The Brighton resuscitation ambulances: a continuing experiment in prehospital care by ambulance staff.

Two ambulances from the existing fleet in Brighton and one in Hove are equipped with portable defibrillator-oscilloscope units. Selected attendants have been trained not only to defibrillate patients but also to perform endotracheal intubation and administer intravenous atropine and lignocaine for carefully defined indications. In the two years up to December 1975 the ambulances responded to 2253 calls which were considered possible emergencies. Retrospective analysis showed that half of these had been for patients with myocardial infarction, coronary insufficiency, or angina. The ambulances took a median time of five minutes to reach a patient. Attempts at resuscitation were made in 207 patients with circulatory arrest, of whom 160 had ventricular fibrillation. Coordinated rhythm was restored at least transiently in 66 patients, and 27 of them survived to leave hospital. Sixteen of the survivors had been in ventricular fibrillation before the arrival of the ambulance. The delay before admission to hospital was reduced: over 50% of patients carried in the ambulances were admitted within two hours of the onset of major symptoms. No extra ambulance staff have been employed for the scheme. The increased load on hospital services has been limited by encouraging a rational admission policy and also by early discharge.     

Risk-benefit stratification as a guide to lidocaine prophylaxis of primary ventricular fibrillation in acute myocardial infarction: an analytic review.

Early investigators suggested that ventricular fibrillation without heart failure in acute myocardial infarction was reliably preceded by warning arrhythmias, and that suppression of such arrhythmias with intravenous lidocaine could avoid the need for resuscitation. While the efficacy and safety of lidocaine have been substantiated, the reliability of warning arrhythmias as predictors for primary ventricular fibrillation has not. We present data showing that the risk of primary ventricular fibrillation is most dependent on the patient''s age and the interval since the onset of his symptoms, rather than on the presence of warning arrhythmias. We have estimated that lidocaine prophylaxis would have to be given to about 12 patients in the highest risk group (patients under age 50 and within six hours of the onset of symptoms), compared to about 400 patients in the lowest risk group (patients above age 70 and more than 24 hours since the onset of symptoms), to prevent one episode of primary ventricular fibrillation in each group. We propose that these risk stratifications, as adapted to the conditions in specific hospitals, provide the most rational approach to lidocaine prophylaxis of primary ventricular fibrillation.     

Treatment of acute myocardial infarction with anisoylated plasminogen streptokinase activator complex.

A controlled trial in 149 patients admitted to a district hospital with probable myocardial infarction tested the effect of 30 units of anisoylated plasminogen streptokinase activator complex (APSAC) on indices of infarct size. Patients were grouped prospectively according to whether they entered the trial within two and a half hours (early entry) or between two and a half and four hours (late entry) after onset of the symptoms. Sixty seven of 73 patients in the control group showed increased plasma activity of myocardial creatine kinase isoenzyme that was diagnostic of infarction compared with only 60 of 76 who received APSAC. The difference was significant overall but occurred predominantly in the early entry group. The patients who received APSAC had more early ventricular arrhythmias, compatible with reperfusion, and showed greater preservation of R waves during admission to hospital. Unwanted effects were generally minor and more common in the actively managed group than the control group (26% v 3%). After nine to 12 months of follow up 12 patients in the control group had died compared with seven in the actively managed group. The ease of administration and the apparent efficacy of APSAC suggest that it is suitable for use in a district hospital for patients with suspected acute myocardial infarction.     

Sudden Death in Hospital after Discharge from Coronary Care Unit

In a group of 339 patients with acute myocardial infarction treated in a coronary care unit, 273 left the unit while improving and were expected to leave hospital alive; 23 had a cardiac arrest or died suddenly while still in hospital—17 died immediately or after temporary resuscitation and six were resuscitated to leave hospital alive. Ventricular fibrillation was found in 13 of the 20 patients attended by the cardiac arrest team. The incidents were scattered from the 4th to the 24th day after the onset of infarction. Risk factors in these “late sudden death” patients were compared with the 250 patients who left the unit while improving and did not die or suffer cardiac arrest. The patients susceptible to late sudden death were characterized early in their hospital course by the findings of severe, predominantly anterior infarction, left ventricular failure, persistent sinus tachycardia, and frequent ventricular arrhythmias. It is suggested that such patients be chosen for prolonged observation in a second-stage coronary care unit.     

Mobile Intensive Care in Myocardial Infarction

In the first six months of its existence a mobile intensive care unit was used to admit 95 patients with definite or probable myocardial infarction to the local district hospital. Though the area served was a rural one, with a radius of about 25 miles from the hospital, the average interval between receiving a call and starting intensive care was less than 30 minutes. Five patients with ventricular fibrillation were successfully resuscitated by the mobile team outside hospital. The mobile unit has made it possible to admit many more patients with myocardial infarction to hospital than before, and we believe its cost and use of skilled staff are justified by the results. The unit reduces the delay between the onset of symptoms and initiation of intensive care and thus diminishes the risk of primary ventricular fibrillation, which is maximal soon after the onset of symptoms. Since mobile intensive care removes the risk of transport it allows concentration of cases of acute myocardial infarction in the larger hospitals.     

Reduction of ventricular arrhythmias by early intravenous atenolol in suspected acute myocardial infarction.

The effect of intravenous atenolol on ventricular arrhythmias in acute myocardial infarction was assessed in 182 patients admitted within 12 hours of the onset of chest pain. Ninety-five patients were randomised to receive 5 mg intravenous atenolol followed immediately by 50 mg by mouth and 50 mg 12 hours later, then 100 mg daily for 10 days; 87 patients served as controls. The treated patients had significantly fewer ventricular extrasystoles; 58 control patients (67%) had R-on-T extrasystoles compared with only 25 treated patients (26%) (2p less than 0.0001); repetitive ventricular arrhythmias were detected in 64 control patients (74%) and 55 treated patients (58%) (2p less than 0.05). Heart rate was significantly reduced from 77 +/- 1 beats/min at entry to 65 +/- 1 beats/min (2p less than 0.001) in the first hour after intravenous atenolol, and in addition the rate was significantly different from that in the control group. There was no difference in the incidence of heart failure, but fewer patients in the treated group received other antiarrhythmic agents or digoxin. These results show that early intravenous atenolol prevents ventricular arrhythmias in suspected acute myocardial infarction.     

Reduced risk of death at 28 days in patients taking a beta blocker before admission to hospital with myocardial infarction.

OBJECTIVE--To see whether patients taking an oral beta blocker at the time of admission to hospital with myocardial infarction have a reduced risk of death at 28 days. DESIGN--Retrospective analysis of data collected on patients admitted over four years. SETTING--Community based study. PATIENTS--2430 Consecutive patients living in the Perth statistical division admitted to hospital with myocardial infarction during 1984-7. MAIN OUTCOME MEASURE--Survival at 28 days among patients taking a beta blocker at onset of myocardial infarction. RESULTS--Patients were grouped into those who were and were not taking a beta blocker at the time of admission. Though patients taking a beta blocker were older and more likely to have a history of myocardial infarction, angina, or hypertension, the overall mortality at 28 days was similar in the two groups. A logistic regression model used to adjust for factors predictive of cardiac death at 28 days confirmed that patients taking a beta blocker at the time of admission had a significantly reduced risk of death (relative risk 0.50; 95% confidence interval 0.34 to 0.76). Though the incidence of fatal ventricular fibrillation was similar in the two groups, mean peak creatine kinase activity was significantly lower in the beta blocker group. CONCLUSIONS--These data support the value of long term use of beta blockers in patients at risk of myocardial infarction. They suggest that patients taking these agents before admission to hospital with myocardial infarction have a significant survival advantage at 28 days, which may be due to a reduction in infarct size.     

Late ventricular fibrillation following successful resuscitation from postinfarction cardiogenic shock with intraaortic balloon pumping

Early ventricular fibrillation occurs in approximately 5% of patients admitted for acute myocardial infarction. Although late ventricular fibrillation (> 48 hours postinfarction) may occur in stable patients, it occurs more commonly when severe left ventricular power failure is present. We have encountered late ventricular fibrillation in three of 42 (7%) patients treated with intraaortic balloon pumping (IABP) for profound cardiogenic shock secondary to myocardial infarction. These patients progressed to our hemodynamic Class A prior to weaning, and were thought to be stable prior to IABP removal. They were the only ones who expired after achieving Class A status. The episodes of late ventricular fibrillation occurred after the patients had been successfully weaned from IABP and were free of arrhythmias. This experience suggests that prolonged antiarrhythmic therapy may be indicated for postinfarction patients who have had ventricular dysrhythmias during IABP support.     

Time delays in provision of thrombolytic treatment in six district hospitals. Joint Audit Committee of the British Cardiac Society and a Cardiology Committee of Royal College of Physicians of London.

OBJECTIVE--To measure the delays between onset of symptoms and admission to hospital and provision of thrombolysis in patients with possible acute myocardial infarction. DESIGN--Observational study of patients admitted with suspected myocardial infarction during six months. SETTING--Six district general hospitals in Britain. SUBJECTS--1934 patients admitted with suspected myocardial infarction. MAIN OUTCOME MEASURES--Route of admission to hospital and time to admission and thrombolysis. RESULTS--Patients who made emergency calls did so sooner after onset of symptoms than those who called their doctor (median time 40 (95% confidence interval 30 to 52) minutes v 70 (60 to 90) minutes). General practitioners took a median of 20 (20 to 25) minutes to visit patients, rising to 30 (20 to 30) minutes during 0800-1200. The median time from call to arrival in hospital was 41 (38 to 47) minutes for patients who called an ambulance from home and 90 (90 to 94) minutes for those who contacted their doctor. The median time from arrival at hospital to thrombolysis was 80 (75 to 85) minutes for patients who were treated in the cardiac care unit and 31 (25 to 35) minutes for those treated in the accident and emergency department. CONCLUSION--The time from onset of symptoms to thrombolysis could be reduced substantially by more effective use of emergency services and faster provision of thrombolysis in accident and emergency departments.     

Early identification of patients at low risk of death after myocardial infarction and potentially suitable for early hospital discharge.

OBJECTIVES--To find (a) whether data available shortly after admission for acute myocardial infarction can provide a reliable prognostic indicator of survival at 28 days, and (b) whether such an indicator might be used to identify patients at low risk of death and suitable for early discharge. DESIGN--Retrospective analysis of data collected on patients admitted to a coronary care unit for acute myocardial infarction. A validation sample was selected at random from these patients. SETTING--Coronary care units in Perth, Western Australia. SUBJECTS--6746 patients aged under 65 and resident in the Perth Statistical Division who during 1984-92 were admitted to a coronary care unit with symptoms of myocardial infarction. MAIN OUTCOME MEASURES--Sensitivity and specificity of several models for predicting survival at 28 days after myocardial infarction, and detailed performance characteristics of a particular model. RESULTS--Patients with a pulse rate of 100 beats/min or less, aged 60 or under, and with symptoms typical of myocardial infarction, no past history of myocardial infarction or diabetes, and no significant Q wave in the admission electrocardiogram had a very high chance of survival at 28 days (99.2%). These patients made up one third of all patients studied. CONCLUSION--The prognostic index identifies patients very soon after admission who are at low risk of death and potentially eligible for early discharge from hospital or the coronary care unit. Computing the index does not need complex cardiac investigations.     

Inpatient deaths from acute myocardial infarction, 1982-92: analysis of data in the Nottingham heart attack register.

OBJECTIVE: To assess longitudinal trends in admissions, management, and inpatient mortality from acute myocardial infarction over 10 years. DESIGN: Retrospective analysis based on the Nottingham heart attack register. SETTING: Two district general hospitals serving a defined urban and rural population. SUBJECTS: All patients admitted with a confirmed acute myocardial infarction during 1982-4 and 1989-92 (excluding 1991, when data were not collected). MAIN OUTCOME MEASURES: Numbers of patients, background characteristics, time from onset of symptoms to admission, ward of admission, treatment, and inpatient mortality. RESULTS: Admissions with acute myocardial infarction increased from 719 cases in 1982 to 960 in 1992. The mean age increased from 62.1 years to 66.6 years (P < 0.001), the duration of stay fell from 8.7 days to 7.2 days (P < 0.001), and the proportion of patients aged 75 years and over admitted to a coronary care unit increased significantly from 29.1% to 61.2%. A higher proportion of patients were admitted to hospital within 6 hours of onset of their symptoms in 1989-92 than in 1982-4, but 15% were still admitted after the time window for thrombolysis. Use of beta blockers increased threefold between 1982 and 1992, aspirin was used in over 70% of patients after 1989, and thrombolytic use increased 1.3-fold between 1989 and 1992. Age and sex adjusted odds ratios for inpatient mortality remained unchanged over the study period. CONCLUSIONS: Despite an increasing uptake of the "proved" treatments, inpatient mortality from myocardial infarction did not change between 1982 and 1992.     

Hospital Mortality in Acute Myocardial Infarction

All 757 patients with acute myocardial infarction admitted to the three public hospitals in Auckland during one year were studied. About 7% died from cardiac arrhythmia four days or more after the onset of infarction. These patients had severe infarcts with circulatory failure on or shortly after admission to hospital. Late death from arrhythmia in patients recovering from circulatory failure may in many cases be preventable with anti-arrhythmic drugs.     

The effect of bretylium tosylate on ventricular arrhythmias in patients with acute myocardial infarction]

Sixty three patients with the acute myocardial infarction, aged between 34 and 85 years, admitted to the Intensive Cardiological Care Unit during the first 12 hours following the infarction were randomly divided into two groups. Patients of group I (20 subjects) were treated with nitroglycerin and additional intravenous infusions of bretylium tosylate in the dose of 5 mg/kg administered every 6 hours for 48-72 hours. Patients of group II (33 subjects) were mainly treated with intravenous nitroglycerin. A type and incidence of the ventricular arrhythmias, conduction disorders in AV node, and hemodynamic complications were analysed during the first 72 hours. It was found that bretylium tosylate reduces the incidence of ventricular arrhythmias accompanying myocardial infarction but after 2-3 hours following its administration (p < 0.05). Therefore, bretylium tosylate should be administrated to patients with the acute myocardial infarction in combination with other rapidly acting anti-arrhythmic drug. Bretylium tosylate increases also the effectiveness of electric defibrillation in patients with ventricular fibrillation or ventricular tachyarrhythmia. No evidence of the effectiveness of bretylium tosylate on atrio-ventricular conduction and hemodynamic complications of myocardial infarction was found.     

Mobile Coronary Care Provided by Ambulance Personnel

Mobile coronary care has been provided in Brighton by ambulance personnel without immediate help from physicians or nurses. No additional vehicles or staff were required. The capital cost of the experiment was therefore small and additional running costs were negligible. The results have been monitored by retrospective analysis of electrocardiograms recorded in the ambulance and stored on magnetic tape. In the first 12 months of operation to July 1972, 1,082 patients with suspected cardiac emergencies were carried in two vehicles. Subsequent analysis showed that 76% of these patients had acute symptoms from ischaemic heart disease or had circulatory arrest. Eighty-six per cent. of arrhythmias were diagnosed correctly by the ambulance attendants. Though only eight cases of primary ventricular fibrillation occurred during or shortly before transit all were successfully reversed, and five of these patients subsequently left hospital alive. Other benefits of the scheme have included an appreciable reduction in the median delay between onset of presenting symptoms in patients with acute myocardial ischaemia and their admission to hospital.     

80例急性心肌梗死患者心电监护及护理

目的总结急性心肌梗死患者心电监护及护理经验。方法对本院性心肌梗死患者及时进行心电监护,对出现的心律失常者进行对症处理。结果本组80例患者中出现心律失常55例,其中室性心律失常48例,临床治愈45例;出现心室颤动7例,4例及时电复律转为窦性心律,3例抢救无效死亡。本组心律失常均发生在心肌梗死后1周内,尤其是发病24小时内,出现最多。结论心律失常是心肌梗死患者常见的并发症,也是患者死亡的主要原因,持续心电监护对患者心律失常的及时发现、明确诊断、指导抢救有重要意义。     

Long-term Prognosis following Ventricular Fibrillation in Acute Ischaemic Heart Disease

Of 160 patients who survived ventricular fibrillation complicating acute ischaemic heart disease, 80 had had a clinically mild coronary attack. Most of the long-term survivors had ventricular fibrillation within 24 hours of the onset of symptoms. The longterm prognosis of the survivors was similar to that of patients whose myocardial infarction was not complicated by ventricular fibrillation. Those patients who survived ventricular fibrillation which occurred within four hours of the onset of symptoms were younger, usually had had a mild coronary attack, and had the most favourable longterm prognosis. The number of episodes of ventricular fibrillation did not affect adversely the long-term prognosis. Of those who at the time of review were eligible to work, 86% were fit to work and 68% were actually at work.     

Lack of relation between venous plasma total catecholamine concentrations and ventricular arrhythmias after acute myocardial infarction.

Electrocardiographic tracings were recorded continuously to monitor ventricular tachycardia and R-on-T and R-on-apex-T ventricular premature beats, and repeated estimations of venous plasma total catecholamine concentrations were carried out in 26 patients admitted to a coronary care unit with acute myocardial infarction. No relation existed between the increased catecholamine concentrations found in these patients and the incidence of ventricular arrhythmias occurring six to 48 hours after the onset of symptoms.     

Prognosis of patients with "chest pain ?cause".

All 662 patients admitted to the two coronary care units in Nottingham during 12 consecutive months were followed up prospectively for one year. At the time of discharge from hospital they were categorised according to set criteria into the following diagnostic groups: definite, probable, or possible myocardial infarction; ischaemia heart disease without infarction; chest pain ?cause; and other diagnoses. Eighty-nine patients (13% of admissions) were categorised as having chest pain ?cause. No deaths occurred among these patients during the observation period, although two were readmitted with myocardial infarction. Patients with chest pain ?cause had few problems during the year after admission, and at the end of that time 75% were in their original employment. Patients admitted with ischaemic heart disease had a similar death rate (between six weeks and one year after admission) to those with myocardial infarction, and only 36% were in their original employment one year after admission. Chest pain ?cause is a clinically useful diagnostic category to which patients may be allocated after only simple investigations.     

Intravenous tissue plasminogen activator and size of infarct,left ventricular function,and survival in acute myocardial infarction.

STUDY OBJECTIVE--To assess effect of intravenous recombinant tissue type plasminogen activator on size of infarct, left ventricular function, and survival in acute myocardial infarction. DESIGN--Double blind, randomised, placebo controlled prospective trial of patients with acute myocardial infarction within five hours after onset of symptoms. SETTING--Twenty six referral centres participating in European cooperative study for recombinant tissue type plasminogen activator. PATIENTS--Treatment group of 355 patients with acute myocardial infarction allocated to receive intravenous recombinant plasminogen activator. Controls comprised 366 similar patients allocated to receive placebo. INTERVENTION--All patients were given aspirin 250 mg and bolus injection of 5000 IU heparin immediately before start of trial. Patients in treatment group were given 100 mg recombinant tissue plasminogen activator over three hours (10 mg intravenous bolus, 50 mg during one hour, and 40 mg during next two hours) by infusion. Controls were given placebo by same method. Full anticoagulation treatment and aspirin were given to both groups until angiography (10-22 days after admission). beta Blockers were given at discharge. END POINT--Left ventricular function at 10-22 days, enzymatic infarct size, clinical course, and survival to three month follow up. MEASUREMENTS AND MAIN RESULTS--Mortality was reduced by 51% (95% confidence interval -76 to 1) in treated patients at 14 days after start of treatment and by 36% (-63 to 13) at three months. For treatment within three hours after myocardial infarction mortality was reduced by 82% (-95 to -31) at 14 days and by 59% (-83 to -2) at three months. During 14 days in hospital incidence of cardiac complications was lower in treated patients than controls (cardiogenic shock, 2.5% v 6.0%; ventricular fibrillation, 3.4% v 6.3%; and pericarditis, 6.2% v 11.0% respectively), but that of angioplasty or artery bypass, or both was higher (15.8% v 9.6%) during the first three months. Bleeding complications were commoner in treated than untreated patients. Most were minor, but 1.4% of treated patients had intracranial haemorrhage within three days after start of infusion. Enzymatic size of infarct, determined by alpha hydroxybutyrate dehydrogenase concentrations, was less (20%, 2p = 0.0018) in treated patients than in controls. Left ventricular ejection fraction was 2.2% higher (0.3 to 4.0) and end diastolic and end systolic volumes smaller by 6.0 ml (-0.2 to -11.9) and 5.8 ml (-0.9 to -10.6), respectively, in treated patients. CONCLUSION--Recombinant tissue type plasminogen activator with heparin and aspirin reduces size of infarct, preserves left ventricular function, and reduces complications and death from cardiac causes but at increased risk of bleeding complications4+     

Transthoracic ventricular defibrillation in adults.

A prospective study of the energy required for transthoracic ventricular defibrillation in adults showed that in 42 (81%) out of 52 episodes of ventricular fibrillation shocks of 100 watt-seconds (Ws) of stored energy were successful. Out of 233 episodes, 222 (95%) were converted by 200 W s shocks. Among patients in whom primary ventricular fibrillation occurred within one hour of the onset of acute myocardial infarction, 200 W s shocks were successful in 40 (98%) out of 41 episodes. When low-energy shocks failed, a stored energy of 400 W s invariably succeeded. The need for large and expensive defibrillators that store more than 400 W s and are less readily available is therefore questioned.