as correct compression point (Items 7), rate (Item 8) and compression fatigue (Item 11), 81.6%, 93.9% and 81.6%, respectively, strongly agreed that V-CPR helped them to recognize mistakes. For CPR quality issues, such as compression depth and release (Items 9 and 10), only 59.2% and 63.3% strongly agreed, while 18.4% and 20.4 % disagreed. Still, 83% strongly agreed that they were able to see that their feedback improved the quality of the CPR effort through the video stream, while only 2% disagreed (Item 12).Over 77% of the EMS dispatchers found the image quality of the video to be sufficient, whereas 12% disagreed (Item 21). A majority of 95.9 % strongly agreed that V-CPR helped them recognize and give corrective feedback during CPR, which they would not have recognized with T-CPR only (Item 13). Additionally, 42% strongly agreed and 46% agreed that they had the impression V-CPR helped them motivate the subject more that T-CPR alone could have done (Item 14).Interestingly, 30% agreed that they found the video-assisted method more stressful or exhausting than the telephone-assisted method, while 63% strongly disagreed (Item 20). Still, 75% strongly agreed and 24% agreed that V-CPR was helpful in guiding the subjects on CPR and resulted in better CPR quality (Item 15). In addition, 85% strongly agreed that video-assisted CPR facilitates the instruction of CPR (Item 16). Regarding their own bias, 28% admitted that they were skeptical about video technology used in CPR, while 38% and 30%, respectively, disagreed or strongly disagreed that they were skeptical before (Item 19).Eighty-three percent disagreed that they would prefer T-CPR only in the future (Item 17). Sixty-one percent strongly agreed and 38% agreed that that they would like to see V-CPR as an aid in their dispatching work in the future (Item 18). A summary of the questionnaire and the corresponding results is shown in As actual CPR data about compression rate and depth was stored via the onboard software of the manikin, a direct comparison to the assessment of the dispatchers was possible. Regarding the statement of item 8, “The video image let me see errors in thorax compression rate,” 93.9% strongly agreed. Comparing it to the actual compression rate achieved in these cases, it became obvious that only 32.6% performed a correct mean compression rate over eight minutes, while the majority (67.4%) did not perform a correct mean compression rate recommended by the international guidelines on resuscitation .Regarding item 9, “The video image let me see errors in thorax compression depth,” approximately 60% strongly agreed that only 48.3% of the volunteers actually performed a mean compression depth over eight minutes according to the guidelines .Video-assisted CPR is a new tool for dispatchers to guide callers in providing CPR. While some studies focusing on the impact of V-CPR on CPR quality have been conducted, there is a paucity of research regarding EMS dispatchers’ attitudes to V-CPR.While the concept of V-CPR has been around for over a decade, its large-scale deployment in EMS was never achieved due to technical limitations.9A similar study to ours was conducted in 2008 in Norway. There, dispatchers were interviewed after simulated V-CPR sessions (with a Nokia N90). The answers in those taped interviews were then coded into categories, analyzed, and descriptively presented. The authors concluded that the video element improved the dispatchers’ understanding of the emergency situation and that it assisted them in their work. But in their assessment, the dispatchers also stated that the video picture could “interfere” with their normal protocol, as it sometimes could be “noisy,” “chaotic,” and distracting. They also complained that the image quality was sometimes insufficient, as motion of the camera led to “interference.”3With our study, conducted over a decade later with state-of-the-art technology, we tried to systematically investigate V-CPR acceptance and usefulness from the perspectives of EMS dispatchers, who are the key players in its utilization. The overwhelming majority of the dispatchers in our study felt that V-CPR was beneficial to their work, helpful in instructing CPR, and offered a new quality in the emergency query process. However, dispatchers were nearly split in their attitude of V-CPR helping them with their diagnosis, with a trend toward agreement.Dispatchers in general strongly agreed that the video stream showed them errors in the resuscitation effort. Namely, dispatchers in 80–90% of the cases strongly agreed it to be helpful in the recognition of the correct compression point, frequency, and compression fatigue. In contrast, only around 60% strongly agreed that V-CPR helped them to recognize mistakes in compression depth and release. Interestingly, however, we found a huge discrepancy between the assessment of the observed CPR and the actual performed CPR – as compression rate and depth were only correctly performed in 32% and 48% of the cases, respectively, in which the dispatchers strongly agreed that V-CPR helped them in recognizing these mistakes.The reason for this surprising discrepancy is not clear. On the one hand, this might be attributed to technical reasons, such as image quality, video frame rate, or the angle in which the scene was being filmed. Contrary to this, most dispatchers found that the video quality was sufficient to evaluate CPR, which is in strong contrast to studies from over a decade ago, in which V-CPR was deemed unfavorable due to its poor video quality.Another important reason for this contradiction might be attributed to the dispatchers’ operating experience with V-CPR. Even though trained and seasoned in T-CPR, the video element represents a new aspect to their work, as dispatchers are not yet accustomed to visually evaluate a live CPR. This might be enforced by our finding that about 30% conceded and agreed that the video-assisted method was more stressful or exhausting than normal T-CPR (while 63% strongly disagreed). We conclude that these might be indicators that dispatchers need special theoretical-practical training and perhaps emotional support before using V-CPR. Still, the majority of dispatchers in our study agreed that V-CPR facilitated their task and was advantageous to T-CPR and reported that they would like to see V-CPR become part of their dispatching work in the future.This study investigated a small group of only male, older, and very experienced dispatchers in an artificial scenario on a CPR manikin. Further studies should be conducted on a larger scale and perhaps in a real emergency situation with all genders to increase its generalizability.Video-assisted CPR is a novel technology that was highly embraced by EMS dispatchers in our study. Dispatchers praised the new abilities provided by it. However, our results indicate that the benefits of V-CPR are not a given, as use of V-CPR did not automatically result in an overall improvement in guideline-compliant CPR quality. Dispatchers need further training and guidance to integrate V-CPR into their workflow.


A retrospective cohort study was conducted for adult bystander-witnessed OHCA patients administered DA-CPR due to presumed cardiac etiology between January 1, 2018 and October 31, 2019 in Seoul, Korea. The primary and secondary outcomes were the differences in favorable neurologic outcome and survival to discharge rates in adult OHCA patients in the two instruction groups. Binary logistic regression analysis was performed to identify the outcome predictors after DA-CPR. A total of 2109 adult OHCA patients with DA-CPR were enrolled. Numbers of elderly patients in audio instruction and video instruction were 1260 (73.2%) and 214 (55.3%), respectively. Elderly patients and those outside the home or medical facility were more likely to receive video instruction. Favorable neurologic outcome was observed more in patients who received video-instructed DA-CPR  than in patients who received audio-instructed DA-CPR . The survival to discharge rate was also higher in video-instructed DA-CPR  than in audio-instructed DA-CPR . Video-instructed DA-CPR was significantly associated with neurologic recovery  and survival to discharge  compared to audio-instructed DA-CPR in adult OHCA patients after adjusting for age, gender, underlying diseases and CPR location. Video-instructed DA-CPR was associated with favorable outcomes in adult patients with OHCA in a metropolitan city equipped with sufficient experience and facilities The incidence rate of OHCA was 37.5 per 100,000 population in 2006 and increased to 46.8 per 100,000 population in 2010. Since cardiac arrest patients can be resuscitated within four minutes after proper treatment without neurologic complications, bystander cardiopulmonary resuscitation (CPR) is a key factor in improving the survival and neurologic recovery of patients with OHCA2. Dispatcher-assisted CPR (DA-CPR) has been performed to improve the quality of bystander CPR. Song et al.3 reported that DA-CPR increased neurologic recovery rates (2.0% in 2010 and 3.6% in 2011) and discharge survival rates (7.1% in 2010 and 9.4% in 2011). In most cases of OHCA, DA-CPR has been carried out by audio instruction via a telephone call4. Due to the nature of audio instruction, the patients’ condition can only be identified through the caller’s eye. Accordingly, concerns are raised during audio-instructed DA-CPR such as whether (1) it is a cardiac arrest situation, (2) CPR is being performed correctly, and (3) the patient’s condition changed during CPR. In addition, the need for real-time feedback has increased in terms of the correct CPR position and rate. As mobile phone technology has developed, the number of video calls has increased in real life5. Therefore, there has been an issue of whether audio or video instruction is more effective for DA-CPR in real life. Theoretically, video-instructed CPR allows for real-time feedback between the dispatcher and caller and better identification of the patient’s condition than audio-instruction6. A meta-analysis conducted by Lin et al.7 revealed that video-instructed DA-CPR provided significantly improved chest compression rates with more correct hand positions. Recently, Lee et al.5 reported early clinical experience with video-instructed DA-CPR and analyzed the survival outcomes compared to those from audio-instructed CPR in Seoul, a metropolitan city in Korea, between January and December in 2017 In their study, video-instructed DA-CPR was associated with a higher rate of survival to discharge and favorable neurologic outcomes via unadjusted analysis. However, this relationship was not statistically significant in the adjusted analysis. We postulated that the inclusion of 3-month trial period results and incorrect CPR posture may have affected the outcomes despite the instruction provided. Therefore, further study is required to evaluate the clinical efficacy of video-instructed DA-CPR under circumstances of ample experience and facilities. In this study, we aimed to investigate whether video-instructed DA-CPR resulted in improved neurologic recovery and survival to discharge compared to audio-instructed DA-CPR in a city setting.Out-of-hospital cardiac arrest (OHCA) is one of the leading causes of death and millions of people each year die from OHCA. In Korea, the number of out-of-hospital cardiac arrests is increasing every year with increases in population age and cardiovascular diseasesA total of 5041 cases of OHCA assessed by EMS were collected after screening the initial data from the Seoul Emergency Operation Center. After excluding unknown, non-bystander-witnessed arrest cases, and EMS-witnessed arrests cases n = 2648), presumed non-cardiac etiology (n = 256), and pediatric cases (n = 28), 2109 cases were eligible for the final analysis . Elderly patients (> 65 years) and those outside the home or medical facility were more likely to be associated with the use of video-instructed DA-CPR (p < 0.0001) Fig. .Figure 3The rate of favorable neurologic outcome was 19.4% (75 out of 387) in patients who received video-instructed DA-CPR and 6.8% (117 out of 1722) in those who received audio-instructed DA-CPR  in video-instructed DA-CPR and 12.3% (211 out of 1722) in audio-instructed DA-CPR. Higher rates of survival to discharge was closely related to video instruction  . However, the effect was not prominent in achieving improved survival to discharge compared with audio instruction . For those with shockable rhythm such as VT and VF, video instructed DA-CPR was associated with favorable neurologic outcome  and survival to discharge .9. In cases of impending cardiac arrest, witnesses often misinterpret patient movements as signs of life when they encounter agonal breathing and tremors10. Accordingly, improvement in the initial CPR quality administered by a witness without delay at the scene is the main issue affecting the prognosis of OHCA patients. Theoretically, a video call can be advantageous for providing information and a better understanding of the dispatchers compared to audio calls. Johnsen et al.6 reported that video-assisted DA-CPR allowed for appropriate feedback to the dispatchers and improved rescuer compliance in a simulation study. A meta-analysis7 also revealed that video instruction allowed for a faster chest compression rate (104.8 in video instruction vs 80.6 in audio instruction) and a lower risk of incorrect hand positioning. However, the delayed initiation of chest compression was observed in video-instructed DA-CPR compared to audio-instructed DA-CPR. In the real clinical field, there has been a concern about the delay of CPR initiation during the video call connection process due to the adjustment of the camera angle, change of the screen, and monitoring the patient’s condition. To avoid delaying the CPR procedures at our institution, the first cycle of CPR was performed by audio instruction and then another caller was asked to switch to a video call. Although Lee et al.5 did not find significant differences in the time intervals between video and audio instruction (p = 0.12), further randomized controlled trials are necessary to identify the optimal protocol for video-instructed DA-CPR to obtain favorable neurological recovery and survival to discharge rates without a delay in initiating CPR.At the scene, the rapid recognition of cardiac arrest and subsequent CPR delivered in the right position were important in achieving a favorable prognosis in patients with OCHA5. In the analysis conducted after adjusting for all covariates, video-instructed DA-CPR did not increase favorable neurologic outcomes  and survival to discharge rates 5. However, that study investigated data from 2017, including the 3-month trial period results  when caller was not good at using a mobile phone and could not be connected to a video call; (2) when the caller was confused and could not respond properly to the dispatcher’s instructions; (3) when there was no other person in the vicinity other than one caller; and (4) when caller was connected to a video call, it was difficult to transmit information on the site because proper operation such as camera switching was not possible. In this case, feedback data obtained through video-instructed DA-CPR can be used to help the witness perform appropriate resuscitation during audio-instructed DA-CPR. In addition, the dispatcher provides proper management due to real-time feedback via the video-call until the EMS arrives at the scene. Professional first-aid treatment such as airway maintenance and the infusion of fluid or vasopressors can also be performed. Accordingly, a more effective linkage between prehospital and hospital treatment is expected through video calls.There might be concerns about how long the trial peiord will take for a video-instructed CPR system to perform properly in acutal clinical practice at places other than Seoul. Two big obstacles to implementing a video-instructed CPR were citizens’ perception and the presence of smartphone capable of making video calls. At the beginning, there was a tendency to reject the change from audio to video call instruction. However, these cases were gradually reduced by increasing public awareness through national news to promote video-instructed DA-CPR. Smartphone penetration rate in the population of Korea was approximatley 95%. Accordingly, it was relatively easy to change from audio to video call at the scence. If these two issues are resolved well, 3 months would be sufficient for the trial period. Additionally, it is necessary to solve potential problem in running the system during the same trial period.11. Lee et al.11 have reported significantly deeper depth of mean chest compression and improvement in adequate position (approximately 92% in the video instruction vs 82% in the audio instruction) with video-instructed DA-CPR compared to those with conventional audio-instructed DA-CPR in a simulation results of 131 volunteers. Especially, the effect was prominent for those taught by video instruction with a rapid transition from audio call. Nevertheless, it cannot accurately reflect actual clinical fields. Thus, further studies are needed to specifically investigate how much CPR quality is improved by video instructed DA-CPR in a real emergent situation.There is a question about how much video instruction improves the CPR quality in actual emergency. We wanted to investigate this too. However, it was impossible to record in detail how CPR behavior changed by video instruction in a busy emergent situation. Thus, this study had a limitation in that it could not present numerically whether or not the specific CPR quality was increased by video instruction in terms of proper CPR position, compression depths and rates, and compressor postures in the real world. However, this was investigated through a simulation study focusing on the corrected effect by video instruction defined as the protocol with audio call-to-video call transition12 reported that favorable survival rate at 1 month was 21.3% in patients with pVT/VF, 2.7% in those with PEA, and 0.6% in those with asystole. Accordingly, video-instructed DA CPR could be a confounder to influence results due to increased shockable rhythm such as VT and VF. To address this possibility, we performed a stratified analysis  was established in 2002. The SEOC is in charge of disasters such as typhoons, floods, heavy rain, strong wind, heavy snow, and earthquakes as well as emergency medical consultation and medical guidance in situations that threaten the safety and property of Seoul citizens. Currently, the system has been established with 24 fire departments and 151 emergency medical services. After the standard DA-CPR protocol is applied5, a more systematic and immediate consultation is performed by professional medical staff. The emergency command system is operated by following a written protocol. First, when a call comes in, the primary situation call-taker receives the report and roughly ascertains the main contents of the report. Then, the call-taker confirms the chief complaint and delivers the dispatch order to each EMS. In particular, if emergency treatment is needed, including instruction after a prehospital cardiac arrest, a phone call to an emergency medical dispatcher is made immediately. The dispatcher ascertains the patient's condition and provides first aid guidance as necessary. In an out-of-hospital cardiac arrest, the secondary dispatcher immediately executes a dispatcher CPR order and shares information about the patient's condition with the emergency unit until they arrive at the scene. When the paramedics arrive, they contact to the first aid doctor in the center by phone, providing information on the patient’s condition to the doctor and performing procedures according to the medical guidance provided  after providing CPR instruction to the caller, the 119 consultant identifies the patient’s condition through a video call; (2) the 119 consultant provides proper CPR techniques including the rescuer’s position, hand position, and the adequate chest compression rate and depth until the emergency medical service (EMS) arrives; and (3) an emergency medicine doctor affiliated with the 119 situation room in SEOC constantly interacts with the EMS from the scene to the hospital. Video-instructed DA-CPR was attempted if the following conditions were met: (1) the presence of two or more bystanders and (2) the availability of a video call when CPR guidance based on the telephone consultation protocol was initiated by the secondary dispatcher5. Cardiac arrest was divided into two groups of presumed cardiac origin and non-cardiac origin. Non-cardiac origin was defined as a cardiac arrest due to external causes, respiratory diseases, stroke, or malignant tumor based on hospital records13. Records regarding demographical factors, underlying diseases, CPR location, and time from collapse to CPR were reviewed. The demographics included gender and age. Age over 65 years was used to define elderly patients14. The underlying diseases were hypertension, diabetes mellitus, coronary artery disease, cerebrovascular disease, and cancer. The CPR location was divided into three groups of home, medical or nursing institutions, and other places. The time from collapse to CPR was categorized into four groups of time < 4 min, ≥ 4 and < 8 min, ≥ 8 and < 15 min, and > 15 min15.We collected data from the EMS-assessed out-of-hospital cardiac arrest database in the SEOC between January 1, 2018 and October 31, 2019  before arriving at the hospital. Study design was performed according to the principles of the Declaration of Helsinki and were approved by the Institutional Review Board of the Chuncheon Sacred Heart Hospital (IRB No. 2020-09-016). All methods were performed in accordance with the relevant guidelines and regulations in manuscript.The primary outcome was the difference in favorable neurologic outcome in the video-instructed DA-CPR and audio-instructed DA-CPR. The favorable neurologic outcome was defined as cerebral performance category (CPC) scores of 1 and 2 measured at hospital discharge, indicating independent activities of daily life after CPRhttp://www.Medcalc.org) with a statistical significance indicated at p < 0.05.Continuous variables are described as the mean and standard deviation (SD). A Chi-square or Student’s t-test was performed to find differences according to the type of CPR instruction. Univariate analysis was performed to find relevant factors for outcomes such as favorable neurologic outcome and survival to discharge in adult OHCA patients. Multivariable logistic regression analysis was performed further to confirm the statistical independence of variables after adjusting for age, gender, underlying diseases, time from collapse to CPR, and CPR location. The results were expressed as adjusted odds ratios (aORs) with 95% confidence intervals (CIs). In this study, the first rhythm itself could be a confounder influencing results of this study. To address this possibility, we further performed a stratified analysis using the Cochran-Mantel–Haenszel Method to examine the primary association of interest at different levels of a confounding factor (Supplemental Table Data collection and study design were performed according to the principles of the Declaration of Helsinki and were approved by Coordinating Ethnics Committee of the Chuncheon Sacred Heart Hospital.Supplementary Information.


Aim of the Study: The aim was to compare cardiopulmonary resuscitation (CPR) quality of an automated external defibrillator (AED) with and without additional video instruction during basic life support (BLS) by laypersons.Methods: First-year medical students were randomized either to an AED with audio only or audio with additional video instructions during CPR. Each student performed 4 min of single-rescuer chest compression only BLS on a manikin  using the AED. The primary outcome was the effective compression ratio during this scenario. This combined parameter was used to evaluate the quality of chest compressions by multiplying compressions with correct depth, correct hand position, and complete decompression by flow time. Secondary outcomes were percentages of incomplete decompression and hand position, mean compression rate, time-related parameters, and subjective assessments.Results: Effective compression ratio did not differ between study groups in the overall sample (p = 0.337) or in students with (p = 0.953) or without AED experience (p = 0.278). Additional video instruction led to a higher percentage of incorrect decompressions (p = 0.014). No significant differences could be detected in time-related resuscitation parameters. An additional video was subjectively rated as more supporting (p = 0.001).Conclusions: Audio–video instructions did not significantly improve resuscitation quality in these laypersons despite that it was felt more supportive. An additional video to the verbal AED prompts might lead to cognitive overload. Therefore, future studies might target the influence of the video content and the potential benefits of video instructions in specific populations. Out-of-hospital cardiac arrest is among the leading causes of death in Europe . In the The aim of our study was to investigate the differences in CPR quality and subjective rating between AED audio–video prompts and audio prompts only. We hypothesized that adding additional video instructions to the conventional AED audio instructions improves CPR quality measured by effective compression ratio (ECR).The study was performed at the Medical University of Vienna, Austria, between October and December 2016. The requirement for ethical approval was waived by the Ethics Committee of the Medical University of Vienna (No. 1945/2016).In this open randomized, controlled parallel group study, we enrolled medical students at the beginning of the obligatory first aid course during the first semester of medical school. In order to include laypersons only, professionally trained individuals like emergency medicine technicians, paramedics, or nurses with intermediate or advanced life support training, according to the European Resuscitation Council, were excluded from the study. Further exclusion criteria were age < 18, inadequate German language skills, and injuries that made it impossible to adequately perform CPR. The students were informed that study participation was voluntary and would not influence their grades of their first aid course.After providing written informed consent, medical students were stratified into two groups: (I) students with AED experience (who had a first aid course with AED training before starting to study medicine) and (II) students without any AED experience (never took a first aid course or participated in a first aid course without AED training).https://www.meduniwien.ac.at/randomizer/web/login.php).After stratification, students were randomly assigned equally to one of two groups: (1) AED group with audio–video prompts and (2) AED group with audio prompts only, using the Randomizer for Clinical Trials  started at the same time. Then, the defibrillation pads were applied accordingly on the manikin, and defibrillation had to be administered as programmed for this study before the students started with single-rescuer chest compression only CPR according to the ERC 2015 guidelines  with medium thorax resistance to assess CPR quality. The accuracy of the manikins and software measurements was assessed prior to the study as described earlier . Differevia a stopwatch by trained investigators. Data were collected on a computer  using the Ambu CPR software . The AEDs  used in the study were adjusted during the study to indicate shockable rhythms only. This AED offers a display providing video instructions in addition to the audio prompts. The AED was placed next to the manikin's head to offer a good view on the display. To create the reproducible conditions, two identical models were used in the two interventional groups. The display in the voice-only group was covered with a non-transparent adhesive lamination.Time-related parameters  were measured The primary outcome parameter was the ECR. This ratio describes the general performance of CPR considering correct hand positioning, chest compression depth, and complete decompression multiplied by the flow time fraction as described previously . SecondaAll study participants were asked to evaluate their subjective experience using a questionnaire concerning AED use and their personal assessment of CPR quality after testing on a 10-point Likert scale (10 points representing the highest and 0 representing the lowest rating). The last two questions evaluated the usefulness of the video instruction during resuscitation and were answered by the participants of the audio–video group only. The full questionnaire can be found as Electronic The main outcome ECR was compared between the two randomization groups (audio–video prompt AED vs. audio-only prompt AED) using a Wilcoxon rank sum test at a pre-specified significance level of 0.05. Based on a previous investigation, the sample size was calculated under the assumption that the standard deviation of ECR would be 0.3 . A samplFurther, ECR and a set of secondary outcomes were compared between the two randomization groups as well as between subjects with and without previous AED experience. Metric variables were described by median and interquartile range (presented in square brackets) and were compared between groups using Wilcoxon tests. For the single binary variable indicating appropriate mean compression rate, absolute and relative frequencies were calculated, and the groups were compared using a chi-squared test. Tests for interactions between the randomization group and AED experience were calculated from linear or logistic regression models, as appropriate, including the randomization group, the binary indicator of previous AED experience, and the interaction of both factors as predictor variables. The hypothesis tests for secondary outcomes are considered exploratory and no multiple testing correction was applied.A total of 606 medical students were screened for this study. Out of those, 462 were included for randomization and 144 were not eligible due to exclusion criteria. We accepted all available students even if the pre-calculated sample size was lower. One hundred and twelve study participants used an AED before, whereas 350 participants had no AED experience at all. After the exclusion of 17 cases due to missing data, 54 trained participants in the audio group and 55 trained participants in the audio–video group were analyzed. In the group without previous AED experience, 166 participants received audio instruction and 170 received audio–video instruction .The gender distribution between groups was equal and no significant difference in age was found. Participants' characteristics are reported in p = 0.014).The effective compression ratio in the audio group did not differ from that in the audio–video group in either AED experience stratum. No difference was found between the ECR of participants with and without AED experience . Audio–vp = 0.050]. The percentage of compressions with incorrect pressure point was comparable for all the groups (Participants with previous AED experience performed significant deeper compressions than participants without AED experience . There was no significant difference in time needed to place the defibrillator pads and to the first chest compression after shock administration between the audio and the audio–video groups. Also, the peri-shock pause did not vary significantly between these groups  vs. 203 (202–205) s, e groups .p = 0.031].Participants with AED experience administered the first shock earlier  and supporting ; 89% of participants with and 98% of participants without previous AED experience felt supported by the audio–video instructions (p = 0.009). An interesting finding resulting from the analysis of the questionnaire is that inexperienced participants rated themselves on the 10-point Likert scale and stated that they paid significantly more attention to the video than trained individuals .The subjective rating of resuscitation quality did not correlate with the objective performance measured by ECR  . Due to Differences in AED design and audio prompts are influencing CPR quality , 11. In Certainly, a limitation of this study is that in our setting we were not able to assess the influence, strength, and weaknesses of the content of this specific instructional video as it was given and predetermined by the providing device distributor.We included a sufficient and high number of study participants and first-year medical students who were at the start of their medical education. We considered them as laypersons, as they did not receive any specific emergency medical education prior to this study. Therefore, the results of this study seem generalizable to laypersons with a minimum of CPR education.The addition of video prompts to conventional audio prompts did not lead to improved CPR quality. Further studies might investigate specific video content possibly in relation to CPR performance feedback or video prompts for specific target groups of rescuers. Another issue to study might be the influence of video prompts on overcoming the fear to perform CPR and how it might improve the willingness to perform CPR using an AED.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The study was performed at the Medical University of Vienna, Austria between October and December 2016. The requirement for ethical approval was waived by the Ethics Committee of the Medical University of Vienna (No: 1945/2016). Participants provided written informed consent.FE: conceptualization, methodology, investigation, project administration, writing—original draft, and writing—review and editing. EF: methodology, investigation, and writing—review and editing. HL: resources, investigation, and writing—review and editing. DS: software, data curation, formal analysis, and writing—review and editing. RR: methodology, formal analysis, and writing—review and editing. KR: formal analysis and writing—review and editing. RG: conceptualization, methodology, supervision, and writing—review and editing. HF: conceptualization, methodology, project administration, resources, supervision, and writing—review and editing. All authors contributed to the article and approved the submitted version.RG is the ERC Director of Training and Education, ILCOR Task Force Chair Education, Implementation, and Teams; Associate Editor of Resuscitation Plus, European Journal of Anesthesiology; and Editor-in-Chief of Trends in Anaesthesia and Critical Care. The remaining 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.


Demand for federal nutrition assistance programs is increasing as the older population grows and further accelerated with the COVID-19 pandemic. Older adult nutrition programs are based on federal nutrition guidelines that have traditionally focused on healthy populations, yet many older adults have multiple chronic conditions/advanced age. Some guidelines are changing; the 2020 Dietary Guidelines for Americans recognize older adults’ risk for malnutrition and also need for adequate protein to prevent lean muscle loss with age. The 2020 Older Americans Act (OAA) reauthorization included reduction of malnutrition in OAA’s official purpose and added program participant screening for malnutrition. The OAA requires State Agencies on Aging submit multiyear strategic plans to receive program funding, but it is unknown how the plans address risks for malnutrition, including overweight, underweight, and muscle loss (sarcopenia/frailty). We searched 51 State Agency on Aging strategic plans posted at advancingstates.org to determine their frequency of mentioning nutrition, malnutrition/underweight/undernutrition, obesity/overweight, frail/frailty, sarcopenia, and dietary supplements/oral nutrition supplements (DS/ONS)/meal replacements. Every state plan included nutrition but less than a third included malnutrition. There was wide variability in how nutrition and malnutrition were incorporated into state goals and strategies. Very few plans included obesity, frailty, and DS/ONS terms; none included sarcopenia. Although there has been some movement, there is need for many State Agencies on Aging plans to address all aspects of malnutrition including overweight, underweight/other factors related to muscle loss (sarcopenia/frailty) that adversely impact healthy aging. Wide disparities in plan structure/use of terms create opportunities for more common approaches/definitions.


Malnutrition in older adults has been recognised as a challenging health concern associated with not only increased mortality and morbidity, but also with physical decline, which has wide ranging acute implications for activities of daily living and quality of life in general. Malnutrition is common and may also contribute to the development of the geriatric syndromes in older adults. Malnutrition in the old is reflected by either involuntary weight loss or low body mass index, but hidden deficiencies such as micronutrient deficiencies are more difficult to assess and therefore frequently overlooked in the community-dwelling old. In developed countries, the most cited cause of malnutrition is disease, as both acute and chronic disorders have the potential to result in or aggravate malnutrition. Therefore, as higher age is one risk factor for developing disease, older adults have the highest risk of being at nutritional risk or becoming malnourished. However, the aetiology of malnutrition is complex and multifactorial, and the development of malnutrition in the old is most likely also facilitated by ageing processes. This comprehensive narrative review summarizes current evidence on the prevalence and determinants of malnutrition in old adults spanning from age-related changes to disease-associated risk factors, and outlines remaining challenges in the understanding, identification as well as treatment of malnutrition, which in some cases may include targeted supplementation of macro- and/or micronutrients, when diet alone is not sufficient to meet age-specific requirements. The World Health Organization (WHO) has declared Healthy Ageing a priority of its work on ageing between 2016 and 2030 and developed a policy framework which emphasizes the need for action across multiple sectors [Biology of ageing is understood as the time related decline of physiological functions, leading to changes in functional performance of different organ systems as well as with reduced resilience to physical, cognitive and mental stressors, however, there are great individual differences in these changes. Advanced age is associated with reduced adaptive and regenerative capacity which is leading to higher rates of morbidity . On the The treatment of malnutrition requires early identification and multimodal intervention, in hospitalized patients as well as community dwelling older adults. However, treatment modality still poses a challenge for nutritional therapy with yet open questions ,13. ThisAlthough clinical malnutrition predominantly occurs in patients in hospitals, care situations or nursing homes, malnutrition, nutritional risk and specific nutrient deficiencies in particular, are a common albeit frequently overlooked occurrence in community-dwelling old people ,15.Consequences of malnutrition are deleterious and far reaching and have been described in detail . While dMalnutrition in general has serious implications for clinical outcome, for recovery from disease, trauma and surgery and is associated with increased morbidity and mortality both in acute and chronic disease  and has Depending on the type of malnutrition, protein catabolism can be pronounced. Disease-related malnutrition therefore leads to rapid skeletal muscle wasting, whereas age-related malnutrition is associated with a slower but progressive loss of muscle mass. The effects of protein catabolism are prominently reflected by lower muscle mass, muscle strength and function with severe implications for physical performance . At the Malnutrition-related protein catabolism and micronutrient deficiency have been prominently linked to the impairment of immune function , which iWound healing as well as tissue recovery are also impaired in malnutrition, which in part can be attributed to micronutrient deficiency . This clOne particularity of malnutrition in older adults is that the impact appears to be more severe than in younger adults. Studies have not only shown that changes in body composition in malnutrition occur to a greater extent in older compared to younger adults , but alsMalnutrition plays an important role in the development of certain geriatric syndromes. Geriatric syndromes are complex multifactorial conditions occurring in higher age with serious implications for health  and haveInvoluntary weight loss, a hallmark of malnutrition, is inevitably associated with loss of skeletal muscle mass, which appears to occur at a greater extent in higher age. This increases the risk of developing sarcopenia, a phenomenon which is characterized by the loss of both muscle mass as well as muscle strength and function. As these two entities frequently occur together, this has led to the new term “sarcopenia malnutrition syndrome”  and a neA phenomenon, which is often overseen in this content but nonetheless is important in an increasingly obese society, is sarcopenic obesity , which dAs sarcopenia has been called the biological substrate of frailty, the close relationship between malnutrition and sarcopenia suggests a link between malnutrition and frailty as well. Not surprisingly, involuntary weight loss, which is an indicator of catabolism, is a major risk factor for developing physical frailty . Weight Moreover, fatigue is also one of the core elements of frailty. Fatigue has been described as a relentless exhaustion affecting the ability to carry out physical and mental activities  and has Due to the proposed relationship between long-term dietary patterns and cognitive function, malnutrition has also been linked to cognitive impairment ,50, althIt is well established that malnutrition is associated with increased mortality in both acute and chronic disease, and this effect is still observed in older adults. The risk for both short-term mortality in acute conditions  as well 2 if <70 years, or <22 kg/m2 if >70 years), reduced muscle mass , and two etiologic criteria: reduced food intake or assimilation , and inflammation (acute disease/injury or chronic disease-related). It is proposed that the diagnosis of malnutrition is based upon the presence of at least one phenotypic and one etiologic criterion, and in a second step different thresholds of the criteria can be used for severity grading of malnutrition. The GLIM criteria are subject of numerous ongoing validation studies. A recently published study on community-dwelling older adults participating in a long-term osteoporosis trial in Hongkong demonstrated that the GLIM criteria were associated with a higher risk for sarcopenia, frailty, and mortality during a 14-year follow-up period [Despite an ongoing debate, there is still no universally accepted definition of malnutrition . Therefop period . While tp period .Nutritional risk is less well defined but commonly understood to be a condition in which the present nutritional status is at imminent risk of impairment due to a range of factors such as medical history, comorbidities or drugs which might increase dietary requirements or interfere with nutrient absorption or metabolism. Further factors may include physical, mental or cognitive status which might prevent the older person to properly care for themselves as well as socio-economic factors which hinder access to a varied high-quality diet .Screening tools which are suitable for the use in older adults need to focus on the most important risk factors for malnutrition in high age, in order not only to diagnose manifest malnutrition but also to capture the risk to develop malnutrition as described above. That way, screening tools can be used to identify patients early in order to initiate nutritional treatment. Several screening tools have been established for the specific use in older adults, but the most widely used and most studied instrument is the Mini Nutritional Assessment (MNA) in its long or short form. However, due to its broad range of covered topics, the specificity of the MNA has been questioned, as it is associated with a high risk of “over-diagnosing” malnutrition in the old . This prScreening for and treating malnutrition has also been acknowledged as one of the first necessary steps in the identification and treatment of sarcopenia . Recent Clinical malnutrition results from an imbalance between macronutrient intake and requirement , which cAlso, depending on the type of malnutrition and underlying disease, protein catabolism can be pronounced. Protein requirements are therefore further increased in older adults with malnutrition or disease (1.2–1.5 g/kg body weight) ,66.One specific form of malnutrition frequent in older adults are micronutrient deficiencies ,69. In cThe reasons for insufficient micronutrient intake vary including not only a low amount of food, but typically also the choice of food and the lack of variety. Prices, availability of foods rich in vitamins, trace elements and minerals can reduce the intake of micronutrients. On the other hand, ageing is also associated with changes that facilitate deficiencies in calcium, vitamin D, vitamin B12, Fe, magnesium, and Zn among other important nutrients. Large studies on the micronutrient serum status in older adults are rare due to the costs and efforts. The Population Based KORA-Age Study, a representative cohort study, recently showed subclinical micronutrient deficiencies in community-dwelling old . 52.0% oMoreover, it is known that inflammation, which is common in older adults, affects trace element status and their biomarkers, resulting in depleted plasma stores of Fe, Zn, and manganese, a phenomenon which is partly known as nutritional immunity and serves as a defence against invading pathogens .Due to the multifactorial role of micronutrients in various metabolic processes as well as immune functioning, cell proliferation and growth, signalling processes and genomic stability, micronutrient deficiencies are in turn involved in the pathogenesis of a variety of conditions and age-related diseases . One of Despite the body of evidence describing the personal and clinical consequences of malnutrition and its economic impact on the health care system, malnutrition in the old remains a considerable problem with reported high frequencies, especially in situations of dependency . This haPrevalence of malnutrition, however, strongly depends on the setting, on underlying or accompanying diseases as well as on screening and assessment methods. Numerous studies have investigated prevalence of malnutrition in hospital and nursing home settings; but recently, several meta-analyses have been published which also use meta-regression to further explore determinants. Although the specific number of malnutrition prevalence differs between meta-analyses, the main findings are comparable, showing the lowest percentage of malnourished individuals in the community setting and the highest percentage in acute and subacute care settings, higher prevalence rates in higher age as well as sex-specific differences, as women had the highest risk. Also, region and instrument used to identify malnutrition had a significant impact on prevalence. One systematic review and meta-analysis of prevalence data of malnutrition and nutritional risk in older adults across different healthcare settings showed a wide range of malnutrition from 3% in the community setting to approximately 30% in rehabilitation and subacute care, even though the review only included studies using the MNA . This stRecent advances in prevalence research has also included re-evaluation of large pool datasets using harmonized definitions of malnutrition indicators such as low BMI, weight loss, low food intake and combinations of these. Wolters et al. were able to show varying prevalence of malnutrition according to the different criteria used and concluded that it might be more useful to consider the criteria separately as each may reflect a distinct nutritional problem .Malnutrition in older adults is of complex and multifactorial origin. A variety of factors such as life-style factors, disease and ageing processes may be involved and interaction between these factors is common. Understanding risk factors is crucial in order to address malnutrition effectively, but the complex aetiology of malnutrition is still not perfectly understood.In industrial countries, disease is one of the most common reasons for developing malnutrition and the onset of malnutrition can be both acute and slow. Age in itself is an established non-modifiable risk factor for malnutrition. Higher age is associated with physiological changes which can potentially slowly result in or further malnutrition such as impaired taste and smell, decreased gastric flexibility, reduced appetite, etc. As higher age clearly increases the risk for disease, there is considerable risk for potentiation of nutritional problems.Recent research has particularly focussed on the evidence of potentially modifiable risk factors of clinical malnutrition, as targeting these risk factors is a fundamental element in the prevention and treatment of malnutrition. A recent meta-analysis investigated which factors are associated with incident malnutrition and identified marital situation, hospitalisation and physical limitations as the most important predictors . AnotherIn a modified Delphi process, an international expert group therefore developed a model for the theoretical framework on the aetiology of malnutrition termed DoMAP  and specifically, potential causative mechanisms . The modPhysiological factors which may precipitate malnutrition in higher age include sensory impairment such as diminished taste or olfactory dysfunction, delayed gastric emptying, and disturbed motility leading to a functional decline of the ageing gut . Ageing Moreover, a decrease in gastrointestinal hormones , with concomitant adverse changes in anorectic signalling , orexin A, leptin, cholecystokinin (CCK)) ,102,103 Last but not least, in the case of reduced smell and taste, the reward system in the central nervous system (CNS) is hampered in the perception of pleasure associated with palatable foods  which maSome of the pathway dysregulations can be attributed to the chronically elevated inflammation observed in higher age since enhanced cytokine levels , interleukin (IL)-1β) are able to affect appetite regions in the CNS ,110. ThePostprandial regulation in older adults has gained increasing attention in the last decade, especially with regard to muscle protein synthesis. In the old, a blunted postprandial muscle protein synthesis in response to dietary protein has been described ,119,120,Recent research has also focussed on postprandial regulation of metabolic parameters. Age-related changes in postprandial glucose and insulin have been well established ,124, butTaken together, in contrast to disease-related mechanisms such as catabolism, which can result in acute weight loss and malnutrition, altered appetite regulation in higher age and changes in postprandial metabolism are associated with gradual changes that may not necessarily result in manifest malnutrition but contribute to or exacerbate existent nutritional problems and facilitate nutritional deficiencies.Under physiological conditions, inflammatory processes represent a desired, strictly controlled and usually self-limiting reaction. However, chronic inflammation has long-term negative effects on the entire system. Increasing knowledge indicates that ageing is accompanied by slightly but chronically elevated inflammation levels. This sterile and silent inflammation in old adults has been termed “inflammaging” . InflammAlthough underlying mechanisms are still not fully elucidated, inflammaging has been characterized as a chronic low-grade inflammatory status, which not only is reflected by higher pro-inflammatory levels, but by a remarkable imbalanced cytokine network ,139. ResMeanwhile, it is widely recognized that inflammaging is partly responsible for triggering many age-related diseases, e.g., Alzheimer’s Disease (“neuroinflammation”) , atherosTaken together, the aetiology of malnutrition is complex, and a multitude of risk factors can contribute to or aggravate the development of malnutrition as illustrated in Acknowledging the different and complex risk factors, which can result in or aggravate malnutrition or contribute to the risk of developing it, it becomes clear that treatment of malnutrition is as complicated and challenging. Dependent on both setting and the situation of the older adult, different therapy approaches are warranted.Regarding the overwhelming evidence that protein requirements are higher in older age ,66, adeqAvailable studies so far have delivered conflicting evidence on the benefits of nutritional theory. Recently, an international panel of nutrition experts identified the shortcomings of these studies which include heterogeneous study populations and too short or varying treatment duration as well as issues relating study methodology such as inadequately described control group and no placebo, no blinding of study personnel, frequently no intention-to-treat-analyses as well as selective outcome presentation . TherefoA recent meta-analysis, which did not find convincing evidence of the use of oral nutritional supplements in the treatment of malnutrition in older patients, also highlighted the need for more and larger trials to identify suitable and effective interventions for treating malnutrition . PoolingDespite the overwhelming evidence regarding the negative outcome of malnourished older adults, there are still many remaining challenges in the understanding, identification and treatment of malnutrition in older adults. They concern both the prevention of slow onset age-associated malnutrition as well as the treatment of disease-related malnutrition. One particular concern regarding the prevention of malnutrition is that some nutritional requirements are not well established in higher age. Micronutrient and trace element concentrations have been shown to change with age  and haveTaken together, a need to critically appraise current nutrient recommendations for the older age group has been identified, and the WHO has been challenged to issue guidelines . There iMoreover, although recent research on determinants of malnutrition has added considerable new evidence, the impact of ageing-related changes on the long-term development of malnutrition, still needs further elucidation. One example is the ageing gut and its altered microbiome, which have gained attention in the last years. Emerging technologies, such as e.g., high-throughput culturing, will further the research on ageing microbiome, so its role in the development of malnutrition might soon be elucidated. Novel dietary approaches which modulate the ageing microbiome such as the Mediterranean diet  are of iLastly, not only the prevention of malnutrition, but also the topic of treatment of malnutrition needs more research, in terms of well-designed and adequately powered clinical trials in order to ensure sufficient statistical power to identify true treatment effects. Moreover, relevant outcome parameters need to be included, and a careful selection of target populations with well-defined malnutrition is necessary. Also, more research is needed for treatment approaches which specifically target the underlying causes of malnutrition themselves  i.e., caTaken together, more research is needed to understand which ageing-related changes are early predictors/precursors of malnutrition that in turn can be addressed in order to prevent the development of nutritional deficiencies. For clinically manifest malnutrition, more studies need to be performed in older adults in order to identify the suitable treatment for the various settings.


This cross-sectional study quantifies the number and duration of distinct advertisements that appear during child-directed videos on a video-sharing platform as well as the frequency of age-inappropriate ads. A recent analysis of online videos viewed by young children showed that 85% contained ads, of which 20% had age-inappropriate content, such as violence or political messages.3 for this cross-sectional study, we identified the top 10 most-subscribed English-language made-for-kids channels on YouTube.com4 as of December 16, 2020. Because this was a content analysis of publicly available data, this study did not require institutional review board approval, per the policy of the University of Michigan. For each channel, we watched the 5 videos with the highest view counts, confirming that the videos were child-directed based on the video’s availability on the video-sharing platform’s counterpart for children younger than 13 years and the lack of a comments section. We chose to view only 5 videos per channel based on observations that ads typically appear in similar patterns within channels. One investigator (S.L.Y.) watched each video once in its entirety, recorded metadata ; ad number, duration, and placement ; and coded ad age-appropriateness (reliability κ = 0.951).1 The Adapting methods from Alruwaily et alWe calculated the duration of ads by summing the duration of preroll, interstitial, postvideo, and banner ads . We created 2 ad duration variables: total duration if not skipped and total duration if skipped after 5 seconds (if skip option provided), adjusting both for video duration. For each video and channel, we calculated the proportion of age-inappropriate ads. Descriptive summary statistics were calculated in Excel 2016 (Microsoft).The 50 videos sampled contained a total of 286 ads, with a mean of 5.72 ads per video . Sidebar ads were most common (119 [41.6%]), followed by preroll (48 [16.8%]), banner (42 [14.7%]), interstitial (41 [14.3%]), and postvideo (36 [12.6%]) ads. Overall, the mean total duration of ads (not skipped) was 0.56 minutes per minute of video  and 0.04 minutes per minute of video if skipped  . Age-inaThere was variability in ad frequency and duration between channels . For exa5 Although research suggests that young children can identify preroll ads on video-sharing platforms,6 it is not known how frequently they skip ads in practice. In future policy discussions, attention should be paid to the dose of advertising children receive—and the resulting profits channels receive—during video viewing. Video-sharing platforms could consider placing restrictions on advertising load and using human review for age-appropriateness of ads. Clinicians can guide parents on finding ad-free video platforms or helping children identify and skip ads.2 Limitations of this study include its focus on English-language videos and the dynamic nature of video popularity.This analysis of advertising frequency and duration on the most popular child-directed online video channels found that advertising load and age-appropriateness varied widely. On some channels, unskipped ads played for as much time, or longer than, the video itself and exceeded television ad limits.


In the last few decades, video game playing progressively became a widespread activity for many people, in childhood as well in adulthood. An increasing amount of literature has focused on pathological and non-pathological correlates of video game playing, with specific attention towards Internet Gaming Disorder (IGD). While many neurobiological studies in this field were based on neuroimaging, highlighting structural and functional brain changes among video game users, only a limited number of studies investigated the presence of biochemical correlates of video gaming. The present work aims to summarize and review the available literature about biochemical changes linked to video game use in IGD patients as well as non-pathological users, and the differences in between. Results may shed light on risks and benefits of video games, providing directions for further research on IGD treatment and, on other hand, on the potential role of video games in therapeutic or preventive protocols for specific conditions. Internet gaming disorder (IGD) has represented a matter of interest in psychiatric research since the early 1990s. It is usually defined as a continuous and repeated involvement with video games, often leading to significant daily, work, and/or educational disruptions ,3. The fSeveral psychiatric conditions, such as impulsiveness, depression, social anxiety, obsessive-compulsive disorder (OCD), and autism spectrum disorder (ASD) have been more frequently associated with the presence of IGD ,9,10. OtAccording to previous studies, common neuroimaging alterations were reported between IGD and SUD, including decreased gray matter volume and lower density in the anterior cingulate cortex, an increased gray matter volume in striatal regions , or an iDespite the increasing body of neuroimaging and neurophysiological studies about the effects of video game playing among IGD patients and, to a lesser extent, among non-pathological video game users, to date, only a limited amount of research specifically investigated the biochemical correlates of video game use. Most of the biochemical studies in this field seem to confirm the central role of dopamine (DA) in this condition, a neurotransmitter already known for its crucial role in drug and alcohol dependence, mediating reward and withdrawal mechanisms ,32. ScanSeveral studies reported evidence of a dopaminergic pathway alteration among individuals with SUD  or behavThe interest in hormonal changes among subjects with IGD is based on the growing evidence of the involvement of the hypothalamic–pituitary–adrenal (HPA) axis in both SUD and behavioural addictions . An altePark et al.  focused Other studies focused on BDNF, which was hypothesized to be involved in the development and maintenance of addictive disorders . PreviouA single study led by Han et al.  focused A more recent study  conducteFinally, Lee et al.  comparedSS-5HTTLPR), which was associated in previous studies with AUD [CRHR1) (rs28364027) gene in the IGD group (N = 118) compared to HC (N = 112), which have been previously associated with AUD [Han et al.  focused with AUD  and MDD with AUD , among swith AUD  assessedwith AUD , PG [102with AUD , and higwith AUD . The T-vwith AUD . Park etwith AUD  highlighwith AUD . More rewith AUD  investigwith AUD . In linewith AUD , the resAll the studies are summarized in Due its well-known role in learning, sensorimotor integration, reinforcement of behaviour, and attention ,112, DA NE and Epi were firstly investigated by Eisenhofer et al. in 1985 . In thisLeague of Legends) against other people or against the computer.Research concerning hormone secretion during video gaming has mainly focused on cortisol levels, starting with a first study in 1998  that meaFollowing the spreading hypothesis of a supposed link between media violence  against other people or against the computer. Results showed no changes in testosterone, DHEA, or androstenedione levels in either of the settings, while aldosterone levels were significantly reduced in both. When playing against other people, a positive correlation was found between the duration of the game and the increase in testosterone, DHEA, and androstenedione. In this framework, the lack of a significant increase in the hormone’s levels might also be correlated to the short duration of the game (15–27 min), in line with a previous study that suggested how increases in testosterone are more likely to occur in competitions longer than 15 min compared to shorter ones [Other studies focused on testosterone, with interesting results. Oxford et al.  evaluateter ones .The interest in energy expenditure and glucose levels while and/or after video game playing rose after the reported evidence about a correlation between the number of hours spent daily playing electronic games and an increased risk of obesity ,139,140.All the studies are summarized in Since the spreading of video game use in the general population, most of the studies in the field of brain sciences have been inclined to focus on possible harmful consequences of video gaming from both a medical and psychosocial point of view ,148, sucStudies about biochemical changes related to video gaming among non-pathological users, on the other hand, showed a more complex picture. Studies on DA seem to confirm the association between gaming and DA release, stressing the addictive potential of this activity ,114, whi“joint attentional scene”, such as the cognitive stimulation towards understanding the intentionality of the other participants, the specific organization of communication methods and behavioural synchronization, the ability of changing perspective and point of view, the possibility of learning new skills and the perception of one-self as a subject within a specific community [In the last few decades, several authors focused on evaluating the possible use of video games for increasing well-being and promoting individual growth . Video gommunity . In thisommunity ,168.Several authors reported cognitive improvements related to video game use in healthy individuals, such as positive changes in reaction times, implementation of conceptual thinking, executive functioning, attention, memory, creativity, improvement of hand eye coordination, and spatial visualization ability ,171,172.Globally, results on biochemical correlates of video gaming seem to suggest interesting perspectives, highlighting both potentially harmful  and potentially beneficial (such as stress control or cognitive improvements) consequences. In this framework, the activity of video gaming should be considered a variable whose effects may vary depending on the specific kind of game, on environmental contexts, and on individual vulnerabilities. From a clinical point of view, it is of the utmost importance to further investigate the specific mechanisms that may lead to different pathways. Further studies should aim to improve our knowledge on this subject, in order to clarify when video game use should be recommended, limited, or avoided, depending on the need of the individual.


Quantum key distribution (QKD) is a promising technique to share unconditionally secure keys between remote parties. As an essential part of a practical QKD system, reconciliation is responsible for correcting the errors due to the quantum channel noise by exchanging information through a public classical channel. In the present work, we propose a novel syndrome-based low-density parity-check (LDPC) reconciliation protocol to reduce the information leakage of reconciliation by fully utilizing the syndrome information that was previously wasted. Both theoretical analysis and simulation results show that our protocol can evidently reduce the information leakage as well as the number of communication rounds. Quantum key distribution (QKD) is a promising technique to share secure keys via insecure quantum and classical channels between two remote parties, usually called Alice and Bob . Unlike m and n represent the lengths of syndrome S was generated as m syndrome bits of S were transmitted to the other party for LDPC decoding. In this way, a high efficiency could be achieved only when the actual QBER of the frame fluctuated in a narrow region around the estimated QBER. Specifically, for a lower QBER, the efficiency would decrease due to excessive information leakage, and for a higher QBER, the efficiency would also decrease due to an increase in the frame error rate (FER), i.e., the rate of frames that cannot be corrected. However, for a QKD system operating in a practical condition, its QBER might vary significantly in consecutive frames [Many IR protocols have been proposed aiming at minimizing the information leakage of IR, i.e., improving the IR efficiency. The terms of IR protocols and IR efficiency are hereafter referred to simply as protocols and efficiency, respectively. Among all these protocols, the low-density parity-check (LDPC) code based protocols ,20,21,22stems in . In earlstems in . Then, te frames ,25. To pR could be adjusted to adapt to the QBER fluctuations, thus higher efficiencies within a wider QBER range were achieved with only one LDPC code. However, this protocol still needed a priori estimation of the QBER and large frame-length LDPC codes. To address this issue, the blind protocol was proposed [To overcome such shortcomings, the rate-adaptive protocol was proposed . In thisproposed . On the proposed , an incrproposed  via intrS of length m is considered to leak m-bit information to Eve and this m-bit information will be discarded in the PA step. However, the actual error rate between Alice’s and Bob’s syndromes is usually not equal to, but less than 50% in a practical IR implementation. This observation indicates that the actual amount of information obtained by Eve is less than m-bit, and some syndrome information has been wasted. If this wasted syndrome information can be used in LDPC decoding, the efficiency can be further improved. In light of this, we propose a novel LDPC-based protocol to fully utilize this wasted syndrome information. In our protocol, we focus on a set of frames rather than a single frame. By replacing some punctured bits from random bits with syndrome bits, the previous wasted syndrome information can be taken as an advantage in our protocol. The efficiency of our protocol is proved to be better than previous LDPC protocols. In addition, our protocol is easy to implement. Simulation results show that our protocol achieves better efficiency and less communication consumption than the comparative protocols.Although LDPC-based protocols have been well studied, we find out that there remains much room for performance improvement in a practical QKD system. We notice that an LDPC syndrome The rest of this paper is organized as follows. q, which is usually referred to as QBER. Therefore, for a frame of length n, the theoretical lower limit of the revealed information for successful reconciliation can be calculated by m syndrome bits are leaked to Eve in the previous LDPC protocols, an important performance metric f for IR is given asIn a DV-QKD system, the discrepancies between Alice’s and Bob’s frames can be assumed to be the transmission result over a binary symmetric channel (BSC)  with crof is always greater than 1, and the smaller f is, the better IR performs.Obviously, R, we know from Equation ,,2), the s and p at the beginning of the protocol, the blind protocol [d bits were initially regarded as punctured bits. In case of a decoding failure, the decoding process would resume again by revealing some punctured bits in the next round, i.e., these punctured bits were transformed into shortened bits. In this way, a high f was achieved even with a short frame length. According to Equation  magnitude, which contributed to the decoding process. Since the shortened bits were not only selected from the punctured bits, IR could continue even in the absence of punctured bits. In this way, the convergence was formally guaranteed by the fact that in the worst-case scenario, all the bits of the frame were revealed .w frames to be reconciled and consider these frames as a whole when calculating the efficiency. Since Alice and Bob perform the same operation when constructing the frames, without loss of generality, we mainly focus on the operations at Alice’s side. In addition, in both n and the m, respectively.In this part, we elaborate upon the main idea of our protocol and analyze its improvement in efficiency by contrasting the workflow of the previous LDPC protocols fnew and T. Let Let The Specific Procedure of Our Protocol is as Follows.Step 0: Initialization. Alice and Bob divide the frames to be reconciled into two layers. The frames in Step 1: Syndrome puncturing. Alice and Bob sequentially initialize the punctured bits T by the syndrome bits from Step 2: Layered decoding. The interactive decoding process of T are initialized according to the theoretical error rate of We note that the principal difference between our protocol and the previous protocols is that our protocol adds an additional step “Step 1” and needs to control the decoding processes between layers in “Step 2”. Because these additional costs are negligible, we believe our protocol is low cost and easy to implement. We can also see from “Step 0” that our protocol is compatible with nearly all commonly used LDPC protocols.The performance improvement of our protocol is attributed to its full utilization of the wasted syndrome information. It is important to note that our protocol performs well under three conditions as described below. First, our protocol requires several frames to be reconciled together. Second, the error rate of syndrome bits of We note that the typical frame lengths for blind and rate-adaptive protocols are 2 ,22 and 1In addition, let q decreases from q is from q strays away from Even when an LDPC code is designed for a desired QBER In addition to the above-mentioned scenario in which puncturing and shortening techniques are applied, our protocol is also well suitable for the scenario in which the standard LDPC codes are applied. As we know, it is widely accepted in the quantum cryptography community that designing a highly efficient LDPC code is really a challenging task. For this reason, the off-the-shelf standard LDPC codes have been widely used in industrial QKD systems ,28. The Next, we analyze whether p to n is 10%, which provides enough available punctured bits for T. For the rate-adaptive protocol, the situation is similar to that in blind protocol when q is around q increases to p decreases, resulting in a decrease in From “Step 0” of our protocol, we know that our protocol is based on the previous LDPC-based protocols. The most commonly used LDPC-based protocols are rate-adaptive, blind and symmetric-blind protocols. Based on each protocol, we analyze the corresponding q from 1% to 5%, which most current DV-QKD systems focus on. In terms of LDPC decoding, we use our previous reported simplified LDPC decoding algorithm and the syndrome-based early termination strategy [In our simulation, we apply rate-adaptive and symmetric-blind protocols in “Step 0” of our protocol, respectively. The performance of our protocol is also compared with these two protocols. We design a set of QC-LDPC codes with lgorithm  and stanlgorithm , respected as in . Becauseq gradually increases to 2.5%. However, these results do not hamper the effectiveness of our protocol. This is because the efficiency is more determined by the intrinsic performance of an LDPC code than the adaptivity of an LDPC protocol when q approaches to the QBER according to which the LDPC code is designed.From the comparison results in For comparison with symmetric-blind protocols, we apply a set of standard LDPC codes from the IEEE 802.11n . From FiIn this paper, we propose a novel syndrome-based LDPC protocol with high efficiency and low communication consumption. This protocol focuses on a set of frames rather than a single frame. By applying the novel syndrome-puncturing technique, the previous wasted syndrome information can be taken advantage of in our protocol. Furthermore, our protocol is easy to implement and compatible with nearly all commonly used LDPC reconciliation protocols. Simulation results show that our protocol not only improves the efficiency but also decreases the mean number of communication rounds. Note that our protocol is particularly suitable for low QBERs, which most DV-QKD systems focus on.Furthermore, our protocol may have implications for other forward-error-correction code-based reconciliation protocols. If we can fully utilize the wasted information leakage caused by the transmitted bits with an error rate less than 50%, the efficiency can be further improved.