Recurrence of ventricular fibrillation in out-of-hospital cardiac arrest: Clinical evidence and underlying ionic mechanisms.

Defibrillation remains the optimal therapy for terminating ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OHCA) patients, with reported shock success rates of ∼90%. A key persistent challenge, however, is the high rate of VF recurrence (∼50-80%) seen during post-shock cardiopulmonary resuscitation (CPR). Studies have shown that the incidence and time spent in recurrent VF are negatively associated with neurologically-intact survival. Recurrent VF also results in the administration of extra shocks at escalating energy levels, which can cause cardiac dysfunction. Unfortunately, the mechanisms underlying recurrent VF remain poorly understood. In particular, the role of chest-compressions (CC) administered during CPR in mediating recurrent VF remains controversial. In this review, we first summarize the available clinical evidence for refibrillation occurring during CPR in OHCA patients, including the postulated contribution of CC and non-CC related pathways. Next, we examine experimental studies highlighting how CC can re-induce VF via direct mechano-electric feedback. We postulate the ionic mechanisms involved by comparison with similar phenomena seen in commotio cordis. Subsequently, the hypothesized contribution of partial cardiac reperfusion (either as a result of CC or CC independent organized rhythm) in re-initiating VF in a globally ischaemic heart is examined. An overview of the proposed ionic mechanisms contributing to VF recurrence in OHCA during CPR from a cellular level to the whole heart is outlined. Possible therapeutic implications of the proposed mechanistic theories for VF recurrence in OHCA are briefly discussed.

Assessing the quality of chest compressions with a DIY low-cost manikin (LoCoMan) versus a standard manikin: a quasi-experimental study in primary education.

Extending the access to cardiopulmonary resuscitation (CPR) training to a wider public is an important step in increasing survivability of out-of-hospital cardiac arrest. However, often price and maintenance of CPR manikins are barriers that prevent training at schools. This study aims to evaluate the learning of hands-only (HO) CPR by practicing with a low-cost manikin (LoCoMan) with visual qualitative feedback and to compare the results with the skills acquired by practice on a conventional manikin. A quasi-experimental study with 193 schoolchildren (10 to 12 years old) who were allocated to two groups: the LoCoMan group was taught via an integrative approach (science combined with physical education (PE)) and practiced on a handmade manikin, and a control group practiced in a traditional setting with a commercial manikin (Resusci Junior, Laerdal, Norway). All participants practiced for 1 hands-on skill session before performing a post-test on an instrumented CPR manikin. The outcomes including HO-CPR performance variables were compared between groups. The LoCoMan and control groups both achieved acceptable percentage of HO-CPR quality (57% and 71%, p = 0.004). Among 6th-graders, there were no significant differences in HO-CPR quality between LoCoMan 68% and control 71%, p = 0.66. The control group achieved better chest compression depth while the LoCoMan group showed more compressions with adequate chest recoil.     Conclusion: Schoolchildren are able to build and use a low-cost manikin with visual feedback. The integrative learning approach used in this study may be a feasible alternative methodology for training and learning HO-CPR in schools when commercial manikins are not available. What is Known: • Access to CPR training should be universal and independent of age, location, financial means, or access to qualified instructors. • Scientific societies promote the implementation of CPR in schools, so that teachers and schoolchildren can play a multiplier role in their environment, but the gap in CPR learning is related to cultural, economic factors or access to resources and materials. What is New: • LoCoMan may be a useful device for teaching and learning CPR in schoolchildren from the age of 10 and upwards. • LOCOMAN shows that it is feasible and possible to build a low-cost manikin (about €5 in the European Region) and to integrate it into an integrative educational project, and outlines how this could be done. this approach can be an incentive for teachers to attempt teaching CPR, but also for education outside the formal environment.

Chest compression quality comparing 1-min vs 2-min rotation of rescuers wearing N95 masks.

BACKGROUND: During the COVID-19 pandemic, cardiopulmonary resuscitation (CPR) performed by rescuers wearing well-sealed respirators such as N95 masks, was associated with significant reduction in the chest compression rate and depth. This was attributed to fatigue during the standard 2-min rescuer rotations. We hypothesized that in such situations, rotating rescuers every one minute, instead of the standard two minutes would improve CPR quality. AIM: To compare the quality of chest compressions when rescuers wearing N95 masks are rotated every one minute, instead of the standard practice of two-minute rotations. METHODS: A randomized, controlled, crossover trial was conducted, with the approval of the institutional Ethics Committee. Medical students who volunteered as rescuers were trained to perform high-quality chest compressions on a manikin, and then randomly allocated into pairs. Each pair was randomized to one of two trial groups viz. one-minute rotations crossed-over to two-minute rotations; and vice versa. Thus, each pair performed CPR with one-minute rotations, as well as two-minute rotations Each CPR session included chest compressions for a duration of 12 min. The outcome parameters included CPR quality, compression depth, compression rate, and chest compression fraction. Rescuer fatigue was measured before and after each study session using the modified Borg scale. RESULTS: Fifty-six participants completed the study. The overall CPR quality was statistically similar in the study arms (median 88% vs. 81%, p = 0.09). However, the minute-to-minute inter-arm comparison revealed significantly lower CPR quality in the 2-min rotation arm, at the end of minutes 4, 6, 8, 10 and 12 (respective p-values 0.03, 0.001, 0.008, 0.02, 0.002). A similar trend was observed in compression depth also. Rescuer fatigue score was significantly less with 1-min rotations compared to 2-min rotations (p < 0.001). Rescuer vital signs and cardiorespiratory parameters were not different with the two types of rotations. CONCLUSION: During CPR performed by rescuers wearing N95 masks, the quality of CPR appears to be superior with rescuers rotating at 1-min instead of 2-min intervals. More frequent rotation was also associated with less rescuer fatigue.

Optimal chest compression for cardiac arrest until the establishment of ECPR: Secondary analysis of the SAVE-J II study.

INTRODUCTION: The widespread incorporation of extracorporeal cardiopulmonary resuscitation (ECPR) for out-of-hospital cardiac arrest requires the delivery of effective and high-quality chest compressions prior to the initiation of ECPR. The aim of this study was to evaluate and compare the effectiveness of mechanical and manual chest compressions until the initiation of ECPR. METHODS: This study was a secondary analysis of the Japanese retrospective multicenter registry "Study of Advanced Life Support for Ventricular Fibrillation by Extracorporeal Circulation II (SAVE-J II)". Patients were divided into two groups, one receiving mechanical chest compressions and the other receiving manual chest compressions. The primary outcome measure was mortality at hospital discharge, while the secondary outcome was the cerebral performance category (CPC) score at discharge. RESULTS: Of the 2157 patients enrolled in the SAVE-J II trial, 453 patients (329 in the manual compression group and 124 in the mechanical compression group) were included in the final analysis. Univariate analysis showed a significantly higher mortality rate at hospital discharge in the mechanical compression group compared to the manual compression group (odds ratio [95% CI] = 2.32 [1.34-4.02], p = 0.0026). Multivariate analysis showed that mechanical chest compressions were an independent factor associated with increased mortality at hospital discharge (adjusted odds ratio [95% CI] = 2.00 [1.11-3.58], p = 0.02). There was no statistically significant difference in CPC between the two groups. CONCLUSION: For patients with out-of-hospital cardiopulmonary arrest who require ECPR, extreme caution should be used when performing mechanical chest compressions.

A Case of Coronary Artery Perforation Caused by Manual Cardiopulmonary Resuscitation in the Catheterization Laboratory.

Cardiopulmonary resuscitation (CPR) is essential for the survival of cardiac arrest patients, but it can cause severe traumatic complications. In the catheterization laboratory, various physical constraints complicate the appropriate performance of CPR. However, we are not aware of reports of CPR complications in this setting. Here, we report a case of coronary artery perforation (CAP) caused by manual CPR in the catheterization laboratory. The patient, a 68-year-old woman, initially underwent successful percutaneous coronary intervention (PCI) for unstable angina. Back in the ward, the patient experienced acute stent thrombosis, which resulted in cardiac arrest, and another PCI was performed under ongoing manual CPR. Although revascularization was successful, sudden CAP occurred, leading to cardiac tamponade. Despite extensive treatment efforts, the patient died 18 hours later.Initially, the compression site of CPR was on the midline of the sternum; however, the compression site shifted to the left, to just above the left anterior descending artery, by the time that CAP was detected via angiography. This corresponded to the area where rib fractures were observed upon computed tomography, suggesting the possibility of traumatic CAP due to manual CPR. The physical constraints in the catheterization laboratory can lead to an inappropriate CPR technique and severe traumatic complications.

Comparison of chest compression quality between the overlapping hands and interlocking hands techniques: A randomised cross-over trial.

BACKGROUND: Performing quality chest compressions is fundamental to the management of cardiopulmonary arrest. The aim of this study was to compare the efficacy of two hand positions: overlapping versus interlocking for performing chest compressions during cardiopulmonary arrest. METHODS: The HP2C (for Hands Position and Chest Compression) was a prospective, randomised, open-label, cross-over, single-centre study. Participants were recruited from the Emergency Medical Service (EMS) teams and the prehospital firefighter teams. They were randomised to start chest compressions either with overlapping or interlocking hands and then performed the other technique after a washout period. The judgement criteria were the overall chest compressions success score generated by software in accordance with ILCOR recommendations, the quality of compression, release, rate and subjective intensity measured with the Borg scale. RESULTS: A total of 100 participants were included in the study. The mean age of the caregivers was 38 ± 9.3 years. The median CPR score was 79.5% IQR [48.5-94.0] in the overlapping hands group and 71% IQR [38.0-92.8] in the interlocking hands group (p-value = 0.37). There was no significant difference for the other criteria, especially no difference in term of intensity of effort. However, there was a trend towards better results with overlapping hands. CONCLUSIONS: This study failed to demonstrate a difference in effectiveness between overlapping and interlocking hand chest compressions during cardiopulmonary resuscitation.

Compression-associated injuries using CLOVER3000 device in non-survivor patients of OHCA: A retrospective cohort study.

AIM: The incidence of compression-associated injuries from using the CLOVER3000, a new mechanical cardiopulmonary resuscitation (CPR) device, is not well studied in the context of out-of-hospital cardiac arrest (OHCA). Thus, we aimed to compare compression-associated injuries between CLOVER3000 and manual CPR. METHODS: This single-center, retrospective, cohort study used data from the medical records of a tertiary care center in Japan between April 2019 and August 2022. We included adult non-survivor patients with non-traumatic OHCA who were transported by emergency medical services and underwent post-mortem computed tomography. Compression-associated injuries were tested using logistic regression models adjusting for age, sex, bystander CPR performance, and CPR duration. RESULTS: A total of 189 patients (CLOVER3000, 42.3%; manual CPR, 57.7%) were included in the analysis. The overall incidence of compression-associated injuries was similar between the two groups (92.5% vs. 94.54%; adjusted odds ratio (AOR), 0.62 [95% confidence interval (CI), 0.06-1.44]). The most common injury was anterolateral rib fractures with a similar incidence between the two groups (88.7% vs. 88.9%; AOR, 1.03 [95% CI, 0.38 to 2.78]). The second most common injury was sternal fracture in both groups (53.1% vs. 56.7%; AOR, 0.68 [95% CI, 0.36-1.30]). The incidence rates of other injuries were not statistically different between the both groups. CONCLUSION: We observed a similar overall incidence of compression-associated injuries between the CLOVER3000 and manual CPR groups on small sample size.

The Association Between the Duration of Chest Compression and Thoracic Injuries in Patients With Non-Traumatic Out-of-Hospital Cardiac Arrest.

BACKGROUND: Current guidelines emphasize the indispensability of high-quality chest compression for improving survival in patients who experience out-of-hospital cardiac arrest (OHCA). However, chest compression can cause thoracic injuries that may contribute to poor prognosis; therefore, the purpose of this study is to identify the predictors of thoracic injuries and evaluate the association between thoracic injuries and prognosis.Methods and Results: Between June 2017 to July 2019, Utstein-style data on 384 consecutive adult patients who experienced non-traumatic OHCA and who were transferred to our hospital (Aso Iizuka Hospital) were collected. Each patient underwent a full-body computed tomography scan. Two-hundred and thirty-four patients (76%) had thoracic injuries (Group-T). The duration of chest compression was significantly longer in Group-T than in patients without thoracic injuries (Group-N; 43 vs. 32 min, respectively, P<0.001). Multivariate analysis revealed that older age and longer chest compression duration were predictors of thoracic injuries (odds ratios 1.03 and 1.07, respectively, P≤0.005). Among patients who achieved return of spontaneous circulation, Kaplan-Meier curves showed a significantly higher cumulative survival rate in Group-N than in Group-T at the 30-day follow up (log-rank test P=0.009). CONCLUSIONS: Older age and longer chest compression duration were independent predictors of thoracic injuries due to chest compression in patients who experienced non-traumatic OHCA. Moreover, the presence of thoracic injuries was associated with worse short-term prognosis.

Injury characteristics and hemodynamics associated with guideline-compliant CPR in a pediatric porcine cardiac arrest model.

BACKGROUND: Guidelines for depth of chest compressions in pediatric cardiopulmonary resuscitation (CPR) are based on sparse evidence. OBJECTIVE: We sought to evaluate the performance of the two most widely recommended chest compression depth levels for pediatric CPR (1.5 in. and 1/3 the anterior-posterior diameter- APd) in a controlled swine model of asphyxial cardiac arrest. METHODS: We executed a 2-group, randomized laboratory study with an adaptive design allowing early termination for overwhelming injury or benefit. Forty mixed-breed domestic swine (mean weight = 26 kg) were sedated, anesthetized and paralyzed along with endotracheal intubation and mechanical ventilation. Asphyxial cardiac arrest was induced with fentanyl overdose. Animals were untreated for 9 min followed by mechanical CPR with a target depth of 1.5 in. or 1/3 the APd. Advanced life support drugs were administered IV after 4 min of basic resuscitation followed by defibrillation at 14 min. The primary outcomes were return of spontaneous circulation (ROSC), hemodynamics and CPR-related injury severity. RESULTS: Enrollment in the 1/3 APd group was stopped early due to overwhelming differences in injury. Twenty-three animals were assigned to the 1.5 in. group and 15 assigned to the 1/3 APd group, per an adaptive group design. The 1/3 APd group had increased frequency of rib fracture (6.7 vs 1.7, p < 0.001) and higher proportions of several anatomic injury markers than the 1.5 in. group, including sternal fracture, hemothorax and blood in the endotracheal tube (p < 0.001). ROSC and hemodynamic measures were similar between groups. CONCLUSION: In this pediatric model of cardiac arrest, chest compressions to 1/3APd were more harmful without a concurrent benefit for resuscitation outcomes compared to the 1.5 in. compression group.

Efficacy of cardiopulmonary resuscitation performance while wearing a powered air-purifying respirator.

BACKGROUND: The use of personal protective equipment for respiratory infection control during cardiopulmonary resuscitation (CPR) is a physical burden to healthcare providers. The duration for which CPR quality according to recommended guidelines can be maintained under these circumstances is important. We investigated whether a 2-min shift was appropriate for chest compression and determined the duration for which chest compression was maintained in accordance with the recommended guidelines while wearing personal protective equipment. METHODS: This prospective crossover simulation study was performed at a single center from September 2020 to October 2020. Five indicators of CPR quality were measured during the first and second sessions of the study period. All participants wore a Level D powered air-purifying respirator (PAPR), and the experiment was conducted using a Resusci Anne manikin, which can measure the quality of chest compressions. Each participant conducted two sessions. In Session 1, the sequence of 2 min of chest compressions, followed by a 2-min rest, was repeated twice; in Session 2, the sequence of 1-min chest compressions followed by a 1-min rest was repeated four times. RESULTS: All 34 participants completed the study. The sufficiently deep compression rate was 65.9 ± 31.1% in the 1-min shift group and 61.5 ± 30.5% in the 2-min shift group. The mean compression depth was 52.8 ± 4.3 mm in the 1-min shift group and 51.0 ± 6.1 mm in the 2-min shift group. These two parameters were significantly different between the two groups. There was no significant difference in the other values related to CPR quality. CONCLUSIONS: Our findings indicated that 1 min of chest compressions with a 1-min rest maintained a better quality of CPR while wearing a PAPR.

Paediatric In-hospital cardiopulmonary resuscitation quality and outcomes in children with CHD during nights and weekends.

BACKGROUND: Survival after paediatric in-hospital cardiac arrest is worse on nights and weekends without demonstration of disparity in cardiopulmonary resuscitation quality. It is unknown whether these findings differ in children with CHD. This study aimed to determine whether cardiopulmonary resuscitation quality might explain the hypothesised worse outcomes of children with CHD during nights and weekends. METHODS: In-hospital cardiac arrest data collected by the Pediatric Resuscitation Quality Collaborative for children with CHD. Chest compression quality metrics and survival outcomes were compared between events that occurred during day versus night, and during weekday versus weekend using multivariable logistic regression. RESULTS: We evaluated 3614 sixty-second epochs of chest compression data from 132 subjects between 2015 and 2020. There was no difference in chest compression quality metrics during day versus night or weekday versus weekend. Weekday versus weekend was associated with improved survival to hospital discharge (adjusted odds ratio 4.56 [1.29,16.11]; p = 0.02] and survival to hospital discharge with favourable neurological outcomes (adjusted odds ratio 6.35 [1.36,29.6]; p = 0.02), but no difference with rate of return of spontaneous circulation or return of circulation. There was no difference in outcomes for day versus night. CONCLUSION: For children with CHD and in-hospital cardiac arrest, there was no difference in chest compression quality metrics by time of day or day of week. Although there was no difference in outcomes for events during days versus nights, there was improved survival to hospital discharge and survival to hospital discharge with favourable neurological outcome for events occurring on weekdays compared to weekends.

Adequacy of compression positioning using the feedback device during chest compressions by medical staff in a simulation study.

BACKGROUND: The 2020 American Heart Association guidelines recommend the use of a feedback device during chest compressions (CCs). However, these devices are only placed visually by medical personnel on the lower half of the sternum and do not provide feedback on the adequacy of the pressure-delivery position. In this study, we investigated whether medical staff could deliver CCs at the adequate compression position using a feedback device and identified where the inadequate position was compressed. METHODS: This simulation-based, prospective single-centre study enrolled 44 medical personnel who were assigned to four different groups based on the standing position and the hand in contact with the feedback device as follows: right-left (R-l), right-right (R-r), left-right (L-r), and left-left (L-l), respectively. The sensor position where the maximal average pressure was applied during CCs using the feedback device were ascertained with a flexible capacitive pressure sensor. We determined if this position is the adequate compression position or not. The intergroup differences in the frequency of the adequate compression position, the maximal average pressure, compression rate, depth and recoil were determined. RESULTS: The frequencies of adequate compression positioning were 55, 50, 58, and 60% in the R-l, R-r, L-r, and L-l groups, respectively, with no significant intergroup difference (p = 0.917). Inadequate position occurred in the front, back, hypothenar and thenar sides. The maximal average pressure did not significantly differ among the groups (p = 0.0781). The average compression rate was 100-110 compressions/min in each group, the average depth was 5-6 cm, and the average recoil was 0.1 cm, with no significant intergroup differences (p = 0.0882, 0.9653, and 0.2757, respectively). CONCLUSIONS: We found that only approximately half of the medical staff could deliver CCs using the feedback device at an adequate compression position and the inadequate position occurred in all sides. Resuscitation courses should be designed to educate trainees about the proper placement during CCs using a feedback device while also evaluating the correct compression position.

How effective are chest compressions when wearing mask? A randomised simulation study among first-year health care students during the COVID-19 pandemic.

BACKGROUND: The resuscitation guidelines provided for the COVID-19 pandemic strongly recommended wearing personal protective equipment. The current study aimed to evaluate and compare the effectiveness of chest compressions and the level of fatigue while wearing two different types of mask (surgical vs. cloth). METHODS: A randomized, non-inferiority, simulation study was conducted. Participants were randomised into two groups: surgical mask group (n = 108) and cloth mask group (n = 108). The effectiveness (depth and rate) of chest compressions was measured within a 2-min continuous chest-compression-only CPR session. Data were collected through an AMBU CPR Software, a questionnaire, recording vital parameters, and using Borg-scale related to fatigue (before and after the simulation). For further analysis the 2-min session was segmented into 30-s intervals. RESULTS: Two hundred sixteen first-year health care students participated in our study. No significant difference was measured between the surgical mask and cloth mask groups in chest compression depth (44.49 ± 10.03 mm vs. 45.77 ± 10.77 mm), rate (113.34 ± 17.76/min vs. 111.23 ± 17.51/min), and the level of fatigue (5.72 ± 1.69 vs. 5.56 ± 1.67) (p > 0.05 in every cases). Significant decrease was found in chest compression depth between the first 30-s interval and the second, third, and fourth intervals (p < 0.01). CONCLUSION: The effectiveness of chest compressions (depth and rate) was non-inferior when wearing cloth mask compared to wearing surgical mask. However, the effectiveness of chest compressions decreased significantly in both groups during the 2-min chest-compression-only CPR session and did not reach the appropriate chest compression depth range recommended by the ERC.

Effect of a dynamic mattress on chest compression quality during cardiopulmonary resuscitation.

BACKGROUND: In-hospital cardiac arrest is a medical emergency that occurs on a regular basis. As patients most at risk for an in-hospital cardiac arrest are usually positioned on a dynamic mattress, it is important to measure the effect of mattress compressibility on chest compression quality during cardiopulmonary resuscitation (CPR). High-quality CPR is essential for patient survival and good neurological outcome. AIMS AND OBJECTIVES: To examine the effect of an inflated dynamic overlay mattress on chest compression quality during CPR and to explore the predictive effect of health care providers' anthropometric factors, hand positioning and mattress type on chest compression frequency and depth. DESIGN: Manikin-based single-blinded randomised controlled trial. METHODS: Nursing students (N = 70) were randomised to a control (viscoelastic foam mattress) or intervention group (inflated dynamic overlay mattress on top of a viscoelastic foam mattress) and had to perform chest compressions over a 2-minute period. Compression rate, depth and hand positioning were registered. The 2015 European Resuscitation Council (ERC) guidelines were used as a reference. RESULTS: The mean difference in chest compression depth between control and intervention groups was 2.86 mm (P = .043). Both groups met the guidelines for adequate chest compression quality, as recommended by the ERC. A predictive effect of health care providers' body height and weight, mattress type and hand positioning on compression depth could be demonstrated (P = .004). CONCLUSIONS: CPR in bedridden patients on a dynamic overlay mattress has a negative effect on the quality of chest compressions. Mean chest compression depth decreases significantly. However, clinical significance of the results may be debatable. Mattress type, body weight and hand positioning appear to be significant predictors for adequate chest compression depth. RELEVANCE TO CLINICAL PRACTICE: A firm surface under the patient is needed during CPR. Special attention must be paid to correct hand positioning during CPR.

Continuous chest compressions with asynchronous ventilation improve survival in a neonatal swine model of asphyxial cardiac arrest.

BACKGROUND: Guidelines for neonatal resuscitation recommend a 3:1 compression to ventilation ratio. However, this recommendation is based on expert opinion and consensus rather than strong scientific evidence. Our primary aim was to assess whether continuous chest compressions with asynchronous ventilations would increase return of spontaneous circulation (ROSC) rate and survival compared to the 3:1 chest compression to ventilation ratio. METHODS: This was a prospective, randomized, laboratory study. Twenty male Landrace-Large White pigs, aged 1-4 days with an average weight 1.650 ± 228.3 g were asphyxiated and left untreated until heart rate was less than 60 bpm or mean arterial pressure was below 15 mmHg. Animals were then randomly assigned to receive either continuous chest compressions with asynchronous ventilations (n = 10), or standard (3:1) chest compression to ventilation ratio (n = 10). Heart rate and arterial pressure were assessed every 30 s during cardiopulmonary resuscitation (CPR) until ROSC or asystole. All animals with ROSC were monitored for 4 h. RESULTS: Coronary perfusion pressure (CPP) at 30 s of CPR was significantly higher in the experimental group (45.7 ± 16.9 vs. 21.8 ± 6 mmHg, p < 0.001) and remained significantly elevated throughout the experiment. End-tidal carbon dioxide (ETCO2) was also significantly higher in the experimental group throughout the experiment (23.4 ± 5.6 vs. 14.7 ± 5.9 mmHg, p < 0.001). ROSC was observed in six (60%) animals treated with 3:1 compression to ventilation ratio and nine (90%) animals treated with continuous chest compressions and asynchronous ventilation (p = 0.30). Time to ROSC was significantly lower in the experimental group (30 (30-30) vs. 60 (60-60) sec, p = 0.021). Of note, 7 (77.8%) animals in the experimental group and 1 (16.7%) animal in the control group achieved ROSC after 30 s (0.02). At 4 h, 2 (20%) animals survived in the control group compared to 7 (70%) animals in the experimental group (p = 0.022). CONCLUSION: Continuous chest compressions with asynchronous ventilations significantly improved CPP, ETCO2, time to ROSC, ROSC at 30 s and survival in a porcine model of neonatal resuscitation.

Effects of cardiopulmonary resuscitation on direct versus video laryngoscopy using a mannequin model.

INTRODUCTION: During the last decade, guidelines for cardiopulmonary resuscitation has shifted, placing chest compressions and defibrillation first and airway management second. Physicians are being forced to intubate simultaneously with uninterrupted, high quality chest compressions. Using a mannequin model, this study examines the differences between direct and video laryngoscopy, comparing their performance with and without simultaneous chest compressions. METHODS: Fifty emergency medicine physicians were randomly assigned to intubate a mannequin six times, using direct laryngoscopy (DL) and with two video laryngoscopy (VL) systems, a C-MAC traditional Macintosh blade and a GlideScope hyperangulated blade, with and without simultaneous chest compressions. A total of 300 intubations were completed and variables including intubation times, accuracy, difficulty, success rates and glottic views were recorded. RESULTS: The C-MAC VL system resulted in quicker intubations compared to DL (p = 0.007) and the GlideScope VL system (p = 0.039) during active chest compressions. Compared to DL, intubations were rated easier for both the C-MAC (p < 0.0001) and the GlideScope (p < 0.0001). Intubation failure rates were also higher when DL was used compared to either the C-MAC or GlideScope (p = 0.029). VL devices provided a superior overall Cormack-Lehane grade view compared to DL (p < 0.0001). The presence of chest compressions significantly impaired Cormack-Lehane views during direct laryngoscopy (p = 0.007). Chest compressions made the intubation more difficult under DL (p = 0.002) and when using the C-MAC (p = 0.031). Chest compressions also made ETT placement less accurate when using DL (p = 0.004). CONCLUSION: Using a mannequin model, the C-MAC conventional VL blade resulted in decrease intubation times compared with DL or the GlideScope hyperangulated VL blade system. Overall, VL out performed DL in terms of providing a superior glottic view, minimizing failed attempts, and improving physician's overall perception of intubation difficulty. Chest compressions resulted in worse Cormack-Lehane views and higher rates of inaccurate endotracheal tube placement with DL, compared to VL.

Chest compressions during ventilation in out-of-hospital cardiopulmonary resuscitation cause fragmentation of the airflow.

INTRODUCTION: When a patient suffers an out-of-hospital cardiac arrest, ventilation and chest compressions are often given simultaneously during cardiopulmonary resuscitation. These simultaneous chest compressions may cause a fragmentation of the airflow, which may lead to an ineffective ventilation. This study focusses on the occurrence and quantification of this fragmentation and its effect on ventilation. MATERIALS AND METHODS: This study is a single-center observational study, held at Ghent University Hospital. A custom-built bidirectional flow sensor was used to quantify the volumes of ventilation. Adult cardiac arrest patients who were prehospitally intubated and resuscitated by the medical emergency team were eligible for inclusion. Data of the patients who were ventilated and received simultaneous chest compressions, was used to calculate the volumes of ventilation and the amount and volumes of fragmentation. All data in this study is reported as mean (standard deviation; range). RESULTS: Data of 10 patients (7 male) with a mean age of 71 years (14;51-87) was used in this study. The mean ventilation frequency was 12/min (2;9-16), the mean minute volume and tidal volume were respectively 6.21 L (1.51;3.79-8.15) and 514 mL (99;422-682). Fragmentation of the airflow was observed in all patients, with an average of 3 (1;2-5) fragments per inspiration and a mean volume of 214 mL (65;112-341) per fragment. DISCUSSION AND CONCLUSION: Chest compressions during ventilation caused fragmentation of the airflow in all patients. There was wide variation in the number and volume of the fragments between patients. The importance of quantification of airflow volumes and the effect fragmentation of the airflow on the efficacy of ventilation can be essential in improving cardiopulmonary resuscitation techniques and therefore needs further investigation.

Optimization of End-to-End Convolutional Neural Networks for Analysis of Out-of-Hospital Cardiac Arrest Rhythms during Cardiopulmonary Resuscitation.

High performance of the shock advisory analysis of the electrocardiogram (ECG) during cardiopulmonary resuscitation (CPR) in out-of-hospital cardiac arrest (OHCA) is important for better management of the resuscitation protocol. It should provide fewer interruptions of chest compressions (CC) for non-shockable organized rhythms (OR) and Asystole, or prompt CC stopping for early treatment of shockable ventricular fibrillation (VF). Major disturbing factors are strong CC artifacts corrupting raw ECG, which we aimed to analyze with optimized end-to-end convolutional neural network (CNN) without pre-filtering or additional sensors. The hyperparameter random search of 1500 CNN models with 2-7 convolutional layers, 5-50 filters and 5-100 kernel sizes was done on large databases from independent OHCA interventions for training (3001 samples) and validation (2528 samples). The best model, named CNN3-CC-ECG network with three convolutional layers (filters@kernels: 5@5,25@20,50@20) presented Sensitivity Se(VF) = 89%(268/301), Specificity Sp(OR) = 91.7%(1504/1640), Sp(Asystole) = 91.1%(3325/3650) on an independent test OHCA database. CNN3-CC-ECG's ability to effectively extract features from raw ECG signals during CPR was comprehensively demonstrated, and the dependency on the CPR corruption level in ECG was tested. We denoted a significant drop of Se(VF) = 74.2% and Sp(OR) = 84.6% in very strong CPR artifacts with a signal-to-noise ratio of SNR < -9 dB, p < 0.05. Otherwise, for strong, moderate and weak CC artifacts (SNR > -9 dB, -6 dB, -3 dB), we observed insignificant performance differences: Se(VF) = 92.5-96.3%, Sp(OR) = 93.4-95.5%, Sp(Asystole) = 92.6-94.0%, p > 0.05. Performance stability with respect to CC rate was validated. Generalizable application of the optimized computationally efficient CNN model was justified by an independent OHCA database, which to our knowledge is the largest test dataset with real-life cardiac arrest rhythms during CPR.

Testing mechanical chest compression devices of different design for their suitability for prehospital patient transport - a simulator-based study.

BACKGROUND: Mechanical chest compression (mCPR) offers advantages during transport under cardiopulmonary resuscitation. Little is known how devices of different design perform en-route. Aim of the study was to measure performance of mCPR devices of different construction-design during ground-based pre-hospital transport. METHODS: We tested animax mono (AM), autopulse (AP), corpuls cpr (CC) and LUCAS2 (L2). The route had 6 stages (transport on soft stretcher or gurney involving a stairwell, trips with turntable ladder, rescue basket and ambulance including loading/unloading). Stationary mCPR with the respective device served as control. A four-person team carried an intubated and bag-ventilated mannequin under mCPR to assess device-stability (displacement, pressure point correctness), compliance with 2015 ERC guideline criteria for high-quality chest compressions (frequency, proportion of recommended pressure depth and compression-ventilation ratio) and user satisfaction (by standardized questionnaire). RESULTS: All devices performed comparable to stationary use. Displacement rates ranged from 83% (AM) to 11% (L2). Two incorrect pressure points occurred over 15,962 compressions (0.013%). Guideline-compliant pressure depth was > 90% in all devices. Electrically powered devices showed constant frequencies while muscle-powered AM showed more variability (median 100/min, interquartile range 9). Although physical effort of AM use was comparable (median 4.0 vs. 4.5 on visual scale up to 10), participants preferred electrical devices. CONCLUSION: All devices showed good to very good performance although device-stability, guideline compliance and user satisfaction varied by design. Our results underline the importance to check stability and connection to patient under transport.

Ventricular Fibrillation Recurrences in Successfully Shocked Out-of-Hospital Cardiac Arrests.

Background and Objectives: The prognostic impact of ventricular fibrillation (VF) recurrences after a successful shock in out-of-hospital cardiac arrest (OOHCA) is still poorly understood, and some evidence suggests a potential pro-arrhythmic effect of chest compressions in this setting. In the present analysis, we looked at the short-term and long-term prognosis of VF recurrences in OOHCA. And their potential association with chest compressions. Materials and Methods: The Progetto Vita, prospectively collecting data on all resuscitation efforts in the Piacenza province (Italy), was used for the present analysis. From the 461 OOHCAs found in a shockable rhythm, only those with optimal ECG tracings and good audio recordings (160) were assessed. Rhythms other than VF post-shock were analyzed five seconds after shock delivery and survival to hospital admission, hospital discharge, and long-term survival data over a 14-year follow-up were collected. Results: Population mean age was 64.4 ± 16.9 years, and 31.9% of all patients were female. Mean time to EMS arrival was 5.9 ± 4.5 min. Short- and long-term survival without neurological impairment were higher in patients without VF recurrence when compared to patients with VF recurrence, independently from the pre-induction rhythm (p < 0.001). After shock delivery, VF recurrence was higher when chest compressions were resumed early after discharge and more vigorously. Conclusions: VF recurrences after a shock could worsen short and long-term survival. The potential pro-arrhythmic effect of chest compressions should be factored in when considering the real risks and benefits of this procedure.