Out-of-hospital cardiac arrest: improved survival with paramedic services

Characterizing the influence of transportation infrastructure on Emergency Medical Services (EMS) in urban area-A case study of Seoul, South Korea

In highly urbanized area where traffic condition fluctuates constantly, transportation infrastructure is one of the major contributing factors to Emergency Medical Service (EMS) availability and patient outcome. In this paper, we assess the impact of traffic fluctuation to the EMS first response availability in urban area, by evaluating the k-minute coverage under 21 traffic scenarios. The set of traffic scenarios represents the time-of-day and day-of-week effects, and is generated by combining road link speed information from multiple historical speed databases. In addition to the k-minute area coverage calculation, the k-minute population coverage is also evaluated for every 100m by 100m grid that partitions the case study area of Seoul, South Korea. In the baseline case of traveling at the speed limit, both the area and population coverage reached nearly 100% when compared to the five-minute travel time national target. Employing the proposed LoST (Loss of Serviceability due to Traffic) index, which measures coverage reduction in percentage compared to the baseline case, we find that the citywide average LoST for area and population coverage are similar at 34.2% and 33.8%. However, district-wise analysis reveals that such reduction varies significantly by district, and the magnitude of area and population coverage reduction is not always proportional. We conclude that the effect of traffic variation is significant to successful urban EMS first response performance, and regional variation is evident among local districts. Complexity in the urban environment requires a more adaptive approach in public health resource management and EMS performance target determination.

Cardiopulmonary Resuscitation Pattern Evaluation Based on Ensemble Empirical Mode Decomposition Filter via Nonlinear Approaches

Good quality cardiopulmonary resuscitation (CPR) is the mainstay of treatment for managing patients with out-of-hospital cardiac arrest (OHCA). Assessment of the quality of the CPR delivered is now possible through the electrocardiography (ECG) signal that can be collected by an automated external defibrillator (AED). This study evaluates a nonlinear approximation of the CPR given to the asystole patients. The raw ECG signal is filtered using ensemble empirical mode decomposition (EEMD), and the CPR-related intrinsic mode functions (IMF) are chosen to be evaluated. In addition, sample entropy (SE), complexity index (CI), and detrended fluctuation algorithm (DFA) are collated and statistical analysis is performed using ANOVA. The primary outcome measure assessed is the patient survival rate after two hours. CPR pattern of 951 asystole patients was analyzed for quality of CPR delivered. There was no significant difference observed in the CPR-related IMFs peak-to-peak interval analysis for patients who are younger or older than 60 years of age, similarly to the amplitude difference evaluation for SE and DFA. However, there is a difference noted for the CI (p < 0.05). The results show that patients group younger than 60 years have higher survival rate with high complexity of the CPR-IMFs amplitude differences.

Multiple in-hospital resuscitation efforts in the elderly

OBJECTIVES

The objective of this study was to determine the characteristics and survival rates of patients receiving cardiopulmonary resuscitation more than once during a single hospitalization.

DESIGN

We analyzed inpatient Medicare data from 1992 to 2005 identifying beneficiaries 65 years old and older who underwent cardiopulmonary resuscitation more than once during the same hospitalization.

MEASUREMENTS

We examined patient and hospital characteristics, survival to hospital discharge, factors associated with survival to discharge, median survival, and discharge disposition.

RESULTS

We analyzed data from 421,394 patients who underwent cardiopulmonary resuscitation during the study period. Four lakh thirteen thousand four hundred three patients received cardiopulmonary resuscitation once during a hospitalization and survival was 17.7% with median survival after discharge being 20.6 months. There were 7,991 patients who received cardiopulmonary resuscitation more than once during the same hospitalization; 8.8% survived the efforts, and median survival after leaving the hospital was 10.5 months. Patients who received more than one episode of cardiopulmonary resuscitation during a hospitalization were significantly less likely to go home after discharge. Greater age, black race, higher burden of chronic illness, and receiving cardiopulmonary resuscitation in a larger or metropolitan hospital were associated with lower survival among patients receiving cardiopulmonary resuscitation more than once.

CONCLUSIONS

Undergoing multiple cardiopulmonary resuscitation events during a hospitalization is associated with substantially reduced short- and long-term survival compared with patients who undergo cardiopulmonary resuscitation once. This information may be useful to clinicians when discussing end-of-life care with patients and families of patients who have experienced return of spontaneous circulation following in-hospital cardiopulmonary resuscitation but remain at risk for recurrent cardiac arrest.

The effect of the AED and AED programs on survival of individuals, groups and populations

OBJECTIVE

The automated external defibrillator (AED) is a tool that contributes to survival with mixed outcomes. This review assesses the effectiveness of the AED, consistencies and variations among studies, and how varying outcomes can be resolved.

METHODS

A worksheet for the International Liaison Committee on Resuscitation (ILCOR) 2010 science review focused on hospital survival in AED programs was the foundation of the articles reviewed. Articles identified in the search covering a broader range of topics were added. All articles were read by at least two authors; consensus discussions resolved differences.

RESULTS

AED use developed sequentially. Use of AEDs by emergency medical technicians (EMTs) compared to manual defibrillators showed equal or superior survival. AED use was extended to trained responders likely to be near victims, such as fire/rescue, police, airline attendants, and casino security guards, with improvement in all venues but not all programs. Broad public access initiatives demonstrated increased survival despite low rates of AED use. Home AED programs have not improved survival; in-hospital trials have had mixed results. Successful programs have placed devices in high-risk sites, maintained the AEDs, recruited a team with a duty to respond, and conducted ongoing assessment of the program.

CONCLUSION

The AED can affect survival among patients with sudden ventricular fibrillation (VF). Components of AED programs that affect outcome include the operator, location, the emergency response system, ongoing maintenance and evaluation. Comparing outcomes is complicated by variations in definitions of populations and variables. The effect of AEDs on individuals can be dramatic, but the effect on populations is limited.

The Efficacy of Advanced Life Support: A Review of the Literature

Introduction:

Jurisdictions throughout the United States and some other parts of the world have invested substantial time and resources into creating and sustaining a prehospital advanced life support (ALS) system without knowing whether the efficacy of ALS-level care had been validated scientifically. In recent years, it has become fashionable for speakers before large audiences to declare that there is no scientific evidence for the clinical effectiveness of ALS-level care in the out-of-hospital setting. This study was undertaken to evaluate the evidence that pertains to the efficacy of ALS-level care in the current scientific literature.

Methods:

An extensive review of the available literature was accomplished using computerized and manual means to identify all applicable articles from 1966 to October, 1995. Selected articles were read, abstracted, analyzed, and compiled Each article also was categorized as presenting evidence supporting or refuting the clinical efficacy of ALS-level care, and a list was constructed that pointed to where the preponderance of the evidence lies.

Results:

Research in this field differs widely in terms of methodological sophistication. Of the 51 articles reviewed, eight concluded that ALS-level care is not any more effective than is basic life support, seven concluded that it is effective in some applications but not for others, and the remainder demonstrated effectiveness. The strongest support for ALS-level care was in the area of responses to victims of cardiac arrest, whereas somewhat more divergent findings related to trauma or non condition-specific studies.

Conclusion:

While not unanimous, the predominant finding of recent research into the clinical effectiveness of advanced life support demonstrates improved effectiveness over basic life support for patients with certain pathologies. More outcomes-based research is needed.

Cardiopulmonary resuscitation in older people – a review

Survival to discharge after in-hospital cardiopulmonary resuscitation (CPR) is about 20% in those aged 65–69 years, declining with advancing age to about 10% in those aged 90 years or more. There are conflicting reports on whether or not advanced age, independent of the severity of acute and chronic illness, is a determinant of outcome. Recognition that the outcome of CPR in hospital patients is often poor has prompted extensive debate regarding the appropriate use of this procedure. In particular, there has been concern about unnecessary CPR in extended-care and hospice settings. Conversely, there has also been evidence that doctors and families may be prone to underestimate the quality of life and likelihood of benefit from CPR in older people and to make resuscitation decisions without considering the preferences of older people themselves. Recent guidelines have attempted to strike a balance between ensuring patient participation whenever possible but without offering illusory choices where CPR is very unlikely to succeed.

Epidemiologic study of in-hospital cardiopulmonary resuscitation in the elderly

BACKGROUND

It is unknown whether the rate of survival after in-hospital cardiopulmonary resuscitation (CPR) is improving and which characteristics of patients and hospitals predict survival.

METHODS

We examined fee-for-service Medicare data from 1992 through 2005 to identify beneficiaries 65 years of age or older who underwent CPR in U.S. hospitals. We examined temporal trends in the incidence of CPR and the rate of survival after CPR, as well as patient- and hospital-level predictors of survival to discharge.

RESULTS

We identified 433,985 patients who underwent in-hospital CPR; 18.3% of these patients (95% confidence interval [CI], 18.2 to 18.5) survived to discharge. The rate of survival did not change substantially during the period from 1992 through 2005. The overall incidence of CPR was 2.73 events per 1000 admissions; the incidence was higher among black and other nonwhite patients. The proportion of patients undergoing in-hospital CPR before death increased over time and was higher for nonwhite patients. The survival rate was lower among patients who were men, were older, had more coexisting illnesses, or were admitted from a skilled-nursing facility. The adjusted odds of survival for black patients were 23.6% lower than those for similar white patients (95% CI, 21.2 to 25.9). The association between race and survival was partially explained by hospital effects: black patients were more likely to undergo CPR in hospitals that have lower rates of post-CPR survival. Among patients surviving in-hospital CPR, the proportion of patients discharged home rather than to a health care facility decreased over time.

CONCLUSIONS

Survival after in-hospital CPR did not improve from 1992 through 2005. The proportion of in-hospital deaths preceded by CPR increased, whereas the proportion of survivors discharged home after undergoing CPR decreased. Black race was associated with higher rates of CPR but lower rates of survival after CPR.

Intellectual and social function of patients surviving cardiac arrest outside the hospital

Thirteen survivors of cardiac arrest outside the hospital were examined by clinical and psychological tests 1-3 years after the incidence, and compared to a matched control group of 13 patients with acute myocardial infarction without cardiac arrest. Psychological tests revealed that 7 patients with previous cardiac arrest and 4 control patients had mild-moderate to moderate-severe dementia. The demential symptoms were not detectable by a clinical interview. Four patients in each group exhibited pronounced anxiety symptoms. There were no clear differences between the two groups in respect of changes in cardiac function and social status after the incidence.

Initial cardiac rhythm correlated to emergency department survival

BACKGROUND

This study attempted to correlate the initial cardiac rhythm and survival from prehospital cardiac arrest, as a secondary end-point.

METHODS

Prospective, randomized, double-blinded clinical intervention trial where bicarbonate was administered to 874 prehospital cardiopulmonary arrest patients in prehospital urban, suburban, and rural emergency medical service environments.

RESULTS

This group's manifested an overall survival rate of 13.9% (110 of 793) of prehospital cardiac arrest patients. The most common presenting arrhythmia was ventricular fibrillation (VF) (45.0%), asystole (ASY) (34.4%), and pulseless electrical activity (PEA) (15.7%). Less commonly found were normal sinus rhythm (NSR) (1.8%), other (1.8%), ventricular tachycardia (VT) (0.6%), and atrioventricular block (AVB) (0.5%) as prearrest rhythms. The best survival was noted in those with a presenting rhythm of AVB (57.1%), VT (33.3%), VF (15.7%), NSR (14.3%), PEA (11.2%), and ASY (11.1%) (p = 0.02). However, there was no correlation between the final cardiac rhythm and outcome, other than an obvious end-of-life rhythm.

CONCLUSION

The most common presenting arrhythmia was VF (45%), while survival is greatest in those presenting with AVB (57.1%).

Survival Outcomes With the Introduction of Intravenous Epinephrine in the Management of Out-of-Hospital Cardiac Arrest

STUDY OBJECTIVE

The benefit of epinephrine in cardiac arrest is controversial and has not been conclusively shown in any human clinical study. We seek to assess the effect of introducing intravenous epinephrine on the survival outcomes of out-of-hospital cardiac arrest patients in an emergency medical services (EMS) system that previously did not use intravenous medications.

METHODS

This observational, prospective, before-after clinical study constitutes phase II of the Cardiac Arrest and Resuscitation Epidemiology project. Included were all patients who are older than 8 years, with nontraumatic out-of-hospital cardiac arrest conveyed by the national emergency ambulance service. The comparison between the 2 intervention groups for survival to discharge was made with logistic regression and expressed in terms of the odds ratio (OR) and the corresponding 95% confidence interval (CI).

RESULTS

From October 1, 2002, to October 14, 2004, 1,296 patients were enrolled into the study, with 615 in the pre-epinephrine and 681 in the epinephrine phase. Demographic and EMS characteristics were similar in both groups. Forty-four percent of patients received intravenous epinephrine in the epinephrine phase. There was no significant difference in survival to discharge (pre-epinephrine 1.0%; epinephrine 1.6%; OR 1.7 [95% CI 0.6 to 4.5]; adjusted for rhythm OR 2.0 [95% CI 0.7 to 5.5]); return of circulation (pre-epinephrine 17.9%; epinephrine 15.7%; OR 0.9 [95% CI 0.6 to 1.2]), or survival to admission (pre-epinephrine 7.5%; epinephrine 7.5%; OR 1.0 [95% CI 0.7 to 1.5]). There was a minimal increase in scene time in the epinephrine phase (10.3 minutes versus 10.7 minutes; 95% CI of difference 0.02 to 0.94 minutes).

CONCLUSION

We were unable to establish a significant survival benefit with the introduction of intravenous epinephrine to an EMS system. More research is needed to determine the effectiveness of drugs such as epinephrine in resuscitation.

La desfibrilación temprana en la comunidad: romper barreras para salvar vidas

It is considered that in Spain, every year, we have more than 24,500 out-of-hospital cardiac arrests. Around 85% of these are secondary to ventricular fibrillation, with possibility of reversion in more than 90% if defibrillation is performed in the first minute of arrhythmia. However, if we delay this defibrillation, survival possibilities disappear in a few minutes. Clinical advances in last decades have not achieved satisfactory results in the treatment of cardiac arrest as survival rates at hospital discharge do not exceed 7%. Aware of this situation, the International Scientific Societies are recommending decreasing time to defibrillation, advising, at best, a time less than five minutes between the 112-call (emergency) and adequate electric discharge. Development of automated defibrillators in Emergency Medical Systems and their use by <<first responders>> of <<non-health care>> emergency services (police, fire fighters, etc) contribute to reach this objective. Because of this, Emergency Medical Systems are modifying their assistance strategies, to implement the early defibrillation as <<key to survival>>. Literature showed the effective value of automated defibrillators in the public areas but their efficiency level is less than that reached with the Emergency Services. Efficiency depends on multiple factors such as type of installation, accessibility level to emergency medical services or incidence rate of sudden cardiac arrest. Thus, their introduction should be preceded by a cost-effectiveness study. Effectiveness of automated defibrillators at home, where up to 80% of cardiac arrest are produced, has still not been evaluated. Nevertheless, in the USA, its marketing with this indication has been authorized.

Survival from prehospital cardiac arrest is critically dependent upon response time

STUDY OBJECTIVE

This study correlated the delay in initiation of bystander cardiopulmonary resuscitation (ByCPR), basic (BLS) or advanced cardiac (ACLS) life support, and transport time (TT) to survival from prehospital cardiac arrest. This was a secondary endpoint in a study primarily evaluating the effect of bicarbonate on survival.

DESIGN

Prospective multicenter trial.

SETTING

Patients treated by urban, suburban, and rural emergency medical services (EMS) services.

PATIENTS

Eight hundred and seventy-four prehospital cardiac arrest patients.

INTERVENTIONS

This group underwent conventional ACLS intervention followed by empiric early administration of sodium bicarbonate noting resuscitation times. Survival was measured as the presence of vital signs on emergency department (ED) arrival. Data analysis utilized Student's t-test and logistic regression (p<0.05).

RESULTS

Survival was improved with decreased time to BLS (5.52 min versus 6.81 min, p=0.047) and ACLS (7.29 min versus 9.49 min, p=0.002) intervention, as well as difference in time to return of spontaneous circulation (ROSC). The upper limit time interval after which no patient survived was 30 min for ACLS time, and 90 min for transport time. There was no overall difference in survival except at longer arrest times when considering the primary study intervention bicarbonate administration.

CONCLUSION

Delay to the initiation of BLS and ACLS intervention influenced outcome from prehospital cardiac arrest negatively. There were no survivors after prolonged delay in initiation of ACLS of 30 min or greater or total resuscitation and transport time of 90 min. This result was not influenced by giving bicarbonate, the primary study intervention, except at longer arrest times.

Delaying shock for cardiopulmonary resuscitation: does it save lives?

PURPOSE OF REVIEW

Out-of-hospital cardiac arrest claims more than 450,000 lives annually in North America. Many communities have dedicated significant resources to provide rapid defibrillator response for patients in ventricular fibrillation. In spite of these efforts, mortality from out-of-hospital cardiac arrest has not improved significantly. Emerging evidence suggests some patients in ventricular fibrillation arrest may be harmed by immediate defibrillation.

RECENT FINDINGS

Recent laboratory studies have shown benefit in performing a period of chest compressions (cardiopulmonary resuscitation) prior to defibrillation in models with more than 4 minutes of induced ventricular fibrillation. During the initial 4 minutes the heart is more amenable to electrical defibrillation. Between 4-10 minutes, chest compressions create some coronary perfusion and fill the left ventricle to prepare the heart for electric shock. These findings, in conjunction with most emergency medical service response times reported to be 5-8 minutes, have prompted human investigation into a strategy of chest compression first. A recent randomized controlled trial reported a fivefold increase in survival for patients with more than 5 minutes of VF who received 3 minutes of chest compressions prior to defibrillation compared with those who had not.

SUMMARY

Current guidelines call for rapid defibrillation as the most important 'link' in the 'chain of survival'. For most ventricular fibrillation patients who have professional rescuers arrive after 5-8 minutes of ventricular fibrillation, however, immediate defibrillation is likely to be ineffective. Counterintuitively, these patients may benefit from a period of chest compressions prior to being shocked.

Cardiac Arrest Resuscitation Evaluation in Los Angeles: CARE-LA

STUDY OBJECTIVE

We determine survival for out-of-hospital cardiac arrests in Los Angeles using the Utstein method and compare these data with that reported for other urban and suburban areas.

METHODS

This was a prospective observational cohort study of adult patients in Los Angeles presenting with nontraumatic, out-of-hospital cardiac arrest and with attempted out-of-hospital resuscitative efforts between July 1, 2000, and July 1, 2001. Entry criteria, time intervals, and nodal events conformed to Utstein template recommendations. The single target endpoint was neurologically intact survival at hospital discharge.

RESULTS

Of 2,021 consecutive cardiac arrest patients on whom resuscitation was attempted, 1,700 (84%) met entry criteria as a primary cardiac event. Overall, neurologically intact survival was 1.4% (99% confidence interval [CI] 0.8% to 2.4%) Three patients were lost to follow-up. Survival from bystander-witnessed ventricular fibrillation was 6.1% (99% CI 3.3% to 11.0%). Absolute survival differences from witnessed ventricular fibrillation was higher but not statistically different than that from Chicago (-3%; 99% CI -8% to 2%) and New York City (-2%; 99% CI -6% to 3%). The rate of bystander cardiopulmonary resuscitation (CPR) for our population was 28%, for which the overall survival rate was 2.1%. The survival rate for patients with witnessed arrests and bystander CPR was 3.2%. Among patients with no bystander CPR, the survival rate was 1.0%.

CONCLUSION

Survival from out-of-hospital cardiac arrest in Los Angeles was low but similar to that reported for New York and Chicago. This low survival rate may be due to population density, low bystander CPR rates, and traffic congestion delaying emergency response.

Prediction rules for estimating neurologic outcome following out-of-hospital cardiac arrest

BACKGROUND

No valid model has been developed to predict survival following out-of-hospital cardiac arrest. The purpose of this study was to develop a prediction model for meaningful survival following out-of-hospital cardiac arrest using variables available during resuscitation.

METHODS

This was a retrospective cohort study. Consecutive adult cardiac arrest patients were studied between 1994 and 2001. Variables included age, sex, race/ethnicity, arrest location, whether the arrest was witnessed, initial rhythm, whether CPR was performed, patient downtime, paramedic response time, survival to hospital discharge, and Glasgow Coma Score (GCS) at hospital discharge. Classification and Regression Tree analysis was used to develop decision rules to predict meaningful survival, as defined by the patient's discharge GCS.

RESULTS

Of the 754 patients, 16 (2%) survived with a GCS > or =13, 15 (2%) survived with a GCS = 14, and 5 (0.7%) survived with a GCS = 15. The decision rule for survival with a GCS > or = 13 incorporated whether the arrest was witnessed and the patient's age, resulting in a negative predictive value (NPV) of 99.8%. The rule for survival with a GCS > or = 14 incorporated the initial arrest rhythm, whether the arrest was witnessed, and the patient's age, resulting in a NPV of 99.6%. The rule for survival with a GCS = 15 incorporated only the interval between collapse and the initiation of life support, resulting in a NPV of 99.8%.

CONCLUSIONS

This study reports decision rules for potential meaningful survival following out-of-hospital cardiac arrest with high NPVs for each. Future studies need to be performed to prospectively validate these models.

Impact of community-wide deployment of biphasic waveform automated external defibrillators on out-of-hospital cardiac arrest in Taipei

OBJECTIVES

To determine the impact and outcome of out-of-hospital cardiac arrests (OHCA) while using automated external defibrillators (AED) with biphasic waveforms and its effectiveness when using the Utstein Style community-wide in Taipei.

MATERIAL AND METHODS

A one-year study was conducted to collect OHCA patients with AED utilization prospectively in Taipei City. All events and variables were recorded in the Utstein Style. Electrocardiography and voice records recovered from AED data cards were analysed. The endpoints were survival outcomes.

RESULTS

Of 653 OHCA patients with AED utilization, only 80 (12.6%) patients with 635 true arrests presented with ventricular fibrillation or tachycardia (VF/VT) as the initial rhythm. The interval between call-to-shock was 5 min longer than call-to-EMS arrival (9.3 min versus 4.0 min). Fourteen (25%) of the 55 witnessed VF/VT arrests survived to home discharge. Ninety-seven percent of shockable rhythms were successfully terminated with less than three shocks. For all OHCA patients, initial rhythm of VF/VT (OR 3.4; 95% CI = 1.2-9.4), witnessed status (OR 4.7; 95% CI = 1.3-16.6), and presence of organised rhythm irrespective of pulse during prehospital resuscitation (OR 9.2; 95% CI = 3.2-26.8) demonstrated an independent association with survival to home discharge. For VF/VT arrests, witnessed status, shorter call-to-shock time, high successful rate of the first shock, fewer averaged number of shocks delivered for each patient, and presence of an organised rhythm during prehospital resuscitation showed a likelihood to predict to predict discharged survival in univariate analysis.

CONCLUSIONS

Low frequency of VF arrests is unique to certain eastern populations but without a reduction of AED shock efficacy with biphasic waveform. Besides initial VF and witnessed status, a prehospital post-shock organized rhythm irrespective of pulse appears to be correlated to survival. Certain circumstances in a congested metropolitan city consume time to deliver shocks even after EMS arrival, and might require bystander or public access defibrillation.

Assessment of quality of life and cognitive function after out-of-hospital cardiac arrest with successful resuscitation

This prospective cohort study evaluated the impact of the time-related elements of the "chain of survival" on the quality of life of patients, taking their characteristics into account. Between 1995 and 2002, consecutive, out-of-hospital cardiac arrest patients from Amsterdam and the surrounding areas were included in this study. A total of 227 patients (12%) survived to hospital discharge and 174 were definitive survivors who were available for assessment at 6 months. Quality of life was measured with the 136-item Sickness Impact Profile (SIP); cognitive functioning was assessed through the Mini Mental State Examination. SIP profiles were compared with profiles of an open Dutch population of the elderly and patients who experienced a stroke. Time intervals of the chain of survival were calculated from the estimated moment of collapse and related to outcome using regression analysis. The SIP profile of survivors was a little above the reference profile, indicating a slightly poorer quality of life, and below the profile of patients after stroke, indicating a better quality of life. Impaired cognitive function was associated with delay in the start of cardiopulmonary resuscitation (odds ratio 4.3, 95% confidence interval 1.0 to 19). Absence of the need for advanced cardiopulmonary life support was associated with better cognitive functioning (odds ratio 0.3, 95% confidence interval 0.1 to 0.9). Female gender and older age were associated with impaired physical functioning. Trends were found for better outcomes after early access, immediate resuscitation, early defibrillation, and early advanced care.

VF recurrence: characteristics and patient outcome in out-of-hospital cardiac arrest

BACKGROUND

Refibrillation after successful defibrillation in out-of-hospital cardiac arrest is a frequent event. Little is known of factors that predispose to the occurrence of refibrillation. The effect of recurrence of ventricular fibrillation (VF) on survival is not known.

METHODS

Data of patients in out-of-hospital cardiac arrest were collected in a combined first responder and paramedic programme in Amsterdam, the Netherlands. Continuous recorded rhythm data of 322 patients covering the entire out-of-hospital resuscitation attempt was included in the analysis. Recurrence of VF was recorded, the patient and process characteristics were analysed in relation to the occurrence of refibrillation. The number of refibrillations was related to survival.

RESULTS AND CONCLUSION

Of the studied patients 79% had at least one recurrence of VF, and a median number of two times 25-75%; one to four times). The median time from successful first shock to VF recurrence was 45 s (25-75%: 23-115 s). A significant inverse relation was found between the number of refibrillations and survival of out-of-hospital cardiac arrest. The recurrence of VF was independent of the underlying cardiac disorder, the time to defibrillation, the defibrillation waveform and other characteristics of the patient and the process. Anti-arrhythmics should be considered in all patients found in VF to reduce the number of recurrences.

Out-of-hospital defibrillation with automated external defibrillators: postshock analysis should be delayed

STUDY OBJECTIVE

The American Heart Association protocols for use of automated external defibrillators (AEDs) recommend that a rhythm analysis be done immediately after each defibrillation attempt. However, shock is often followed by electrical silence or marginally organized electrical activity before ventricular fibrillation (VF) or ventricular tachycardia (VT) recurs. The optimal timing of postshock analysis for identification of recurrent VF/VT is unknown. This study examines the time to recurrence of VF/VT after a defibrillation attempt with AED.

METHODS

Over an 18-month period, all tapes from patients with out-of-hospital cardiac arrest who received shocks at least once with an AED were screened for recurrent VF/VT. All cases come from a single emergency medical services system providing basic life support, defibrillation with AED, and intubation with an esophageal-tracheal twin-lumen airway device (Combitube) for a population of 633,511 individuals. Pediatric and traumatic cases were excluded. When VF/VT recurred within 3 minutes of the defibrillation attempt, rhythm strips were printed and included in the study. Two cardiology fellows, blinded to the study objectives, measured the time from defibrillation to recurrent VF/VT for each strip.

RESULTS

Over the study period, 222 tapes from 96 patients met the inclusion criteria. Only 44 (20%) occurrences of VF/VT had recurred within 6 seconds of defibrillation, 162 (73%) at 60 seconds, and 200 (90%) at 90 seconds.

CONCLUSION

Eighty percent of VF/VT recurred more than 6 seconds after defibrillation and were missed when using current American Heart Association AED protocols. Subsequent analysis should be postponed until at least 30 seconds after defibrillation. Performing 30 seconds of chest compressions after defibrillation before subsequent AED rhythm analysis would increase AED identification of VF/VT to 52%.

Ability of laypersons to estimate short time intervals in cardiac arrest

STUDY OBJECTIVE

Estimates of time intervals by bystanders are considered critical in cardiac arrest, and are often used in other disorders such as stroke and myocardial infarction. Because they have never been previously studied, we sought to determine their accuracy.

METHODS

This study was performed by prospective collection of bystander estimates (made at the time of the arrest) of the time from calling 911 to the arrival of urban fire department first responders, and comparison with actual measured response interval from computerized records, in all out-of-hospital cardiac arrests from January 1996 through June 1998.

RESULTS

The fire department responded to 1,015 patients in cardiac arrest during the study period. First responders arrived before advanced life support providers to 831 patients, who thus met study entry criteria. Bystander estimates were obtained in 497 of these 831 patients, who did not differ in key characteristics from those lacking estimates. The bystander's average estimated fire department response interval was 5.6 minutes (95% confidence interval [CI] 5.2 to 5.9 minutes) and the actual measured interval to the patient's side from computer records was 6.1 minutes (95% CI 5.9 to 6.4 minutes). However, the median error of the bystander estimate (1.3 minutes) was 32% of the median of the actual measured on-scene interval, and there was no correlation between the bystander estimates and the measured interval in individual cases (R </=0.14), regardless of which intervals were examined. Seventy-five percent of the bystander estimates erred by 20% or more. When bystanders estimated a response interval as excessively long, they were almost invariably wrong, but they also usually failed to identify intervals that actually were long.

CONCLUSION

Although many diagnostic and research conclusions are based on interval estimates from laypersons, we found no correlation between estimates and actual measured intervals in cardiac arrest. Current methodology may not be developed well enough to provide reliable data for research or quality assurance, and other clinical time estimates by patients and bystanders may be equally unreliable.

Automatic external defibrillators: lessons from the past, present and future

Coronary artery disease remains the leading cause of death in the United States and most developed countries. Many of the victims die from sudden cardiac arrests, resulting from dysrhythmias-most commonly ventricular fibrillation. Since most cardiac arrests occur outside the hospital, implementing emergency services in the field will have a great impact on survival. With the development of the modern automatic external defibrillator (AED), early recognition and correction of these dysrhythmias by lay rescuers can significantly improve outcome from sudden death. This paper reviews the past, present and future development and applications of AEDs.

Outcome from out-of-hospital cardiac arrest caused by nonventricular arrhythmias: contribution of successful resuscitation to overall survivorship supports the current practice of initiating out-of-hospital ACLS

STUDY OBJECTIVE

Studies indicate that ventricular tachycardia (VT) and ventricular fibrillation (VF) are no longer the most common rhythms initially documented in out-of-hospital sudden cardiac death. Although the outcome from asystole and rhythms designated as pulseless electrical activity (PEA) is reported as poor (approximately 1% survival), resuscitative efforts for these patients are still encouraged. The purpose of this study was to determine the potential contribution that this patient group makes to overall survivorship.

METHODS

During this 2-year prospective study, all patients in cardiopulmonary arrest who were transported to the study institution after out-of-hospital Advanced Cardiac Life Support (ACLS) interventions were considered eligible for inclusion. Patients younger than 18 years of age and those in posttraumatic arrest were excluded. Age, sex, first-documented arrest rhythm, presence of a witness to the arrest, performance of bystander CPR, survival to hospital discharge, and functional status at discharge were recorded.

RESULTS

A total of 197 patients met the inclusion criteria. The initial rhythm was VF/VT in 59 (30%; 95% confidence interval [CI], 24% to 37%) and asystole/PEA in 138 (70%; 95% CI, 64% to 76%). There was 1 hospital survivor in the VT/VF group; 9 patients (7%; 95% CI, 4% to 13%) in the asystole/PEA group survived to hospital discharge. Of the asystole/PEA survivors, 100% (95% CI, 66% to 100%) had a witnessed arrest and 56% (95% CI, 21% to 86%) received bystander CPR. Fifty-six percent (95% CI, 21% to 86%) of the asystole/PEA survivors were discharged at a functional level equivalent to that preceding arrest.

CONCLUSION

In this study, patients in asystole/PEA comprised 90% of the survivors. The outcome for patients with asystole/PEA whose arrest was witnessed and who received bystander CPR may be greater than previously estimated and supports the current practice of initiating aggressive out-of-hospital ACLS in this patient group.

The Ontario Prehospital Advanced Life Support (OPALS) Study: rationale and methodology for cardiac arrest patients

The Ontario Prehospital Advanced Life Support Study represents the largest prehospital study yet conducted, worldwide. This study will involve more than 25,000 cardiac arrest, trauma, and critically ill patients over an 8-year period. The study will evaluate the incremental benefit of rapid defibrillation and prehospital Advanced Cardiac Life Support measures for cardiac arrest survival and the benefit of Advanced Life Support for patients with traumatic injuries and other critically ill prehospital patients. This article describes the OPALS study with regard to the rationale and methodology for cardiac arrest patients.

Advanced life support vs basic life support field care: an outcome study

OBJECTIVE

To determine whether the provision of advanced life support (ALS) field care has any impact on patient outcome in the urban Canadian environment.

METHODS

A convenience cohort study was conducted of all emergent ambulance transfers of adults to an urban Canadian hospital from May 22 to July 31, 1996. Data were collected from ambulance call reports regarding presenting complaint and field interventions applied, and from hospital records regarding time in the ED, hospital length of stay (LOS), and discharge disposition. Patient outcomes were compared within 7 presenting complaint groups (chest pain, altered level of consciousness, shortness of breath, abdominal pain, motor vehicle crash, falls, and other) by field care level: level 1--BLS (basic life support) vs levels 2 and 3--ALS.

RESULTS

The study population consisted of 1,397 patients. No significant differences were seen between BLS and ALS patients on baseline demographics. ED triage score did not depend on field care level for any group, implying that those in the ALS group were not inherently sicker. Outcome measures (ED LOS, admission rates, and hospital LOS) showed no significant differences between BLS and ALS for each presenting complaint group. Discharge dispositions were analyzed by chi2 but were not varied enough to allow reliable analysis. Observation of trends suggested no difference between BLS and ALS.

CONCLUSIONS

There was no beneficial impact on the measured patient outcomes found in association with the provision of ALS vs BLS field care in Metropolitan Toronto for patients who were brought to a nontrauma center.

Cardiopulmonary resuscitation: a review for clinicians

Attempts at cardiopulmonary resuscitation (CPR) date from antiquity, but it is only in the last 50 years that a scientifically-based methodology has been developed. External chest compressions is the standard method for managing circulatory arrest, however, numerous alterations of this technique have been proposed in attempts to improve outcome from CPR. Defibrillation is the single most important therapy for the management of ventricular fibrillation or pulseless ventricular tachycardia. Adrenergic agents used to improve myocardial and cerebral perfusion are also the subject of considerable investigation with new agents entering clinical study. This paper reviews the history, current techniques and pharmacotherapy as well as controversial issues in the management of patients with cardiac arrest.

Cardiopulmonary resuscitation on television. Miracles and misinformation

BACKGROUND

Responsible, shared decision making on the part of physicians and patients about the potential use of cardiopulmonary resuscitation (CPR) requires patients who are educated about the procedure's risks and benefits. Television is an important source of information about CPR for patients. We analyzed how three popular television programs depict CPR.

METHODS

We watched all the episodes of the television programs ER and Chicago Hope during the 1994-1995 viewing season and 50 consecutive episodes of Rescue 911 broadcast over a three-month period in 1995. We identified all occurrences of CPR in each episode and recorded the causes of cardiac arrest, the identifiable demographic characteristics of the patients, the underlying illnesses, and the outcomes.

RESULTS

There were 60 occurrences of CPR in the 97 television episodes--31 on ER, 11 on Chicago Hope, and 18 on Rescue 911. In the majority of cases, cardiac arrest was caused by trauma; only 28 percent were due to primary cardiac causes. Sixty-five percent of the cardiac arrests occurred in children, teenagers, or young adults. Seventy-five percent of the patients survived the immediate arrest, and 67 percent appeared to have survived to hospital discharge.

CONCLUSIONS

The survival rates in our study are significantly higher than the most optimistic survival rates in the medical literature, and the portrayal of CPR on television may lead the viewing public to have an unrealistic impression of CPR and its chances for success. Physicians discussing the use of CPR with patients and families should be aware of the images of CPR depicted on television and the misperceptions these images may foster.

Effectiveness of emergency medical services for victims of out-of-hospital cardiac arrest: a metaanalysis

STUDY OBJECTIVE

To determine the relative effectiveness of differences in response time interval, proportion of bystander CPR, and type and tier of emergency medical services (EMS) system on survival after out of hospital cardiac arrest.

METHODS

We performed a comprehensive literature search, excluding EMS systems other than those of interest (systems of interest were those comprising one tier with providers of basic life support [BLS] or advanced life support [ALS] and those comprising two tiers with providers of BLS or BLS-defibrillation followed by ALS), patient population of fewer than 100 cardiac arrests, studies in which we could not determine the total number of arrests of presumed cardiac origin, and studies lacking data on survival to hospital discharge. Metaanalysis using generalized linear model with dispersion estimation for random effects was then performed.

RESULTS

Increased survival to hospital discharge was significantly associated with tier (P < .01), response time interval (P < .01), and bystander CPR (P = .04). A significant interaction was detected between response time interval and bystander CPR (P = .02). For the studies analyzed, survival was 5.2% in a one-tier EMS system or 10.5% in a two-tier EMS system. A 1-minute decrease in mean response time interval was associated with absolute increases in survival rates of .4% and .7% in a one-tier and two-tier EMS systems, respectively.

CONCLUSION

Increased survival to hospital discharge may be associated with decreased response time interval and with the use of a two-tier EMS system as opposed to a one-tier system. The data available for this analysis were suboptimal. Policymakers need more methodologically rigorous research to have more reliable and valid estimates of the effectiveness of different EMS systems.

Early endothelial damage and leukocyte accumulation in piglet brains following cardiac arrest

This study examined the early microvascular and neuronal consequences of cardiac arrest and resuscitation in piglets. We hypothesized that early morphological changes occur after cardiac arrest and reperfusion, and that these findings are partly caused by post-resuscitation hypertension. Three groups of normothermic piglets (37.5 degrees - 38.5 degrees C) were investigated: group 1, non-ischemic time controls; group 2, piglets undergoing 8 min of cardiac arrest by ventricular fibrillation, 6 min of cardiopulmonary resuscitation (CPR) and 4 h of reperfusion; and group 3, non-ischemic hypertensive controls, receiving 6 min of CPR after only 10 s of cardiac arrest followed by 4-h survival. Immediately following resuscitation, acute hypertension occurred with peak systolic pressure equal to 197 +/- 15 mm Hg usually lasting less than 10 min. In reacted vibratome sections, isolated foci of extravasated horseradish peroxidase were noted throughout the brain within surface cortical layers and around penetrating vessels in group 2. Stained plastic sections of leaky sites demonstrated variable degrees of tissue injury. While many sections were unremarkable except for luminal red blood cells and leukocytes, other specimens contained abnormal neurons, some appearing irreversibly injured. The number of vessels containing leukocytes was higher in group 2 than in controls (3.8 +/- 0.6% vs 1.4 +/- 0.4% of vessels, P < 0.05). Evidence for irreversible neuronal injury was only seen in group 2. Endothelial vacuolization was higher in groups 2 and 3 than in group 1 (P < 0.05). Ultrastructural examination of leaky sites identified mononuclear and polymorphonuclear leukocytes adhering to the endothelium of venules and capillaries only in group 2. The early appearance of luminal leukocytes in ischemic animals indicates that these cells may contribute to the genesis of ischemia reperfusion injury in this model. In both groups 2 and 3 endothelial cells demonstrated vacuolation and luminal discontinuities with evidence of perivascular astrocytic swelling. Widespread microvascular and neuronal damage is present as early as 4 h after cardiac arrest in infant piglets. Hypertension appears to play a role in the production of some of the endothelial changes.

Death and resuscitation in the pediatric emergency department

STUDY OBJECTIVE

To describe a population of patients who arrived in a pediatric emergency department with pulse and respirations but then sustained cardiopulmonary or respiratory arrest while in the ED.

DESIGN

Retrospective case series of patients from July 1987 to June 1993.

SETTING

Urban, tertiary care pediatric ED.

PARTICIPANTS

All patients who sustained cardiopulmonary or respiratory arrest while in the ED.

RESULTS

Thirty-two cases of cardiopulmonary (n = 18) or respiratory arrest (n = 14) were identified, for an incidence of 1.2 arrests per 10,000 patient visits. Causes of arrest varied widely. Excluding those patients with do-not-resuscitate orders (n = 2), an initial response to resuscitative efforts was obtained in 22 of 30 (73%) patients. Overall rates of survival to discharge from the ED and from the hospital were 21 of 30 (70%) and 15 of 30 (50%), respectively. Of those patients who survived to hospital discharge, 12 of 15 (80%) were discharged at a baseline level of overall function.

CONCLUSION

Cardiopulmonary or respiratory arrest in the pediatric emergency department is rare. The rate of survival of such an arrest is superior to that in outpatient arrests but inferior to that in inpatient arrests.

Can correct closed-chest compressions be performed during prehospital transport?

INTRODUCTION

The resuscitation rate from out-of-hospital cardiac arrest is low. There are many factors to be considered as contributing to this phenomenon. One factor not previously considered is the impact of a moving ambulance environment on the ability to perform closed-chest compressions.

HYPOTHESIS

Proper closed-chest compressions can be performed in a moving ambulance.

METHODS

A cardiopulmonary resuscitation (CPR) training mannequin with an attached skill meter (Skillmeter ResusciAnnie, Laerdal, Armonk, N.Y., USA) that measures each chest compression for proper depth and hand placement was used. Ten emergency medical technician-basic (EMT-B) certified prehospital providers were assigned into one of five teams. Each team performed a total of four sessions of five minutes of continuous closed-chest compressions on the mannequin. Two sessions were done by each team: one in the control environment with the mannequin placed on the floor, and the other in the experimental environment with the mannequin placed in the back of a moving ambulance. The ambulance was operated without warning lights and siren, and all traffic rules were obeyed. The percentage of correct closed-chest compressions was recorded for each session, and the mean values were compared using Student's t-test with alpha set at 0.01 for statistical significance.

RESULTS

Ten sessions of compressions were done in both environments. The mean percentage of correct compressions was 77.6 +/- 15.6 for the control group and 45.6 +/- 18.3 for the ambulance group (p = 0.0005).

CONCLUSION

A moving ambulance environment appears to impair the ability to perform closed-chest compressions.

Quality of bystander cardiopulmonary resuscitation influences outcome after prehospital cardiac arrest

To evaluate the influence of quality of bystander cardiopulmonary resuscitation (CPR) on outcome in prehospital cardiac arrest we consecutively included patients with prehospital cardiac arrest treated by paramedics in a community run ambulance system in Oslo, Norway from 1985 to 1989. Good CPR was defined as palpable carotid or femoral pulse and intermittent chest expansion with inflation attempts. Outcome measure was hospital discharge rate. One hundred and forty-nine of 334 patients (45%) received bystander CPR. The discharge rate after good BCPR (23%) was higher than after no good BCPR (1%, P < 0.0005) or after no BCPR (6%, P < 0.0005). There was no difference between no good and no BCPR (P = 0.1114). There were no differences in paramedic response interval between the groups, but the mean interval from start of unconsciousness to initiation of CPR (arrest-CPR interval) was significantly shorter in the group receiving good bystander CPR (2.5 min, 95% confidence interval (CI): 1.7-3.3 min) than no good CPR (6.6 min, CI: 5.2-8.0 min) or no bystander CPR (7.8 min, CI: 7.2-8.4 min). Bystanders started CPR more frequently in public than in the patient's home (58 vs. 34%, P < 0.0005). Good bystander CPR was associated with a shorter arrest-CPR interval and improved hospital discharge rate as compared to no good BCPR or no BCPR.

Methodology-dependent variation in documentation of outcome predictors in out-of-hospital cardiac arrest

OBJECTIVE

To identify variation in outcome predictor documentation in out-of-hospital cardiac arrest associated with two different methods of data collection: concurrent questioning of personnel following a resuscitation attempt and archival report review.

METHODS

All patients > or = 18 years old who had out-of-hospital cardiac arrests, verified using the New York City 911 telephone system, between October 1, 1990, and April 1, 1991, were eligible for inclusion. The authors reviewed the first 200 cases of presumed primary cardiac arrest involving a resuscitation attempt among 3,243 consecutive ambulance call reports for cardiac arrest occurring during the study period. This archival data set was compared with data for the same 200 cases gathered through direct interview of field personnel by trained paramedics. The two data sets had been compiled independently by different individuals, using the same data collection instrument, which conformed to the Utstein template.

RESULTS

Comparison of the data obtained from ambulance records with the data obtained from interviews of prehospital personnel revealed several areas of variance. Of note was a significantly lower proportion of bystander-witnessed ventricular fibrillation (VF) in the data set gathered from written reports (7% vs 18%; 95% CI for the difference 4-18%; p = 0.001).

CONCLUSION

differences in methods of collection of out-of-hospital cardiac arrest data are associated with a more than twofold variation in the reported incidences of witnessed cardiac arrests manifesting as VF. Methodology-dependent variation in this important "denominator" may produce substantially different estimates of survival within the same cohort of patients.

Methodology for data collection to study prehospital cardiac arrest in New York City: the PHASE methodology. PreHospital Arrest Survival Evaluation Group

STUDY OBJECTIVE

To describe an effective methodology for the investigation of prehospital cardiac arrest in large cities.

DESIGN

Observational cohort study.

SETTING

New York City emergency medical services system.

PARTICIPANTS

All cardiac arrests dispatched by the 911 system between October 1, 1990, and March 31, 1991.

INTERVENTIONS

Trained paramedics performed immediate postarrest interviews with prehospital and hospital care providers using a standardized data collection instrument.

RESULTS

Of 3,239 consecutive, confirmed cardiac arrests in which resuscitation was attempted, 2,329 (72%) were of cardiac etiology. Information was sought for 15 of the 17 core events and times recommended by the Utstein Consensus Conference Data were obtained in more than 98% of cases for all except one of these core events and times. One core time yielded data in 96% of cases. All patients were followed until death or discharge home. None were lost to follow-up.

CONCLUSION

Concurrent, interactive acquisition of prehospital cardiac arrest data in a large urban setting captured over 98% of the core data recommended for completion of the Utstein template. This methodology may be a suitable means of investigating prehospital cardiac arrest in large cities.

Effect of an in-flight helicopter environment on the performance of ALS interventions

INTRODUCTION

Patients transported by air ambulance are often critically ill and, thus, have a relatively high likelihood of requiring advanced life support (ALS) measures during transport. Despite this fact, the ability of the air medical crew to perform ALS interventions efficiently while in flight has not been investigated.

SETTING

The study was conducted with BO 105 and BK 117 helicopters and a ground transport unit at a university hospital-based air ambulance service.

METHODS

Ten flight nurses were timed performing various ALS tasks while in flight in each aircraft and in the ground ambulance. Mean times for performance of each task in the aircraft and in the ground unit were analyzed using Dunnett's method for analysis of multiple means; alpha was set at 0.01.

RESULTS

Times required to perform all ALS tasks were significantly increased in the BO 105 setting compared to the setting of the BK 117 or the ground ambulance (p < 0.01). Times for performance of interventions in the BK 117 did not differ significantly from corresponding times in the ground setting.

CONCLUSION

It appears that the environment of the BO 105 may impose limitations on the timely performance of certain ALS interventions.

Predicting survival from out-of-hospital cardiac arrest: a graphic model

STUDY OBJECTIVE

To develop a graphic model that describes survival from sudden out-of-hospital cardiac arrest as a function of time intervals to critical prehospital interventions.

PARTICIPANTS

From a cardiac arrest surveillance system in place since 1976 in King County, Washington, we selected 1,667 cardiac arrest patients with a high likelihood of survival: they had underlying heart disease, were in ventricular fibrillation, and had arrested before arrival of emergency medical services (EMS) personnel.

METHODS

For each patient, we obtained the time intervals from collapse to CPR, to first defibrillatory shock, and to initiation of advanced cardiac life support (ACLS).

RESULTS

A multiple linear regression model fitting the data gave the following equation: survival rate = 67%-2.3% per minute to CPR-1.1% per minute to defibrillation-2.1% per minute to ACLS, which was significant at P < .001. The first term, 67%, represents the survival rate if all three interventions were to occur immediately on collapse. Without treatment (CPR, defibrillatory shock, or definitive care), the decline in survival rate is the sum of the three coefficients, or 5.5% per minute. Survival rates predicted by the model for given EMS response times approximated published observed rates for EMS systems in which paramedics respond with or without emergency medical technicians.

CONCLUSION

The model is useful in planning community EMS programs, comparing EMS systems, and showing how different arrival times within a system affect survival rate.

Out-of-hospital transcutaneous pacing by emergency medical technicians in patients with asystolic cardiac arrest

BACKGROUND

Transcutaneous cardiac pacemakers generate electrical stimuli that pace the heart through external electrodes that adhere to the chest wall. Transcutaneous pacing has been useful in some patients with bradycardia, but its efficacy in patients with asystole and full cardiac arrest has been limited, possibly because of delays in the initiation of pacing. We studied the efficacy of early transcutaneous pacing in patients with out-of-hospital asystolic cardiac arrest.

METHODS

For three years we provided transcutaneous pacemakers to about half the fire districts in a large emergency-medical-services system (the intervention group). In these districts, we authorized emergency medical technicians (EMTs) to begin transcutaneous pacing in patients with cardiac arrest and primary asystole or post-defibrillation asystole. Pacing was done as early as possible, before endotracheal intubation or intravenous medication. EMTs in the other fire districts (the control group) treated similar patients with basic cardiopulmonary resuscitation but without transcutaneous pacing.

RESULTS

The EMTs in the intervention group initiated transcutaneous pacing in 112 of the 278 patients with primary asystole. Of these patients, 22 (8 percent) were admitted to the hospital, and 11 (4 percent) were discharged. Among the 259 patients treated by the EMTs in the control group, 21 (8 percent) were admitted to the hospital, and 5 (2 percent) were discharged. The two groups did not differ significantly with respect to the rate of hospital admission or survival. Survival after early pacing for post-defibrillation asystole was no better than survival after pacing for primary asystole.

CONCLUSIONS

Transcutaneous pacing appears to offer no benefit in patients with asystolic cardiac arrest, even when it is performed as early as possible by EMTs in the field. Our data suggest that the widespread implementation of early transcutaneous pacing for out-of-hospital asystolic cardiac arrest would be ineffective.

Survival from out-of-hospital cardiac arrest: effects of patient age and presence of 911 Emergency Medical Services phone access

The purpose of this investigation was to determine factors associated with survival from out-of-hospital cardiac arrest, including effects of 911 Emergency Medical Services telephone access and the age of patient. Subjects included 1,753 prehospital cardiac arrest patients in Iowa. Patient survival status and other variables were compared for patients with access to a 911 service with those who did not, and for different age categories, using univariate associations and multivariate logistic regression analysis. The presence of 911 telephone access was significantly associated with survival from out-of-hospital cardiac arrest (9.18% versus 5.35% survival for 911 versus no 911 groups, respectively). This association was partially the result of the significant association of 911 with decreased time from collapse to call for help, decreased time to cardiopulmonary resuscitation (CPR), and decreased time to first shock (if in ventricular fibrillation [VF]). Younger age was significantly associated with survival in univariate analyses (8.94% versus 6.26% survival for younger versus older age groups, respectively), but this was not an independent association, which is indicated by the lack of significance of age in the multivariate model.

Ensuring the effectiveness of community-wide emergency cardiac care

To improve emergency cardiac care (ECC) on the national or international level, we must translate to the rest of our communities the successes found in cities with high survival rates. In recent years, important developments have evolved in our understanding of the treatment and evaluation of cardiac arrest. Some of the most important of these developments include 1) recognition of the chain of survival, which is necessary to achieve high survival rates; 2) widespread acceptance that survival rates must be assessed routinely to ensure continuous quality improvements in the emergency medical services (EMS) system; and 3) development of improved methods for performing survival rate studies that will maximize the effectiveness of information gathering and analysis. While each community should determine how to optimize their own ECC services, some general guidelines are useful. Successful treatment of cardiac arrest starts in the community with prevention and education, including early recognition of the signs and symptoms of cardiovascular ischemia. Obtaining 911 service (and preferably enhanced 911) should be a top priority for all communities. EMS dispatchers should dispatch the unit to the scene in less than one minute, provide critical information to the responders regarding the type of emergency, and offer the caller telephone-assisted CPR instructions. The EMS first-responders should strive to arrive at the patient's side in less than four minutes, be able to immediately defibrillate if necessary, and begin basic CPR. An excellent strategy to accomplish this is to equip and train all fire-fighting units in the operation of automatic external defibrillators and dispatch them as a first-responder team. To manage the cardiac arrest patient, a minimum of two rescuers trained in advanced cardiac life support plus two or more rescuers trained in basic life support are needed. Furthermore, an EMS system is not complete without on-going evaluation. Therefore, the 1992 National Conference on CPR and ECC strongly endorses the position that all ECC systems assess their survival rates through an ongoing quality improvement process and that all members of the chain of providers should be represented in the outcome assessment team. We still have much to discover regarding optimal techniques of CPR, methods for data collection, and optimal structure of an EMS system. Research in these areas will provide the foundation for future changes in EMS systems development.