The causative rhythm in out-of-hospital cardiac arrests witnessed by the emergency medical services in the Heartstart Scotland Project

What's the cardiac rhythm at the time of cardiac arrest? Disputed dogma or true fact?

It was widely accepted that malignant ventricular arrhythmias (VA) are the main direct initial cause for cardiac arrest and sudden cardiac death (SCD), but diverging data tended to demonstrate that asystole or pulseless activity were becoming the most prevalent cardiac rhythms at the time of cardiac arrest. We challenge here these conceptions and reinforce the persisting prominent role of VA in SCD.

Out-of-hospital cardiac arrest with onset witnessed by emergency medical services: Implications for improvement in overall survival

Out-of-hospital cardiac arrest (OHCA) remains a major public health problem. Even in high-income countries, survival rates have plateaued in the range of ten percent, stimulating an ongoing interest in developing novel approaches to resuscitation. Emergency Medical Services (EMS)-witnessed OHCAs constitute a subgroup of overall OHCA that occur after the arrival of EMS, leading to rapid initiation of resuscitation and significantly improved survival. In this narrative review we summarize and interpret recent developments in knowledge of EMS-witnessed OHCA regarding prevalence, demographics, location, circumstances, survival outcomes and clinical profile. We examine the possibility of informing novel resuscitation approaches and enhancing mechanistic knowledge by studying EMS-witnessed OHCA, with the goal of improving overall survival from OHCA.

Aminophylline for bradyasystolic cardiac arrest in adults

BACKGROUND

In cardiac ischaemia, the accumulation of adenosine may lead to or exacerbate bradyasystole and diminish the effectiveness of catecholamines administered during resuscitation. Aminophylline is a competitive adenosine antagonist. Case studies suggest that aminophylline may be effective for atropine-resistant bradyasystolic arrest.

OBJECTIVES

To determine the effects of aminophylline in the treatment of patients in bradyasystolic cardiac arrest, primarily survival to hospital discharge. We also considered survival to admission, return of spontaneous circulation, neurological outcomes and adverse events.

SEARCH METHODS

For this updated review, we searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, LILACS, ClinicalTrials.gov and WHO International Clinical Trials Registry Platform in November 2014. We checked the reference lists of retrieved articles, reviewed conference proceedings, contacted experts and searched further using Google.

SELECTION CRITERIA

All randomised controlled trials comparing intravenous aminophylline with administered placebo in adults with non-traumatic, normothermic bradyasystolic cardiac arrest who were treated with standard advanced cardiac life support (ACLS).

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed the studies and extracted the included data. We contacted study authors when needed. Pooled risk ratio (RR) was estimated for each study outcome. Subgroup analysis was predefined according to the timing of aminophylline administration.

MAIN RESULTS

We included five trials in this analysis, all of which were performed in the prehospital setting. The risk of bias was low in four of these studies (n = 1186). The trials accumulated 1254 participants. Aminophylline was found to have no effect on survival to hospital discharge (risk ratio (RR) 0.58, 95% confidence interval (CI) 0.12 to 2.74) or on secondary survival outcome (survival to hospital admission: RR 0.92, 95% CI 0.61 to 1.39; return of spontaneous circulation: RR 1.15, 95% CI 0.89 to 1.49). Survival was rare (6/1254), making data about neurological outcomes and adverse events quite limited. The planned subgroup analysis for early administration of aminophylline included 37 participants. No one in the subgroup survived to hospital discharge.

AUTHORS' CONCLUSIONS

The prehospital administration of aminophylline in bradyasystolic arrest is not associated with improved return of circulation, survival to admission or survival to hospital discharge. The benefits of aminophylline administered early in resuscitative efforts are not known.

Aminophylline for bradyasystolic cardiac arrest in adults

BACKGROUND

In cardiac ischaemia, the accumulation of adenosine may lead to or exacerbate bradyasystole and diminish the effectiveness of catecholamines administered during resuscitation. Aminophylline is a competitive adenosine antagonist. Case studies suggest that aminophylline may be effective for atropine-resistant bradyasystolic arrest.

OBJECTIVES

To determine the effects of aminophylline in the treatment of patients in bradyasystolic cardiac arrest, primarily survival to hospital discharge. We also considered survival to admission, return of spontaneous circulation, neurological outcomes and adverse events.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library, Issue 4, 2009), MEDLINE, EMBASE, CINAHL, LILACS, ClinicalTrials.gov and WHO International Clinical Trials Registry Platform. We checked the reference lists of retrieved articles, reviewed conference proceedings, contacted experts and searched further using Google. The search strategy was updated in March 2012.

SELECTION CRITERIA

All randomised controlled trials comparing intravenous aminophylline with administered placebo in adults with non-traumatic, normothermic bradyasystolic cardiac arrest who were treated with standard advanced cardiac life support (ACLS).

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed the studies and extracted the included data. We contacted study authors when needed. Pooled risk ratio (RR) was estimated for each study outcome. Subgroup analysis was predefined according to the timing of aminophylline administration.

MAIN RESULTS

Five trials are included in this analysis, all of which were performed in the prehospital setting. The risk of bias was low in four of these studies (n = 1186). The trials accumulated 1254 participants. Aminophylline was found to have no effect on survival to hospital discharge (RR 0.58, 95% confidence interval (CI) 0.12 to 2.74) or on secondary survival outcome (survival to hospital admission: RR 0.92, 95% CI 0.61 to 1.39; return of spontaneous circulation: RR 1.15, 95% CI 0.89 to 1.49). Survival was rare (6/1254), making data about neurological outcomes and adverse events quite limited. The planned subgroup analysis for early administration of aminophylline included 37 participants. No one in the subgroup survived to hospital discharge.

AUTHORS' CONCLUSIONS

The prehospital administration of aminophylline in bradyasystolic arrest is not associated with improved return of circulation, survival to admission or survival to hospital discharge. The benefits of aminophylline administered early in resuscitative efforts are not known.

Defibrillation success rates for electrically-induced fibrillation: hair of the dog

Accidental electrocutions kill about 1000 individuals annually in the USA alone. There has not been a systematic review or modeling of elapsed time duration defibrillation success rates following electrically-induced VF. With such a model, there may be an opportunity to improve the outcomes for industrial electrocutions and further understand arrest-related-deaths where a TASER(®) electrical weapon was involved. We searched for MedLine indexed papers dealing with defibrillation success following electrically-induced VF with time durations of 1 minute or greater post VF induction. We found 10 studies covering a total of 191 experiments for defibrillation of electrically-induced VF for post-induction durations out to 16 minutes including 0-9 minutes of pre-shock chest compressions. The results were fitted to a logistic regression model. Total minutes of VF and use of pre-shock chest compressions were significant predictors of success (p < .00005 and p= .003 respectively). The number of minutes of chest compressions was not a predictor of success. With no compressions, the 90% confidence of successful defibrillation is reached at 6 minutes and the median time limit for success is 9.5 minutes. However, with pre-shock chest compressions, the modeled data suggest a 90% success rate at 10 minutes and a 50% rate at 14 minutes.1.

The stability of electrically induced ventricular fibrillation

The first recorded heart rhythm for cardiac arrest patients can either be ventricular fibrillation (VF) which is treatable with a defibrillator, or asystole or pulseless electrical activity (PEA) which are not. The time course for the deterioration of VF to either asystole or PEA is not well understood. Knowing the time course of this deterioration may allow for improvements in emergency service delivery. In addition, this may improve the diagnosis of possible electrocutions from various electrical sources including utility power, electric fences, or electronic control devices (ECDs) such as a TASER(®) ECD. We induced VF in 6 ventilated swine by electrically maintaining rapid cardiac capture, with resulting hypotension, for 90 seconds. No circulatory assistance was provided. They were then monitored for 40 minutes via an electrode in the right ventricle. Only 2 swine remained in VF; 3 progressed to asystole; 1 progressed to PEA. These results were used in a logistic regression model. The results are then compared to published animal and human data. The median time for the deterioration of electrically induced VF in the swine was 35 minutes. At 24 minutes VF was still maintained in all of the animals. We conclude that electrically induced VF is long-lived--even in the absence of chest compressions.

Public access defibrillation: time to access the public

STUDY OBJECTIVE

Public accessible automated external defibrillators (AEDs) are increasingly made available in highly frequented places, allowing coincidental bystanders to defibrillate with minimal delay if necessary. Although the public, as the largest and most readily available group of potential rescuers, is assigned a key role in this concept of "public" access defibrillation, it is unknown whether bystanders are actually sufficiently prepared. We therefore investigate knowledge and attitudes toward AEDs among the public.

METHODS

Standardized interviews were conducted at the Central Railway Station of Amsterdam, the Netherlands, a highly frequented and AED-equipped public place with a high number of travelers and visitors from all over the world.

RESULTS

Surveys from 1,018 participants from a total of 38 nations were analyzed, revealing a considerable lack of knowledge among the public. Less than half of participants (47%) would be willing to use an AED, and more than half (53%) were unable to recognize an AED. Overall, only a minority of individuals have sufficient knowledge and would be willing to use an AED. Differences between subgroups were identified, which may aid to tailor public information campaigns to specific target audiences.

CONCLUSION

Only a minority of individuals demonstrate sufficient knowledge and willingness to operate an AED, suggesting that the public is not yet sufficiently prepared for the role it is destined for. Wide-scale public information campaigns are an important next step to exploit the lifesaving potential of public access defibrillation.

Mechanisms of ventricular fibrillation initiation in MADIT II patients with implantable cardioverter defibrillators

BACKGROUND

The availability of stored intracardiac electrograms from implantable defibrillators (ICDs) has facilitated the study of the mechanisms of ventricular tachyarrhythmia onset. This study aimed to determine the patterns of initiation of ventricular fibrillation (VF) in Multicenter Automatic Defibrillator Implantation Trial (MADIT) II patients along with associated electrocardiogram (ECG) parameters and clinical characteristics.

METHODS

Examination of stored electrograms enabled us to evaluate the rhythm preceding each episode of VF and to calculate (intracardiac) ECG parameters including QT, QT peak (QTp), coupling interval, and prematurity index.

RESULTS

Sixty episodes of VF among 29 patients (mean age 64.4 +/- 2.5 years) were identified. A single ventricular premature complex (VPC) initiated 46 (77%) episodes whereas a short-long-short (SLS) sequence accounted for 14 (23%) episodes. Of the 29 patients studied, 23 patients had VF episodes preceded by a VPC only, two patients with SLS only, and four patients with both VPC and SLS-initiated episodes. There were no significant differences between initiation patterns in regards to the measured ECG parameters; a faster heart rate with SLS initiation (mean RR prior to VF of 655 +/- 104 ms for SLS and 744 +/- 222 ms for VPC) approached significance (P = 0.06). The two patients with SLS only were not on beta-blockers compared to 83% of the VPC patients.

CONCLUSION

Ventricular fibrillation is more commonly initiated by a VPC than by a SLS sequence among the MADIT II population. Current pacing modes designed to prevent bradycardia and pause-dependent arrhythmias are unlikely to decrease the incidence of VPC-initiated episodes of VF.

[Public access defibrillation. Limited use by trained first responders and laymen]

As ventricular fibrillation is the most frequent initial heart rhythm causing out-of-hospital sudden cardiac arrest, defibrillation is of essential significance. Automated external defibrillators (AEDs) have been available for some years and as a result defibrillation can be carried out by individuals other than physicians and healthcare providers such as trained first responders and untrained lay rescuers. This so-called public access defibrillation nourished hope of progress in the treatment of sudden cardiac arrest. However, several limitations exist, such as low frequency of sudden cardiac arrest in public, rare use of publicly placed AEDs, low cost effectiveness, legal requirements and insufficient public willingness to help. Due to these restrictions of public access defibrillation other measures are more promising than the attempt at general distribution of AEDs. These measures are primary or secondary prophylaxis of sudden cardiac arrest, general knowledge of adequate activation of emergency medical services, implementation of first responder teams equipped with AEDs and particularly a better education in and application of the well-established principles of cardiopulmonary resuscitation.

A comparison of electrically induced cardiac arrest with cardiac arrest produced by coronary occlusion

OBJECTIVE

The present study was undertaken to compare an animal model of electrically induced VF with ischemically induced VF. In a preponderance of models of cardiac arrest and resuscitation in intact animals, ventricular fibrillation (VF) is induced by an alternating current delivered directly to the epicardium or endocardium. Yet, the applicability of such animal models has been challenged for it is not an electrical current alone but rather a current generated in the ischemic myocardium that triggers VF. Accordingly, a potentially more clinically relevant model was investigated in which spontaneous VF followed acute myocardial ischemia.

METHODS

Twenty anesthetized pigs were randomized to either electrical fibrillation or myocardial ischemia following transient occlusion of the left anterior descending (LAD) coronary artery.

RESULTS

VF was untreated for 7 min in both models after which mechanical ventilation and precordial compression were begun. Defibrillation was attempted after 5 min of CPR in both groups. VF appeared within 5.7+/-2.0 min of LAD occlusion.

CONCLUSIONS

A significant increase in the number of post-resuscitation premature ventricular beats and recurrent VF followed ROSC and a significantly greater number of shocks was required for restoration of spontaneous circulation (ROSC) after LAD occlusion. Nevertheless, early post-resuscitation myocardial dysfunction, neurological recovery and 72 h survival were indistinguishable between the two models.

Resuscitation by primary care doctors

BACKGROUND

Sudden cardiac arrest is a common mechanism of premature death in the community. Resuscitation is often possible, but no large study of resuscitation by doctors who practice there has been published.

METHODS

General practitioners (GPs) equipped with defibrillators reported 555 patients with cardiac arrest in whom they attempted resuscitation.

FINDINGS

Average age was 65.4, 75% male. Most arrests (49%) occurred at the patient's home but some (18%) occurred at or near the doctors' surgeries. Heart disease was responsible for 88% of the arrests: in these cases resuscitation to leave hospital alive was frequently successful (148 of 436 attempts, 34%). Success was rare (one of 59, <2%) when the arrest was due to non-cardiac disease. Resuscitation was most common when the first monitored rhythm was shockable (VF/VT) and defibrillated promptly: 144 out of 351 (41%) patients surviving. VF/VT was most common with early rhythm monitoring, particularly when the doctor was present (63% survival), or nearby (54%). When VF/VT complicated AMI, 72% of those defibrillated within 1min of onset survived. With delayed attendance, the frequency of VF/VT fell and asystole or Pulseless Electrical Activity (PEA) became more common. Survival after resuscitation was rare for patients presenting with these rhythms: five of 202 (2.5%). No such patient survived unless the rhythm could be converted to VF/VT with drugs or basic life support and subsequently shocked.

CONCLUSION

Primary care doctors equipped with defibrillators attend patients with cardiac arrest under circumstances in which resuscitation is frequently successful. This presents a unique opportunity to reduce mortality from sudden cardiac arrest.

Aminophylline in bradyasystolic cardiac arrest: a randomised placebo-controlled trial

BACKGROUND

Endogenous adenosine might cause or perpetuate bradyasystole. Our aim was to determine whether aminophylline, an adenosine antagonist, increases the rate of return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest.

METHODS

In a double-blind trial, we randomly assigned 971 patients older than 16 years with asystole or pulseless electrical activity at fewer than 60 beats per minute, and who were unresponsive to initial treatment with epinephrine and atropine, to receive intravenous aminophylline (250 mg, and an additional 250 mg if necessary) (n=486) or placebo (n=485). The patients were enrolled between January, 2001 and September, 2003, from 1886 people who had had cardiac arrests. Standard resuscitation measures were used for at least 10 mins after the study drug was administered. Analysis was by intention-to-treat. This trial is registered with the ClinicalTrials.gov registry with the number NCT00312273.

FINDINGS

Baseline characteristics and survival predictors were similar in both groups. The median time from the arrival of the advanced life-support paramedic team to study drug administration was 13 min. The proportion of patients who had an ROSC was 24.5% in the aminophylline group and 23.7% in the placebo group (difference 0.8%; 95% CI -4.6% to 6.2%; p=0.778). The proportion of patients with non-sinus tachyarrhythmias after study drug administration was 34.6% in the aminophylline group and 26.2% in the placebo group (p=0.004). Survival to hospital admission and survival to hospital discharge were not significantly different between the groups. A multivariate logistic regression analysis showed no evidence of a significant subgroup or interactive effect from aminophylline.

INTERPRETATION

Although aminophylline increases non-sinus tachyarrhythmias, we noted no evidence that it significantly increases the proportion of patients who achieve ROSC after bradyasystolic cardiac arrest.

Survival after out-of-hospital cardiac arrests in Katowice (Poland): outcome report according to the “Utstein style”

The purpose of this study was to evaluate the outcome of out-of-hospital cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in the city of Katowice, Poland, during a period of 1 year prior to the planned reorganization of the national emergency system. Data were collected prospectively according to a modified Utstein style. To ensure accurate data collection, a special method of reporting resuscitation events with the use of a tape-recorder was introduced. Patients were followed for a 1-year period. Between 1 July 2001 and 30 June 2002, out-of-hospital cardiac arrest was confirmed in 1153 patients. Cardiopulmonary resuscitation was attempted in 188 patients. Cardiac arrest of presumed cardiac aetiology (147) was bystander witnessed in 105 (71%) cases and lay-bystander basic life support was performed in 35 (24%). In the group of bystander witnessed arrest ventricular fibrillation (VF) or tachycardia was documented in 59, asystole in 40 and other non-perfusing rhythms in six patients. Of 147 patients with cardiac aetiology, return of spontaneous circulation (ROSC) was achieved in 64 (44%) patients, 15 (10%) were discharged alive and 9 (6%) were alive 1 year later. Most of these patients had a good neurological outcome. Time to first defibrillatory shock was significantly shorter for survivors (median 7 min) compared to non-survivors (median 10 min). The most important resuscitation and patient characteristics associated with survival were VF as initial rhythm, arrest witnessed, and lay-bystander CPR.

Potential impact of public access defibrillators on survival after out of hospital cardiopulmonary arrest: retrospective cohort study

OBJECTIVE

To estimate the potential impact of public access defibrillators on overall survival after out of hospital cardiac arrest.

DESIGN

Retrospective cohort study using data from an electronic register. A statistical model was used to estimate the effect on survival of placing public access defibrillators at suitable or possibly suitable sites.

SETTING

Scottish Ambulance Service.

SUBJECTS

Records of all out of hospital cardiac arrests due to heart disease in Scotland in 1991-8.

MAIN OUTCOME MEASURES

Observed and predicted survival to discharge from hospital.

RESULTS

Of 15 189 arrests, 12 004 (79.0%) occurred in sites not suitable for the location of public access defibrillators, 453 (3.0%) in sites where they may be suitable, and 2732 (18.0%) in suitable sites. Defibrillation was given in 67.9% of arrests that occurred in possibly suitable sites for locating defibrillators and in 72.9% of arrests that occurred in suitable sites. Compared with an actual overall survival of 744 (5.0%), the predicted survival with public access defibrillators ranged from 942 (6.3%) to 959 (6.5%), depending on the assumptions made regarding defibrillator coverage.

CONCLUSIONS

The predicted increase in survival from targeted provision of public access defibrillators is less than the increase achievable through expansion of first responder defibrillation to non-ambulance personnel, such as police or firefighters, or of bystander cardiopulmonary resuscitation. Additional resources for wide scale coverage of public access defibrillators are probably not justified by the marginal improvement in survival.

The epidemiology of out-of-hospital 'sudden' cardiac arrest

It is difficult to assemble data from an out-of-hospital cardiac arrest since there is often lack of objective information. The true incidence of sudden cardiac death out-of-hospital is not known since far from all of these patients are attended by emergency medical services. The incidence of out-of-hospital cardiac arrest increases with age and is more common among men. Among patients who die, the probability of having a fatal event outside hospital decreases with age; i. e. younger patients tend to more often die unexpectedly and outside hospital. Among the different initial arrhythmias, ventricular fibrillation is the most common among patients with cardiac aetiology. The true distribution of initial arrhythmias is not known since several minutes most often elapse between collapse and rhythm assessment. Most patients with out-of-hospital cardiac arrest have a cardiac aetiology. Out-of-hospital cardiac arrests most frequently occur in the patient's home, but the prognosis is shown to be better when they occur in a public place. Witnessed arrest, ventricular fibrillation as initial arrhythmia and cardiopulmonary resuscitation are important predictors for immediate survival. In the long-term perspective, cardiac arrest in connection with acute myocardial infarction, high left ventricular ejection fraction, moderate age, absence of other heart failure signs and no history of myocardial infarction promotes better prognosis. Still there is much to learn about time trends, the influence of patient characteristics, comorbidity and hospital treatment among patients with prehospital cardiac arrest.

Factors affecting short- and long-term prognosis among 1069 patients with out-of-hospital cardiac arrest and pulseless electrical activity

AIMS

To describe the epidemiology, resuscitation factors and prognosis among a consecutive population of patients suffering from out-of-hospital cardiac arrest (OHCA) where pulseless electrical activity (PEA) was the first arrhythmia recorded on emergency medical services (EMS) arrival.

METHODS

Analysis of data collected prospectively on all patients regardless of age succumbing to OHCA during 1980-1997 in the community of Gothenburg where EMS initiated resuscitative measures.

RESULTS

4662 patients with OHCA were attended by the EMS during the study period. Of these, 1069 (23%) were judged as having PEA as the first recorded arrhythmia; 158 (15%) of these were admitted alive to hospital and 26 (2.4%) were discharged alive. Survivors to discharge had a significantly larger share of bystander cardiopulmonary resuscitation (CPR) (28 vs. 8%, P=0.008), significantly higher levels of consciousness (8% awake vs. 0%, P<0.001) and higher median systolic blood pressure (145 vs. 106 mmHg, P<0.001) on arrival at hospital. No patient with unwitnessed cardiac arrest and PEA over 80 years old survived.

CONCLUSION

Survival among patients suffering from OHCA and PEA is poor, especially among the elderly unwitnessed cases and those who do not receive bystander CPR. The latter seems to be of utmost importance among these patients.

Electrophysiological deterioration during long-duration ventricular fibrillation

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Aminophylline in undifferentiated out-of-hospital asystolic cardiac arrest

PRIMARY OBJECTIVE

To determine if the introduction of intravenous aminophylline, a nonspecific adenosine receptor antagonist, into the resuscitation algorithm of asystole will increase return of spontaneous circulation when used in undifferentiated prehospital cardiac arrest.

METHODS

An urban, prehospital, prospective, randomized, double-blind, placebo-controlled trial of nonpregnant normothermic adults suffering nontraumatic out-of-hospital asystolic cardiac arrest. Subjects were treated in accordance with published advanced cardiac life support guidelines and standard pharmacotherapy. They were randomly assigned to receive either placebo or aminophylline along with the initial boluses of atropine and epinephrine. Cardiac rhythms and carotid pulses were monitored throughout the resuscitation.

RESULTS

Eighty-two patients were entered into the trial. Forty-five patients were assigned to the placebo group and 37 received aminophylline. Nine of 45 controls (20%; 95% CI 10-35%) achieved return of spontaneous circulation compared to ten of 37 (27%; 95% CI 14-44%) in the aminophylline group.

CONCLUSIONS

We were not able to show a statistically significant improvement in return of spontaneous circulation when aminophylline was given during the early resuscitation phase of undifferentiated asystolic cardiac arrest in the prehospital setting with this sample size.

Gatekeepers: a missed opportunity for safe transport

OBJECTIVE

To assess whether contact with a health care provider or gatekeeper increases the use of an ambulance for patients with acute chest pain.

METHODS

A convenience sample of adults > or =40 years of age presenting with a chief complaint of chest pain were interviewed by trained personnel regarding transport used to come to the ED. The study was performed at the ED of an urban university hospital. Patients with hemodynamic instability and those receiving thrombolytics or emergency angioplasty were excluded. Patients were asked about access to a primary health care provider and contact with a provider regarding this ED visit, including instructions given for transportation.

RESULTS

Of the 450 interviewed patients, 42% arrived by ambulance. Those who had contact with a health care provider prior to the ED visit were less likely to come by ambulance than those without contact, 31% vs 51% (p < 0.001). Of the patients who had cardiac enzymes obtained to work up for their chest pain, 34% with health provider contact vs 57% without health provider contact arrived by ambulance (p < 0.001). Of those with acute myocardial infarction, 30% with health provider contact vs 66% without health provider contact came by ambulance (p < 0.03). Patients who recalled transport instructions from their providers tended to follow those instructions. The majority of patients who recalled no specific transport instructions arrived by personal automobile.

CONCLUSION

Of patients presenting to an ED for evaluation of chest pain, those who made contact with a health care provider were less likely to arrive via ambulance.

Characteristics of prehospital cardiac arrest patients in Japan and determinant factors for survival

Two hundred forty-seven consecutive patients who had prehospital cardiac arrest and were transferred to a municipal hospital were studied to elucidate the characteristics of these patients and to investigate factors for improving the survival rate among prehospital cardiac arrest patients. Detailed information on 130 patients with cardiac etiology was analyzed: 110 were confirmed dead in the emergency department (group A); 14 survived less than 1 week (group B); 6 survived longer than 1 week (group C). Only one patient received cardiopulmonary resuscitation (CPR) from a bystander, and none received electrical defibrillation before arriving at hospital because, at the time, emergency personnel were not allowed to perform advanced life support (ALS) in Japan. The three characteristics for better prognosis after prehospital cardiac arrest were found to be as follows: being witnessed on collapse, receiving prompt ALS, and ventricular fibrillation on arrival at hospital. The survival rate would have been higher if more lay people could have performed CPR and if emergency unit personnel had been allowed to perform ALS.

Cardiac arrests witnessed by EMS personnel in a multitiered system: epidemiology and outcome

The purpose of the study was to determine the epidemiology and the etiology of cardiac arrests witnessed by emergency medical services (EMS) personnel and the survival from resuscitation according to the Utstein style. Consecutive prehospital cardiac arrests witnessed by EMS personnel in the Helsinki City EMS system between January 1, 1994 and December 31, 1995 were included in this prospective cohort study. A total of 809 cardiac arrests were registered during the study period, 108 (13.3%) of which were EMS-witnessed. The incidence of EMS-witnessed cardiac arrests was 1.8 per 1,000 urgent calls per year. Resuscitation was attempted in 94 patients, 45 of whom (47.9%) were hospitalized alive and 15 of whom (16.0%) were discharged. Fourteen of the survivors were discharged with overall performance category I or II. Cardiac etiology was verified in 60 (55.6%) cases. In multivariate analysis, initial rhythm of ventricular fibrillation and cardiac etiology remained independent factors of survival. These results indicate that overall survival rates in EMS-witnessed cardiac arrests have remained low but those who survive are discharged without major neurological sequelae. Noncardiac etiology accounts for 45% of cases and seems to be a major determinant of low overall survival rates.

Advanced life support: role of the rural registered nurse

This paper provides a human face to advanced life support (ALS) and its assention within rural nursing practice. Over the past 5 years the issue of defibrillation and who performs it has been debated. This paper will add to the discussion. It examines the history surrounding the development of ALS, education within the hospital and isolated rural setting competency testing. It questions the limited role of current nursing practice and makes recommendations for stretching the boundaries of the nursing role in ALS. Emphasis is placed on the rural perspective and its consequent implications for individuals living in a rural environment.

Type of arrhythmia at EMS arrival on scene in out-of-hospital cardiac arrest in relation to interval from collapse and whether a bystander initiated CPR

Outcome after cardiac arrest is strongly related to whether the patient has ventricular fibrillation at the time the emergency medical service (EMS) arrives on the scene. The occurrence of various arrhythmias at the time of EMS arrival among patients with out-of-hospital cardiac arrest was studied in relation to the interval from collapse and whether cardiopulmonary resuscitation (CPR) was initiated by a bystander. The patients studied were all those with out-of-hospital cardiac arrest in Goteborg, Sweden, between 1980 and 1992 in whom CPR was attempted by the arriving EMS and for whom the interval between collapse and the arrival of EMS was known. In all, information on the time of collapse and the arrival of EMS was available for 1,737 patients. Among patients for whom EMS arrived within 4 minutes of collapse, 53% were found in ventricular fibrillation/tachycardia. There was a successive decline in occurrence of such arrhythmias with time. However, when the interval exceeded 20 minutes, ventricular fibrillation/tachycardia was still observed in 27% of cases. Bystander CPR increased the occurrence of such arrhythmias regardless of the interval between collapse and EMS arrival.

Optimal defibrillation strategy and follow-up of out-of-hospital cardiac arrest. The Belgian CPCR Study Group

In the current climate of rising healthcare cost, resuscitation efforts performed outside the hospital are critically evaluated because of their limited success rate in some settings. As part of a quality assurance program between the 1st January 1991 and 31st December 1993, six centres of the Belgian CPCR study group prospectively registered cardiac arrest (CA) patients and their treatment according to the Ustein Style recommendations. In the group (n = 511) of patients initially found in ventricular fibrillation (VF) a significantly better survival rate was observed for those patients who received a 1st defibrillatory shock by the 1st tier (n = 142 (27.8%)) as compared to those defibrillated after arrival of the 2nd tier (n = 369 (72.2%)). Median time to delivery of the first shock was significantly shorter (5 min) in the 1st tier group. In a second part of the study we describe long-term management of the 28 surviving VF patients, treated by the single EMS system of Brugge between 1st January 1991 and 30th April 1995: only 6 patients eventually received an implantable cardioverter defibrillator (ICD), whereas coronary revascularization was performed in 9 patients, and 3 patients were discharged on amiodarone only. Satisfactory long-term survival after out-of-hospital VF can be achieved by an early shock followed by advanced life support and appropriate definitive treatment.

Paramedics and technicians are equally successful at managing cardiac arrest outside hospital

OBJECTIVE

To examine the effect on survival of treatment by ambulance paramedics and ambulance technicians after cardiac arrest outside hospital.

DESIGN

Prospective study over two years from 1 April 1992 to 31 March 1994.

SETTING

Accident and emergency department of university teaching hospital.

SUBJECTS

502 consecutive adult patients with out of hospital cardiopulmonary arrest of cardiac origin.

INTERVENTIONS

Treatment by ambulance technicians or paramedics both equipped with semiautomatic defibrillators.

MAIN OUTCOME MEASURES

Rate of return of spontaneous circulation, hospital admission, and survival to hospital discharge.

RESULTS

Rates of return of spontaneous circulation, hospital admission, and survival to hospital discharge were not significantly different for patients treated by paramedics as opposed to ambulance technicians. Paramedics spent significantly longer at the scene of the arrest than technicians (P < 0.0001).

CONCLUSIONS

The response of ambulance paramedics to patients with cardiopulmonary arrest outside hospital does not provide improved outcome when compared with ambulance technicians using basic techniques and equipped with semi-automatic defibrillators.