A rapid response system for out-of-hospital cardiac emergencies.

We have reviewed several aspects of our initial 5 years' experience with an out-of-hospital emergency medical care system. This system is stratified and provides for rapid primary response and, when indicated, secondary response by specially trained paramedical personnel. Patient care is physician-supervised and closely monitored. Although considerable attention has been directed to acute complications of ischemic heart disease, particularly the problem of sudden cardiac death, the system is broadly based and responds to all medical emergencies. We are impressed with the ability of nonphysicians to acquire certain medical skills and judgment. Indeed, the effectiveness of this system is largely dependent on paramedical personnel. Such systems of prehospital emergency medical care will probably have an impact greater than that of hospital coronary care units in reducing the mortality from ischemic heart disease.     

Early defibrillation in out-of-hospital sudden cardiac death: an Australian experience.

All patients with primary cardiac disease presenting with out-of-hospital sudden cardiac death (OH-SCD) to a provincial hospital were reviewed retrospectively over a 5-year period from 1985 to 1989. This coincided with the introduction of out-of-hospital defibrillation (OH-DEFIB) by ambulance officers. Of 215 patients, 17 (9%) survived to leave hospital alive, 15 of whom underwent OH-DEFIB. There was an increase in survivors from 4%, prior to OH-DEFIB, to 9% of all cardiac arrests, but this was not statistically significant (P = 0.3). However, long term survival amongst immediate survivors was associated with a statistically significant improvement following the introduction of OH-DEFIB (15 of 30 (50%) vs. 2 of 19 (10.5%), P < 0.01). Mean call-out, at-scene and transfer times did not significantly vary between survivors and non-survivors. A total of 155 (72%) had a known cardiac history, with the majority (74%) of arrests occurring at home. Of 134 witnessed arrests, only 46 (34%) underwent bystander-initiated cardiopulmonary resuscitation (CPR). A programme in CPR aimed at relatives of known cardiac patients, and the adoption of a paramedic protocol which improves oxygenation at the time of arrest are recommended.     

Flying Squad response to medical emergencies.

The Flying Squad of the Accident and Emergency Department, of the Derbyshire Royal Infirmary, was established in 1955 by Collins. The initial function was to provide emergency care to victims of industrial accidents. However, the spectrum of emergencies they now respond to has expanded and includes predominantly road traffic accidents and medical emergencies. Despite the proliferation of Flying Squads their benefit has been difficult to quantify even in a trauma setting (Robertson & Steedman, 1985; Gorman & Coals, 1983). The outcome in medical emergencies is reported as dismal (Robertson & Steedman, 1985; Rowley & Collins, 1979) yet the number of calls for the flying squad to attend medical emergencies are many. Previous reports have recorded 20-30% of Squad calls responding to medical emergencies (Gorman & Coals, 1983; Rowley & Collins, 1979; Steedman & Robertson, 1986; Harrop & Bodiwala, 1983).     

Prehospital cardiac arrest--a critical analysis of factors affecting survival

During a 10-year period, 5631 cardiac arrests were treated in our paramedic system. In all, 4216 resuscitations were attempted, of which 533 (12.6%) resulted in saves, defined as hospital discharges. Patients presenting with an initial rhythm of coarse ventricular fibrillation or ventricular tachycardia were found to have significantly increased save rates in comparison to those presenting with an initial arrest rhythm of asystole/fine ventricular fibrillation or electromechanical dissociation (P less than or equal to 0.01). When controlling for witnessed arrest, 303 of 1905 (15.9%) of all witnessed arrests were saves vs. 230 of 2311 (10%) of unwitnessed arrests (P less than or equal to 0.01). Witnessed bystander/first responder external cardiac compression- cardiopulmonary resuscitation (ECC-CPR) was found not to influence save rate. One hundred eighty-one of 1248 bystander/first responder witnessed arrests (14.5%) who had external ECC-CPR initiated before paramedic advanced life support arrival were saves, compared with 38 of 252 (15.1%) who had no ECC-CPR initiated until paramedic arrival; this was not statistically significant. Advanced life support response times in saved patients with witnessed cardiac arrests were analyzed. Ninety-five percent of all saves had a response time of less than 10 min. We conclude that, when evaluating the effectiveness of CPR, the variables of witnessing of arrest, presenting arrest rhythm, and respective response times must be controlled or analyzed.     

Nineteen years' experience of out-of-hospital cardiac arrest in Gothenburg--reported in Utstein style

OBJECTIVE: To describe the outcome in the Utstein style for out of hospital cardiac arrest in Gothenburg, over a period of 19 years. METHODS: All consecutive cases of cardiac arrest between 1980 and 1999 in which the emergency medical service (EMS) system responded and attempted resuscitation were reported and followed up for 1 year. RESULTS: In all, there were 5270 attempts. 3871 (73%) of which were regarded as being of a cardiac aetiology. In these cases, information on witnessed status was missing in 782 cases (20%). Of the remaining 3089 cases, 2066 (67%) were bystander witnessed, 791 (26%) were unwitnessed and 232 (8%) crew witnessed. The median interval between a call for the ambulance and the arrival of the first ambulance was 5 min. Thirteen percent of the bystander-witnessed cases were discharged from hospital. Of the unwitnessed cases, only 2% were discharged from hospital, whereas 22% of the crew-witnessed cases were discharged. Of the patients with a bystander-witnessed cardiac arrest of a cardiac aetiology found in ventricular fibrillation (VF), 20% were discharged from hospital. CONCLUSION: In this large Utstein style study of out of hospital cardiac arrest stretching over almost 19 years, we report high survival rates both for patients suffering a bystander-witnessed cardiac arrest, and for the subgroup suffering a bystander-witnessed cardiac arrest with VF as the first recorded rhythm. These high survival rates can in part be explained by the short time intervals from calls being received by the emergency dispatch centre (EDC) to the arrival of the emergency medical service at the scene.     

Predicting survival from out-of-hospital cardiac arrest.

OBJECTIVE: To determine the effect of a return of spontaneous circulation (RO SC) on survival to hospital discharge as compared to other established predictors of survival. METHODS: A retrospective case review of all out-of-hospital primary cardiac arrests from 01 January, 1992 to 31 December 1994 was conducted. The relative values of age, race, gender, presenting cardiac rhythm, witnessed event, initiation of CPR by bystanders, response time intervals, and return of spontaneous circulation (ROSC) in an Utstein-template database were tested as predictors of survival of patients who had suffered a cardiac arrest in the out-of-hospital setting. The ROSC was defined as return of spontaneous circulation prior to and present upon arrival at the emergency department. Predictors were evaluated for statistical significance using a logistic regression analysis (p < 0.05). Odds ratios (OR) and 95% confidence intervals (CI) with positive and negative predictive values (PPV, NPV) were calculated. RESULTS: Of 832 patients with primary cardiac arrest, 153 (18.4%) had ROSC and 67 (8.1%) survived to hospital discharge. Comparing survivors to nonsurvivors, the mean values for age were 64 to 67 years, with 59.7% to 36.1% being witnessed, 35.8% to 23.9% having bystander CPR initiated, 88.1% to 48.4% having ventricular fibrillation (V-fib) and 82.1% to 64.0% having ROSC. An initial electrocardiographic rhythm of V-fib (p = 0.009; OR = 2.2; CI = 1.2-3.9), and ROSC (p < 0.0001; OR = 5.2; CI = 3.6-7.5) are statistically significant predictors of survival to hospital discharge. The PPV was 13.8% for V-fib and 35.9% for ROSC, and the NPV was 98.0% for V-fib and 98.2% for ROSC. CONCLUSION: Presenting V-fib and out-of-hospital ROSC are significant predictors of survival from cardiac arrest. Failure to obtain ROSC in the out-of-hospital setting strongly suggests consideration for terminating resuscitation efforts.     

Clinical experience with a low-energy pulsed biphasic waveform in out-of-hospital cardiac arrest

The efficiency of a pulsed biphasic waveform (PBW) was compared with that of biphasic truncated exponential (BTE) waveforms. First defibrillation shock outcome was studied in a population of 104 out-of-hospital cardiac arrest patients in ventricular fibrillation as the presenting rhythm. The call to first shock time was 8.2+/-5.4 min. At 5s post-shock, defibrillation efficiency was 90%. The arrest was witnessed in only 50% of the patients and only 5% received bystander CPR. Despite these limitations 38% of the patients achieved restoration of a spontaneous circulation at departure from scene and 9.8% were discharged from the hospital. These observations demonstrate a rate of first shock success in termination of ventricular fibrillation comparable to that reported with biphasic truncated exponential waveforms in out-of-hospital cardiac arrest.     

An outcome study of out-of-hospital cardiac arrest using the Utstein template--a Japanese experience

Publication of the Utstein style template has made it possible to evaluate and compare national, regional, and hospital based Emergency Medical Services. This research was a national investigation to present outcome data for out-of-hospital cardiac arrest (OHCA) patients in Japan. 3029 OHCA patients who were transported to 10 Emergency and Critical Care Medical Center from November 1997 to April 1999 were recorded according to the Utstein style and the outcome evaluated by logistic regression analysis. Among 3029 OHCA patients, 109 were found dead. The remaining 2920 patients who underwent cardiopulmonary resuscitation (CPR) by emergency medical technicians (EMT) were included in this study. Among these patients, 1294 were considered of primary cardiac origin patients by the EMT and 722 of these patients suffered a witnessed cardiac arrest. Bystander CPR were performed in 28.4% of these witnessed patients and the discharge rate was 3.5% overall and 11.4% in witnessed VF/VT. Outcome analysis showed that a discharge rate in witnessed primary cardiac arrest was 30% in prehospital resuscitation which was 7.5 times higher than in-hospital emergency room resuscitation groups (4.0%). The longer the interval between an emergency telephone call and defibrillation, the lower the 1 month survival rate, which reached almost 0% at 30 min. Follow up evaluation after discharge revealed that the survival rate rapidly decreased from 24 h to 3 months, then became a plateau in primary cardiac patients was rapidly decreased from 24 h to 1 month, then became a near plateau in non-cardiac origin group. To improve the resuscitation rate in the prehospital phase, a prehospital medical control system should be developed with expansion of on scene techniques by Japanese paramedics such as tracheal intubation, administration of emergency drugs and early defibrillation with standing orders. Education and motivation of first responders will be needed and every effort should be concentrated on improving bystander CPR rate.     

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.     

Electrocardiographic evaluation of defibrillation shocks delivered to out-of-hospital sudden cardiac arrest patients.

OBJECTIVE: Following out-of-hospital defibrillation attempts, electrocardiographic instability challenges accurate assessment of defibrillation efficacy and post-shock rhythm. Presently, there is no precise definition of defibrillation efficacy in the out-of-hospital setting that is consistently used. The objective of this study was to characterize out-of-hospital cardiac arrest rhythms following low-energy biphasic and high-energy monophasic shocks in order to precisely define defibrillation efficacy and establish uniform criteria for the evaluation of shock performance. METHODS: Automatic external defibrillators (AEDs) delivering 150 J impedance-compensating biphasic or 200-360 J monophasic damped sine waveform shocks were observed in a combined police and paramedic program. ECGs from 29 biphasic patients and 87 monophasic patients were classified as organized, asystole or VF at post-shock times of 3, 5, 10, 20 and 60 s. RESULTS: Post-shock time (P<0.0001) and shock waveform type (P = 0.02) affected the classification of post-shock rhythm. At each analysis time, there were more patients in VF following high-energy monophasic shocks than following 150 J biphasic shocks (P<0.0001). The percentage of patients in VF increased with post-shock time. The rate of VF recurrence was not a function of shock type, indicating that refibrillation is largely a function of the patient's underlying cardiac disease. CONCLUSION: Defibrillation should uniformly be defined as termination of VF for a minimum of 5-s after shock delivery. Rhythms should be reported at 5-s after shock delivery to assess early effects of the defibrillation shock and at 60-s after shock delivery to assess the interaction of the defibrillation therapy and factors such as post-shock myocardial dysfunction and the patient's underlying cardiac disease.     

Survival from out-of-hospital cardiac arrest. A multivariate analysis

A recursive estimation model is used to investigate the roles of cardiopulmonary resuscitation (CPR) and advanced life support in improving survival from out-of-hospital cardiac arrest. The importance of life support measures is clearly evidenced in the analysis: Fewer elapsed minutes between the cardiac arrest and the start of CPR increase the probabilities of both a favorable cardiac rhythm and defibrillation and the probability of survival. Similarly, a shorter elapsed time between the start of CPR and defibrillation is significantly related to a higher probability of survival of the cardiac arrest. Personal characteristics also contribute to survival, but primarily via their association with a favorable initial postarrest cardiac rhythm and the probability of defibrillation. The initial postarrest cardiac rhythm is shown to be an indicator of the heart's condition, but when other factors associated with survival are included in the analysis, it does not independently influence an individual's probability of survival.     

Arterial pH in out-of-hospital cardiac arrest: response time as a determinant of acidosis

It is unclear why some victims of out-of-hospital cardiac arrest are severely acidotic on arrival to the emergency department (ED), whereas others have a pH within normal limits. To explain the difference among patients, the authors collected data on 119 consecutive out-of-hospital adult nontraumatic cardiac arrest victims brought to the University of Nebraska Medical Center by paramedic rescue squad between December 1982 and January 1984. Patients who experienced restoration of spontaneous circulation (ROSC) in the field had a normal pH (7.40 +/- 0.13) as compared with the pH of patients still receiving cardiopulmonary resuscitation (CPR) on arrival at the ED (7.18 +/- 0.20). A rapid paramedic response time was the best determinant of ROSC and a normal pH on arrival at the ED. Bystander CPR neither significantly increased the number of patients with ROSC in the field nor protected against the development of acidosis, but did improve the neurological outcome of survivors. The presence of acidosis in patients still receiving CPR on arrival in the ED could not be predicted on the basis of paramedic response time, amount of sodium bicarbonate given in the field, whether or not the collapse was witnessed, or whether or not bystander CPR had been performed. Patients who were acidotic had a significantly higher (P less than 0.001) Paco2 (101 +/- 33 mm Hg) and a lower Pao2 (41 +/- 69 mm Hg) than patients with a normal pH (Paco2 37 +/- 10 mm Hg, Pao2 134 +/- 107 mm Hg). Adequacy of ventilation is the principal determinant of acidosis in patients who are still receiving CPR on arrival at the ED.     

Comparison of lactate or BE during out-of-hospital cardiac arrest to determine metabolic acidosis.

During cardiopulmonary resuscitation, pH and base excess (BE) decrease to a variable degree due to metabolic acidosis. The main cause has been shown to be lactate, which cannot be eliminated sufficiently because of low perfusion during cardiac massage. Both BE and lactate can be measured in the prehospital phase. The aim of the study was to determine if BE and lactate are comparable variables during cardiopulmonary resuscitation (CPR) and if the measurement of lactate level alone would be sufficient to determine the patient's metabolic status and sufficiently reliable to determine the administration of buffer solutions. During the observation period, we registered 31 patients (21 males, ten females) who were resuscitated according to European Resuscitation Council recommendations, who had blood gas analysis and lactate levels measured in blood taken by arterial puncture or arterial line. The first measurement from each patient was taken after primary resuscitation (within 5-20 min). The mean lactate level was 9.85+/-2.98 (range, 4.1-18.7) mmol/l, and the mean BE was -15.0+/-5.98 (range, 5.5 to -24.3). There were statistically significant correlations between the lactate level and BE and pH (linear correlation, r=-0.673, P<0,001 and r=-0,683, P<0,001, respectively), but not with pO2 and pCO2. The receiver-operated curve analysis showed that a cut-off point of 7.0 mmol/l lactate indicates a BE below -10 with a sensitivity of 96% and a specificity of 67%. Lactate measurement is a valuable tool to determine metabolic acidosis during CPR and may be able to replace blood gas analysis in this situation.     

Therapeutic hypothermia after out-of-hospital cardiac arrest due to Brugada syndrome

A 56-year-old man was admitted to our hospital after successful resuscitation for out-of-hospital cardiac arrest. Electrocardiogram on admission showed right bundle branch block and ST segment elevation in leads V1-3. Subsequent intravenous infusion of isoproterenol rapidly resolved ST segment elevation, suggesting Brugada syndrome. Therapeutic hypothermia, that was performed with a target temperature of 34.0 degrees C did not induce ST segment elevation in leads V1-3. The J-ST segment elevation rather became much more normal, suggesting a beneficial effect of mild therapeutic hypothermia. Serial ECG showed the temporal variation of ST segment elevation, and pilsicainide challenge test showed the occurrence of ST segment elevation, confirming the diagnosis of Brugada syndrome. Clinical observation suggested that mild therapeutic hypothermia reversed the Brugada phenotype through the prevention of fever as well as being indicated for cerebral protection after cardiac arrest. In conclusion, therapeutic hypothermia with a temperature of 34.0 degrees C can be used safely in Brugada syndrome.