Quality of resuscitation: flight attendants in an airplane simulator use a new mechanical resuscitation device--a randomized simulation study

Purpose

Cardiopulmonary resuscitation (CPR) during flight is challenging and has to be sustained for long periods. In this setting a mechanical-resuscitation-device (MRD) might improve performance.In this study we compared the quality of resuscitation of trained flight attendants practicing either standard basic life support (BLS) or using a MRD in a cabin-simulator.

Methods

Prospective, open, randomized and crossover simulation study. Study participants, competent in standard BLS were trained to use the MRD to deliver both chest compressions and ventilation. 39 teams of two rescuers resuscitated a manikin for 12 min in random order, standard BLS or mechanically assisted resuscitation. Primary outcome was “absolute hands-off time” (sum of all periods during which no hand was placed on the chest minus ventilation time). Various parameters describing the quality of chest compression and ventilation were analysed as secondary outcome parameters.

Results

Use of the MRD led to significantly less “absolute hands-off time” (164 ± 33 s vs. 205 ± 42 s, p < 0.001). The quality of chest compression was comparable among groups, except for a higher compression rate in the standard BLS group (123 ± 14 min⁻¹ vs. 95 ± 11 min⁻¹, p < 0.001). Tidal volume was higher in the standard BLS group (0.48 ± 0.14 l vs. 0.34 ± 0.13 l, p < 0.001), but we registered fewer gastric inflations in the MRD group (0.4 ± 0.3% vs. 16.6 ± 16.9%, p < 0.001).

Conclusion

Using the MRD resulted in significantly less “absolute hands-off time”, but less effective ventilation. The translation of higher chest compression rate into better outcome, as shown in other studies previously, has to be investigated in another human outcome study.     

Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: a prospective interventional study

AIMS: To compare quality of CPR during out-of-hospital cardiac arrest with and without automated feedback. MATERIALS AND METHODS: Consecutive adult, out-of-hospital cardiac arrests of all causes were studied. One hundred and seventy-six episodes (March 2002-October 2003) without feedback were compared to 108 episodes (October 2003-September 2004) where automatic feedback on CPR was given. Automated verbal and visual feedback was based on measured quality with a prototype defibrillator. Quality of CPR was the main outcome measure and survival was reported as specified in the protocol. RESULTS: Average compression depth increased from (mean +/- S.D.) 34 +/- 9 to 38 +/- 6 mm (mean difference (95% CI) 4 (2, 6), P < 0.001), and median percentage of compressions with adequate depth (38-51 mm) increased from 24% to 53% (P < 0.001, Mann-Whitney U-test) with feedback. Mean compression rate decreased from 121 +/- 18 to 109 +/- 12 min(-1) (difference -12 (-16, -9), P = 0.001). There were no changes in the mean number of ventilations per minute; 11 +/- 5 min(-1) versus 11 +/- 4 min(-1) (difference 0 (-1, 1), P = 0.8) or the fraction of time without chest compressions; 0.48 +/- 0.18 versus 0.45 +/- 0.17 (difference -0.03 (-0.08, 0.01), P = 0.08). With intention to treat analysis 7/241 control patients were discharged alive (2.9%) versus 5/117 with feedback (4.3%) (OR 1.5 (95% CI; 0.8, 3), P = 0.2). In a logistic regression analysis of all cases, witnessed arrest (OR 4.2 (95% CI; 1.6, 11), P = 0.004) and average compression depth (per mm increase) (OR 1.05 (95% CI; 1.01, 1.09), P = 0.02) were associated with rate of hospital admission. CONCLUSIONS: Automatic feedback improved CPR quality in this prospective non-randomised study of out-of-hospital cardiac arrest. Increased compression depth was associated with increased short-term survival. TRIAL REGISTRATION: ClinicalTrials.gov (NCT00138996), http://www.clinicaltrials.gov/.     

Optimal refresher training intervals for AED and CPR skills: a randomised controlled trial

AIM: To determine the optimal refresher training interval for lay volunteer responders in the English National Defibrillator Programme who had previously undertaken a conventional 4-h initial class and a first refresher class at 6 months. METHODS: Subjects were randomised to receive either two additional refresher classes at intervals of 7 and 12 months or one additional refresher class after 12 months. RESULTS: Greater skill loss had occurred when the second refresher class was undertaken at 12 compared with 7 months. Skill retention however, was higher in the former group, ultimately resulting in no significant difference in final skill performance. There was no significant difference in performance between subjects attending two versus three refresher classes. On completion of refresher training all subjects were able to deliver countershocks, time to first shock decreased by 17s in both groups, and the proportion of subjects able to perform most skills increased. The execution of several important interventions remained poor, regardless of the total number of classes attended or the interval between them. These included CPR skills, defibrillation pad placement, and pre-shock safety checks. Refresher classes held more frequently and at shorter intervals increased subjects' self-assessed confidence, possibly indicating greater preparedness to use an AED in a real emergency. CONCLUSIONS: This study shows that the ability to deliver countershocks is maintained whether the second refresher class is held at seven or 12 months after the first. To limit skill deterioration between classes, however, refresher training intervals should not exceed 7 months. The quality of instruction given should be monitored carefully. Learning and teaching strategies require review to improve skill acquisition and maintenance.     

Detection of ventricular fibrillation in the presence of cardiopulmonary resuscitation artefacts

Providing cardiopulmonary resuscitation (CPR) to a patient in cardiac arrest introduces artefacts into the electrocardiogram (ECG), corrupting the diagnosis of the underlying heart rhythm. CPR must therefore be discontinued for reliable shock advice analysis by an automated external defibrillator (AED). Detection of ventricular fibrillation (VF) during CPR would enable CPR to continue during AED rhythm analysis, thereby increasing the likelihood of resuscitation success. This study presents a new adaptive filtering method to clean the ECG. The approach consists of a filter that adapts its characteristics to the spectral content of the signal exclusively using the surface ECG that commercial AEDs capture through standard patches. A set of 200 VF and 25 CPR artefact samples collected from real out-of-hospital interventions were used to test the method. The performance of a shock advice algorithm was evaluated before and after artefact removal. CPR artefacts were added to the ECG signals and four degrees of corruption were tested. Mean sensitivities of 97.83%, 98.27%, 98.32% and 98.02% were achieved, producing sensitivity increases of 28.44%, 49.75%, 59.10% and 64.25%, respectively, sufficient for ECG analysis during CPR. Although satisfactory and encouraging sensitivity values have been obtained, further clinical and experimental investigation is required in order to integrate this type of artefact suppressing algorithm in current AEDs.     

Poor chest compression quality with mechanical compressions in simulated cardiopulmonary resuscitation: a randomized, cross-over manikin study

Introduction

Mechanical chest compression devices are being implemented as an aid in cardiopulmonary resuscitation (CPR), despite lack of evidence of improved outcome. This manikin study evaluates the CPR-performance of ambulance crews, who had a mechanical chest compression device implemented in their routine clinical practice 8 months previously. The objectives were to evaluate time to first defibrillation, no-flow time, and estimate the quality of compressions.

Methods

The performance of 21 ambulance crews (ambulance nurse and emergency medical technician) with the authorization to perform advanced life support was studied in an experimental, randomized cross-over study in a manikin setup. Each crew performed two identical CPR scenarios, with and without the aid of the mechanical compression device LUCAS. A computerized manikin was used for data sampling.

Results

There were no substantial differences in time to first defibrillation or no-flow time until first defibrillation. However, the fraction of adequate compressions in relation to total compressions was remarkably low in LUCAS-CPR (58%) compared to manual CPR (88%) (95% confidence interval for the difference: 13–50%). Only 12 out of the 21 ambulance crews (57%) applied the mandatory stabilization strap on the LUCAS device.

Conclusions

The use of a mechanical compression aid was not associated with substantial differences in time to first defibrillation or no-flow time in the early phase of CPR. However, constant but poor chest compressions due to failure in recognizing and correcting a malposition of the device may counteract a potential benefit of mechanical chest compressions.     

Effectiveness of the new 'Mobile AED Map' to find and retrieve an AED: A randomised controlled trial

Background

Although early shock with an automated external defibrillator (AED) is one of the several key elements to save out-of-hospital cardiac arrest (OHCA) victims, it is not always easy to find and retrieve a nearby AED in emergency settings. We developed a cell phone web system, the Mobile AED Map, displaying nearby AEDs located anywhere. The simulation trial in the present study aims to compare the time and travel distance required to access an AED and retrieve it with and without the Mobile AED Map.

Methods

Design: Randomised controlled trial. Setting: Two fields where it was estimated to take 2 min (120-170 m) to access the nearest AED. Participants were randomly assigned to either the Mobile AED Map group or the control group. We provided each participant in both groups with an OHCA scenario, and measured the time and travel distance to find and retrieve a nearby AED.

Results

Forty-three volunteers were enrolled and completed the protocol. The time to access and retrieve an AED was not significantly different between the Mobile AED Map group (400 ± 238 s) and the control group (407 ± 256 s, p = 0.92). The travel distance was significantly shorter in the Mobile AED Map group (606 m vs. 891 m, p = 0.019). Trial field conditions affected the results differently.

Conclusions

Although the new Mobile AED Map reduced the travel distance to access and retrieve the AED, it failed to shorten the time. Further technological improvements of the system are needed to increase its usefulness in emergency settings (UMIN000002043).     

Comparison of hands-off time during CPR with manual and semi-automatic defibrillation in a manikin model

BACKGROUND: Rhythm analysis with current semi-automatic external defibrillators (AEDs) requires mandatory interruptions of chest compressions that may compromise the outcome after cardiopulmonary resuscitation (CPR). We hypothesised that interruptions would be shorter when the defibrillator was operated in manual mode by trained and certified ambulance personnel. MATERIALS AND METHODS: Sixteen pairs of ambulance personnel operated the defibrillator (Lifepak((R))12) in both semi-automatic (AED) and manual (MED) mode in a randomised, cross-over manikin CPR study, following the ERC 2000 Guidelines. RESULTS: Median time from last chest compression to shock delivery (with interquartile range) was 17s (13, 18) versus 11s (6, 15) (mean difference (95% CI) 6s (2, 10), p=0.004). Similarly, median time from shock delivery to resumed chest compressions was 25s (22, 26) versus 8s (7, 12) (median difference 13s, p=0.001) in the AED and MED groups, respectively. While sensitivity for identifying ventricular fibrillation (VF) in both modes and specificity in the AED mode were 100%, specificity was 89% in manual mode. Thus, some unwarranted shocks resulting in hands-off time (time without chest compressions) were given in manual mode. However, mean hands-off-ratio (time without chest compressions divided by total resuscitation time) was still lower, 0.2s (0.1, 0.3) versus 0.3s (0.28, 0.32) in manual mode, mean difference 0.10s (0.05, 0.15), p=0.001. CONCLUSION: Paramedics performed CPR with less hands-off time before and after shocks on a manikin with manual compared to semi-automatic defibrillation following the 2000 Guidelines. However, 12% of the shocks given manually were inappropriate.     

Death in correctional facilities: opportunities for automated external defibrillation

BACKGROUND: Death due to cardiovascular disease occurs more frequently in prisons than the national average. Due to close surveillance 24 h/day, the ability to reach the patient within 3 min and time consuming access for the EMS crews, it was hypothesised that the deployment of automated external defibrillators (AEDs) might make improvements regarding Call-to-the-First-AED-Prompt (CTP) interval and formed the aim of this study. METHODS: Our investigation was analysed on an intention to treat basis and conducted in a prospective, open and observational design. As the primary outcome, the CTP-intervals were compared to the arrival intervals of the EMS. As a secondary outcome, an analysis of all deceased inmates was described. RESULTS: The average daily population of inmates in Austrian correctional facilities is 7714. During a period of 13 months, 10 instances in which an AED was activated and electrodes attached to a collapsed inmate, were reported. The CTP-interval (median+/-S.D.) was 2.3+/-1.6 S.D. min. It took the EMS 10.0+/-4.3 S.D. min. to arrive at the patient's side. Four out of 10 cases of cardiac arrest occurred due to myocardial infarction. Of 39 deceased inmates, a post mortem examination was completed in 34 cases. In 13 cases, cardiovascular disease was the cause of death. DISCUSSION: The main finding was a four-fold reduction of the CTP-interval. This fact indicates the potential improvements which could be achieved with the deployment of AEDs. Our secondary objective revealed that death due to cardiovascular disease was found in a high proportion and could be considered to be a strong incentive to initiate programmes to counter cardiovascular death in prison.     

Pauses in chest compression and inappropriate shocks: a comparison of manual and semi-automatic defibrillation attempts

BACKGROUND: Semi-automatic defibrillation requires pauses in chest compressions during ECG analysis and charging, and prolonged pre-shock compression pauses reduce the chance of a return of spontaneous circulation (ROSC). We hypothesised that pauses are shorter for manual defibrillation by trained rescuers, but with an increased number of inappropriate shocks given for a non-VF/VT rhythm. METHODS: From a prospective study of CPR quality during in- and out-of-hospital cardiac arrest, the duration of pre-shock, inter-shock, and post-shock pauses were compared with Mann-Whitney U-test during manual and AED mode with the same defibrillator, and proportions of inappropriate shocks were compared with Chi-squared tests. RESULTS: A 635 manual and 530 semi-automatic shocks were studied. Number of shocks per episode was similar for the two groups. All pauses measured in seconds (s) were shorter for manual use (P<0.0001); median (25, 75 percentiles); 15 (11, 21) versus 22 (18, 28) pre-shock, 13 (9, 20) versus 23 (22, 26) inter-shock, and 9 (6, 18) versus 20 (11, 31) post-shock, but 163 (26%) manual shocks were inappropriate compared with 30 (6%) AED shocks, odds ratio (OR) 5.7 (95% CI; 3.8-8.7). A 150 (78%) of the inappropriate shocks were delivered for organised rhythms. The proportion of inappropriate manual shocks was higher for resident physicians in-hospital than paramedics out-of-hospital; 77/228 (34%) versus 86/407 (21%), OR 1.9 (1.3-2.7). CONCLUSION: Manual defibrillation resulted in shorter pauses in chest compressions, but a higher frequency of inappropriate shocks. A higher formal level of education did not prevent inappropriate shocks. Trial registrationhttp://www.clinicaltrials.gov/ (NCT00138996 and NCT00228293).     

Comparison of three instructional methods for teaching cardiopulmonary resuscitation and use of an automatic external defibrillator to high school students

OBJECTIVE: To evaluate new instructional methods for teaching high school students cardiopulmonary resuscitation (CPR) and automated external defibrillator (AED) knowledge, actions and skills. METHODS: We conducted a cluster-controlled trial of 3 instructional interventions among Seattle area high school students, with random allocation based on classrooms, during 2003-04. We examined two new instructional methods: interactive-computer training and interactive-computer training plus instructor-led (hands-on) practice, and compared them with traditional classroom instruction that included video, teacher demonstration and instructor-led (hands-on) practice, and with a control group. We assessed CPR and AED knowledge, performance of key AED and CPR actions, and essential CPR ventilation and compressions skills 2 days and 2 months after training. All outcomes were transformed to a scale of 0-100%. RESULTS: For all outcome measures mean scores were higher in the instructional groups than in the control group. Two days after training all instructional groups had mean CPR and AED knowledge scores above 75%, with use of the computer program scores were above 80%. Mean scores for key AED actions were above 80% for all groups with training, with hands-on practice enhancing students' positive outcomes for AED pad placement. Students who received hands-on practice more successfully performed CPR actions than those in the computer program only group. In the 2 hands-on practice groups the scores for 3 of the outcomes ranged from 57 to 74%; they were 32 to 54% in the computer only group. For the outcome of continuing CPR until the AED was available scores were high, 89 to 100% in all 3 training groups. Mean CPR skill scores were low in all groups. The highest mean score for successful ventilations was 15% and for compressions, 29%. The pattern of results was similar after 2 months. CONCLUSIONS: We found evidence that interactive computer based self instruction alone was sufficient to teach CPR and AED knowledge and AED actions to high school students. All forms of instruction were highly effective in teaching AED use. In contrast to AED skills, CPR remains a set of difficult psychomotor skills that is challenging to teach to high school students as well as other members of the lay public.     

Feasibility of automated rhythm assessment in chest compression pauses during cardiopulmonary resuscitation

Aim

To demonstrate the feasibility of doing a reliable rhythm analysis in the chest compression pauses (e.g. pauses for two ventilations) during cardiopulmonary resuscitation (CPR).

Methods

We extracted 110 shockable and 466 nonshockable segments from 235 out-of-hospital cardiac arrest episodes. Pauses in chest compressions were already annotated in the episodes. We classified pauses as ventilation or non-ventilation pause using the transthoracic impedance. A high-temporal resolution shock advice algorithm (SAA) that gives a shock/no-shock decision in 3 s was launched once for every pause longer than 3 s. The sensitivity and specificity of the SAA for the analyses during the pauses were computed.

Results

We identified 4476 pauses, 3263 were ventilation pauses and 2183 had two ventilations. The median of the mean duration per segment of all pauses and of pauses with two ventilations were 6.1 s (4.9–7.5 s) and 5.1 s (4.2–6.4 s), respectively. A total of 91.8% of the pauses and 95.3% of the pauses with two ventilations were long enough to launch the SAA. The overall sensitivity and specificity were 95.8% (90% low one-sided CI, 94.3%) and 96.8% (CI, 96.2%), respectively. There were no significant differences between the sensitivities (P = 0.84) and the specificities (P = 0.18) for the ventilation and the non-ventilation pauses.

Conclusion

Chest compression pauses are frequent and of sufficient duration to launch a high-temporal resolution SAA. During these pauses rhythm analysis was reliable. Pre-shock pauses could be minimised by analysing the rhythm during ventilation pauses when CPR is delivered at 30:2 compression:ventilation ratio.     

A manually powered mechanical resuscitation device used by a single rescuer: a randomised controlled manikin study

Purpose

The goal of this randomized, open, controlled crossover manikin study was to compare the performance of “Animax”, a manually operated hand-powered mechanical resuscitation device (MRD) to standard single rescuer basic life support (BLS).

Methods

Following training, 80 medical students performed either standard BLS or used an MRD for 12 min in random order. We compared the quality of chest compressions (effective compressions, compression depth and rate, absolute hands-off time, hand position, decompression), and of ventilation including the number of gastric inflations. An effective compression was defined as a compression performed with correct depth, hand position and decompression.

Results

The use of the MRD resulted in a significantly higher number of effective compressions compared to standard BLS (67 ± 34 vs. 41 ± 34%, p < 0.001). In a comparison with standard BLS, the use of the MRD resulted in less absolute hands-off time (264 ± 57 vs. 79 ± 40 s, p < 0.001) and in a higher minute-volume (1.86 ± 0.7 vs. 1.62 ± 0.7 l, p = 0.020). However, ventilation volumes were below the 2005 ERC guidelines for both methods. Gastric inflations occurred only in 0 ± 0.1% with the MRD compared to 3 ± 7% during standard BLS (p < 0.001).

Conclusion

Single rescuer cardio-pulmonary resuscitation with the manually operated MRD was superior to standard BLS regarding chest compressions in this simulation study. The MRD delivered a higher minute-volume but did not achieve the recommended minimal volume. Further clinical studies are needed to test the MRD's safety and efficacy in patients.     

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.     

Strong corruption of electrocardiograms caused by cardiopulmonary resuscitation reduces efficiency of two-channel methods for removing motion artefacts in non-shockable rhythms

AimCardiopulmonary resuscitation (CPR) artefact removal methods provide satisfactory results when the rhythm is shockable but fail on non-shockable rhythms. We investigated the influence of the corruption level on the performance of four different two-channel methods for CPR artefact removal.Materials and methods395 artefact-free ECGs and 13 pure CPR artefacts with corresponding blood pressure readings as a reference channel were selected. Using a simplified additive data model we generated CPR-corrupted signals at different signal-to-noise ratio (SNR) levels from ?10 to +10 dB. The algorithms were optimized on learning data with respect to SNR improvement and then applied to testing data. Sensitivity and specificity were derived from the shock/no-shock advice of an automated external defibrillator before CPR corruption and after artefact removal.ResultsSensitivity for the filtered data (>95%) was significantly superior to that for the unfiltered data (76%), p < 0.001. However, specificity was similar for the filtered and unfiltered data (<90% vs 89.3%). For large artefacts (?10 dB) specificity decreased below 70%. No important difference in the performance of the four algorithms was found.ConclusionUsing a simplified data model we showed that, when the ECG rhythm is non-shockable, two-channel methods could not reduce CPR artefacts without affecting the rhythm analysis for shock recommendation. The reason could be poor reconstruction when the artefacts are large. However, poor reconstruction was not a hindrance to re-identifying shockable rhythms. Future investigations should both include the refinement of filter methods and also focus on reducing motion artefacts already at the recording stage.     

Layperson’s performance on an unconversant type of AED device: A prospective crossover simulation experimental study

BACKGROUND:Diverse models of automated external defibrillators (AEDs) possess distinctive features. This study aimed to investigate whether laypersons trained with one type of AED could intelligently use another initial contact type of AED with varying features.METHODS:This was a prospective crossover simulation experimental study conducted among college students. Subjects were randomly trained with either AED1 (AED1 group) or AED2 (AED2 group), and the AED operation performance was evaluated individually (Phase I test). At the 6-month follow-up AED performance test (Phase II test), half of the subjects were randomly switched to use another type of AED, which formed two switches (Switch A: AED1-1 group vs. AED2-1 group; Switch B: AED2-2 group vs. AED1-2 group).RESULTS:A total of 224 college students participated in the study. In the phase I test, a significantly higher proportion of successful defibrillation and shorter shock delivery time to achieve successful defibrillation was observed in the AED2 group than in the AED1 group. In the phase II test, no statistical differences were observed in the proportion of successful defibrillation in Switch A (51.4% vs. 36.6%, P=0.19) and Switch B (78.0% vs. 53.7%, P=0.08). The median shock delivery time within participants achieving successful defibrillation was significantly longer in the switched group than that of the initial group in both Switch A (89 [81–107] s vs. 124 [95–135] s, P=0.006) and Switch B (68 [61.5–81.5] s vs. 95.5 [55–131] s, P<0.001).CONCLUSION:College students were able to effectively use AEDs different from those used in the initial training after six months, although the time to shock delivery was prolonged.     

A different rescuer changing strategy between 30:2 cardiopulmonary resuscitation and hands-only cardiopulmonary resuscitation that considers rescuer factors: a randomised cross-over simulation study with a time-dependent analysis

Aim

To compare the time-dependent changes in the quality of chest compressions in 30:2 cardiopulmonary resuscitation (CPR) and hands-only cardiopulmonary resuscitation (HO-CPR) and to evaluate how individual rescuer factors affect the quality of chest compressions over time for both CPR techniques.

Methods

Total 1028 adult hospital and university workers participated in CPR training programs including sessions of 30:2 CPR and HO-CPR. Tests of both CPR methods were performed in a random order using a manikin with Skill-Reporter™. Data were collected from 863 subjects. The time-dependent changes in chest compressions quality and the effects of individual rescuer factors (age, gender, body mass index (BMI), prior CPR training and experience) were analysed using the general linear model for a repeated-measures procedure.

Results

In HO-CPR, the mean proportion of correct compressions depth (MPCD) decreased significantly throughout the time sectors following 20–40 s (74.4–50.4% in 100–120 s) compared to 30:2 CPR (83.4–76.3% in 100–120 s) (p < 0.0001). A significant decline of MPCD (MPCD < 70%) was initially observed at 40–60 s in HO-CPR, however, this pattern was not observed in 30:2 CPR. Individual rescuer factors minimally affected the time-dependent change in MPCD during 30:2 CPR. For HO-CPR, all rescuer factors except for male or obese/overweight (BMI ≥ 25) were associated with a significant declines of MPCD, and these decline were usually observed from 40 to 60 s.

Conclusion

Switching rescuers at an interval of 2-min is reasonable for 30:2 CPR. However, for HO-CPR switching rescuers every 1-min may be preferable except when rescuers are male or obese/overweight (BMI ≥ 25).     

Effects of two retraining strategies on nursing students’ acquisition and retention of BLS/AED skills: A cluster randomised trial

AimTo determine and compare the effects of two different retraining strategies on nursing students’ acquisition and retention of BLS/AED skills.MethodsNursing students (N = 177) from two European universities were randomly assigned to either an instructor-directed (IDG) or a student-directed (SDG) 4-h retraining session in BLS/AED. A multiple-choice questionnaire, the Cardiff Test, Laerdal SkillReporter^® software and a self-efficacy scale were used to assess students’ overall competency (knowledge, psychomotor skills and self-efficacy) in BLS/AED at pre-test, post-test and 3-month retention-test. GEE, chi-squared and McNemar tests were performed to examine statistical differences amongst groups across time.ResultsThere was a significant increase in the proportion of students who achieved competency for all variables measuring knowledge, psychomotor skills and self-efficacy between pre-test and post-test in both groups (all p-values < 0.05). However, at post-test, significantly more students in the SDG achieved overall BLS/AED competency when compared to IDG. In terms of retention at 3 months, success rates of students within the IDG deteriorated significantly for all variables except ≥70% of chest compressions with correct hand position (p-value = 0.12). Conversely, the proportion of students who achieved competency within the SDG only decreased significantly in ‘mean no flow-time≤5s’ (p-value = 0.02). Furthermore, differences between groups’ success rates at retention-test also proved to be significantly different for all variables measured (all p-values < 0.05).ConclusionThis study demonstrated that using a student-directed strategy to retrain BLS/AED skills has resulted in a higher proportion of nursing students achieving and retaining competency in BLS/AED at three months when compared to an instructor-directed strategy.     

High acceptance of a home AED programme by survivors of sudden cardiac arrest and their families

PURPOSE: The feasibility and acceptance of providing sudden cardiac arrest survivors with life supporting first aid training and automated external defibrillators (AEDs) at their homes is unknown. Preliminary experiences are reported here. METHODS: Trained medical students provided life supporting first aid courses including AED training to cardiac arrest survivors. Patients were asked to invite relatives and friends to such training sessions at their home. Laerdal Little Anne and Heartstart AED Trainer were used. An AED was placed at the patients' disposal. A refresher course took place 1 year later. Questionnaires were used to evaluate the project. RESULTS: Since 1999, 88 families have been trained and provided with an AED. Immediately after the training 90% (66% "agree", 24% "maybe yes") believed they would perform first aid correctly, 1 year later 98% did so (68% "agree", 29% "maybe yes") (p=0.03). Families considered feeling much safer having an AED at home. The handling of an AED was regarded to be easy and AEDs would even be used on strangers. Only on one occasion an AED was used in a real emergency situation. CONCLUSION: Providing patients and relatives with life support first aid and AED training at their homes is feasible and has raised no major objections by the family members. All have considered handling of an AED much simpler than providing basic life support and therefore none think that it would be a major problem to use it in case of an emergency. This still has to be proven.     

Out-of-hospital cardiopulmonary resuscitation with the AutoPulse system: a prospective observational study with a new load-distributing band chest compression device

OBJECTIVE: To evaluate the effectiveness, the safety, and the practicability of the new automated load-distributing band resuscitation device AutoPulse in out-of-hospital cardiac arrest in the midsized urban emergency service of Bonn city. STUDY DESIGN: Prospective, observational study. METHODS: Measurements of effectiveness were the proportion of patients with a return of spontaneous circulation (ROSC) and end-tidal carbon-dioxide (etCO(2)) values during cardiopulmonary resuscitation (CPR). The indications of safety was the proportion of injuries caused by the device, and practicability was assessed by the measurement of the time taken to setup the AutoPulse. RESULTS: Forty-six patients were resuscitated with the device from September 2004 to May 2005. In 25 patients (54.3%) ROSC was achieved, 18 patients (39.1%) were admitted to intensive care unit (ICU), and 10 patients (21.8%) were discharged from ICU. End-tidal capnography showed significantly higher etCO(2) values in patients with ROSC than in patients without ROSC. The mean time to setup the AutoPulse was 4.7+/-5.9 min, but activation of the device after arrival at the scene in 2 min or less was possible in 67.4%. No injuries were detected after use of the AutoPulse-CPR. CONCLUSION: The AutoPulse system is an effective and safe mechanical CPR device useful in out-of-hospital cardiac arrest CPR. Automated CPR devices may play an increasingly important role in CPR in the future because they assure continuous chest compressions of a constant quality.