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.

The Role of Chest Compressions on Ventilation during Advanced Cardiopulmonary Resuscitation

Background: There is growing interest in the quality of manual ventilation during cardiopulmonary resuscitation (CPR), but accurate assessment of ventilation parameters remains a challenge. Waveform capnography is currently the reference for monitoring ventilation rate in intubated patients, but fails to provide information on tidal volumes and inspiration-expiration timing. Moreover, the capnogram is often distorted when chest compressions (CCs) are performed during ventilation compromising its reliability during CPR. Our main purpose was to characterize manual ventilation during CPR and to assess how CCs may impact on ventilation quality. Methods: Retrospective analysis were performed of CPR recordings fromtwo databases of adult patients in cardiac arrest including capnogram, compression depth, and airway flow, pressure and volume signals. Using automated signal processing techniques followed by manual revision, individual ventilations were identified and ventilation parameters were measured. Oscillations on the capnogram plateau during CCs were characterized, and its correlation with compression depth and airway volume was assessed. Finally, we identified events of reversed airflow caused by CCs and their effect on volume and capnogram waveform. Results: Ventilation rates were higher than the recommended 10 breaths/min in 66.7% of the cases. Variability in ventilation rates correlated with the variability in tidal volumes and other ventilatory parameters. Oscillations caused by CCs on capnograms were of high amplitude (median above 74%) and were associated with low pseudo-volumes (median 26 mL). Correlation between the amplitude of those oscillations with either the CCs depth or the generated passive volumes was low, with correlation coefficients of -0.24 and 0.40, respectively. During inspiration and expiration, reversed airflow events caused opposed movement of gases in 80% of ventilations. Conclusions: Our study confirmed lack of adherence between measured ventilation rates and the guideline recommendations, and a substantial dispersion in manual ventilation parameters during CPR. Oscillations on the capnogram plateau caused by CCs did not correlate with compression depth or associated small tidal volumes. CCs caused reversed flow during inspiration, expiration and in the interval between ventilations, sufficient to generate volume changes and causing oscillations on capnogram. Further research is warranted to assess the impact of these findings on ventilation quality during CPR.

Evaluation of compressor fatigue at 150 compressions per minute during cardiopulmonary resuscitation using a large dog manikin

OBJECTIVE

To determine whether CPR providers can perform chest compressions (CC) appropriately at a rate of 150 compressions per minute during a 2-minute cycle and to identify the presence of rescuer fatigue.

DESIGN

High fidelity simulator study.

SETTING

University veterinary teaching hospital.

SUBJECTS

Sixty subjects, 30 women and 30 men.

INTERVENTIONS

Subjects performed CC at 150 compressions per minute on a dog manikin for 2 minutes. Real-time depth of compressions, compression release, and compression rate were measured using a CPR training device. Demographic data from the subjects were analyzed alongside data obtained from the monitoring device.

MEASUREMENTS AND MAIN RESULTS

Only 38.3% of participants were able to perform CC with appropriate depth and release at 150 compressions per minute during a 2-minute cycle. There was a decay in the quality of CC between the first and the second minute. The number of compressions and percentage of compressions with correct release were similar among various genders, ages, and professions. In contrast, the percentage of compressions with correct depth was significantly higher among individuals with higher body mass index (correlation coefficient [r] = 0.293; P = 0.023) and higher biceps brachii muscle circumference during muscle contraction (r = 0.423; P = 0.001).

CONCLUSIONS

This study suggests that increasing the compression rate to 150 compressions per minute in large dogs using the thoracic pump technique might not be viable because most participants were not able to sustain enough appropriate CC. Rescuer fatigue affects compression depth at this rate, leading to a decay in CPR quality.

Poor Concordance of One-Third Anterior-Posterior Chest Diameter Measurements With Absolute Age-Specific Chest Compression Depth Targets in Pediatric Cardiac Arrest Patients

Background Current pediatric cardiac arrest guidelines recommend depressing the chest by one-third anterior-posterior diameter (APD), which is presumed to equate to absolute age-specific chest compression depth targets (4 cm for infants and 5 cm for children). However, no clinical studies during pediatric cardiac arrest have validated this presumption. We aimed to study the concordance of measured one-third APD with absolute age-specific chest compression depth targets in a cohort of pediatric patients with cardiac arrest. Methods and Results This was a retrospective observational study from a multicenter, pediatric resuscitation quality collaborative (pediRES-Q [Pediatric Resuscitation Quality Collaborative]) from October 2015 to March 2022. In-hospital patients with cardiac arrest ≤12 years old with APD measurements recorded were included for analysis. One hundred eighty-two patients (118 infants >28 days old to <1 year old, and 64 children 1 to 12 years old) were analyzed. The mean one-third APD of infants was 3.2 cm (SD, 0.7 cm), which was significantly smaller than the 4 cm target depth (P<0.001). Seventeen percent of the infants had one-third APD measurements within the 4 cm ±10% target range. For children, the mean one-third APD was 4.3 cm (SD, 1.1 cm). Thirty-nine percent of children had one-third APD within the 5 cm ±10% range. Except for children 8 to 12 years old and overweight children, the measured mean one-third APD of the majority of the children was significantly smaller than the 5 cm depth target (P<0.05). Conclusions There was poor concordance between measured one-third APD and absolute age-specific chest compression depth targets, particularly for infants. Further study is needed to validate current pediatric chest compression depth targets and evaluate the optimal chest compression depth to improve cardiac arrest outcomes. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02708134.

A Case Report on Successful Resuscitation of a Two-Month-Old Infant in the Emergency Room: Neonatal Resuscitation Program (NRP) Guidelines in Practice

Infants that appear with respiratory distress or cardiac arrest require immediate attention, and neonatal resuscitation is a crucial skill that can significantly impact the outcome. Here, we discuss a case of a two-month-old baby who needed ER resuscitation. The patient needed immediate assistance due to respiratory distress and cyanosis. This case study emphasizes how crucial it is to follow the Neonatal Resuscitation Program (NRP) algorithm because it allows the patient to have a successful outcome. Regarding the decision on whether to use NRP or Pediatric Advanced Life Support (PALS) guidelines for the two-month-old infant, it was ultimately decided to use the NRP guidelines. This decision was based on the preference of the institution. This case was successfully handled, highlighting the importance of complete training and adherence to the NRP recommendations for healthcare workers involved in neonatal care.

A Randomized, Controlled Animal Study: 21% or 100% Oxygen during Cardiopulmonary Resuscitation in Asphyxiated Infant Piglets

Background: During pediatric cardiopulmonary resuscitation (CPR), resuscitation guidelines recommend 100% oxygen (O2); however, the most effective O2 concentration for infants unknown. Aim: We aimed to determine if 21% O2 during CPR with either chest compression (CC) during sustained inflation (SI) (CC + SI) or continuous chest compression with asynchronized ventilation (CCaV) will reduce time to return of spontaneous circulation (ROSC) compared to 100% O2 in infant piglets with asphyxia-induced cardiac arrest. Methods: Piglets (20−23 days of age, weighing 6.2−10.2 kg) were anesthetized, intubated, instrumented, and exposed to asphyxia. Cardiac arrest was defined as mean arterial blood pressure < 25 mmHg with bradycardia. After cardiac arrest, piglets were randomized to CC + SI or CCaV with either 21% or 100% O2 or the sham. Heart rate, arterial blood pressure, carotid blood flow, and respiratory parameters were continuously recorded. Main results: Baseline parameters, duration, and degree of asphyxiation were not different. Median (interquartile range) time to ROSC was 107 (90−440) and 140 (105−200) s with CC + SI 21% and 100% O2, and 600 (50−600) and 600 (95−600) s with CCaV 21% and 100% O2 (p = 0.27). Overall, six (86%) and six (86%) piglets with CC + SI 21% and 100% O2, and three (43%) and three (43%) piglets achieved ROSC with CCaV 21% and 100% O2 (p = 0.13). Conclusions: In infant piglets resuscitated with CC + SI, time to ROSC reduced and survival improved compared to CCaV. The use of 21% O2 had similar time to ROSC, short-term survival, and hemodynamic recovery compared to 100% oxygen. Clinical studies comparing 21% with 100% O2 during infant CPR are warranted.

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.

Influence of Personal Protective Equipment on the Quality of Chest Compressions: A Meta-Analysis of Randomized Controlled Trials

Background: Randomized controlled trials (RCTs) evaluating the influence of personal protective equipment (PPE) on quality of chest compressions during cardiopulmonary resuscitation (CPR) showed inconsistent results. Accordingly, a meta-analysis was performed to provide an overview.

Methods: Relevant studies were obtained by search of Medline, Embase, and Cochrane's Library databases. A random-effect model incorporating the potential heterogeneity was used to pool the results.

Results: Six simulation-based RCTs were included. Overall, pooled results showed that there was no statistically significant difference between the rate [mean difference (MD): −1.70 time/min, 95% confidence interval (CI): −5.77 to 2.36, P = 0.41, I² = 80%] or the depth [MD: −1.84 mm, 95% CI: −3.93 to 0.24, P = 0.11, I² = 73%] of chest compressions performed by medical personnel with and without PPE. Subgroup analyses showed that use of PPE was associated with reduced rate of chest compressions in studies before COVID-19 (MD: −7.02 time/min, 95% CI: −10.46 to −3.57, P < 0.001), but not in studies after COVID-19 (MD: 0.14 time/min, 95% CI: −5.77 to 2.36, P = 0.95). In addition, PPE was not associated with significantly reduced depth of chest compressions in studies before (MD: −3.34 mm, 95% CI: −10.29 to −3.62, P = 0.35) or after (MD: −0.97 mm, 95% CI: −2.62 to 0.68, P = 0.25) COVID-19. No significant difference was found between parallel-group and crossover RCTs (P for subgroup difference both > 0.05).

Conclusions: Evidence from simulation-based RCTs showed that use of PPE was not associated with reduced rate or depth of chest compressions in CPR.

Singapore Basic Cardiac Life Support and Automated External Defibrillation Guidelines 2021

Basic Cardiac Life Support and Automated External Defibrillation (BCLS+AED) refers to the skills required in resuscitating cardiac arrest casualties. On recognising cardiac arrest, the rescuer should call for '995' for Emergency Ambulance and immediately initiate chest compressions. Good-quality chest compressions are performed with arms extended, elbows locked, shoulders directly perpendicular over the casualty's chest, and the heel of the palm placed on the lower half of the sternum. The rescuer compresses hard and fast at 4-6 cm depth for adults at a compression rate of 100-120 per minute, with complete chest recoil after each compression. Two quick ventilations of 400-600 mL each can be delivered via a bag-valve-mask after every 30 chest compressions. Alternatively, a trained, able and willing rescuer can provide mouth-to-mouth ventilation. Cardiopulmonary resuscitation should be stopped only when the casualty wakes up, the emergency team takes over care, or when an automated external defibrillator prompts for heart rhythm analysis or delivery of a shock.

Devices to enhance organ perfusion during cardiopulmonary resuscitation

INTRODUCTION

The recommended method of cardiopulmonary resuscitation (CPR) has been closed-chest cardiac compressions, but the development of CPR adjunctive devices has called into question the efficacy and role of these adjunctive devices. In this review, we provide a comprehensive evaluation and discussion on the commercially available noninvasive CPR adjuncts used during out-of-hospital cardiac arrest (OHCA).

AREAS COVERED

We review the three most common CPR adjunctive devices: the piston mechanism, the load distributing band, and the impedance threshold device. All three CPR adjunctive devices have preclinical data to support their use during cardiac arrest. In clinical trials, limited data show improvement in survival and neurologic recovery for these devices, and there is insufficient high-level evidence to support their use over manual chest compressions. However, there is a role for them when adequate manual chest compressions are not feasible.

EXPERT OPINION

The commercially available CPR adjuncts do not consistently show improved outcomes in the literature. There is still a need for research and development into innovative solutions to improve OHCA survival and neurologic recovery. Efforts focused on increasing the speed of CPR initiation and increasing perfusion to the cerebral and coronary vasculature have the potential to advance resuscitative practices.

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.

Effect of a Larger Flush Volume on Bioavailability and Efficacy of Umbilical Venous Epinephrine during Neonatal Resuscitation in Ovine Asphyxial Arrest

The 7th edition of the Textbook of Neonatal Resuscitation recommends administration of epinephrine via an umbilical venous catheter (UVC) inserted 2-4 cm below the skin, followed by a 0.5-mL to 1-mL flush for severe bradycardia despite effective ventilation and chest compressions (CC). This volume of flush may not be adequate to push epinephrine to the right atrium in the absence of intrinsic cardiac activity during CC. The objective of our study was to evaluate the effect of 1-mL and 2.5-mL flush volumes after UVC epinephrine administration on the incidence and time to achieve return of spontaneous circulation (ROSC) in a near-term ovine model of perinatal asphyxia induced cardiac arrest. After 5 min of asystole, lambs were resuscitated per Neonatal Resuscitation Program (NRP) guidelines. During resuscitation, lambs received epinephrine through a UVC followed by 1-mL or 2.5-mL normal saline flush. Hemodynamics and plasma epinephrine concentrations were monitored. Three out of seven (43%) and 12/15 (80%) lambs achieved ROSC after the first dose of epinephrine with 1-mL and 2.5-mL flush respectively (p = 0.08). Median time to ROSC and cumulative epinephrine dose required were not different. Plasma epinephrine concentrations at 1 min after epinephrine administration were not different. From our pilot study, higher flush volume after first dose of epinephrine may be of benefit during neonatal resuscitation. More translational and clinical trials are needed.

Adequacy of hand positioning by medical personnel during chest compression in a simulation study

Aim

During chest compressions (CCs), the hand position at the lower half of the sternum is not strictly maintained, unlike depth or rate. This study was conducted to determine whether medical staff could adequately push at a marked location on the lower half of the sternum, identify where the inappropriate hand position was shifted to, and correct the inappropriate hand position.

Methods

This simulation‐based, prospective single‐center study enrolled 44 medical personnel. Pressure and hand position during CC were ascertained using a flexible pressure sensor. The participants were divided into four groups by standing position and the hand in contact with the sternum: right–left (R–l), right–right (R–r), left–right (L–r), and left–left (L–l). We compared the groups and the methods: the manual method (MM), the thenar method, and the hypothenar method (HM).

Results

Among participants using the MM, 80% did not push adequately at the marked location on the lower half of the sternum; 60%–90% of the inadequate positions were shifted to the hypothenar side. CCs with the HM facilitated stronger pressure, and the position was minimally shifted to the hypothenar side.

Conclusion

Medical staff could not push at an appropriate position during CCs. Resuscitation courses should be designed to educate personnel on the appropriate position for application of maximal pressure while also evaluating the position during CCs.

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.

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.

Is Chest Compression Superimposed with Sustained Inflation during Cardiopulmonary Resuscitation an Alternative to 3:1 Compression to Ventilation Ratio in Newborn Infants?

Approximately 0.1% for term and 10-15% of preterm infants receive chest compression (CC) in the delivery room, with high incidence of mortality and neurologic impairment. The poor prognosis associated with receiving CC in the delivery room has raised concerns as to whether specifically-tailored cardiopulmonary resuscitation methods are needed. The current neonatal resuscitation guidelines recommend a 3:1 compression:ventilation ratio; however, the most effective approach to deliver chest compression is unknown. We recently demonstrated that providing continuous chest compression superimposed with a high distending pressure or sustained inflation significantly reduced time to return of spontaneous circulation and mortality while improving respiratory and cardiovascular parameters in asphyxiated piglet and newborn infants. This review summarizes the current available evidence of continuous chest compression superimposed with a sustained inflation.

Use of a Simple Ultrasound Device to Identify the Optimal Area of Compression for Out-of-Hospital Cardiac Arrest

Background Despite automated defibrillation and compression-first resuscitation, out-of-hospital cardiac arrest (OHCA) survival remains low. Resuscitation guidelines recommend that chest compressions should be done over the lower half of the sternum, but evidence indicates that this is often associated with outflow obstruction. Emerging studies suggest that compression directly over the left ventricle (LV) may improve survival and outcomes, but rapid and reliable localization of the LV is a major obstacle for those first responding to OHCA. This study aimed to determine if a simplified, easy-to-use ultrasound device (bladder scanner) can reliably locate the heart when applied over the intercostal spaces of the anterior thorax in supine patients. Furthermore, we sought to describe the association between largest scan volumes and underlying cardiac anatomy with particular attention to the long axis of the LV. Methodology We recruited healthy male and female volunteers over 40 years of age. Using a bladder scanner to evaluate the left sternal border and mid-clavicular lines, we determined the maximal scan volumes at 10 intercostal spaces for each participant. Cardiac ultrasound was then used to evaluate the corresponding underlying cardiac anatomy and determine the area overlying the long-axis view of the LV. Descriptive statistics (means with standard deviations [SD], medians with interquartile ranges, and frequencies with proportions) were used to quantify demographic information, typical scan volumes across the chest, the frequencies of the best long-axis LV view location. This was then repeated for left sternal border assessments only. Kappa was determined when evaluating agreement between the largest left sternal border scan volume and the best long-axis LV view location. Results The long-axis LV was the predominant structure underlying the largest scan volume in 39/51 (76.5%) patients. When limited to left sternal border volumes only, the long axis of the LV was underlying the maximum volume intercostal space in 46/51 (90.2%; 95% confidence interval [CI]: 78.6%, 96.7%). The largest left sternal border scan volumes were located over the best long-axis LV view in 39/51 (76.5%, 95% CI: 62.5%, 87.2%) of the study participants with a Kappa statistic of 0.68 (95% CI: 0.52, 0.84; p < 0.0001).  Conclusions In this cross-sectional study of healthy volunteers, an easy-to-use ultrasound device (bladder scanner) was able to reliably localize the heart. Largest scan volumes over the left sternal border showed substantial agreement with the intercostal space overlying the long axis of the LV. Further investigations are warranted to determine if such localization is reliable in cardiac arrest patients.

Return of Spontaneous Circulation Depends on Cardiac Rhythm During Neonatal Cardiac Arrest in Asphyxiated Newborn Animals

Objective: Pulseless electrical activity (PEA) occurs in asphyxiated newborn piglets and infants. We aimed to examine whether different cardiac rhythms (asystole, bradycardia, PEA) affects the resuscitation outcomes during continuous chest compressions (CC) during sustained inflations (CC+SI). Design: This study is a secondary analysis of four previous randomized controlled animal trials that compared CC+SI with different CC rate (90 or 120/min), SI duration (20 or 60 s), peak inflation pressure (10, 20, or 30 cmH₂O), and oxygen concentration (18, 21, or 100%). Setting and Subjects: Sixty-six newborn mixed breed piglets (1-3 days of age, weight 1.7-2.4 kg) were obtained on the day of experimentation from the University Swine Research Technology Center. Interventions: In all four studies, piglets were randomized into intervention or sham. Piglets randomized to "intervention" underwent both hypoxia and asphyxia, whereas, piglets randomized to "sham" received the same surgical protocol, stabilization, and equivalent experimental periods without hypoxia and asphyxia. Measurements: To compare differences in asphyxiation time, time to return of spontaneous circulation (ROSC), hemodynamics, and survival rate in newborn piglets with asystole, bradycardia or PEA. Main Results: Piglets with PEA (n = 29) and asystole (n = 13) had a significantly longer asphyxiation time and time to ROSC vs. bradycardia (n = 24). Survival rates were similar between all groups. Compared to their baseline, mean arterial pressure and carotid blood flow were significantly lower 4 h after resuscitation in all groups, while being significantly higher in the bradycardia group. Conclusion: This study indicates that cardiac rhythm before resuscitation influences the time to ROSC and hemodynamic recovery after ROSC.

Chest compressions quality during sudden cardiac arrest scenario performed in virtual reality: A crossover study in a training environment

Potential attributes of virtual reality (VR) can be a breakthrough in the improvement of sudden cardiac arrest (SCA) training. However, interference with the virtual world is associated with the need of placing additional equipment on the trainee's body. The primary aim of the study was to evaluate if it does not affect the quality of chest compressions (CCs).91 voluntarily included in the study medical students participated twice in the scenario of SCA - Traditional Scenario (TS) and Virtual Reality Scenario (VRS). In both cases two minutes of resuscitation was performed.If VRS was the first scenario there were significant differences in CCs depth (VRS - Me = 47 mm [IQR 43 - 52] vs TS - Me = 48 mm [IQR 43 - 55]; P = .02) and chest relaxation (VRS - Me = 37% [IQR 5 - 91] vs TS - Me = 97% [IQR 87 - 100]; P < .001). 97.8% of respondents believe that training with the use of VR is more effective than a traditional method (P < .01). Most of the study group (91%, P < .01) denied any negative symptoms during the VR scenario.Virtual reality can be a safe and highly valued by medical students, method of hands-on CPR training. However additional VR equipment placed on the trainee's body may cause chest compressions harder to provide. If it is not preceded by traditional training, the use of VR may have an adverse impact on depth and full chest relaxation during the training. To make the best use of all the potential that virtual reality offers, future studies should focus on finding the most effective way to combine VR with traditional skill training in CPR courses curriculum.

Late Intraocular Lens Dislocation Resulting From Haptic Breakage Following Cardiopulmonary Resuscitation

We report a case of an asymptomatic 65-year-old male who on routine eye examination had anterior dislocation of an intraocular lens (IOL) implant placed 23 years prior. Ten months prior to presentation, the patient had cardiac surgery complicated by cardiac arrest requiring chest compressions. Dislocation of an intraocular lens is a rare complication of cataract surgery. One of the causative factors for haptic breakage in our case was the polyimide haptic material. Polyimide has been shown to become brittle over time in warm and moist environments such as the human eye. This case demonstrates a case of late IOL dislocation chest compressions and, to the best of our knowledge, the first such case reported in the literature.

Ultrasound-Guided Chest Compressions in Out-of-Hospital Cardiac Arrests

BACKGROUND

There is a significant variability in survival rates for cardiopulmonary resuscitation (CPR) in out of-hospital cardiac arrest (OHCA), and some data indicate that ultrasound improves CPR.

OBJECTIVES

We evaluated the feasibility of ultrasound for monitoring chest compressions in OHCA.

METHODS

We planned a prospective study in patients with an ultrasound-integrated CPR for OHCA. Chest compressions were performed on the intermammillary line (IML), but the position was changed according to the quality of the heart squeezing, evaluated by ultrasound. End-tidal carbon dioxide (ETCO₂) was used as the control parameter. Then we compared the area with the highest squeezing with the position of the heart in the chest computed tomography (CT) scans of 20 hospitalized patients.

RESULTS

Chest compressions were good, partial, and inadequate on the IML in 58.4%, 48.9%, and 2.8% of cases, respectively. These percentages were 75%, 25%, and 0% after these modifications: none (47.2%), increased depth (8.3%), hands moved on the lower third of the sternum (27.8%), on left parasternal line of the lower part of the sternum (13.9%), and on the center of the sternum (1 case). Accordingly, ETCO₂ improved significantly (20.37 vs. 37.10, p < 0.0001). The CT scans showed that the larger biventricular area (BVA) was under the parasternal line of the lower third of the sternum, and the mean distance IML-BVA was 5.7 cm.

CONCLUSIONS

Our study has demonstrated that CPR in OHCA can be improved using ultrasound and changing the position of the hands. This finding was connected with the ETCO₂ and confirmed by chest CT scans.

Should chest compressions be considered an aerosol-generating procedure? A literature review in response to recent guidelines on personal protective equipment for patients with suspected COVID-19

There is disagreement between international guidelines on the level of personal protective equipment (PPE) required for chest compressions for patients with suspected COVID-19. This discrepancy centres on whether they are considered to be an aerosol-generating procedure (AGP), thus requiring airborne protection to prevent transmission to healthcare workers (HCWs). The need to don higher-level PPE has to be weighed against the resulting delay to emergency treatment.We performed a literature search on this topic which found eight relevant studies. All were observational with low patient numbers and multiple confounding factors, but describe cases of acute respiratory infection transmission during chest compressions. One systematic review concluded that chest compressions were not an AGP. Two simulated studies (released as preprints) potentially demonstrate aerosol generation. Given that there is evidence for infection transmission during chest compressions, we conclude that a precautionary approach with appropriate PPE is necessary to protect HCW from contracting a potentially fatal infection.

Cardiopulmonary Resuscitation of Asystolic Newborn Lambs Prior to Umbilical Cord Clamping; the Timing of Cord Clamping Matters!

Background: Current guidelines recommend immediate umbilical cord clamping (UCC) for newborns requiring chest compressions (CCs). Physiological-based cord clamping (PBCC), defined as delaying UCC until after lung aeration, has advantages over immediate UCC in mildly asphyxiated newborns, but its efficacy in asystolic newborns requiring CC is unknown. The aim of this study was to compare the cardiovascular response to CCs given prior to or after UCC in asystolic near-term lambs.

Methods: Umbilical, carotid, pulmonary, and femoral arterial flows and pressures as well as systemic and cerebral oxygenation were measured in near-term sheep fetuses [139 ± 2 (SD) days gestation]. Fetal asphyxia was induced until asystole ensued, whereupon lambs received ventilation and CC before (PBCC; n = 16) or after (n = 12) UCC. Epinephrine was administered 1 min after ventilation onset and in 3-min intervals thereafter. The PBCC group was further separated into UCC at either 1 min (PBCC₁, n = 8) or 10 min (PBCC₁₀, n = 8) after return of spontaneous circulation (ROSC). Lambs were maintained for a further 30 min after ROSC.

Results: The duration of CCs received and number of epinephrine doses required to obtain ROSC were similar between groups. After ROSC, we found no physiological benefits if UCC was delayed for 1 min compared to immediate cord clamping (ICC). However, if UCC was delayed for 10 min after ROSC, we found significant reductions in post-asphyxial rebound hypertension, cerebral blood flow, and cerebral oxygenation. The prevention of the post-asphyxial rebound hypertension in the PBCC₁₀ group occurred due to the contribution of the placental circulation to a low peripheral resistance. As a result, left and right ventricular outputs continued to perfuse the placenta and were evidenced by reduced mean pulmonary blood flow, persistence of right-to-left shunting across the ductus arteriosus, and persistence of umbilical arterial and venous blood flows.

Conclusion: It is possible to obtain ROSC after CC while the umbilical cord remains intact. There were no adverse effects of PBCC compared to ICC; however, the physiological changes observed after ROSC in the ICC and early PBCC groups may result in additional cerebral injury. Prolonging UCC after ROSC may provide significant physiological benefits that may reduce the risk of harm to the cerebral circulation.

Asynchronous ventilation at 120 compared with 90 or 100 compressions per minute improves haemodynamic recovery in asphyxiated newborn piglets

OBJECTIVE

To determine whether different chest compression (CC) rates during continuous CC with asynchronous ventilations (CCaV) reduce time to return of spontaneous circulation (ROSC) and improved haemodynamic recovery in piglets aged 24-72 hours with asphyxia-induced asystole.

METHODS

Thirty piglets (aged 24-72 hours) were anaesthetised, intubated, instrumented and exposed to 30 min normocapnic hypoxia followed by asphyxia. Piglets were randomised into four groups: CCaV with CC rate of 90 (CCaV+90, n=8), 100 (CCaV+100, n=8) or 120 compressions per minute (CCaV+120, n=8), and a sham-operated group (n=6). Cardiac function, carotid blood flow, cerebral and renal oxygenation and respiratory parameters were continuously recorded. Cerebral cortical tissue was harvested and assayed for inflammatory and injury markers.

RESULTS

All three intervention groups had a similar number of piglets achieving ROSC (6/8, 5/8 and 5/8 for CCaV+120, CCaV+100 and CCaV+90, respectively) and mean ROSC time (120, 90 and 90 s for CCaV+120, CCaV+100 and CCaV+90, respectively). The haemodynamic recovery (indicated by carotid flow, cerebral and renal perfusion) was similar between CCaV+120 and sham by the end of experiment. In comparison, CCaV+90 and CCaV+100 had significantly reduced haemodynamic recovery compared with sham operated (p≤0.05). Inflammatory (interleukin [IL]-6 and IL-1β) and injury markers (lactate) were significantly higher in the frontoparietal cortex of CCaV+90 and CCaV+100 compared with sham, whereas brain injury markers were similar between CCaV+120 and sham.

CONCLUSIONS

Although there was no difference between the groups in achieving ROSC, the haemodynamic recovery of CCaV+120 was significantly improved compared with CCaV+90 and CCaV+100, which were also associated with higher cerebral inflammatory and brain injury markers.

Asphyxiated Female and Male Newborn Piglets Have Similar Outcomes With Different Cardiopulmonary Resuscitation Interventions

Background: Male newborns have a greater risk of poor cardiovascular and respiratory outcomes compared to females. The mechanisms associated with the "male disadvantage" remains unclear. We have previously shown no difference between male and female newborn piglets during hypoxia, asphyxia, resuscitation, and post-resuscitation recovery. However, it is unknown if there are differences in resuscitation outcomes between males and females during different cardiopulmonary resuscitation techniques. Intervention and Measurements: Secondary analysis of 184 term newborn mixed breed duroc piglets (1-3 days of age, weighing 2.0 (0.2) kg) from seven different studies, which were exposed to 30-50 min of normocapnic hypoxia followed by asphyxia until asystole. This was followed by cardiopulmonary resuscitation. For the analysis, piglets were divided into male and female groups, as well as resuscitation technique groups (sustained inflation, 3:1 compression-to-ventilation ratio, or asynchronous ventilations during chest compressions). Cardiac function, carotid blood flow, and cerebral oxygenation were continuously recorded throughout the experiment. Main results: Regardless of resuscitation technique, there was no significant difference between males and females in the number achieving return of spontaneous circulation (ROSC) [95/123 (77%) vs. 48/61 (79%)], the time to achieve ROSC [112 (80-185) s vs. 110 (77-186) s], and the 4-h survival rate [81/95 (85%) vs. 40/48 (83%)]. Levels of the injury markers interleukin (IL)-1ß, IL-6, IL-8, and tumor necrosis factor-α in frontoparietal cortex tissue homogenates were similar between males and females. Conclusions: Regardless of resuscitation technique, there was no significant effect of sex on resuscitation outcome, survival, and hemodynamic recovery in asphyxiated newborn piglets.

Simulation in Neonatal Resuscitation

Approximately 1 in 10 newborns will require basic resuscitation interventions at birth. Some infants progress to require more advanced measures including the provision of positive pressure ventilation, chest compressions, intubation and administration of volume/cardiac medications. Although advanced resuscitation is infrequent, it is crucial that personnel adequately trained in these techniques are available to provide such resuscitative measures. In 2000, Louis Halmalek et al. called for a "New Paradigm in Pediatric Medical Education: Teaching Neonatal Resuscitation in a Simulated Delivery Room Environment." This was one of the first articles to highlight simulation as a method of teaching newborn resuscitation. The last decades have seen an exponential growth in the area of simulation in newborn care, in particular in newborn resuscitation and stabilization. Simulation is best defined as an instructional strategy "used to replace or amplify real experiences with guided experiences that evoke or replicate substantial aspects of the real world in a fully interactive manner." Simulation training has now become an important point of how we structure training and deliver improved healthcare to patients. Some of the key aspects of simulation training include feedback, deliberate practice, outcome measurement, retention of skills and curriculum integration. The term "Train to win" is often used in sporting parlance to define how great teams succeed. The major difference between sports teams is that generally their game day comes once a week, whereas in newborn resuscitation every day is potentially "game day." In this review we aim to summarize the current evidence on the use of simulation based education and training in neonatal resuscitation, with particular emphasis on the evidence supporting its effectiveness. We will also highlight recent advances in the development of simulation based medical education in the context of newborn resuscitation to ensure we "train to win."

The Effect of Operator Position on the Quality of Chest Compressions Delivered in a Simulated Ambulance

BACKGROUND

Ambulances are where patient care is often initiated or maintained, but this setting poses safety risks for paramedics. Paramedics have found that in order to optimize patient care, they must compromise their own safety by standing unsecured in a moving ambulance.

HYPOTHESIS/PROBLEM

This study sought to compare the quality of chest compressions in the two positions they can be delivered within an ambulance.

METHODS

A randomized, counterbalanced study was carried out with 24 paramedic students. Simulated chest compressions were performed in a stationary ambulance on a cardiopulmonary resuscitation (CPR) manikin for two minutes from either: (A) an unsecured standing position, or (B) a seated secured position. Participants' attitudes toward the effectiveness of the two positions were evaluated.

RESULTS

The mean total number of chest compressions was not significantly different standing unsecured (220; SD = 12) as compared to seated and secured (224; SD = 21). There was no significant difference in mean compression rate standing unsecured (110 compressions per minute; SD = 6) as compared to seated and secured (113 compressions per minute; SD = 10). Chest compressions performed in the unsecured standing position yielded a significantly greater mean depth (52 mm; SD = 6) than did seated secured (26 mm; SD = 7; P < .001). Additionally, the standing unsecured position produced a significantly higher percentage (83%; SD = 21) for the number of correct compressions, as compared to the seated secured position (8%; SD = 17; P < .001). Participants also believed that chest compressions delivered when standing were more effective than those delivered when seated.

CONCLUSIONS

The quality of chest compressions delivered from a seated and secured position is inferior to those delivered from an unsecured standing position. There is a need to consider how training, technologies, and ambulance design can impact the quality of chest compressions.

Synchronized Chest Compressions for Pseudo-PEA: Proof of Concept and a Synching Algorithm

Objective: The two objectives of this report are: first, to describe a comparison of chest compressions unsynchronized or synchronized to native cardiac activity in a porcine model of hypotension, and second, to develop an algorithm to provide synchronized chest compressions throughout a range of native heart rates likely to be encountered when treating PEA cardiac arrest. Methods: We adapted our previously developed signal-guided CPR system to provide compressions synchronized to native electrical activity in a porcine model of hypotension as a surrogate of PEA arrest. We describe the first comparison of unsynchronized to synchronized compressions in a single animal as a proof-of-concept. We developed an algorithm to provide optimal synchronized chest compressions regardless of intrinsic PEA heart rate while simultaneously maintaining the chest compression rate within a desired range. We tested the algorithm with computer simulations measuring the proportion of intrinsic and compression beats that were synchronized, and the compression rate and its standard deviation, as a function of intrinsic heart rate and heart rate jitter. Results: We demonstrate and compare unsynchronized versus synchronized chest compressions in a single porcine model with an intrinsic rhythm and hypotension. Synchronized, but not unsynchronized, chest compressions were associated with increased blood pressure and coronary perfusion pressure. Our synchronized chest compression algorithm is able to provide synchronized chest compressions to over 90% of intrinsic beats for most heart rates while maintaining an average compression rate between 90 and 140 compressions per minute with relatively low variability. Conclusions: Synchronized chest compression therapy for pulseless electrical rhythms is feasible. A high degree of synchronization can be maintained over a broad range of intrinsic heart rates while maintaining the compression rate within a satisfactory range. Further investigation to assess benefit for treatment of PEA is warranted.

Real-Time Cardiopulmonary Resuscitation Feedback and Targeted Training Improve Chest Compression Performance in a Cohort of International Healthcare Providers

BACKGROUND

Optimal cardiopulmonary resuscitation (CPR) performance is the foundation of successful cardiac arrest resuscitation. However, health care providers perform inadequate compressions. Better training techniques and real-time CPR feedback may improve compression performance.

OBJECTIVE

We sought to evaluate the impact of a targeted training program combined with real-time defibrillator CPR feedback on chest compression performance in an international cohort of health care providers.

METHODS

Physicians, nurses, respiratory therapists, and technicians from 6 hospitals in 5 countries (Taiwan, Singapore, China, Bahrain, and Kuwait) participated in a standardized resuscitation workshop. Chest compression was measured before and after didactics and activation of CPR feedback. Compressions were performed for 1 min on standard CPR manikins placed on a hospital bed and backboard and measured using ZOLL R Series defibrillators. The percentage of compressions meeting target values for depth and rate were compared before and after the workshop and activation of real-time CPR feedback. No depth maximum was defined to allow for mattress compression.

RESULTS

Chest compressions were more likely to meet targets for depth (71-95%, odds ratio [OR] 8.61 [95% confidence interval {CI} 4.42-16.77], p < 0.001), rate (41-81%, OR 6.4 [95% CI 4.2-9.8], p < 0.001), and both depth and rate (5-42%, OR 2.4 [95% CI 6.7-22.9], p < 0.001) after the workshop and activation of real-time CPR feedback.

CONCLUSIONS

A targeted training intervention combined with real-time CPR feedback improved chest compression performance among health care providers from various countries.

Chest Compressions for Bradycardia during Neonatal Resuscitation-Do We Have Evidence?

The International Liaison Committee on Resuscitation (ILCOR) recommends the initiation of chest compressions (CC) during neonatal resuscitation after 30 s of effective ventilation if the infant remains bradycardic (defined as a heart rate less than 60 bpm). The CC are performed during bradycardia to optimize organ perfusion, especially to the heart and brain. Among adults and children undergoing cardiopulmonary resuscitation (CPR), CC is indicated only for pulselessness or poor perfusion. Neonates have a healthy heart that attempts to preserve coronary and cerebral perfusion during bradycardia secondary to asphyxia. Ventilation of the lungs is the key step during neonatal resuscitation, improving gas exchange and enhancing cerebral and cardiac blood flow by changes in intrathoracic pressure. Compressing the chest 90 times per minute without synchrony with innate cardiac activity during neonatal bradycardia is not based on evidence and could potentially be harmful. Although there are no studies evaluating outcomes in neonates, a recent pediatric study in a hospital setting showed that when CC were initiated during pulseless bradycardia, a third of the patients went into complete arrest, with poor survival at discharge. Ventilation-only protocols such as helping babies breathe are effective in reducing mortality and stillbirths in low-resource settings. In a situation of complete cardiac arrest, CC reinitiates pulmonary flow and supports gas exchange. However, the benefit/harm of performing asynchronous CC during bradycardia as part of neonatal resuscitation remains unknown.

Ventilation During Cardiopulmonary Resuscitation: What Have We Learned From Models?

The optimization of ventilation during cardiopulmonary resuscitation (CPR) is a broad field of research. Recent physiological observations in this field challenge the current understanding of respiratory and circulatory interactions. Thanks to different models available (bench, animal, human), the understanding of physiological phenomena occurring during CPR has progressed. In this review, we describe the clinical observations that have led to the emerging concept of lung volume reduction and associated thoracic airway closure. We summarize the clinical and animal observations supporting these concepts. We then discuss the different contributions of bench, animal, and human models to the understanding of airway closure and their impact on intrathoracic pressure, airway closure, and hemodynamics generated by chest compression. The limitation of airway pressure and ventilation, resulting from airway closure reproducible in models, may play a major role in ventilation and gas exchange impairment observed during prolonged resuscitation.

Use of a simulation-based advanced resuscitation training curriculum: Impact on cardiopulmonary resuscitation quality and patient outcomes

Background

Despite a continued focus on improved cardiopulmonary resuscitation quality, survival remains low from in-hospital cardiac arrest. Advanced Resuscitation Training has been shown to improve survival to hospital discharge and survival with good neurological outcome following in-hospital cardiac arrest at its home institution. We sought to determine if Advanced Resuscitation Training implementation would improve patient outcomes and cardiopulmonary resuscitation quality at our institution.

Methods

This was a prospective, before-after study of adult in-hospital cardiac arrest victims who had cardiopulmonary resuscitation performed. During phase 1, standard institution cardiopulmonary resuscitation training was provided. During phase 2, providers received the same quantity of training, but with emphasis on Advanced Resuscitation Training principles. Primary outcomes were return of spontaneous circulation, survival to hospital discharge, and neurologically favorable survival. Secondary outcomes were cardiopulmonary resuscitation quality parameters.

Results

A total of 156 adult in-hospital cardiac arrests occurred during the study period. Rates of return of spontaneous circulation improved from 58.1 to 86.3% with an adjusted odds ratios of 5.31 (95% CI: 2.23-14.35, P < 0.001). Survival to discharge increased from 26.7 to 41.2%, adjusted odds ratios 2.17 (95% CI: 1.02-4.67, P < 0.05). Survival with a good neurological outcome increased from 24.8 to 35.3%, but was not statistically significant. Target chest compression rate increased from 30.4% of patients in P1 to 65.6% in P2, adjusted odds ratios 4.27 (95% CI: 1.72-11.12, P = 0.002), and target depth increased from 23.2% in P1 to 46.9% in P2, adjusted odds ratios 2.92 (95% CI: 1.16-7.54, P = 0.024).

Conclusions

After Advanced Resuscitation Training implementation, there were significant improvements in cardiopulmonary resuscitation quality and rates of return of spontaneous circulation and survival to discharge.

Chest Compressions in the Delivery Room

Annually, an estimated 13–26 million newborns need respiratory support and 2–3 million newborns need extensive resuscitation, defined as chest compression and 100% oxygen with or without epinephrine in the delivery room. Despite such care, there is a high incidence of mortality and neurologic morbidity. The poor prognosis associated with receiving chest compression alone or with medications in the delivery room raises questions as to whether improved cardiopulmonary resuscitation methods specifically tailored to the newborn could improve outcomes. This review discusses the current recommendations, mode of action, different compression to ventilation ratios, continuous chest compression with asynchronous ventilations, chest compression and sustained inflation optimal depth, and oxygen concentration during cardiopulmonary resuscitation.

Sex Differences Between Female and Male Newborn Piglets During Asphyxia, Resuscitation, and Recovery

Background: Male and female newborns have differences in their fetal development, fetal-to-neonatal transition, and postnatal morbidity. However, the cardiovascular fetal-to-neonatal adaption is similar between sexes. No study has examined sex differences in newborns during hypoxia, asphyxia, cardio-pulmonary resuscitation, or post-resuscitation recovery. Methods: Secondary analysis (two previous publications and two studies currently under peer-review) of 110 term newborn mixed breed piglets (1-3 days of age, weighing 2.0 ± 0.2 kg), which were exposed to 30 min normocapnic hypoxia followed by asphyxia until asystole, which was achieved by disconnecting the ventilator and clamping the endotracheal tube. This was followed by cardio-pulmonary resuscitation. For the analysis piglets were divided into female and male groups. Cardiac function, carotid blood flow, and cerebral and renal oxygenation were continuously recorded throughout the experiment. Results: A total of 35/41 (85%) female and 54/69 (78%) male piglets resuscitated achieved ROSC (p = 0.881). The median (IQR) time to achieve return of spontaneous circulation in females and males was 111 (80-228) s and 106 (80-206) s (p = 0.875), respectively. The 4-h survival rate was similar between females and males with 28/35 (80%) and 49/54 (91%) piglets surviving (p = 0.241), respectively. Conclusions: No difference between female and male newborn piglets was observed during hypoxia, asphyxia, resuscitation, and post-resuscitation recovery.

Does the use of cardiopulmonary resuscitation feedback devices improve the quality of chest compressions performed by doctors? A prospective, randomized, cross-over simulation study

BACKGROUND

The aim of the study was to compare the quality of chest compressions (CCs) carried out with and without the use of the TrueCPR device during simulated cardiopulmonary resuscitations conducted by trainee doctors.

METHODS

The study was a prospective, randomized, cross-over simulation study. The study involved 65 trainee doctors who were tasked with performing a 2-min cycle of uninterrupted CCs under conditions of a simulated cardiopulmonary resuscitation of adults. CC were carried out in two scenarios: with and without TrueCPR chest compression support. Participants did not have experience in the use of CCs prior to this study.

RESULTS

The depth of compressions in regard to CC techniques were varied by 45 mm (IQR 43-48) for manual CC and 53 mm (IQR 51-55) for the TrueCPR device (p < 0.001). The incidence of CCs with and without TrueCPR was: 112 (IQR 103-113) vs. 129 (IQR 122-135) compressions (p = 0.002). The degree of complete chest relaxation with the TrueCPR device was 95% (IQR 76-99) and without the device, 33% (IQR 29-38) (p < 0.001).

CONCLUSIONS

In the simulation study performed, the use of the TrueCPR device resulted in a significant improvement in the quality of CCs in relation to frequency and depth of CCs and correctness of chest relaxation.

Does use of the LUCAS device improve mortality in adult patients with out-of-hospital cardiac arrest?

Out-of-hospital cardiac arrest (OHCA) is a common occurrence in the UK, with 60,000 cases reported annually. To improve outcomes among these patients it is necessary to improve links in the cardiac arrest chain of survival. Cardiopulmonary resuscitation (CPR) is one of the main elements of this chain because it reduces further ischaemic insult in the brain and heart by contributing to blood flow. However, even the best manual CPR provides only 20%-30% of the normal cardiac output. Despite the emphasis on timely CPR at the correct rate and depth, delivery of compressions is suboptimal for many patients and mechanical devices may improve outcomes. This article critically appraises two important papers on the use of mechanical CPR for OHCA. It also suggests potential uses for this treatment option and areas for future research.

The Association between Cardiopulmonary Resuscitation in Out-of-Hospital Settings and Chest Injuries: A Retrospective Observational Study

OBJECTIVES

The aim of this study was to assess the risk of cardiopulmonary resuscitation (CPR) performed in out-of-hospital settings for chest injuries in patients with out-of-hospital cardiac arrest (OHCA).

METHODS

This retrospective, observational study was conducted in an emergency critical care medical center in Japan. Non-traumatic OHCA patients transferred to the hospital from April 2013 through August 2016 were analyzed. The outcome was defined by chest injuries related to CPR, which is composite of rib fractures, sternal fractures, and pneumothoraces. A multivariate logistic regression analysis was performed to assess the independent risk factors for chest injuries related to CPR. The threshold of out-of-hospital CPR duration that increased risk of chest injuries was also assessed.

RESULTS

A total of 472 patients were identified, of whom 233 patients sustained chest injuries. The multivariate logistic regression model showed that the independent risk factors for chest injuries were age and out-of-hospital CPR duration (age: AOR=1.06 [95% CI, 1.04 to 1.07]; out-of-hospital CPR duration: AOR=1.03 [95% CI, 1.01 to 1.05]). In-hospital CPR duration was not an independent risk factor for chest injuries. When the duration of out-of-hospital CPR extended over 15 minutes, the likelihood of chest injuries increased; however, this association was not statistically significant.

CONCLUSIONS

Long duration of out-of-hospital CPR was an independent risk factor for chest injuries, possibly due to the difficulty of maintaining adequate quality of CPR. Further investigations to assess the efficacy of alternative CPR devices are expected in cases requiring long transportation times. Takayama W , Koguchi H , Endo A , Otomo Y . The association between cardiopulmonary resuscitation in out-of-hospital settings and chest injuries: a retrospective observational study. Prehosp Disaster Med. 2018;33(2):171-175.

An insidious and deadly complication of mechanical chest compressions in a patient on anticoagulation and the subtle echocardiographic findings that enabled timely diagnosis

Good-quality chest compressions improve outcomes in cardiac arrest. While manual chest compressions are suboptimal in this regard, the LUCAS device has been shown to improve the effectiveness of chest compressions during cardiopulmonary resuscitation (CPR). The complication rate associated with mechanical CPR, however, has not been adequately studied. Limited evidence suggests no difference in internal injury between manual and mechanical CPR. We report the case of a patient on anticoagulation who developed a mediastinal hematoma post mechanical CPR and on whom subtle findings on initial echocardiography could have alerted the clinician to this complication early during the clinical course. This case further suggests that there may be special populations of patients in whom we may need to be more vigilant in the use of mechanical CPR.

A Review of Oxygen Use During Chest Compressions in Newborns-A Meta-Analysis of Animal Data

Background: International consensus statements for resuscitation of newborn infants recommend provision of 100% oxygen once chest compressions are required. However, 100% oxygen exacerbates reperfusion injury and reduces cerebral perfusion in newborn babies. Objective: We aimed to establish whether resuscitation with air during chest compression is feasible and safe in newborn infants compared with 100% oxygen. Methods: Systematic search of PubMed, Google Scholar and CINAHL for articles examining variable oxygen concentrations during chest compressions in term newborns. Results: Overall, no human studies but eight animal studies (n = 323 animals) comparing various oxygen concentrations during chest compression were identified. The pooled analysis showed no difference in mortality rates for animals resuscitated with air vs. 100% oxygen (risk ratio 1.04 [0.35, 3.08], I² = 0%, p = 0.94). ROSC was also similar between groups with a mean difference of -3.8 [-29.7-22] s, I² = 0%, p = 0.77. No difference in oxygen damage or adverse events were identified between groups. Conclusions: Air had similar time to ROSC and mortality as 100% oxygen during neonatal chest compression. A large randomized controlled clinical trial comparing air vs. 100% oxygen during neonatal chest compression is warranted.

Performance of cardiopulmonary resuscitation feedback systems in a long-distance train with distributed traction

BACKGROUND

Out-of-hospital cardiac arrest is common in public locations, including public transportation sites. Feedback devices are increasingly being used to improve chest-compression quality. However, their performance during public transportation has not been studied yet.

OBJECTIVE

To test two CPR feedback devices representative of the current technologies (accelerometer and electromag- netic-field) in a long-distance train.

METHODS

Volunteers applied compressions on a manikin during the train route using both feedback devices. Depth and rate measurements computed by the devices were compared to the gold-standard values.

RESULTS

Sixty-four 4-min records were acquired. The accelerometer-based device provided visual help in all experiments. Median absolute errors in depth and rate were 2.4 mm and 1.3 compressions per minute (cpm) during conventional speed, and 2.5 mm and 1.2 cpm during high speed. The electromagnetic-field-based device never provided CPR feedback; alert messages were shown instead. However, measurements were stored in its internal memory. Absolute errors for depth and rate were 2.6 mm and 0.7 cpm during conventional speed, and 2.6 mm and 0.7 cpm during high speed.

CONCLUSIONS

Both devices were accurate despite the accelerations and the electromagnetic interferences induced by the train. However, the electromagnetic-field-based device would require modifications to avoid excessive alerts impeding feedback.

Improving Community Survival Rates from Out-of-Hospital Cardiac Arrest

Out of hospital cardiac arrest affects 350,000 Americans yearly and is associated with a high mortality rate. Improving survival rates in this population rests on the prompt and effective implementation of four key principles. These include 1) early recognition of cardiac arrest 2) early use of chest compressions 3) early defibrillation, which in turn emphasizes the importance of public access defibrillation programs and potential for drone technology to allow for early defibrillation in private or rural settings 4) early and aggressive post-arrest care including the consideration of therapeutic hypothermia, early coronary angiography +/- percutaneous coronary intervention and a hyper-invasive approach to out-of-hospital refractory cardiac arrest.

Continuous Chest Compressions During Sustained Inflations in a Perinatal Asphyxial Cardiac Arrest Lamb Model

OBJECTIVE

Continuous chest compressions are more effective during resuscitation in adults. Sustained inflation rapidly establishes functional residual capacity in fluid-filled lungs at birth. We sought to compare the hemodynamics and success in achieving return of spontaneous circulation in an asphyxial cardiac arrest lamb model with transitioning fetal circulation and fluid-filled lungs between subjects receiving continuous chest compressions during sustained inflation and those receiving conventional 3:1 compression-to-ventilation resuscitation.

DESIGN

Prospective, randomized, animal model study.

SETTING

An experimental laboratory.

SUBJECTS

Fourteen newborn term gestation lambs.

INTERVENTIONS

Lambs were randomized into two groups: 3:1 compression-to-ventilation (control) and continuous chest compressions during sustained inflation. The umbilical cord was occluded to induce asphyxia and asystole. The control group was resuscitated per NRP guidelines. In the sustained inflation + continuous chest compressions group, sustained inflation at 35 cm H2O was provided for 30 seconds with 1-second interruptions before another sustained inflation was provided. One hundred twenty chest compressions/min started after the initial sustained inflation. The first dose of IV epinephrine was given at 6 minutes if return of spontaneous circulation was not achieved and then every 3 minutes until return of spontaneous circulation or for a total of four doses.

MEASUREMENT AND RESULTS

All lambs achieved return of spontaneous circulation in a comparable median time (interquartile range) of 390 seconds (225-405 s) and 345 seconds (204-465 s) in the sustained inflation + continuous chest compressions and control groups, respectively. Four of seven (sustained inflation + continuous chest compressions) and three of six (control) lambs required epinephrine to achieve return of spontaneous circulation. Diastolic blood pressures were lower in the sustained inflation + continuous chest compressions (4 ± 2 mm Hg) compared to the control group (7 ± 2 mm Hg), p < 0.05. PaCO2, PaO2, and lactate were similar between the groups during the study period.

CONCLUSION

In this perinatal cardiac arrest lamb model with transitioning fetal circulation and fluid-filled lungs, sustained inflation + continuous chest compressions is as effective as 3:1 compression-to-ventilation resuscitation in achieving return of spontaneous circulation. Half the lambs achieved return of spontaneous circulation without epinephrine. continuous chest compressions during sustained inflation reduced diastolic pressures but did not alter gas exchange or carotid blood flow compared to 3:1 compression-to-ventilation resuscitation.

The effect of step stool use and provider height on CPR quality during pediatric cardiac arrest: A simulation-based multicentre study

OBJECTIVES

We aimed to explore whether a) step stool use is associated with improved cardiopulmonary resuscitation (CPR) quality; b) provider adjusted height is associated with improved CPR quality; and if associations exist, c) determine whether just-in-time (JIT) CPR training and/or CPR visual feedback attenuates the effect of height and/or step stool use on CPR quality.

METHODS

We analysed data from a trial of simulated cardiac arrests with three study arms: No intervention; CPR visual feedback; and JIT CPR training. Step stool use was voluntary. We explored the association between 1) step stool use and CPR quality, and 2) provider adjusted height and CPR quality. Adjusted height was defined as provider height + 23 cm (if step stool was used). Below-average height participants were ≤ gender-specific average height; the remainder were above average height. We assessed for interaction between study arm and both adjusted height and step stool use.

RESULTS

One hundred twenty-four subjects participated; 1,230 30-second epochs of CPR were analysed. Step stool use was associated with improved compression depth in below-average (female, p=0.007; male, p<0.001) and above-average (female, p=0.001; male, p<0.001) height providers. There is an association between adjusted height and compression depth (p<0.001). Visual feedback attenuated the effect of height (p=0.025) on compression depth; JIT training did not (p=0.918). Visual feedback and JIT training attenuated the effect of step stool use (p<0.001) on compression depth.

CONCLUSIONS

Step stool use is associated with improved compression depth regardless of height. Increased provider height is associated with improved compression depth, with visual feedback attenuating the effects of height and step stool use.

An innovative design for cardiopulmonary resuscitation manikins based on a human-like thorax and embedded flow sensors

Cardiopulmonary resuscitation manikins are used for training personnel in performing cardiopulmonary resuscitation. State-of-the-art cardiopulmonary resuscitation manikins are still anatomically and physiologically low-fidelity designs. The aim of this research was to design a manikin that offers high anatomical and physiological fidelity and has a cardiac and respiratory system along with integrated flow sensors to monitor cardiac output and air displacement in response to cardiopulmonary resuscitation. This manikin was designed in accordance with anatomical dimensions using a polyoxymethylene rib cage connected to a vertebral column from an anatomical female model. The respiratory system was composed of silicon-coated memory foam mimicking lungs, a polyvinylchloride bronchus and a latex trachea. The cardiovascular system was composed of two sets of latex tubing representing the pulmonary and aortic arteries which were connected to latex balloons mimicking the ventricles and lumped abdominal volumes, respectively. These balloons were filled with Life/form simulation blood and placed inside polyether foam. The respiratory and cardiovascular systems were equipped with flow sensors to gather data in response to chest compressions. Three non-medical professionals performed chest compressions on this manikin yielding data corresponding to force-displacement while the flow sensors provided feedback. The force-displacement tests on this manikin show a desirable nonlinear behaviour mimicking chest compressions during cardiopulmonary resuscitation in humans. In addition, the flow sensors provide valuable data on the internal effects of cardiopulmonary resuscitation. In conclusion, scientifically designed and anatomically high-fidelity designs of cardiopulmonary resuscitation manikins that embed flow sensors can improve physiological fidelity and provide useful feedback data.

Manual versus Mechanical Chest Compressions on Surfaces of Varying Softness with or without Backboards: A Randomized, Crossover Manikin Study

BACKGROUND

Chest compression quality is decisive for overall outcome after cardiac arrest. Chest compression depth may decrease when cardiopulmonary resuscitation (CPR) is performed on a mattress, and the use of a backboard does not necessarily improve compression depth. Mechanical chest compression devices may overcome this problem.

OBJECTIVES

We sought to investigate the effectiveness of manual chest compressions both with and without a backboard compared to mechanical CPR performed on surfaces of different softness.

METHODS

Twenty-four advanced life support (ALS)-certified rescuers were enrolled. LUCAS2 (Physio-Control, Redmond, WA) delivers 52 ± 2 mm deep chest compressions and active decompressions back to the neutral position (frequency 102 min(-1); duty cycle, 50%). This simulated CPR scenario was performed on a Resusci-Anne manikin (Laerdal, Stavanger, Norway) that was lying on 3 different surfaces: 1) a concrete floor, 2) a firm standard mattress, and 3) a pressure-relieving mattress. Data were recorded by the Laerdal Skill Reporting System.

RESULTS

Manual chest compression with or without a backboard were performed correctly less often than mechanical chest compressions (floor: 33% [interquartile range {IQR}, 27-48%] vs. 90% [IQR, 86-94%], p < 0.001; standard mattress: 32% [IQR, 20-45%] vs. 27% [IQR, 14-46%] vs. 91% [IQR, 51-94%], p < 0.001; and pressure-relieving mattress 29% [IQR, 17-49%] vs. 30% [IQR, 17-52%] vs. 91% [IQR, 87-95%], p < 0.001). The mean compression depth on both mattresses was deeper with mechanical chest compressions (floor: 53 mm [range, 47-57 mm] vs. 56 mm [range, 54-57 mm], p = 0.003; standard mattress: 50 mm [range, 44-55 mm] vs. 51 mm [range, 47-55 mm] vs. 55 mm [range, 54-58 mm], p < 0.001; and pressure-relieving mattress: 49 mm [range, 44-55 mm] vs. 50 mm [range, 44-53 mm] vs. 55 mm [range, 55-56 mm], p < 0.001). In this ∼6-min scenario, the mean hands-off time was ∼15 to 20 s shorter in the manual CPR scenarios.

CONCLUSIONS

In this experimental study, only ∼30% of manual chest compressions were performed correctly compared to ∼90% of mechanical chest compressions, regardless of the underlying surface. Backboard use did not influence the mean compression depth during manual CPR. Chest compressions were deeper with mechanical CPR. The mean hands-off time was shorter with manual CPR.