Effects and limitations of an AED with audiovisual feedback for cardiopulmonary resuscitation: a randomized manikin study

Purpose

Correctly performed basic life support (BLS) and early defibrillation are the most effective measures to treat sudden cardiac arrest. Audiovisual feedback improves BLS. Automated external defibrillators (AED) with feedback technology may play an important role in improving CPR quality. The aim of this simulation study was to investigate if an AED with audiovisual feedback improves CPR parameters during standard BLS performed by trained laypersons.

Methods

With ethics committee approval and informed consent, 68 teams (2 flight attendants each) performed 12 min of standard CPR with the AED's audiovisual feedback mechanism enabled or disabled. We recorded CPR quality parameters during resuscitation on a manikin in this open, prospective, randomized controlled trial. Between the feedback and control-group we measured differences in compression depth and rate as main outcome parameters and effective compressions, correct hand position, and incomplete decompression as secondary outcome parameters. An effective compression was defined as a compression with correct depth, hand position, and decompression.

Results

The feedback-group delivered compression rates closest to the recommended guidelines (101 ± 9 vs. 109 ± 15/min, p = 0.009), more effective compressions (20 ± 18 vs. 5 ± 6%, p < 0.001), more compressions with correct hand position (96 ± 13 vs. 88 ± 16%, p < 0.001), and less leaning (21 ± 31 vs. 77 ± 33%, p < 0.001). However, only the control-group adhered to the recommended compression depth (44 ± 7 mm vs. 39 ± 6, p = 0.003).

Conclusion

Use of an AED's audiovisual feedback system improved some CPR-quality parameters, thus confirming findings of earlier studies with the notable exception of decreased compression depth, which is a key parameter that might be linked to reduced cardiac output.     

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.     

Changing EMS dispatcher CPR instructions to 400 compressions before mouth-to-mouth improved bystander CPR rates

Background

To examine the impact of changing dispatcher CPR instructions (400 compressions: 2 breaths, followed by 100:2 ratio) on rates of bystander CPR and survival in adults with presumed cardiac out-of-hospital arrest (OHCA) in Melbourne, Australia.

Methods

The Victorian Ambulance Cardiac Arrest Registry (VACAR) was searched for OHCA where Emergency Medical Services (EMS) attempted CPR between August 2006 and August 2009. OHCA included were: (1) patients aged ≥18 years old; (2) presumed cardiac etiology; and (3) not witnessed by EMS.

Results

For the pre- and post-study periods, 1021 and 2101 OHCAs met inclusion criteria, respectively. Rates of bystander CPR increased overall (45-55%, p < 0.001) and by initial rhythm (shockable 55-70%, p < 0.001 and non-shockable 40-46%, p = 0.01). In VF/VT OHCA, there were improvements in the number of patients arriving at hospital with a return of spontaneous circulation (ROSC) (48-56%, p = 0.02) and in survival to hospital discharge (21-29%, p = 0.002), with improved outcomes restricted to patients receiving bystander CPR. After adjusting for factors associated with survival, the period of time following the change in CPR instructions was a significant predictor of survival to hospital discharge in VF/VT patients (OR 1.57, 95% CI: 1.15-2.20, p = 0.005).

Conclusion

Following changes to dispatcher CPR instructions, significant increases were seen in rates of bystander CPR and improvements were seen in survival in VF/VT patients who received bystander CPR, after adjusting for factors associated with survival.     

Aspects on the increase in bystander CPR in Sweden and its association with outcome

Aim

To describe changes in the proportion of bystanders performing cardiopulmonary resuscitation (CPR) in out of hospital cardiac arrest (OHCA) in Sweden and to study the impact of bystander CPR on ventricular fibrillation and on survival during various times.

Patients and methods

All patients who suffered from OHCA in Sweden in whom CPR was attempted and who were included in the Swedish cardiac arrest register (SCAR) between 1992 and 2005. Crew witnessed cases were excluded.

Results

In all 34,125 patients were included in the survey. Among witnessed OHCA the proportion of patients receiving bystander CPR increased from 40% in 1992 to 55% in 2005 (p < 0.0001). In non-witnessed OHCA the corresponding proportion increased from 22% to 44% (p < 0.0001). There was a significant increase in bystander CPR regardless of age, sex and place. The increase was only found when CPR was performed by lay persons (21% in 1992 to 40% in 2005; p < 0.0001). Bystander CPR was associated with an increased proportion of patients found in a shockable rhythm and a lower number of shocks to receive return of spontaneous circulation. Bystander CPR was associated with a similar increase in survival early and late in the evaluation.

Conclusion

There was a marked increase in bystander CPR in OHCA, when performed by lay persons, during the last 14 years in Sweden. Bystander CPR was associated with positive effects both on ventricular fibrillation and survival.     

Bystander CPR in south east Scotland increases over 16 years

Background

Out-of-hospital cardiac arrest (OHCA) remains a leading cause of mortality and serious neurological disability across Europe. Without immediate bystander cardiopulmonary resuscitation (CPR), chances of survival are minimal. Despite community initiatives to increase the number of trained CPR providers, the effectiveness of these measures remains unknown and the proportion of OHCA patients receiving bystander CPR in the United Kingdom yet to be established. We sought to identify the change in the rate of bystander CPR in south east Scotland over a 16-year period.

Methods

Retrospective cohort study of all adult non-traumatic OHCA in south east Scotland from 1 January 1992 to 31 December 2007 using the Heartstart Scotland database.

Results

7928 OHCA were included. The proportion of patients receiving bystander CPR increased from 34% in 1992 to 52% in 2007 (p for trend <0.0001). The rate of CPR from bystanders, spouses and from relatives increased significantly over the study period. Patients arresting at home received significantly less bystander CPR than those arresting away from home (39% vs 52%, p < 0.0001) regardless of age or sex.

Conclusion

There has been a significant increase in bystander CPR in south east Scotland during the 16-year period. Bystander CPR is associated with an increased rate of survival and targeted CPR training for relatives of patients at risk of sudden cardiac death may be beneficial.     

Influence of pre-course assessment using an emotionally activating stimulus with feedback: a pilot study in teaching Basic Life Support

Background

Cardiopulmonary resuscitation (CPR) mastery continues to challenge medical professionals. The purpose of this study was to determine if an emotional stimulus in combination with peer or expert feedback during pre-course assessment effects future performance in a single rescuer simulated cardiac arrest.

Methods

First-year medical students (n = 218) without previous medical knowledge were randomly assigned to one of the study groups and asked to take part in a pre-course assessment: Group 1: after applying an emotionally activating stimulus an expert (instructor) gave feedback on CPR performance (Ex). Group 2: after applying the same stimulus feedback was provided by a peer from the same group (Pe); Group 3: standard without feedback (S). Following pre-course assessment, all subjects received a standardized BLS-course, were tested after 1 week and 6 months later using single-rescuer-scenario, and were surveyed using standardized questionnaires (6-point-likert-scales: 1 = completely agree, 6 = completely disagree).

Results

Participants exposed to stimulus demonstrated superior performance concerning compression depth after 6 months independent of feedback-method (Ex: 65.85% [p = 0.0003]; Pe: 57.50% [p = 0.0076] vs. 21.43%). The expert- more than the peer-group was emotionally more activated in initial testing, Ex: 3.26 ± 1.35 [p ≤ 0.0001]; Pe: 3.73 ± 1.53 [p = 0.0319]; S: 4.25 ± 1.37) and more inspired to think about CPR (Ex: 2.03 ± 1.37 [p = 0.0119]; Pe: 2.07 ± 1.14 [p = 0.0204]; S: 2.60 ± 1.55). After 6 months this activation effect was still detectable in the expert-group (p = 0.0114).

Conclusions

The emotional stimulus approach to BLS-training seems to impact the ability to provide adequate compression depth up to 6 months after training. Furthermore, pre-course assessment helped to keep the participants involved beyond initial training.     

Assessment of outcomes and differences between in- and out-of-hospital cardiac arrest patients treated with cardiopulmonary resuscitation using extracorporeal life support

Aim

Cardiopulmonary resuscitation (CPR) using extracorporeal life support (ECLS) for in-hospital cardiac arrest (IHCA) patients has been assigned a low-grade recommendation in current resuscitation guidelines. This study compared the outcomes of IHCA and out-of-hospital cardiac arrest (OHCA) patients treated with ECLS.

Methods

A total of 77 patients were treated with ECLS. Baselines characteristics and outcomes were compared for 38 IHCA and 39 OCHA patients.

Results

The time interval between collapse and starting ECLS was significantly shorter after IHCA than after OHCA (25 (21-43) min versus 59 (45-65) min, p < 0.001). The weaning rate from ECLS (61% versus 36%, p = 0.03) and 30-day survival (34% versus 13%, p = 0.03) were higher for IHCA compared with OHCA patients. IHCA patients had a higher rate of favourable neurological outcome compared to OHCA patients, but the difference was not statistically significant (26% versus 10%, p = 0.07). Kaplan-Meier analysis showed improved 30-day and 1-year survival for IHCA patients treated with ECLS compared to OHCA patients who had ECLS. However, multivariate stepwise Cox regression model analysis indicated no difference in 30-day (odds ratio 0.94 (95% confidence interval 0.68-1.27), p = 0.67) and 1-year survival (0.99 (0.73-1.33), p = 0.95).

Conclusion

CPR with ECLS led to more favourable patient outcomes after IHCA compared with OHCA in our patient group. The difference in outcomes for ECLS after IHCA and OHCA disappeared after adjusting for patient factors and the time delay in starting ECLS.     

Resuscitation feedback and targeted education improves quality of pre-hospital resuscitation in Scotland

Background

Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality and serious neurological morbidity in Europe. Recent studies have demonstrated the adverse physiological consequences of poor resuscitation technique and have shown that quality of cardiopulmonary resuscitation (CPR) is a critical determinant of outcome from OHCA. Telemetry of the defibrillator transthoracic impedance (TTI) trace can objectively measure quality of pre-hospital resuscitation. This study aims to analyse the impact of targeted resuscitation feedback and training on quality of pre-hospital resuscitation.

Methods

Prospective, single centre, cohort study over 13 months (1st December 2009-31st December 2010). Baseline pre-hospital resuscitation data was gathered over a 3-month period. Modems (n = 40) were fitted to defibrillators on ambulance vehicles. Following a resuscitation attempt, the event was sent via telemetry and the TTI trace analysed. Outcome measures were time spent performing chest compressions, compression rate, the interval required to deliver a defibrillator shock and use of automatic or manual cardiac rhythm analysis. Targeted resuscitation classes were introduced and all ambulance crews received feedback following a resuscitation attempt. Pre-hospital resuscitation quality pre and post intervention were compared.

Results

111 resuscitation traces were analysed. Mean hands-on-chest time improved significantly following feedback and targeted resuscitation training (73.0% vs 79.3%, p = 0.007). There was no significant change in compression rate during the study period. There was a significant reduction in median time-to-shock interval from 20.25 s (IQR 15.50-25.50 s) to 13.45 s (IQR 2.25-22.00 s) (p = 0.006). Automatic rhythm recognition fell from 50% to 28.6% (p = 0.03) following intervention.

Conclusion

Telemetry and analysis of the TTI trace following OHCA allows objective evaluation of the quality of pre-hospital resuscitation. Targeted resuscitation training and ambulance feedback improves the quality of pre-hospital resuscitation. Further studies are required to establish possible survival benefit from this technique.     

Chest compression-only cardiopulmonary resuscitation performed by lay rescuers for adult out-of-hospital cardiac arrest due to non-cardiac aetiologies

Objective

Bystander CPR improves survival in patients with out-of-hospital cardiac arrest (OHCA). For adult sudden collapse, bystander chest compression-only CPR (COCPR) is recommended in some circumstances by the American Heart Association and European Resuscitation Council. However, adults who arrest from non-cardiac causes may also receive COCPR. Because rescue breathing may be more important for individuals suffering OHCA secondary to non-cardiac causes, COCPR is not recommended for these cases. We evaluated the relationship of lay rescuer COCPR and survival after OHCA from non-cardiac causes.

Methods

Analysis of a statewide Utstein-style registry of adult OHCA, during a large scale campaign endorsing COCPR for OHCA from presumed cardiac cause. The relationship between lay rescuer CPR (both conventional CPR and COCPR) and survival to hospital discharge was evaluated.

Results

Presumed non-cardiac aetiologies of OHCA accounted for 15% of all cases, and lay rescuer CPR was provided in 29% of these cases. Survival to hospital discharge occurred in 3.8% after conventional CPR, 2.7% after COCPR, and 4.0% after no CPR (p = 0.85). The proportion of patients receiving COCPR was much lower in the cohort of OHCA from respiratory causes (8.3%) than for those with presumed cardiac OHCA (18.0%; p < 0.001).

Conclusions

In the setting of a campaign endorsing lay rescuer COCPR for cardiac OHCA, bystanders were less likely to perform COCPR on OHCA victims who might benefit from rescue breathing.     

Blood pressure during resuscitation in man—The effect of pause during rhythm analysis revisited

Aims

This study reports invasive arterial pressures before and after the rhythm analysing pauses during CPR and evaluates the possible association of the quality of CPR and the length of the pause with blood pressure around the pause.

Materials and methods

Five patients who experienced out-of hospital or in-hospital cardiac arrest were included in the study. Using a monitor/defibrillator with sensing capabilities, the parameters of CPR quality including chest compression depth, rate, force and the duration of interruption were recorded and compared to blood pressure.

Results

Altogether 42 pauses were observed in five patients with a duration of 9 ± 5 s (mean ± SD). The values for systolic (SAP), mean (MAP) and diastolic arterial pressures (DAP) were 107 ± 30, 44 ± 12 and 14 ± 12 mmHg before the pause and 119 ± 34, 49 ± 13 and 14 ± 14 mmHg after the pause, respectively. There was a statistically significant increase in both SAP (12.1 ± 28.2 mmHg; p = 0.021) and MAP (4.2 ± 8.7 mmHg (p = 0.008) and the duration of the pause was identified as an independent factor for that in a linear mixed model. The pause duration up to ten seconds maintained the pressure achieved if the compression depth was immediately according to the guidelines (p = 0.046).

Conclusions

Contrary to the previous animal studies, this preliminary study in humans demonstrates that blood pressures achieved before the rhythm analysis pause do not necessarily decrease after the pause but may even increase if the duration of the pause is under ten seconds and the quality of CPR is good both before and after the pause.     

Out-of-hospital cardiac arrests in young adults in Melbourne, Australia

Background

Characteristics and outcomes of out-of-hospital cardiac arrest (OHCA) in young adults are not well described in Australia.

Methods

A 10-year retrospective case review of all OHCA in young adults (aged 16-39) and not witnessed by EMS, was performed using data from the Victorian Ambulance Cardiac Arrest Registry (VACAR).

Results

Between 2000 and 2009 there were 30,006 adult cardiac arrests of which 3912 (13%) were in this age group. The median (IQR) age was 30 (25-35) years for both sexes with a 3:1 male to female ratio. Overdose was the most common precipitant (33.5%) followed by presumed cardiac (20%). Bystander CPR occurred in 21.2%, EMS median response time was 7 min and resuscitation was attempted in 36% of OHCAs. The presenting rhythm was asystole in 84.6%, PEA in 8.8% and VF/VT in 6.6%. Survival to hospital discharge, for all cause OHCA where resuscitation was attempted, was similar for young adult and older adults (8.8% vs 8.4%, p = 0.2). However, for presumed cardiac aetiology OHCA, young adults had a greater proportion of survivors (14.8% vs 9.0%, p < 0.001). Cardiac arrest with shockable rhythm (VF/pulseless VT) had a survival rate of 31.2% for young adults compared to 18.5% for older adults (p < 0.001).

Conclusion

Survival to hospital discharge rates from OHCA due to a ‘presumed cardiac’ precipitant in young adults is much better than older adults, however, all cause OHCA survival is similar. Multi agency novel upstream preventive strategies aimed at tackling drug overdose may reduce this aetiology of OHCA and save lives.     

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.     

Good outcome in every fourth resuscitation attempt is achievable--an Utstein template report from the Stavanger region

Aim of the study

Out-of-hospital cardiac arrest (OHCA) is a major cause of death in the western world. We wanted to study changes in survival over time and factors linked to this in a region which have already reported high survival rates.

Methods

We used a prospectively collected Utstein template database to identify all resuscitation attempts in adult patients with OHCA of presumed cardiac origin. We included 846 resuscitation attempts and compared survival to discharge with good outcome in two time periods (2001-2005 vs. 2006-2008).

Results

We found no significant differences between the two time periods for mean age (71 and 70 years (p = 0.309)), sex distribution (males 70% and 71% (p = 0.708)), location of the OHCA (home 64% and 63% (p = 0.732)), proportion of shockable rhythms (44% and 47% (p = 0.261)) and rate of return of spontaneous circulation (38% and 43% (p = 0.136)), respectively. Bystander cardiopulmonary resuscitation (CPR), however, increased significantly from 60% to 73% (p < 0.0001), as did the overall rate of survival to discharge from 18% to 25% (p = 0.018). In patients with a shockable first rhythm, rate of survival to discharge increased significantly from 37% to 48% (p = 0.036). In witnessed arrest with shockable rhythm survival to discharge increased from 37% to 52% (p = 0.0105).

Conclusion

Overall, good outcome is now achievable in every fourth resuscitation attempt and in every second resuscitation attempt when patients have a shockable rhythm. The reason for the better outcomes is most likely multi-factorial and linked to improvements in the local chain of survival.     

Quality of chest compressions during continuous CPR; comparison between chest compression-only CPR and conventional CPR

Objectives

This study aimed to compare the time-dependent deterioration of chest compressions between chest compression-only cardiopulmonary resuscitation (CPR) and conventional CPR.

Methods

This study involved 106 and 107 participants randomly assigned to chest compression-only CPR training and conventional CPR training, respectively. Immediately after training, participants were asked to perform CPR for 2 min and the quality of their CPR skills were evaluated. The number of chest compressions in total and those with appropriate depth were counted every 20-s CPR period from the start of CPR. The primary outcome was the CPR quality index calculated as the proportion of chest compressions with appropriate depth among total chest compressions.

Results

The total number of chest compressions remained stable over time both in the chest compression-only and the conventional CPR groups. The CPR quality index, however, decreased from 86.6 ± 25.0 to 58.2 ± 36.9 in the chest compression-only CPR group from 0-20 s through 61-80 s. The reduction was greater than in the conventional CPR group (85.9 ± 25.5 to 74.3 ± 34.0). The difference in the CPR quality index reached statistical significance (p = 0.003) at 61-80 s period.

Conclusions

Chest compressions with appropriate depth decreased more rapidly during chest compression-only CPR than conventional CPR. We recommend that CPR providers change their roles every 1 min to maintain the quality of chest compressions during chest compression-only CPR. (UMIN-CTR C0000000321)     

Are trained individuals more likely to perform bystander CPR? An observational study

Background

This study aimed to evaluate the association of cardiopulmonary resuscitation (CPR) training with bystander resuscitation performance and patient outcomes after out-of-hospital cardiac arrest (OHCA).

Methods

This was a prospective, population-based cohort study of all persons aged 18 years or older with OHCA of presumed intrinsic origin and their rescuers from January through December 2008 in Takatsuki, Osaka prefecture, Japan. Data on resuscitation of OHCA patients were obtained by emergency medical service (EMS) personnel in charge based on the Utstein style. Rescuers’ characteristics including experience of CPR training were obtained by EMS personnel interview on the scene. The primary outcome was the attempt of bystander CPR.

Results

Data were collected for 120 cases out of 170 OHCAs of intrinsic origin. Among the available cases, 60 (50.0%) had previous CPR training (trained rescuer group). The proportion of bystander CPR was significantly higher in the trained rescuer group than in the untrained rescuer group (75.0% and 43.3%; p = 0.001). Bystanders who had previous experience of CPR training were 3.40 times (95% confidence interval 1.31-8.85) more likely to perform CPR compared with those without previous CPR training. The number of patients with neurologically favorable one-month survival was too small to evaluate statistical difference between the groups (2 [3.3%] in the trained rescuer group versus 1 [1.7%] in the untrained rescuer group; p = 0.500).

Conclusions

People who had experienced CPR training had a greater tendency to perform bystander CPR than people without experience of CPR training. Further studies are needed to prove the effectiveness of CPR training on survival.     

Cardiac arrest outcomes before and after the 2005 resuscitation guidelines implementation: evidence of improvement?

Background

Previous studies have reported improvements in out-of-hospital cardiac arrest (OHCA) outcomes with the introduction of the 2005 cardiopulmonary resuscitation guidelines however they have not adjusted for underlying trends in OHCA survival. We compare outcomes before and after the 2005 guideline changes adjusting for underlying trends in OHCA survival.

Methods

The Victorian Ambulance Cardiac Arrest Registry (VACAR) was searched for adult (≥16 years) OHCA of presumed cardiac aetiology, unwitnessed by paramedics with attempted resuscitation. Outcomes for OHCA occurring between 2003 and 2005 were compared with 2007-2009. Segmented regression analysis of interrupted time series data was performed, adjusting for known predictors, to examine changes in survival to hospital and survival to hospital discharge.

Results

For the pre- and post- guideline periods there were 3115 and 3248 OHCAs, respectively. Asystole increased as presenting rhythm (33-43%, p < 0.001) as did median EMS response times (7.1-7.8 min, p < 0.001) over the two periods. VF/VT arrests decreased (40-35.5%, p = 0.001) as did bystander witnessed arrests (63-59%, p = 0.002). On univariate analysis survival to hospital discharge improved between the two periods (9.4-11.8%, p = 0.002) due to improved outcomes in VF/VT (19-28%, p < 0.001). Segmented regression analysis of interrupted time series data showed improvement in the rate of survival to get to hospital for shockable and non-shockable rhythms [OR (95% CI) = 1.54 (1.10-2.15, p = 0.01) and 1.45 (1.10-2.00, p = 0.02), respectively] following implementation of the guidelines however survival to hospital discharge did not improve [OR = 1.07 (0.70-1.62, p = 0.70) and 1.40 (0.69-2.85, p = 0.40), respectively].

Conclusions

OHCA outcomes have improved since introduction of the 2005 CPR guidelines, but multivariable segmented regression analysis adjusting for pre-existing trends in survival suggests that this improvement may not be due to implementation of the 2005 resuscitation guidelines.     

Cardiac arrest due to drowning—Changes over time and factors of importance for survival

Aim

To evaluate changes in characteristics and survival over time in out-of-hospital cardiac arrest (OHCA) due to drowning and describe factors of importance for survival.

Method

Retrospectively reported and treated drowning cases reported to the Swedish OHCA registry between 1990 and 2012, n = 529. The data were clustered into three seven-year intervals for comparisons of changes over time.

Results

There were no changes in age, gender, witnessed status, shockable rhythm or place of OHCA during the time periods. Bystander CPR increased over time, 59% in interval 1992–1998, versus 74% in interval 2006–2012 (p = 0.005). There was a decrease in delay between OHCA and calling for the Emergency Medical Service (EMS) over the years, while calling for the EMS to arrival increased in terms of time. Survival to hospital admission appears to have increased over the years (p = 0.009), whereas survival to one month did not change significantly over time. In a multivariate analysis, witnessed status, female gender, bystander CPR, place–home and EMS response time were associated with survival to hospital admission. For survival to one month, place, age, shockable rhythm and logarithmised delay from calling for an ambulance to arrival were of significance for survival.

Conclusion

In OHCA due to drowning, over a period of 20 years, bystanders have called for help at an earlier stage and administered CPR more frequently in the past few years. Survival to hospital admission has increased, while shockable rhythm and early arrival of the EMS appear to be the most important factors for survival to one month.     

Early selective trans-nasal cooling during CPR improves success of resuscitation in a porcine model of prolonged pulseless electrical activity cardiac arrest

Aim of study

In the present study, we investigated trans-nasal cooling in settings of pulseless electrical activity (PEA). We hypothesized that early trans-nasal cooling during CPR improves outcomes when cardiac arrest is associated with PEA.

Methods

Ventricular fibrillation (VF) was electrically induced in 16 domestic male pigs weighing 40 ± 3 kg. After 14 min of untreated VF, PEA was induced following delivery of one or more electrical shocks. One min after onset of PEA, CPR was started, including chest compression and ventilation. Each animal received 5 min of CPR prior to defibrillation attempt. CPR and resuscitation efforts were discontinued at 15 min unless return to spontaneous circulation was achieved. In 8 animals, selective trans-nasal cooling was begun coincident with start of CPR and 8 randomized controls were identically treated except for trans-nasal cooling. Mean aortic pressure was continuously measured together with aortic and right atrial pressure and nasal, body and right jugular vein temperatures. Coronary perfusion pressure (CPP) was computed from measured data.

Results

Six of eight animals were resuscitated after early trans-nasal cooling, while only one untreated control was resuscitated (p = 0.012). Nasal, body and jugular vein temperatures decreased after cooling. At PC (precordial compression) 5 min, the cooled group recorded a higher CPP (25 ± 5 mmHg) than the non-cooled group (15 ± 4 mmHg, p = 0.001).

Conclusion

When selective trans-nasal cooling was initiated during CPR in the animal model of prolonged cardiac arrest with PEA, CPP was higher and the likelihood of return of spontaneous circulation was improved.     

A new way to analyze resuscitation quality by reviewing automatic external defibrillator data

Aims

High quality cardiopulmonary resuscitation (CPR) plays an important role in survival of out-of-hospital cardiac arrests (OHCAs). We have developed an algorithm to automatically identify the quality of chest compressions from data retrieved from automatic external defibrillators (AEDs).

Methods

Electrocardiographic (ECG) signals retrieved from AEDs were analyzed by a newly developed algorithm to identify fluctuations in CPR. The algorithm contained three steps. First, it decomposed the AED signals into several intrinsic mode fluctuations (IMFs) by empirical mode decomposition (EMD). Second, it identified the dominant IMFs that carried the chest compression signals and weighted the IMFs to both enhance the chest compression oscillations and filter the noise. Third, it calculated the autocorrelation function (ACF) of the reconstructed signals and tested their periodicity. Using this algorithm, several CPR quality indicators were automatically calculated minute-by-minute and compared with those derived by audio and visual review of AED data by experienced physicians.

Results

A total of 77 (29 women, 48 men) OHCA patients were enrolled, and 351 one-min segments were analyzed. The results showed that the CPR quality parameters calculated from the algorithm were highly correlated with those from the manual review (all P < 0.001). The limits of agreement by Bland-Altman analysis were acceptable for chest compression number, total flow time, and no flow time, but not for CPR rate. We also demonstrated that only 41.8 ± 29.8% of time was spent in chest compressions and only 7.5 ± 16.8% was spent in adequate chest compressions.

Conclusion

Our results demonstrated that several indicators of CPR quality can be precisely and automatically determined by analyzing the ECG signals from AEDs using EMD and autocorrelograms.     

Increased survival after EMS witnessed cardiac arrest. Observations from the Resuscitation Outcomes Consortium (ROC) Epistry—Cardiac arrest

Background

Out of hospital cardiac arrest (OHCA) is common and lethal. It has been suggested that OHCA witnessed by EMS providers is a predictor of survival because advanced help is immediately available. We examined EMS witnessed OHCA from the Resuscitation Outcomes Consortium (ROC) to determine the effect of EMS witnessed vs. bystander witnessed and unwitnessed OHCA.

Methods

Data were analyzed from a prospective, population-based cohort study in 10 U.S. and Canadian ROC sites. Individuals with non-traumatic OHCA treated 04/01/06-03/31/07 by EMS providers with defibrillation or chest compressions were included. Cases were grouped into EMS-witnessed, bystander witnessed, and unwitnessed and further stratified for bystander CPR. Multiple logistic regressions evaluated the odds ratio (OR) for survival to discharge relative to the EMS-witnessed group after adjusting for age, sex, public/private location of collapse, ROC site, and initial ECG rhythm. Of 9991 OHCA, 1022 (10.2%) of EMS-witnessed, 3369 (33.7%) bystander witnessed, and 5600 (56.1%) unwitnessed.

Results

The most common initial rhythm in the EMS-witnessed group was PEA which was higher than in the bystander- and unwitnessed groups (p < 0.001). The adjusted OR (95% CI) of survival compared to the EMS-witnessed group was 0.41, (0.36, 0.46) in bystander witnessed with bystander CPR, 0.37 (0.33, 0.43) in bystander witnessed without bystander CPR, 0.17 (0.14, 0.20) in unwitnessed with bystander CPR and 0.21 (0.18, 0.24) in unwitnessed cases without bystander CPR.

Conclusions

Immediate application of prehospital care for OHCA may improve survival. Efforts should be made to educate patients to access 9-1-1 for prodromal symptoms.