Improved survival from cardiac arrest in the community

To blow or not to blow: a randomised controlled trial of compression-only and standard telephone CPR instructions in simulated cardiac arrest

This randomised controlled trial used a manikin model of cardiac arrest to compare skill performance in untrained lay persons randomised to receive either compression-only telephone CPR (Compression-only tel., n=29) or standard telephone CPR instructions (Standard tel., n=30). Performance was evaluated during standardised 10 min cardiac arrest simulations using a video recording and data from a laptop computer connected to the training manikin. A number of subjects in both groups did not open the airway. More than 75% in the Standard tel. group failed to deliver two effective initial rescue breaths, and only 17% provided an adequate inflation volume for subsequent breaths, delivering a median of only five inflations during the entire scenario. Most subjects in both groups gave chest compressions that were too shallow and at an inappropriately rapid rate. Hand position was also poor, but was worse in the group given simplified instructions. There was a significant delay to first compression in both groups, although this interval was shortened by over a minute when ventilations were eliminated from the telephone instruction algorithm (245 vs. 184 s, P<0.001). Over two-and-a-half times as many chest compressions were delivered during an average ambulance response time with compression-only telephone directions compared with standard CPR (461 vs. 186, P<0.001). These variables may be critical in predicting survival from out-of-hospital cardiac arrest. Further research is necessary to establish if modifications to scripted telephone instructions can remedy the identified performance deficiencies. Eliminating instructions for rescue breaths from scripted telephone directions will have little impact on the ventilation of most patients. Research is required to determine if the consequent reduction in the delay to starting chest compressions and the significant increase in the number of compressions delivered can increase survival from out-of-hospital cardiac arrest.

Electrophysiological deterioration during long-duration ventricular fibrillation

BACKGROUND

Probability of survival from sudden cardiac arrest caused by ventricular fibrillation (VF) decreases rapidly with fibrillation duration. We hypothesized that cellular ischemia/fibrillation-induced electrophysiological deterioration underlies decreased survival.

METHODS AND RESULTS

We determined fibrillation monophasic action potential (MAP) morphology including action potential frequency content, duration, cycle length, developing diastolic intervals, and amplitude as a function of ischemic fibrillation duration in 10 isolated rabbit hearts. We also correlated ECG frequency (used clinically) and MAP amplitude and frequency. Fibrillation cycle length and diastole duration increased, whereas APD(100) shortened significantly with time (P:<0.001). Between 1 and 3 minutes, diastole appeared primarily as the result of APD(100) shortening, with only small changes in cycle length. Between 2 and 5 minutes, diastole increased primarily as the result of increased cycle length. Diastole developed progressively from 5% of VF cycles at 5 seconds to approximately 100% of VF cycles by 120 seconds (P:<0.001). Diastole increased from 1% of cycle length at 5 seconds to 62% at 5 minutes. Its duration increased from 4.7 ms at 5 seconds to 90 ms at 5 minutes (P:<0.001). Both MAP and ECG 1/frequency closely correlated with fibrillation cycle length.

CONCLUSIONS

These results show a rapid and progressive electrophysiological deterioration during fibrillation, leading to electrical diastole between fibrillation action potentials. This rapid deterioration may explain the decreased probability of successful resuscitation after prolonged fibrillation. Therefore, a greater understanding of cellular deterioration during fibrillation may lead to improved resuscitation methods, including development of specific defibrillator waveforms for out-of-hospital cardiac arrest.

Randomised controlled trials of staged teaching for basic life support. 1. Skill acquisition at bronze stage

We have investigated a method of teaching community CPR in three stages instead of in a single session. These have been designated bronze, silver, and gold stages. The first involves only opening of the airway and chest compression with back blows for choking, the second adds ventilation in a ratio of compressions to breaths of 50:5, and the third is a conversion to conventional CPR. In a controlled randomised trial of 495 trainees we compared the performance in tests immediately after instruction of those who had received a conventional course and those who had had the simpler bronze level tuition. The tests were based on video recordings of simulated resuscitation scenarios and the readouts from recording manikins. Differences occurred as a direct consequence of ventilation being required in one group and not the other, some variation probably followed from unforeseen minor changes in the way that instruction was given, whilst others may have followed from the greater simplicity in the new method of training. A careful approach was followed by slightly more trainees in the conventional group whilst appreciably more in the bronze group remembered to shout for help (44% vs. 71%). A clear advantage was also seen for bronze level training in terms of those who opened the airway as taught (35% vs. 56%), for checking breathing (66% vs. 88%), and for mentioning the need to phone for an ambulance (21% vs. 32%). Little difference was observed in correct or acceptable hand position between the conventional group who were given detailed guidance and the bronze group who were instructed only to push on the centre of the chest. The biggest differences related to the number of compressions given. The mean delay to first compression was 63 s and 34 s, and the mean duration of pauses between compressions was 16 s and 9 s, respectively. Average performed rates were similar in the two groups, but more in the conventional group compressed too slowly whereas more in the bronze group compressed too rapidly. Observations were made for only three cycles of compression, but extrapolating these to the 8 min often considered a watershed for chances of survival for victims of cardiac arrest, an average of 308 compressions would be expected from those using conventional CPR compared with 675 for those using bronze level CPR. The implications of this difference are discussed.

What can you teach about cardiopulmonary resuscitation (CPR) in 30 seconds? Evaluation of a television campaign

This study evaluated an 8-month media campaign, implemented in western Washington, to educate people on the basic steps of cardiopulmonary resuscitation (CPR) for cardiac arrest. A telephone survey was conducted with a total of 384 adults randomly selected from two towns, one that had been exposed to the campaign (intervention town) and one that had not been exposed to the campaign (comparison town). Results showed that respondents in the intervention town were more likely than respondents in the comparison town to report (a) having heard messages on CPR in the past month, (b) having seen the CPR media campaign, and (c) knowing the three basic steps of CPR. Respondents who had seen the campaign evaluated it very favorably. There were no differences between respondent groups in self-reported CPR training or intentions to perform CPR, suggesting that the campaign had a greater impact on knowledge and awareness than on intentions and behavior.

Prepare to be shocked: the evolving standard of care in treating sudden cardiac arrest

Standards of care are devised by juries in courts of law. They "evolve," in part, according to public expectations as those expectations are honed by the profession in its literature, its forums, and as reported in the popular press and media. Sudden cardiac arrest is a major killer in the United States. A significant number of deaths from sudden cardiac arrest can be prevented by using automatic external defibrillators in the out-of-hospital setting. These devices have become cost effective, reliable, and readily available and the standard of care requiring their use in the out-of-hospital setting has arrived.

Effectiveness of the BBC's 999 training roadshows on cardiopulmonary resuscitation: video performance of cohort of unforewarned participants at home six months afterwards

OBJECTIVE

To examine the competence of a cohort trained in cardiopulmonary resuscitation by the BBC's 999 training roadshows.

DESIGN

Descriptive cohort study applying an innovative testing procedure to a nationwide systematic sample. The test sample received an unsolicited home visit and without warning were required to perform cardiopulmonary resuscitation on a manikin while being videoed. The videos were then analysed for effectiveness and safety using the new test.

SETTING

Nine cities and surrounding areas in the United Kingdom.

SUBJECTS

280 people aged between 11 and 72.

RESULTS

Thirty three (12%) trainees were able to perform effective cardiopulmonary resuscitation, but of these 14 (5%) performed one or more elements in a way that was deemed to be potentially injurious. Thus only 19 (7%) trainees were able at six months to provide safe cardiopulmonary resuscitation. In addition, large numbers of subjects failed to shout for help, effectively assess the status of the patient, or alert an ambulance. Significantly better performances were recorded by those under 45 years old (31 (14%) v 2 (4%) gave effective performances respectively, P < 0.05), those who had attended a subsequent cardiopulmonary resuscitation course (8 (40%) v 25 (10%) gave effective performances respectively, P < 0.0001), and those confident in their initial ability (26 (20%) v 7 (6%) gave effective performances respectively, P < 0.005). Females were significantly less likely than males to perform procedures in a harmful way (117 (62%) v 10 (12%) performed safely respectively, P < 0.005).

CONCLUSION

Television is an effective means of generating large training cohorts. Volunteers will cooperate with unsolicited testing in their home, such testing being a realistic simulation of the stress and lack of forewarning that would surround a real event. Under such conditions the performance of cardiopulmonary resuscitation was disappointing. However, retraining greatly improves performance.

Resuscitation skills of lay public after recent training

STUDY OBJECTIVE

To investigate the ability of laypeople to apply basic CPR techniques after recent training.

DESIGN

Cross-sectional assessment of practical CPR skills.

TYPE OF PARTICIPANTS

151 laypeople who were trained twice in the preceding 20 to 24 months.

MEASUREMENTS AND MAIN RESULTS

Practical skills were tested using six primary recorded variables that describe the quality of CPR techniques in a training situation. A total score on the skills of each participant was computed on the basis of a predefined scoring system. Thirty-three percent of the participants were able to perform adequate CPR. The compression:relaxation ratio, the breathing volume, and the breathing interval were points of concern.

CONCLUSION

Practical skills in basic CPR after a 12-month training interval, though better in this study than in many previous studies, are insufficient in the majority of laypeople. The results of this study could be used to design a better tailored (re)instruction program, with an emphasis on regular, frequent refresher courses.

One-year survival after prehospital cardiac arrest: the Utstein style applied to a rural-suburban system

To evaluate the recently published Utstein algorithm (Ann Emerg Med 1991;20:861), the authors conducted a retrospective review of all advanced life support (ALS) trip sheets and hospital records of patients with prehospital cardiac arrests between January 1988 and December 1989. Telephone follow-up was used to determine 1-year survival rates. Of 713 arrests in the 24-month study period, 601 were of presumed cardiac etiology. Approximately 599 of these charts were available for analysis. One hundred ninety-three (32.2%) of these had return of spontaneous circulation (ROSC), 36 (6.0%) survived to hospital discharge, and 24 were alive at 1-year follow-up (4.0% of total or 67% of survivors to discharge). The Utstein style was found to be a useful algorithmic format for reporting prehospital cardiac arrest data in a manner that should allow direct comparison between emergency medical service (EMS) systems. Existing prehospital record-keeping practices (trip sheets) are easily adapted to this style of data collection, although certain data for the template (eg, resuscitations not attempted and alive at 1-year) are more difficult to ascertain. Additionally, the authors report their own experience during a 2-year period, including data that suggest that the majority of patients with cardiac arrest who survive to hospital discharge are still alive at 1 year.

Clinical experience with three different defibrillators for resuscitation of out of hospital cardiac arrest

Three defibrillators, one manual and two different semiautomatic, were prospectively compared during a one year period for out-of-hospital use by ordinary ambulance personnel with short additional training. Eighty-three cardiac arrest patients were treated with one of two different semiautomatic defibrillators and 26 by an ordinary manual defibrillator. Twenty-nine were found in ventricular fibrillation. Five of these patients were successfully resuscitated and admitted for further hospital care, two survived to be discharged home. The semiautomatic defibrillators were found to be accurate in ECG interpretation, sensitivity and specificity was 100%, respectively, and both were equally effective in defibrillation. There were no differences in conversion rate or in the clinical outcome between the three defibrillators tested. Both semiautomatic defibrillators tested seemed to be safe, reliable and cost-effective. The low survival rate found is most certainly due to a long ambulance delay.