Quality of closed chest compression on a manikin in ambulance vehicles and flying helicopters with a real time automated feedback

Context

Automated verbal and visual feedback improves quality of resuscitation in out-of-hospital cardiac arrest and was proven to increase short-term survival. Quality of resuscitation may be hampered in more difficult situations like emergency transportation. Currently there is no evidence if feedback devices can improve resuscitation quality during different modes of transportation.

Objective

To assess the effect of real time automated feedback on the quality of resuscitation in an emergency transportation setting.

Design

Randomised cross-over trial.

Setting

Medical University of Vienna, Vienna Municipal Ambulance Service and Helicopter Emergency Medical Service Unit (Christophorus Flugrettungsverein) in September 2007.

Participants

European Resuscitation Council (ERC) certified health care professionals performing CPR in a flying helicopter and in a moving ambulance vehicle on a manikin with human-like chest properties.

Interventions

CPR sessions, with real time automated feedback as the intervention and standard CPR without feedback as control.

Main outcome measures

Quality of chest compression during resuscitation.

Results

Feedback resulted in less deviation from ideal compression rate 100 min⁻¹ (9 ± 9 min⁻¹, p < 0.0001) with this effect becoming steadily larger over time. Applied work was less in the feedback group compared to controls (373 ± 448 cm × compression; p < 0.001). Feedback did not influence ideal compression depth significantly. There was some indication of a learning effect of the feedback device.

Conclusions

Real time automated feedback improves certain aspects of CPR quality in flying helicopters and moving ambulance vehicles. The effect of feedback guidance was most pronounced for chest compression rate.     

Effect of vehicle speed on the quality of closed-chest compression during ambulance transport

Introduction

Transport of patients with ongoing cardiopulmonary resuscitation (CPR) occurs frequently. It may not be possible to obtain rapid hospital access while maintaining CPR quality, because the ambulance's high speed can cause increased vibration and vehicle movement. We aimed to assess how the speed of ambulance affects chest compressions.

Materials and methods

Five cycles of CPR were performed to the Resusci Anne manikin with the PC skill reporting system by experienced emergency medical technicians in ambulance traveling at one of four different speeds: stationary, 30, 60, or 90 km/h. Performance and acceleration data of chest compressions at different speeds were compared using repeated measures analysis of variance (ANOVA).

Results

Fractions of chest compressions with adequate depth, duty cycles, average rates of chest compressions, and no flow fractions showed significant differences among different speeds (p = 0.026, <0.001, <0.001, 0.005, respectively), while average depth of chest compressions did not. Accelerations of 2 Hz component and ratios of 3-12 Hz to 0-2 Hz components showed significant differences among different speeds (p = 0.001 for all). None of the outcome variables showed a significant difference between the two types of ambulance.

Conclusions

The speed of ambulance affects some aspects in the quality of chest compression during transport. Chest compressions with excessive depth, the average rate of chest compressions, and no-flow fraction increase as the speed of ambulance increase. Increase in the speed of ambulance also causes relative increase of high frequency acceleration in the chest compression, which represents unnecessary movement and force applied.     

Discriminating the effect of accelerated compression from accelerated decompression during high-impulse CPR in a porcine model of cardiac arrest

Aim of the study

Piston based mechanical chest compression devices deliver compressions and decompressions in an accelerated pattern, resulting in superior haemodynamics compared to manual compression in animal studies. The present animal study compares haemodynamics during two different hybrid compression patterns to a standard compression pattern resembling that of modern mechanical chest compression devices.

Method

In 12 anaesthetized domestic pigs in ventricular fibrillation, coronary perfusion pressures (CPP) and cerebral cortical blood flow (CCBF) was measured, and transesophageal echocardiography (TEE) was performed. Two hybrid compression patterns, one with accelerated trapezoid compression and slower sinusoid decompression (TrS), and one with slower sinusoid compression and accelerated trapezoid decompression (STr), were tested against a standard accelerated trapezoid compression-decompression pattern (TrTr) in a cross-over randomised setup.

Results

There were 7% (1, 14, p = 0.046) lower CCBF and 3 mmHg (1, 5, p = 0.017) lower CPP with the TrS compared to TrTr pattern. No significant difference between STr and TrTr pattern in either CCBF, 6% (−3, 15, p = 0.176) or CPP, 0 mmHg (−2, 3, p = 0.703) was present. Our TEE recordings were insufficient for haemodynamic comparison between the different compression-decompression patterns. Despite standardized sternal piston position and placement of the pigs, TEE revealed varying degree of asymmetrical heart chamber compression in the animals.

Conclusion

Both cardiac and cerebral perfusion benefited from accelerated decompression, while accelerated compression did not improve haemodynamics. The evolution of mechanical CPR is dependent on further research on mechanisms generating forward blood flow during external chest compressions.     

Two-thumb technique is superior to two-finger technique during lone rescuer infant manikin CPR

Objective

Infant CPR guidelines recommend two-finger chest compression with a lone rescuer and two-thumb with two rescuers. Two-thumb provides better chest compression but is perceived to be associated with increased ventilation hands-off time. We hypothesized that lone rescuer two-thumb CPR is associated with increased ventilation cycle time, decreased ventilation quality and fewer chest compressions compared to two-finger CPR in an infant manikin model.

Design

Crossover observational study randomizing 34 healthcare providers to perform 2 min CPR at a compression rate of 100 min⁻¹ using a 30:2 compression:ventilation ratio comparing two-thumb vs. two-finger techniques.

Methods

A Laerdal™ Baby ALS Trainer manikin was modified to digitally record compression rate, compression depth and compression pressure and ventilation cycle time (two mouth-to-mouth breaths). Manikin chest rise with breaths was video recorded and later reviewed by two blinded CPR instructors for percent effective breaths. Data (mean ± SD) were analyzed using a two-tailed paired t-test. Significance was defined qualitatively as p ≤ 0.05.

Result

Mean % effective breaths were 90 ± 18.6% in two-thumb and 88.9 ± 21.1% in two-finger, p = 0.65. Mean time (s) to deliver two mouth-to-mouth breaths was 7.6 ± 1.6 in two-thumb and 7.0 ± 1.5 in two-finger, p < 0.0001. Mean delivered compressions per minute were 87 ± 11 in two-thumb and 92 ± 12 in two-finger, p = 0.0005. Two-thumb resulted in significantly higher compression depth and compression pressure compared to the two-finger technique.

Conclusion

Healthcare providers required 0.6 s longer time to deliver two breaths during two-thumb lone rescuer infant CPR, but there was no significant difference in percent effective breaths delivered between the two techniques. Two-thumb CPR had 4 fewer delivered compressions per minute, which may be offset by far more effective compression depth and compression pressure compared to two-finger technique.     

Mechanical chest compressions with trapezoidal waveform improve haemodynamics during cardiac arrest

Background

During manual chest compressions for cardiac arrest the waveforms of chest compressions are generally sinusoidal, whereas mechanical chest compression devices can have different waveforms, including trapezoidal. We studied the haemodynamic differences of such waveforms in a porcine model of cardiac arrest.

Methods

Eight domestic pigs (weight 31 ± 3 kg) were anaesthetised and instrumented to continuously monitor aortic (AP) and right atrial pressure (RAP), carotid (CF) and cerebral cortical microcirculation blood flow (CCF). Coronary perfusion pressure (CPP) was calculated as the maximal difference between AP and RAP during diastole or decompression phase. After 4 min of electrically induced ventricular fibrillation, mechanical chest compressions were performed with four different waveforms in a factorial design, and in randomized sequence for 3 min each. Resulting differences are presented as mean with 95% confidence intervals.

Results

Mean AP and RAP were higher with trapezoid than sinusoid chest compressions, difference 5.7 (0.7, 11) and 6.3 (2.1, 11) mmHg, respectively. Flow measured as CF and CCF was also improved with trapezoidal waveform, difference 14 (2.8, 26) ml/min and 11 (5.6, 17)% of baseline, respectively, with a parallel, non-significant (P = 0.08) trend for CPP. Active vs. passive decompression to zero level improved CF, but without even a trend for CPP.

Conclusion

Trapezoid chest compressions and active decompression to zero level improved blood flow to the brain. The compression waveform is an additional factor to consider when comparing mechanical and manual chest compressions and when comparing different compression devices.     

The addition of voice prompts to audiovisual feedback and debriefing does not modify CPR quality or outcomes in out of hospital cardiac arrest--a prospective, randomized trial

Aims

Chest compression quality is a determinant of survival from out-of-hospital cardiac arrest (OHCA). ERC 2005 guidelines recommend the use of technical devices to support rescuers giving compressions. This prospective randomized study reviewed influence of different feedback configurations on survival and compression quality.

Materials and methods

312 patients suffering an OHCA were randomly allocated to two different feedback configurations. In the limited feedback group a metronome and visual feedback was used. In the extended feedback group voice prompts were added. A training program was completed prior to implementation, performance debriefing was conducted throughout the study.

Results

Survival did not differ between the extended and limited feedback groups (47.8% vs 43.9%, p = 0.49). Average compression depth (mean ± SD: 4.74 ± 0.86 cm vs 4.84 ± 0.93 cm, p = 0.31) was similar in both groups. There were no differences in compression rate (103 ± 7 vs 102 ± 5 min(−1), p = 0.74) or hands-off fraction (16.16% ± 0.07 to 17.04% ± 0.07, p = 0.38). Bystander CPR, public arrest location, presenting rhythm and chest compression depth were predictors of short term survival (ROSC to ED).

Conclusions

Even limited CPR-feedback combined with training and ongoing debriefing leads to high chest compression quality. Bystander CPR, location, rhythm and chest compression depth are determinants of survival from out of hospital cardiac arrest. Addition of voice prompts does neither modify CPR quality nor outcome in OHCA. CC depth significantly influences survival and therefore more focus should be put on correct delivery. Further studies are needed to examine the best configuration of feedback to improve CPR quality and survival.

Registration

ClinicalTrials.gov (NCT00449969), http://www.clinicalTrials.gov.     

A pilot study of mechanical chest compressions with the LUCAS™ device in cardiopulmonary resuscitation

Aim

The LUCAS™ device has been shown to improve organ perfusion during cardiac arrest in experimental studies. In this pilot study the aim was to compare short-term survival between cardiopulmonary resuscitation (CPR) performed with mechanical chest compressions using the LUCAS™ device and CPR performed with manual chest compressions. The intention was to use the results for power calculation in a larger randomised multicentre trial.

Methods

In a prospective pilot study, from February 1, 2005, to April 1, 2007, 149 patients with out-of hospital cardiac arrest in two Swedish cities were randomised to mechanical chest compressions or standard CPR with manual chest compressions.

Results

After exclusion, the LUCAS and the manual groups contained 75 and 73 patients, respectively. In the LUCAS and manual groups, spontaneous circulation with a palpable pulse returned in 30 and 23 patients (p = 0.30), spontaneous circulation with blood pressure above 80/50 mmHg remained for at least 5 min in 23 and 19 patients (p = 0.59), the number of patients hospitalised alive >4 h were 18 and 15 (p = 0.69), and the number discharged, alive 6 and 7 (p = 0.78), respectively.

Conclusions

In this pilot study of out-of-hospital cardiac arrest patients we found no difference in early survival between CPR performed with mechanical chest compression with the LUCAS™ device and CPR with manual chest compressions. Data have been used for power calculation in a forthcoming multicentre trial.     

The efficacy of straddling external chest compression on a moving stretcher

Objective

To evaluate the efficacy of straddling external chest compression performed on moving stretchers.

Methods

The study was a prospective, randomized, cross-over study on a manikin performed at a university hospital. Twenty subjects were selected from the 40 graduates using random numbers to participate in the study. Participants were randomized to either performing standard or straddling external chest compression followed by the other technique 7 days later. The compression variables and time to first compression were recorded.

Results

Twenty subjects (12 males and 8 females) took part in the study. There were no differences between the standard and straddling external chest compression for the compression rate, effective compression percentage and compression depth. There was no difference between the standard external chest compression and straddling external chest compression for incorrect hand position and incomplete release compression. Time to first compression during straddling external chest compression (10.31 ± 1.65 s) was greater than that during standard external chest compression (2.74 ± 0.40 s) (P < 0.001).

Conclusions

The quality of straddling external chest compression performed on a moving stretcher was as effective as standard external chest compression performed on the floor. By performing straddling external chest compression, time for transporting victims to the emergency department to get advanced life support may be shortened.     

Assessment of chest rise during mask ventilation of preterm infants in the delivery room

Background

Current neonatal resuscitation guidelines recommend using visual assessment of chest wall movements to guide the choice of inflating pressure during positive pressure ventilation (PPV) in the delivery room. The accuracy of this assessment has not been tested. We compared the assessment of chest rise made by observers standing at the infants’ head and at the infants’ side with measurements of tidal volume.

Methods

Airway pressures and expiratory tidal volume (V_Te) were measured during neonatal resuscitation using a respiratory function monitor. After 60 s of PPV, resuscitators standing at the infants’ head (head view) and at the side of the infant (side view) were asked to assess chest rise and estimate V_Te. These estimates were compared with V_Te measurements taken during the previous 30 s.

Result

We studied 20 infants who received a mean (SD) of 23 (4) inflations during the 30 s. Some observer felt unable to assess chest rise both from the head view (6/20) and from the side view (3/20). Observers from both head and side tended to underestimate tidal volume by 3.5 mL and 3.3 mL respectively. Agreement between clinical assessment and measured V_Te was generally poor.

Conclusion

During mask ventilation, resuscitators were unable to accurately assess chest wall movement visually from either head or side view.     

Feasibility and safety of combined percutaneous coronary intervention and therapeutic hypothermia following cardiac arrest

Review

Mild therapeautic hypothermia (MTH) has been associated with cardiac dysrhythmias, coagulopathy and infection. After restoration of spontaneous circulation (ROSC), many cardiac arrest patients undergo percutaneous coronary intervention (PCI). The safety and feasibility of combined MTH and PCI remains unclear. This is the first study to evaluate whether PCI increases cardiac risk or compromises functional outcomes in comatose cardiac arrest patients who undergo MTH.

Methods

Ninety patients within a 6-h window following cardiac arrest and ROSC were included. Twenty subjects (23%) who underwent PCI following MTH induction were compared to 70 control patients who underwent MTH without PCI. The primary endpoint was the rate of dysrhythmias; secondary endpoints were time-to-MTH induction, rates of adverse events (dysrhythmia, coagulopathy, hypotension and infection) and mortality.

Results

Patients who underwent PCI plus MTH suffered no statistical increase in adverse events (P = .054). No significant difference was found in the rates of dysrhythmias (P = .27), infection (P = .90), coagulopathy (P = .90) or hypotension (P = .08). The PCI plus MTH group achieved similar neurological outcomes (modified Rankin Scale (mRS) ≤3 (P = .42) and survival rates (P = .40). PCI did not affect the speed of MTH induction; the target temperature was reached in both groups without a significant time difference (P = .29).

Conclusion

Percutaneous coronary intervention seems to be feasible when combined with MTH, and is not associated with increased cardiac or neurological risk.     

Metronome improves compression and ventilation rates during CPR on a manikin in a randomized trial

Aim

We hypothesized that a unique tock and voice metronome could prevent both suboptimal chest compression rates and hyperventilation.

Methods

A prospective, randomized, parallel design study involving 34 pairs of paid firefighter/emergency medical technicians (EMTs) performing two-rescuer CPR using a Laerdal SkillReporter Resusci Anne^® manikin with and without metronome guidance was performed. Each CPR session consisted of 2 min of 30:2 CPR with an unsecured airway, then 4 min of CPR with a secured airway (continuous compressions at 100 min⁻¹ with 8-10 ventilations/min), repeated after the rescuers switched roles. The metronome provided “tock” prompts for compressions, transition prompts between compressions and ventilations, and a spoken “ventilate” prompt.

Results

During CPR with a bag/valve/mask the target compression rate of 90-110 min⁻¹ was achieved in 5/34 CPR sessions (15%) for the control group and 34/34 sessions (100%) for the metronome group (p < 0.001). An excessive ventilation rate was not observed in either the metronome or control group during CPR with a bag/valve/mask. During CPR with a bag/endotracheal tube, the target of both a compression rate of 90-110 min⁻¹ and a ventilation rate of 8-11 min⁻¹ was achieved in 3/34 CPR sessions (9%) for the control group and 33/34 sessions (97%) for the metronome group (p < 0.001). Metronome use with the secured airway scenario significantly decreased the incidence of over-ventilation (11/34 EMT pairs vs. 0/34 EMT pairs; p < 0.001).

Conclusions

A unique combination tock and voice prompting metronome was effective at directing correct chest compression and ventilation rates both before and after intubation.     

The prevalence of chest compression leaning during in-hospital cardiopulmonary resuscitation

Objective

Successful resuscitation from cardiac arrest requires the delivery of high-quality chest compressions, encompassing parameters such as adequate rate, depth, and full recoil between compressions. The lack of compression recoil (“leaning” or “incomplete recoil”) has been shown to adversely affect hemodynamics in experimental arrest models, but the prevalence of leaning during actual resuscitation is poorly understood. We hypothesized that leaning varies across resuscitation events, possibly due to rescuer and/or patient characteristics and may worsen over time from rescuer fatigue during continuous chest compressions.

Methods

This was an observational clinical cohort study at one academic medical center. Data were collected from adult in-hospital and Emergency Department arrest events using monitor/defibrillators that record chest compression characteristics and provide real-time feedback.

Results

We analyzed 112,569 chest compressions from 108 arrest episodes from 5/2007 to 2/2009. Leaning was present in 98/108 (91%) cases; 12% of all compressions exhibited leaning. Leaning varied widely across cases: 41/108 (38%) of arrest episodes exhibited <5% leaning yet 20/108 (19%) demonstrated >20% compression leaning. When evaluating blocks of continuous compressions (>120 s), only 4/33 (12%) had an increase in leaning over time and 29/33 (88%) showed a decrease (p < 0.001).

Conclusions

Chest compression leaning was common during resuscitation care and exhibited a wide distribution, with most leaning within a subset of resuscitations. Leaning decreased over time during continuous chest compression blocks, suggesting that either leaning may not be a function of rescuer fatiguing, or that it may have been mitigated by automated feedback provided during resuscitation episodes.     

Improving cardiopulmonary resuscitation in the emergency department by real-time video recording and regular feedback learning

Aim of the study

Improvement in the quality of cardiopulmonary resuscitation (CPR) may improve the survival rate following cardiac arrest. The aims of our study were to describe how recording of CPR maneuvers performed in our emergency department with real-time video and regular feedback learning may improve CPR.

Methods

A digital video-recording system enabled us to record and analyze CPR procedures for adult patients from March 2007 to July 2008. Our resuscitation teams received video-recording feedback learning every week.

Results and conclusions

We analyzed 45 cases, divided into three groups of 15 consecutive patients. Instantaneous rates of chest compression showed variation with 75% exceeding 110 cpm. There was a significant difference in instantaneous rates among groups (135 [112-150] in group 1, 123 [110-136] in group 2 and 124 [111-137] cpm in group 3, P  <  0.001). Ratio of hands-off time to total manual compression time (%) significantly decreased over time (Spearman correlation = −0.30, P = 0.04). There were significant differences in hands-off time per minute among the groups (11 [3-28], 6 [2-21] and 7 [2-19] s min⁻¹, P  <  0.001). There was a significant improvement in time delay to first chest compression (11 [5-50], 20 [8-68] and 0 [0-12] s, P = 0.01), but not in time delay to first ventilation (91 [31-190], 65 [17-121] and 24 [9-64] s, P = 0.08). Data are median [25-75% interquartile]. Regular feedback learning from real-time video recording may improve the quality of major CPR variables.     

Continuous mechanical chest compression during in-hospital cardiopulmonary resuscitation of patients with pulseless electrical activity

Survival after in-hospital pulseless electrical activity (PEA) cardiac arrest is poor and has not changed during the last 10 years. Effective chest compressions may improve survival after PEA. We investigated whether a mechanical device (LUCAS™-CPR) can ensure chest compressions during cardiac arrest according to guidelines and without interruption during transport, diagnostic procedures and in the catheter laboratory.

Methods

We studied mechanical chest compression in 28 patients with PEA (pulmonary embolism (PE) n = 14; cardiogenic shock/acute myocardial infarction; n = 9; severe hyperkalemia; n = 2; sustained ventricular arrhythmias/electrical storm; n = 3) in a university hospital setting.

Results

During or immediately after CPR, 21 patients underwent coronary angiography and or pulmonary angiography. Successful return of a spontaneous circulation (ROSC) was achieved in 27 out of the 28 patients. Ten patients died within the first hour and three patients died within 24 h after CPR. A total of 14 patients survived and were discharged from hospital (13 without significant neurological deficit). Interestingly, six patients with PE did not have thrombolytic therapy due to contraindications. CT-angiography findings in these patients showed fragmentation of the thrombus suggesting thrombus breakdown as an additional effect of mechanical chest compressions. No patients exhibited any life-threatening device-related complications.

Conclusion

Continuous chest compression with an automatic mechanical device is feasible, safe, and might improve outcomes after in-hospital-resuscitation of PEA. Patients with PE may benefit from effective continuous chest compression, probably due to thrombus fragmentation and increased pulmonary artery blood flow.     

The optimal phasic relationship between synchronized shock and mechanical chest compressions

Objective

Pauses for shock delivery in chest compressions are detrimental to the success of resuscitation and may be eliminated with the use of mechanical chest compressors. However, the optimal phasic relationship between mechanical chest compression and defibrillation is still unknown. We therefore undertook a study to assess the effects of timing of defibrillation in the mechanical chest compression cycle on the defibrillation threshold (DFT) using a porcine model of cardiac arrest.

Methods

Ventricular fibrillation was electrically induced and untreated for 10 s in 8 domestic pigs weighing between 26 and 30 kg. Mechanical chest compression was then continuously performed for 25 s, followed by a biphasic electrical shock which was delivered to the animal at 6 randomized coupling phases, including a control phase, with a pre-determined energy setting. The control phase was chosen at a constant 2 s following discontinued chest compression. A novel grouped up-and-down DFT testing protocol was used to compare the success rate at different coupling phases. After a recovery interval of 4 min, the testing sequence was repeated, resulting in a total of 60 test shocks delivered to each animal.

Results

No difference between the delivered shock energy, voltage and current were observed among the 6 study phases. The defibrillation success rate, however, was significantly higher when shocks were delivered in the upstroke phase of mechanical chest compression.

Conclusion

Defibrillation efficacy is maximal when electrical shock is delivered in the upstroke phase of mechanical chest compression.     

A novel method to decrease mattress compression during CPR using a mattress compression cover and a vacuum pump

Background

Mattress compression causes feedback devices to over-estimate the chest compression depth measurement during CPR. We propose a novel method to decrease the mattress compression using a vinyl cover. This mattress compression cover encloses the foam mattress and is compressed by a vacuum pump immediately prior to performing CPR.

Methods

Nine CPR providers performed chest compressions on manikins placed on a conventional foam mattress on a bed frame (surface CONV), a backboard and foam mattress on a bed frame (surface BB), and a foam mattress, compressed with a vacuum pump, on a bed frame (surface VAC). Dual accelerometers were used to simultaneously measure the mattress compression and chest compression depths.

Results

The mattress compression depth levels decreased from 14.9 mm (SD 1.4 mm) on surface CONV to 7.0 mm (SD 0.6 mm) on surface VAC (p < 0.001) whereas 14.0 mm (SD 1.3 mm) on surface BB. The total compression depth was 65.4 mm (SD 3.8 mm) on surface CONV, and 58.3 mm (SD 3.0 mm) on surface VAC (p < 0.001).

Conclusion

Using a mattress compression cover and a vacuum pump appears to increase the rigidity of the mattress and allow for efficient chest compressions. This novel method could decrease the mattress compression depth and increase the efficiency of chest compression during CPR in hospitals.     

Quality of chest compressions performed by inexperienced rescuers in simulated cardiac arrest associated with pregnancy

Objective

We aimed to compare the quality of chest compressions performed by inexperienced rescuers in different positions, notably supine and at a 30° inclined lateral position, to ascertain whether high-quality chest compression is feasible on a pregnant subject in cardiac arrest.

Subjects and methods

We performed a prospective, randomised crossover design study. Each participant performed 2-min chest compressions in two different positions on a mannequin: a supine position and a 30° left inclined lateral position. After 2 min of chest compression in one position, the participant took a rest for 10 min to minimise rescuer fatigue and then performed chest compression in the second position. Data on chest compression rate, mean chest compression depth, correct compression depth rate, correct recoil rate, and correct hand position rate were collected. To measure the angle between the rescuer's arm and the victim's chest surface, chest compressions were recorded with a video recorder. After each practice session, participants were asked to report the subjective difficulty of performing chest compressions using a visual analogue scale.

Results

All 32 participants successfully completed the study. The mean compression rate and depth were 121.0 per minute and 53.3 mm in the supine position and 118.8 per minute and 52.0 mm in the inclined lateral position, respectively (p = 0.978 and p = 0.260, respectively). Also, there were no differences in the correct compression depth rate, the correct hand position rate, or the correct recoil rate (p = 0.426, p = 0.467, and p = 0.260, respectively). However, the lowest and highest angles and the subjective difficulty of chest compression differed significantly (p < 0.001, p < 0.001, and p = 0.007, respectively).

Conclusions

Inexperienced rescuers appear to be capable of performing high-quality chest compressions in a 30° inclined lateral position on pregnant women in a simulated cardiac arrest state.     

Performance of chest compressions by laypersons during the Public Access Defibrillation Trial

Background

Increasing evidence indicates that health professionals often may not achieve guideline standards for cardiopulmonary resuscitation (CPR). Little is known about layperson CPR performance.

Methods

The investigation was a retrospective cohort study of cardiac arrest patients treated by layperson CPR and one model of automated external defibrillator (AED) as part of the Public Access Defibrillation Trial (n = 26). CPR was measured using software that integrates the event log, ECG signal, and thoracic impedance signal. We assessed chest compression fraction (proportion of attempted resuscitation spent performing chest compressions), prompted compression fraction (proportion of attempted resuscitation spent performing compressions during AED-prompted periods), compression rate, and compressions per minute.

Results

Of the 26 cases, 13 presented with ventricular fibrillation and 13 with nonshockable rhythms. Overall, during the period when patients did not have spontaneous circulation, the median chest compression fraction was 34% (IQR 17-48%), median prompted chest compression fraction was 49% (IQR 30-66%), and the median chest compression rate was 96/min (IQR 90-110/min). Taken together, the median chest compression delivered per minute among all arrests was 29 (IQR 20-42). CPR characteristics differed according to initial rhythm: median chest compression per minute was 20 (IQR 13-29) among ventricular fibrillation and 42 (IQR 28-47) among nonshockable rhythms (p = 0.003).

Conclusions

In this study of trained laypersons, CPR varied substantially and often did not achieve guideline parameters. The findings suggest a need to improve CPR training, consider changes to CPR protocols, and/or improve the AED-rescuer interface.     

Extended series of cardiac compressions during CPR in a swine model of perinatal asphyxia

Background

The rationale for a compression to ventilation ratio of 3:1 in neonates with primary hypoxic, hypercapnic cardiac arrest is to emphasize the importance of ventilation; however, there are no published studies testing this approach against alternative methods. An extended series of cardiac compressions offers the theoretical advantage of improving coronary perfusion pressures and hence, we aimed to explore the impact of compression cycles of two different durations.

Materials and methods

Newborn swine (n = 32, age 12-36 h, weight 2.0-2.7 kg) were progressively asphyxiated until asystole occurred. Animals were randomized to receive compressions:ventilations 3:1 (n = 16) or 9:3 (n = 16). Return of spontaneous circulation (ROSC) was defined as a heart rate ≥100 beats min⁻¹.

Results

All animals except one in the 9:3 group achieved ROSC. One animal in the 3:1 group suffered bradycardia at baseline, and was excluded, leaving us with 15 animals in each group surviving to completion of protocol. Time to ROSC (median and interquartile range) was 150 s (115-180) vs. 148 s (116-195) for 3:1 and 9:3, respectively (P = 0.74). There were no differences in diastolic blood pressure during compression cycles or in markers of hypoxia and inflammation. The temporal changes in mean arterial blood pressure, heart rate, arterial blood gas parameters, and systemic and regional oxygen saturation were comparable between groups.

Conclusion

Neonatal pigs with asphyxia-induced cardiac arrest did not respond to a compression:ventilation ratio of 9:3 better than to 3:1. Future research should address if alternative compression:ventilation ratios offer advantages over the current gold standard of 3:1.     

2010 American Heart Association recommended compression depths during pediatric in-hospital resuscitations are associated with survival

Aim

Gaps exist in pediatric resuscitation knowledge due to limited data collected during cardiac arrest in real children. The objective of this study was to evaluate the relationship between the 2010 American Heart Association (AHA) recommended chest compression (CC) depth (≥51 mm) and survival following pediatric resuscitation attempts.

Methods

Single-center prospectively collected and retrospectively analyzed observational study of children (>1 year) who received CCs between October 2006 and September 2013 in the intensive care unit (ICU) or emergency department (ED) at a tertiary care children's hospital. Multivariate logistic regression models controlling for calendar year and known potential confounders were used to estimate the association between 2010 AHA depth compliance and survival outcomes. The primary outcome was 24-h survival. The primary predictor variable was event AHA depth compliance, prospectively defined as an event with ≥60% of 30-s epochs achieving an average CC depth ≥51 mm during the first 5 min of the resuscitation.

Results

There were 89 CC events, 87 with quantitative CPR data collected (23 AHA depth compliant). AHA depth compliant events were associated with improved 24-h survival on both univariate analysis (70% vs. 16%, p < 0.001) and after controlling for potential confounders (calendar year of arrest, gender, first documented rhythm; aOR 10.3; CI⁹⁵: 2.75–38.8; p < 0.001).

Conclusions

2010 AHA compliant chest compression depths (≥51 mm) are associated with higher 24-h survival compared to shallower chest compression depths, even after accounting for potentially confounding patient and event factors.