External artifacts by advanced life support providers misleading automated external defibrillators.

BACKGROUND: The ECG analysis algorithm of automated external defibrillators (AEDs) shows reduced sensitivity and specificity in the presence of external artifacts. Therefore, ECG analyses are preceded by voice prompts. We investigated if advanced life support (ALS) providers follow these prompts, and the consequences if they do not. METHODS: In a two-tiered EMS system all 510 ECG analyses from 135 resuscitation attempts with a Laerdal FR2 AED (applied by emergency medical technicians [EMTs] and subsequently used by ALS providers) were prospectively evaluated. The ALS data were compared with data before arrival of ALS providers (EMT data) using Mc Nemar test. RESULTS: In the presence of ALS providers, 286 ECG rhythm analyses were performed. In the 96 analyses with shockable rhythms, artifacts were detected in 35 (36%), leading to a wrongful no shock decision in 19 (20%). Corresponding EMT data were 67 analyses with shockable rhythms, with artifacts in 18 (27%; p<0.001) but a wrongful no shock decision in only 3 (4%; p<0.001). ALS providers also failed to deliver the AED shock in 7 of the 77 analyses with an appropriate shock decision (9%). This was never found in the EMT data. In the 190 analyses of a non-shockable rhythm in the presence of ALS providers, artifacts were detected in 120 (63%) leading to one spurious shock (0.5%). Corresponding EMT data were 157 analyses, with artifacts in 87 (55%; p=0.20) but no spurious shocks. CONCLUSIONS: External artifacts were frequently found, sometimes leading to important errors. Consequently, more training is needed, especially for ALS providers.

Basic life support refresher training of nurses: individual training and group training are equally effective.

BACKGROUND AND OBJECTIVES: Basic life support (BLS) skills of hospital nurses are often poor. We compared individual BLS refresher training (IT; one instructor to one trainee) with group refresher training (GT; one instructor to six trainees). We hypothesised that IT would result in better skill acquisition and retention. METHODS: Nurses from non-critical care wards (n=120) were randomised to IT or GT. Skills were assessed by a 3 min BLS test on a computerised manikin (Laerdal, Norway) immediately before training (T0), immediately after training (T1), and 10 months after training (T2). Results are expressed as median and [interquartile range]. RESULTS: The study was completed by 103 nurses (IT 56, GT 47). For GT the median group size was 5 [4-5]. The median duration of IT was 20 [17-21] min. The median duration of GT was 90 [84-95] or 19 min per trainee. Baseline skills did not differ between GT and IT, except for less compressions with correct depth for IT. At T1 and T2 there were no clinically significant differences between GT and IT for number of ventilations, ventilation volume, number of compressions, compression depth, compression rate and hands off time. Total instructor time was similar for IT and GT training strategies. CONCLUSIONS: There was no difference in IT and GT immediately and 10 months after training. However, training time per nurse for IT was only one fifth, whereas total instructor time did not increase. Although not superior in outcome, IT may be a cost-effective alternative for GT.

Who is reviewing the data review systems of automated external defibrillators? Implications of flawed time lines for clinicians and researchers.

The unintentional print-out by two different software programmes of the same resuscitation-related events stored on a data card of a Laerdal FR2-automated external defibrillator (AED), led to the discovery of flaws in the registration of the time line by one of the commercially available Laerdal software programmes. This observation stresses the need for a continuation of the medical supervision of AED projects, the close co-operation between clinicians and AED manufacturers, the well-controlled introduction of new devices and strict postmarket surveillance programmes.

Abrupt awakening phenomenon associated with gamma-hydroxybutyrate use: a case series.

Case reports mention a sudden awakening from GHB-associated coma but do not specify its time course. The aim of the present case series was to investigate the time course of the awakening from GHB intoxication and the relationship to plasma concentrations of GHB and the presence of other drugs. Unconscious (GCS or=12 was 30 minutes (range 10 to 50 minutes). A subgroup of five patients had a GCS of 3 upon arrival and remained at 3 for a median time of 60 minutes (range 30 to 110 minutes), while the median time for the transition between the last point with GCS 3 and the first with GCS 15 was 30 minutes (range 20 to 60 minutes). This case series illustrates that patients with GHB intoxications remain in a deep coma for a relatively long period of time, after which they awaken over about 30 minutes. This awakening is accompanied by a small change in GHB concentrations. A confounding factor in these observations is co-ingested illicit drugs.

Retention of ventilation skills of emergency nurses after training with the SMART BAG compared to a standard bag-valve-mask.

BACKGROUND AND PURPOSE: Studies show that nurses retain resuscitation skills poorly and that retention of ventilation skills is particularly difficult. We formed the hypothesis that the SMART BAG (SB, O-Two Medical Technologies Inc., Canada), i.e. a bag-valve-mask device with a pressure/flow responsive valve, would assist nurses in providing more efficient ventilation six months after training. MATERIALS AND METHODS: Prior to training, 39 emergency nurses performed CPR for 2 min, in pairs, using a standard bag-valve-mask device (STBVM, Laerdal, Norway) to assess their base line skills. A CPR training manikin (Simulaids, USA) equipped with a PEEP valve in the oesophagus set at 20 cm H2O was used to measure inspiratory time, tidal volume (Vt), peak pressure and gastric insufflation (GI). Immediately following training they were tested using an O-Two STBVM and a SB. Half of the nurses were retested after three months, the other half after six months. Efficient ventilation was defined as a mean Vt>400 ml and GI<50 ml in 1 min. RESULTS: Before training, only 16% of nurses ventilated efficiently: 63% had GI and 28% had Vt<400 ml. Three months after training the efficiency of the STBVM and the SB was high (81 and 75%, respectively). Six months after training, there was a trend towards higher efficiency for the SB (63%) compared to the STBVM (25%) (p=0.07). For instances with the STBVM producing a Vt>400 ml, those without GI had a lower peak pressure than those with GI (7.8 cm H2O versus 17.7 cm H2O, p=0.0001) and showed a trend towards a longer inspiratory time (1.28 s versus 1.08 s, p=0.08). Of all efficient ventilations with a STBVM, 26% had a Vt>600 ml. CONCLUSIONS: Six months after training, nurses ventilated at least as efficiently with the SB, compared with the STBVM. This illustrates the ability of the SB to compensate for the deterioration over time in skill. On the other hand, training with a STBVM should focus primarily on prolonging the inspiratory time, and therefore the peak pressure, whilst maintaining an adequate Vt.

Improved basic life support performance by ward nurses using the CAREvent Public Access Resuscitator (PAR) in a simulated setting.

INTRODUCTION: The CAREvent Public Access Resuscitator (PAR, O-Two Medical Technologies, Ontario, Canada) is a new oxygen-driven device alternating two ventilations with 15 prompts for chest compressions. The PAR is designed for use with a standard resuscitation face mask and is equipped with mask leakage and obstruction alarms. The purpose of this study was to assess the quality of basic life support (BLS) by hospital nurses and to evaluate if BLS with the PAR is better than BLS using the mouth-to-mask technique. METHODS: The study group consisted of 352 nurses from Ghent University Hospital working outside the critical care and emergency departments. BLS skills were measured using a Laerdal Skillreporter manikin (Laerdal, Norway) connected to a Laerdal PC Skillreporting system. To assess base line skills, 200 nurses were tested without previous notice in single rescuer BLS using a pocket mask (PM, Laerdal, Norway) or a bag-valve mask device (Laerdal, Norway) over a period of 2 min. A separate consecutive sample of 152 nurses was randomised to the PM or PAR groups after a standard BLS refresher course. The PAR group received a short period of training in PAR use. Immediately after training, both groups performed the 2 min single rescuer BLS test. RESULTS: Unprepared nurses achieved only 26 compressions and 3 ventilations/min. Immediately after training, nurses using the PAR delivered 54 compressions/min as opposed to 35 for the PM group (p<0.0001). PAR users ventilated six times/min compared to five times for PM users (p<0.0001). CONCLUSION: Immediately after training, the use of the PAR improved BLS performance by ward nurses significantly, bringing the number of ventilations and compressions per minute close to the theoretical maximum achievable within the current guidelines. Retention tests after 6 and 12 months will show if the effect is sustained.

A study comparing the usability of fully automatic versus semi-automatic defibrillation by untrained nursing students.

INTRODUCTION: Current international guidelines prefer the use of semi-automatic external defibrillators (SAEDs) over fully automatic external defibrillators (FAEDs). However, there is a lack of evidence supporting this recommendation. We conducted a study of usability with nursing students comparing the FAED version against the SAED version of the Lifepak CR Plus AED (Medtronic, Redmond, USA). We hypothesized that FAED use would limit the number of operator-device interactions, thereby increasing compliance by the rescuer, safety and speed. METHODS: Sixty-two untrained first year nursing students were randomized to use the FAED or the SAED in a simulated cardiac arrest scenario. During analysis and delivery of three shocks, the AED guided the user with six voice prompts per shock (18 voice prompts per student). Their performance with regard to efficacy and safety was assessed using video recording. RESULTS: All rescuers except for two were able to attach electrodes and deliver a series of three shocks. During rhythm analysis by the device, FAED users made 30/372 (8%) errors against 62/360 (17%) errors for SAED users (P < 0.001). During shock delivery, FAED users made 0/186 errors against 12/180 (7%) for SAED users (P < 0.001). FAED use eliminated long time intervals between the first to the third shock (range 47-49s for FAED versus 41-90s for SAED). CONCLUSION: Despite a lack of BLS skills and AED training, the majority of students demonstrated safe and effective use of the AED. The use of the FAED version of the CR Plus resulted in increased compliance with the protocol and reduced variability in time to deliver three shocks. Further research is needed to confirm these findings in other groups of first responders.

Inaccurate treatment decisions of automated external defibrillators used by emergency medical services personnel: incidence, cause and impact on outcome.

BACKGROUND: The rhythm analysis algorithm (RAA) of automated external defibrillators (AEDs) may be deceived by many factors. In this observational study we assessed RAA accuracy in prehospital interventions. For every rhythm analysis judged to be inaccurate, we looked for causal factors and estimated the impact on outcome. METHODS: In 135 consecutive patients, two physicians reviewed 837 rhythm analyses independently. When they disagreed, a third physician made the final decision. RESULTS: Among 148 shockable episodes, 23 (16%) were not recognized by the RAA due to external artifacts (n=7), fine ventricular fibrillation (VF; n=7), RAA error without external artifacts (n=4) or a combination of factors (n=5). In six cases the omitted/delayed shock was judged to be of clinical relevance: survival with some neurological deficit (n=4), death without regaining consciousness (n=1) and no restoration of spontaneous circulation (n=1). In 689 non-shockable episodes, the RAA decided "shockable" 25 times (4%). This wrongful decision was due to external artifacts (n=9), a concurrent shock of an internal cardioverter defibrillator (n=1), RAA error without external artifacts (n=13) or a combination of factors (n=2). Fifteen spurious shocks were delivered. As these non-shockable rhythms did not deteriorate after the shock, we assumed that no significant harm was done. CONCLUSIONS: Up to 16% of shockable rhythms were not detected and 4% of non-shockable rhythms were interpreted as shockable. Therefore, all AED interventions should be reviewed. Feedback to caregivers may avoid future deleterious interactions with the AED, whereas AED manufacturers may use this information to improve RAA accuracy. This approach may improve the outcome of some VF patients.

Equivalence of the standard monophasic waveform shocks delivered by automated external defibrillators?

OBJECTIVE: To study whether two different types of monophasic waveform shocks (i.e. monophasic damped sinusoidal [MDS] and monophasic truncated exponential [MTE] waveform shocks) are of equivalent efficacy. METHODS: Retrospective review of defibrillation efficacy and outcome in ventricular fibrillation/ventricular tachycardia (VF/VT) patients treated in the same EMS system with AEDs delivering either MDS waveform shocks (n=40) or MTE waveform shocks (n=40). RESULTS: Defibrillation efficacy of the first shock was 82.5% in the MDS group and 70% in the MTE group (P=0.19). Termination of VF by at least one of the first three shocks was found in 95 and 85% of the patients treated with MDS and MTE waveform shocks, respectively (P=0.22). Restoration of spontaneous circulation occurred in 75% of the MDS group and 30% of the MTE group (P=0.0001). Hospital admission rates were 52.5% in the MDS group and 17.5% in the MTE group (P=0.001). Hospital discharge rates were 17.5% in the MDS group and 7.5% in the MTE group (P=0.18). CONCLUSIONS: Our data suggest disparity in efficacy between MDS waveform shocks and MTE waveform shocks. Furthermore, our findings should be taken into consideration when the issue of the control group(s) in future clinical trials on new waveforms is discussed.

Learning effect of a novel interactive basic life support CD: the JUST system.

INTRODUCTION: Electronic interactive learning environments can enhance the learning experience and may prove beneficial in basic life support (BLS) training. As part of the European Union funded project "JUST-in-time health emergency interventions-training of non-professionals by virtual reality and advanced IT tools", an innovative interactive CD-ROM on BLS and other emergency medicine topics was developed. We hypothesised that individuals without previous BLS training could learn CPR techniques from this CD. METHODS: Sixty-two students were randomised into a group studying the JUST CD in a computer class room for up to 60 min, and a control group who did not receive any training (serving as a reference). CD users also completed a satisfaction questionnaire immediately after studying the CD. The BLS skills of both groups were assessed in a mock BLS scenario on a training manikin. BLS performance was video recorded and analysed. RESULTS: After studying the CD for a mean period of 42 min, users of the CD had better assessment skills and were more likely to show a positive helping attitude, but chest compression and breathing techniques were ineffective. Most users rated the CD as very good and a positive learning tool. CONCLUSION: Individuals without prior BLS training showed improved behaviour and assessment skills after exposure to the CD, but motor skill acquisition requires alternative learning strategies.

How do Belgian mobile intensive care units deal with cardiovascular emergencies?

OBJECTIVES: To assess the availability and use of diagnostic tools, therapeutic equipment and drugs for the prehospital treatment of acute coronary syndromes, cardiopulmonary arrest and other cardiovascular emergencies in Belgian physician-staffed and hospital-based mobile intensive care units. METHODS: In April 2001, a questionnaire was sent to all Belgian mobile intensive care unit centres. RESULTS: The response rate was 90%. There was a 100% availability of many drugs and therapeutic equipment, with a well-established role in the care of cardiovascular emergencies: defibrillators, nitrates, epinephrine, atropine and diuretics. Important emergency drugs and tools were not ubiquitously available: external pacemakers (90%), aspirin (90%), bicarbonate (99%), amiodarone (87%), and intravenous beta-blockers (75%). Twelve-lead electrocardiogram recorders and thrombolytics had a rather low availability (46 and 20%, respectively) and were rarely used. There was a high availability of some drugs with limited data to support their use: oral calcium antagonists (61%), bretylium (65%) and isoproterenol (92%). CONCLUSIONS: In Belgian mobile intensive care units the availability and use of technical and diagnostic equipment and cardiac drugs varied to an important extent. A local multidisciplinary evaluation may improve prehospital cardiovascular care by implementing current guidelines.

How to modify the risk-taking behaviour of emergency medical services drivers?

High speed and an aggressive style of driving are major risk factors for serious traffic accidents. Consequently, frontline emergency medical services vehicles have an increased collision risk. We report on two studies designed to modify the risk-taking behaviour of emergency medical services drivers. In the first study, we compared the travel intervals for a second tier unit using two different types of vehicles. We found that the replacement of a sports estate by an ambulance, which can be considered more or less as a change from a speedy and aggressive style of driving to a cautious style of driving with respect for the speed limits, resulted in an increase of the travel interval of only 10-20%. In the second study we found that the installation of a 'black box' in an emergency medical services vehicle, combined with well-defined guidelines for the drivers and a close monitoring system, provides fair but still not optimal results with regard to maximum speed and the occurrence of harsh braking events. Despite some limitations in the study designs, we conclude that for second tier units only a small amount of time is gained by high speed and an aggressive style of driving. Furthermore, we are convinced that a 'black box' is a good tool to modify the risk-taking behaviour of emergency medical services drivers.

Medical problems related to recreational drug use at nocturnal dance parties.

During 'I love techno' (edition 2001), an indoor rave party attended by 37 000 people, data about medical problems (especially drug-related problems) were collected. To place these data in a wider perspective, a similar registration was done during 'De Nacht', a traditional New Year's Eve dance party held at the same location and attended by 12 000 people. Furthermore, a prospective study on the time course of the level of consciousness (Glasgow Coma Score) and blood concentrations of illicit drugs, especially gamma-hydroxybutyrate was set up. The results revealed that during 'I love techno' the incidence of medical problems was high (66.5/10 000 attendees), but not higher than during 'De Nacht' (70.0/10 000 attendees). At 'I love techno', however, mainly illicit drugs were used, more frequently leading to severe drug-related medical problems. The observations in patients with a drug-related medical problem who had taken gamma-hydroxybutyrate showed that for a given level of consciousness the gamma-hydroxybutyrate concentrations may show important differences, that the transition from coma (Glasgow Coma Score < or =7) to full recovery (Glasgow Coma Score 15) takes only 30-60 min (and only a small decrease in gamma-hydroxybutyrate concentrations), and that the time it takes before a comatose patient reaches the above-mentioned 'transition area' may be a few hours.

Quality of resuscitation by first responders using the 'public access resuscitator': a randomized manikin study.

AIM: The CAREvent Public Access Resuscitator (PAR) is an electronic, oxygen-driven cardiopulmonary resuscitation (CPR) device allowing volume-controlled ventilation with a face mask and guiding the rescuer through the resuscitation with voice prompts and visual indications. We hypothesized that 1 year after initial training, the efficacy of ventilation skills (primary outcome) and compression skills (secondary outcome) by first responders using the PAR would be superior compared with CPR with only a face mask. METHODS: Seventy-one first responders were randomized to a group using the PAR (n=35) and a control group using only a face mask (n=36). CPR skills were assessed immediately after training and after 3, 7 and 12 months using a Skill Reporter manikin. Differences between groups over time and the interaction between time and groups were assessed using repeated measures models. Results are reported as mean values and number of participants with good ventilation or compression skills. RESULTS: Twelve months after training, there were more PAR users with adequate tidal volume than face mask users. Other ventilations skills did not differ between groups. There were more PAR users with an adequate number of compressions and with good hand position. Skill decay over 12 months did not differ between groups, except for hand position, where no decline was observed in the PAR group. CONCLUSION: Compared with the face mask, PAR improved tidal volume, compressions per minute and hand position in a manikin setting.

Acquiring basic life support skills in a self-learning station: video alone is not enough.

OBJECTIVES: To develop a self-learning station combining a video with computer exercises to learn cardiopulmonary resuscitation (CPR) to novices, and to assess the efficacy of these two components on CPR acquisition. METHODS: One hundred and twenty-five pharmacy students were trained using learning-while-watching video instructions followed by exercises with voice feedback. The proportion of students with adequate CPR skills (≥ 70% compressions with depth ≥ 50 mm, ≥ 70% compressions with complete release <5 mm, a compression rate between 100 and 120/min, ≥ 70% ventilations with a volume between 400 and 1000 ml) was measured at baseline, after video training and after subsequent voice-feedback training. RESULTS: Complete datasets were obtained for 104 students. After video training, the 70% cut-off for compression depth was achieved in 29/104 students, for complete release in 75/104, for ventilation volume in 44/104. Mean compression rate 100-120/min was adequate in 77/104 students. Compared with baseline results, only rate (29/104 vs. 77/104) and ventilation volume (6/104 vs. 44/104) improved. After subsequent training with voice feedback the proportions were: compression depth 88/104, compression rate 77/104, ventilation volume 74/104 and complete release 90/104. Compared with the skill level after video training only compression rate did not further improve. A score combining the three compression skills resulted in the following success rates: 6/104 (baseline), 15/104 (after the video), 59/104 (after voice feedback). CONCLUSION: Although in a self-learning station video training can introduce CPR skills to novices, additional voice-feedback exercises were needed to achieve acceptable CPR quality.

Excessive chest compression rate is associated with insufficient compression depth in prehospital cardiac arrest.

UNLABELLED: BACKGROUND AND GOAL OF STUDY: The relationship between chest compression rate and compression depth is unknown. In order to characterise this relationship, we performed an observational study in prehospital cardiac arrest patients. We hypothesised that faster compressions are associated with decreased depth. MATERIALS AND METHODS: In patients undergoing prehospital cardiopulmonary resuscitation by health care professionals, chest compression rate and depth were recorded using an accelerometer (E-series monitor-defibrillator, Zoll, U.S.A.). Compression depth was compared for rates <80/min, 80-120/min and >120/min. A difference in compression depth ≥0.5 cm was considered clinically significant. Mixed models with repeated measurements of chest compression depth and rate (level 1) nested within patients (level 2) were used with compression rate as a continuous and as a categorical predictor of depth. Results are reported as means and standard error (SE). RESULTS AND DISCUSSION: One hundred and thirty-three consecutive patients were analysed (213,409 compressions). Of all compressions 2% were <80/min, 62% between 80 and 120/min and 36% >120/min, 36% were <4 cm deep, 45% between 4 and 5 cm, 19% >5 cm. In 77 out of 133 (58%) patients a statistically significant lower depth was observed for rates >120/min compared to rates 80-120/min, in 40 out of 133 (30%) this difference was also clinically significant. The mixed models predicted that the deepest compression (4.5 cm) occurred at a rate of 86/min, with progressively lower compression depths at higher rates. Rates >145/min would result in a depth <4 cm. Predicted compression depth for rates 80-120/min was on average 4.5 cm (SE 0.06) compared to 4.1 cm (SE 0.06) for compressions >120/min (mean difference 0.4 cm, P<0.001). Age and sex of the patient had no additional effect on depth. CONCLUSIONS: This study showed an association between higher compression rates and lower compression depths. Avoiding excessive compression rates may lead to more compressions of sufficient depth.

Efficacy of a self-learning station for basic life support refresher training in a hospital: a randomized controlled trial.

BACKGROUND: Adult basic life support refresher training using voice feedback manikins has been shown to be feasible, but the superiority of this strategy over instructor-led (IL) refresher training for nurses in a hospital has not been studied in randomized trials. OBJECTIVES: To study if adult basic life support refresher training for nurses in a self-learning (SL) station using a voice feedback manikin is more effective than IL training. METHODS: A Resusci Anne Skills Station (Laerdal, Norway) was installed in a small room. A total of 235 nurses were randomized to SL or IL training. After 1 month and after 7 months, the proportions of nurses achieving a mean compression depth of 38-51 mm, a mean compression rate of 80-120/min, incomplete release of at least 5 mm and a mean ventilation volume of 400-1000 ml were compared between the SL and IL groups. RESULTS: After 1 month, the proportion of nurses with any incomplete release of at least 5 mm was significantly lower in the SL group (23 of 54 nurses, 43%) compared with the IL group (33 of 47 nurses, 70%) (P=0.005). After 7 months, a lower proportion of nurses achieved a depth of 38-51 mm in the SL group (13 of 45 nurses, 29%) compared with the IL group (25 of 45 nurses, 56%) (P=0.01). For the other outcome parameters, no differences between SL and IL training could be demonstrated. CONCLUSIONS: This randomized trial in a real-life setting showed that more nurses achieved adequate compression depth, 7 months after IL refresher training compared with training in a SL station. Further research is needed to improve the efficacy of this SL training strategy.

Combining video instruction followed by voice feedback in a self-learning station for acquisition of Basic Life Support skills: a randomised non-inferiority trial.

INTRODUCTION: Current computerised self-learning (SL) stations for Basic Life Support (BLS) are an alternative to instructor-led (IL) refresher training but are not intended for initial skill acquisition. We developed a SL station for initial skill acquisition and evaluated its efficacy. METHODS: In a non-inferiority trial, 120 pharmacy students were randomised to IL small group training or individual training in a SL station. In the IL group, instructors demonstrated the skills and provided feedback. In the SL group a shortened Mini Anne™ video, to acquire the skills, was followed by Resusci Anne Skills Station™ software (both Laerdal, Norway) with voice feedback for further refinement. Testing was performed individually, respecting a seven week interval after training for every student. RESULTS: One hundred and seventeen participants were assessed (three drop-outs). The proportion of students achieving a mean compression depth 40-50mm was 24/56 (43%) IL vs. 31/61 (51%) SL and 39/56 (70%) IL vs. 48/61 (79%) SL for a mean compression depth ≥ 40 mm. Compression rate 80-120/min was achieved in 49/56 (88%) IL vs. 57/61 (93%) SL and any incomplete release (≥ 5 mm) was observed in 31/56 (55%) IL and 35/61 (57%) SL. Adequate mean ventilation volume (400-1000 ml) was achieved in 29/56 (52%) IL vs. 36/61 (59%) SL. Non-inferiority was confirmed for depth and although inconclusive, other areas came close to demonstrate it. CONCLUSIONS: Compression skills acquired in a SL station combining video-instruction with training using voice feedback were not inferior to IL training.