Potential use of thrombolytic therapy before hospitalization

Prehospital Use of Aspirin Rarely Is Associated with Adverse Events

Introduction:

Aspirin is commonly administered for acute coronary syndromes in the prehospital setting. Few studies have addressed the incidence of adverse effects associated with prehospital administration of aspirin. Objective: To determine the incidence of adverse events following the administration of aspirin by prehospital personnel.

Methods:

Multi-center, retrospective, case series that involved all patients who received aspirin in the prehospital setting from (01 August 1999–31 January 2000). Patient encounter forms of the emergency medical services (EMS) of a metropolitan fire department were reviewed. All patients who had a potential cardiac syndrome (i.e., chest pain, dyspnea) as documented on the EMS forms were included in the review. Exclusion criteria included failure to meet inclusion criteria, and chest pain secondary to apparent noncardiac causes (i.e., trauma). Hospital charts were reviewed from a subset of patients at the participating hospitals. The major outcome was an adverse event following prehospital administration of aspirin. This outcome was evaluated during the EMS encounter, at emergency department discharge, or at six and 24-hours post-aspirin ingestion. An adverse event secondary to aspirin ingestion was defined as anaphylaxis or allergic reactions, such as rash or respiratory changes.

Results:

A total of 25,600 EMS encounter forms were reviewed, yielding 2,399 patients with a potential cardiac syndrome. Prior to EMS arrival, 585 patients had received aspirin, and 893 were administered aspirin by EMS personnel. No patients had an adverse event during the EMS encounter. Of these patients, 229 were transported to participating hospitals and 219 medical records were available for review with no adverse reactions recorded during their hospital course.

Conclusion:

Aspirin is rarely associated with adverse events when administered by prehospital personnel for presumed coronary syndromes.

Early management of acute myocardial infarction: thrombolysis, angioplasty, and adjunctive therapies

Early identification and treatment, including administration of intravenous thrombolytics, coronary angioplasty, and adjunctive therapies, has been shown to benefit patients who present with acute myocardial infarction. However, only a small percentage of these patients receive such therapies because of late presentation, associated risks, and controversies around certain myocardial infarct subsets. The logistics involved in carrying out these treatments have resulted in unnecessary prehospital and in-hospital delays. These issues make essential the availability of a streamlined protocol that should be updated at regular intervals to ensure that these time-dependent therapies are more routinely and rapidly utilized. This article discusses these topics in conceptual format and provides a ready-to-use protocol.

Paramedic diagnostic accuracy for patients complaining of chest pain or shortness of breath

INTRODUCTION

A multitude of life-threatening and nonlife-threatening processes cause chest pain and shortness of breath. Prehospital therapy for these patients may be lifesaving and includes pharmacologic interventions, as well as invasive procedures. Appropriate therapy depends on the diagnostic skills of the paramedic.

OBJECTIVE

This study was undertaken to determine the accuracy of the paramedic diagnosis in patients transported with a chief complaint of pain or shortness of breath.

SETTING

Multihospital, one large municipal hospital, one community hospital.

DESIGN

Prospective, cross-sectional study. Paramedics evaluated the patient and then completed a standard form indicating the diagnosis. The paramedic's and final emergency physician's diagnoses were compared to assess the accuracy of the paramedic diagnosis.

POPULATION

All patients who complained of chest pain or shortness of breath, transported to the study centers by the city of Denver paramedics, were eligible for the study. Ninety-nine of the 102 patients enrolled had complete records for analysis and were entered into the study.

RESULTS

Diagnostic concordance data were analyzed by organ system (e.g., cardiac, pulmonary, etc.) and for specific diagnoses using the kappa statistic and McNemar's chi-square analysis for discordant pairs. Using the kappa statistic, there was statistically significant concordance between the paramedic and emergency-physician diagnosis for cardiac (p = 0.0001; kappa value = 0.54) and pulmonary organ systems (p = 0.0001; kappa value = 0.61). Overall, for organ system diagnosis, the paramedics had an 82% accuracy (p = 0.05) rating. For specific cardiac and pulmonary diagnosis, paramedics had good concordance with emergency physicians.

CONCLUSIONS

Overall, paramedics have excellent diagnostic agreement with emergency-physician diagnosis by organ system. They retained good agreement on specific cardiac diagnoses and pulmonary diagnosis.

Early intravenous thrombolysis in acute myocardial infarction: the Jerusalem experience

Myocardial damage in acute myocardial infarction is a time-dependent process. We examined the influence of very early thrombolytic therapy, comparing prehospital to hospital administration, in a consecutive group of patients with myocardial infarction on mortality, complications and the preservation of left ventricular function. Seven hundred sixty patients received early thrombolytic therapy: 114 at home (time delay to treatment 1.4 +/- 0.8 h) and 646 in hospital (2.1 +/- 1.0 h). Sixteen patients died in hospital and significant hemorrhage occurred in 15 (including three patients with hemorrhagic stroke). There was no difference between groups in hospital mortality or rate of complications. The duration of ischemia was shorter in patients with prehospital therapy (pain duration: 3.3 +/- 2.1 vs. 4.0 +/- 2.2; P < 0.05, and time to recovery of the ST segment in the electrocardiogram: 4.3 +/- 3.3 vs. 6.6 +/- 6.3; P < 0.002). Peak plasma creatine kinase was earlier in patients with prehospital therapy (11.2 +/- 5.0 vs. 13.0 +/- 5.8; P < 0.002), although there was no difference between groups in the absolute peak plasma level. Left ventricular function was assessed by contrast ventriculography 1 week after admission (616 patients). Ventricular function was better in patients with prehospital therapy: (ejection fraction of 58 +/- 13% vs. 54 +/- 15%; P < 0.05 and a left ventricular dysfunction index of 534 +/- 515 vs. 691 +/- 519 units; P < 0.05). We conclude that prehospital thrombolytic therapy is feasible and safe. Reperfusion is achieved earlier and more myocardium can be salvaged using this strategy without increasing the rate of complications.

Improving the time to thrombolytic therapy for myocardial infarction by using a quality assurance audit

STUDY OBJECTIVE

To evaluate a program designed to improve the speed of delivery of thrombolytic therapy for myocardial infarction in an emergency department.

DESIGN

Time to administer thrombolytic therapy was evaluated retrospectively in 1988. Then after physician and nurse education, time to therapy was audited in 1989 and 1990, with feedback to physicians.

SETTING

A community hospital ED.

PARTICIPANTS

Eight board-certified emergency physicians were monitored in their treatment of 58 patients.

INTERVENTIONS

After the 1988 audit, the results for each physician were made known. Physician and nurse education was undertaken, and it was agreed to continue the audit. Nurses were encouraged to order ECGs rapidly, physicians were encouraged to make the treatment decision before consulting private physicians, and a goal of therapy in less than one hour was established. Further feedback on times was given to the physicians in 1989.

MEASUREMENTS AND MAIN RESULTS

Mean time from ED arrival to thrombolytic therapy was 63 minutes in 1988, 47 minutes in 1989, and 38 minutes in 1990. This fall in time was significant (P = .0002). The number of patients treated within one hour rose from 45% in 1988 to 67% in 1989 and to 96% in 1990.

CONCLUSION

Auditing time to thrombolytic therapy, combined with physician and nurse education and increased experience, can significantly improve the time to administration of thrombolytic therapy.

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.

Acute myocardial infarction. An updated protocol for thrombolytic therapy

Only a small percentage of patients who have acute myocardial infarction receive the benefit of intravenous thrombolytic therapy, often because logistics result in unnecessary pre-hospital and in-hospital delays. Dr Selig therefore recommends that a streamlined protocol be available and that it be updated at regular intervals to ensure that this time-dependent therapy is more routinely utilized.

Relative importance of emergency medical system transport and the prehospital electrocardiogram on reducing hospital time delay to therapy for acute myocardial infarction: a preliminary report from the Cincinnati Heart Project

Substantial time delays from symptom onset to diagnosis and treatment of patients with acute myocardial infarction have been demonstrated. To determine the relative importance of prehospital mode of patient transport and the relative impact of emergency medical system transport with or without a prehospital cellular electrocardiogram (ECG) on hospital time delays to initiation of thrombolytic therapy, four prospective parallel groups of patients with acute myocardial infarction were evaluated. The median hospital time delay to treatment median (twenty-fifth and seventy-fifth percentiles) was 64 minutes (46 and 87 minutes, respectively, for twenty-fifth and seventy-fifth percentiles) for patients transported by private automobile ("walk-in"); 55 minutes (45 and 68 minutes, respectively) for patients transported by local ambulance; 50 minutes (38 and 81 minutes, respectively) for patients transported by the emergency medical system without a prehospital ECG; and 30 minutes (27 and 35 minutes, respectively) for patients transported by the emergency medical system who had a 12-lead ECG transmitted from the field. Patients transported by the emergency medical system were randomized to receive cellular telephone transmission of a prehospital 12-lead ECG. Specialized emergency medical system transport alone did not facilitate in-hospital initiation of thrombolytic therapy in patients with acute myocardial infarction when compared with those brought by local ambulance or by private automobile. A significant reduction in hospital time delay to treatment was observed only in patients transported by the emergency medical system who had cellular transmission of a prehospital 12-lead ECG from the field.

Time course and interrelation of reperfusion-induced ST changes and ventricular arrhythmias in acute myocardial infarction

With the increasing use of thrombolytic therapy, the presence and time course of reperfusion-induced ventricular arrhythmias and ST-segment changes have become of particular interest. Technical improvements in bipolar Holter monitoring offer the opportunity to record both parameters continuously and simultaneously. Time course and interaction of both parameters in dependence on the onset of thrombolysis and time of reperfusion were investigated in 30 patients with acute myocardial infarction. Reperfusion was achieved in 20 patients after 49 +/- 23 minutes and in another 2 patients after 120 minutes (73%, group A). Vascular occlusion persisted in 8 patients for greater than 24 hours (group B). Sudden ST-segment changes (greater than 0.2 mV/15 min) in the bipolar leads indicated reperfusion in 7 of 22 patients (32%). Idioventricular rhythms, most frequent in reperfused patients (group A: 18 of 22 patients, mean 121 beats/hour), were unspecific reperfusion markers (group B: 5 of 8 patients, 1 beat/hour) unless frequent (p less than 0.05) or longer lasting, repetitive (p less than 0.01) episodes were considered. Premature ventricular beats and couplets (p less than 0.05) were also most frequent in group A (peak frequency 3 to 5 hours after thrombolysis). Ventricular tachycardia observed in 21 of 22 patients (95%) in group A and in 3 of 8 (38%) in group B (p less than 0.01) attained their peak frequency 7 to 9 hours after thrombolysis. They occurred most often in anterior myocardial infarction and were often preceded by frequent singular premature beats (r = 0.78).(ABSTRACT TRUNCATED AT 250 WORDS)

Anistreplase in early acute myocardial infarction and the one-year follow-up

Of consecutive patients seen with first myocardial infarction (88 of whom were treated out-of-hospital by mobile coronary care staff), 139 received 30 units of intravenous anistreplase at a mean of 101 minutes (range 35-180) from onset of symptoms. Thrombolysis in myocardial infarction patency grade 2 or 3 was found in 76/91 (83.5%) patients. At 3-4 months after hospital discharge, the mean global left ventricular ejection fraction and mean infarct-related regional third ejection fraction declined with increasing delay to anistreplase. For the first, second and third hour administrations, global ejection fraction was 54%, 50% and 45% (P = 0.002) and for regional third ejection fractions 49%, 43% and 41% (P = 0.02) respectively. Of the patients, 130 were reviewed at approximately 1 year: reinfarction had occurred in 9, 6 had undergone coronary angioplasty and 1 had coronary arterial bypass grafting performed since discharge. Mean global left ventricular ejection fraction was 52% and mean infarct-related regional third ejection fraction was 51%. Thus, intravenous anistreplase induces high rates of arterial patency. Global and regional third ejection fractions decline with increasing delay in the time of administration of anistreplase. Mortality and morbidity is low in the first year.

Resolved and unresolved issues in the prevention and treatment of coronary artery disease: a workshop consensus statement

Advances in cardiovascular research during the past two decades have resulted in an improved understanding of the chain of events that lead to end-stage coronary artery disease. These developments have been paralleled by therapeutic advances that now make it possible to intervene at virtually every stage in the development of advanced cardiac disease, from asymptomatic persons at risk of developing coronary atherosclerosis to patients with end-stage heart failure. By interrupting this chain of events, perhaps at multiple sites, it may be possible to prevent or slow the development of symptomatic heart disease and hopefully prolong life. Many opportunities exist for obtaining further information regarding the underlying pathophysiology, the fundamental mechanisms of action of interventions designed to prevent and/or treat the development of myocardial ischemia and cardiac failure and for effecting favorably the natural history of various forms of heart disease.

A prospective evaluation of prehospital 12-lead ECG application in chest pain patients

The objective of this study was to prospectively determine the utility, efficiency, and reliability of early prehospital 12-lead electrocardiogram (ECG) application, the improvement in prehospital diagnostic accuracy, and paramedic and base physician opinions regarding early application of prehospital 12-lead ECGs in a broad range of stable chest pain patients. The patient population consisted of cooperative, stable adult prehospital patients with a chief complaint of nontraumatic chest pain of presumed ischemic origin. From July 17, 1989 through January 1, 1990 paramedics acquired prehospital 12-lead ECGs on 680 stable adult chest pain patients. Factors affecting prehospital 12-lead ECG application were evaluated. Paramedic application of prehospital 12-lead ECGs was found to be efficient and reliable, and it can be applied to most cooperative stable adult prehospital chest pain patients. Prehospital 12-lead ECGs significantly improve base physicians' diagnostic accuracy in myocardial infarction, angina, and nonischemic chest pain patients. Paramedic and base physicians' opinions regarding early application of prehospital 12-lead ECGs during patient evaluation were favorable.

Time delays in the diagnosis and treatment of acute myocardial infarction: a tale of eight cities. Report from the Pre-hospital Study Group and the Cincinnati Heart Project

To establish the magnitude of prehospital and hospital delays in initiating thrombolytic therapy for acute myocardial infarction, the time from telephone 911 emergency medical system (EMS) activation to treatment and its components were analyzed from eight separate ongoing trials. This included estimates of ambulance response time, prehospital evaluation and treatment time, and time from admission to the hospital to initiation of thrombolytic therapy. The average time from EMS activation to patient arrival at the hospital was prospectively determined to be 46.1 +/- 8.2 minutes in 3715 patients from eight centers. The time from admission to the hospital to initiation of thrombolytic therapy was retrospectively determined to be 83.8 +/- 55.0 minutes in a separate group of 730 patients from six centers. Both the prehospital and hospital time delays were much longer than those perceived by paramedics and emergency department directors. Shorter hospital time delays were observed in patients in whom a prehospital ECG was obtained as part of a protocol-driven prehospital diagnostic strategy and a diagnosis of acute infarction made before arrival at the hospital (36.3 +/- 11.3 minutes in 13 patients). These results show that the magnitude of time required to evaluate, transport, and initiate thrombolytic therapy will preclude initiation of treatment to most patients within the first hour of symptoms. Implementation of a protocol-driven prehospital diagnostic strategy may be associated with a reduction in time to thrombolytic therapy.

Impact of field-transmitted electrocardiography on time to in-hospital thrombolytic therapy in acute myocardial infarction

To assess the impact of a field-transmitted electrocardiogram (ECG) on patients with possible acute myocardial infarction, randomized and open trials were performed with a portable electrocardiographic system coupled with a cellular phone programmed to automatically transmit ECGs to the base hospital. Consecutive patients served by the 6 units of the Salt Lake City Emergency Rescue System were studied; 71 patients were randomized to in-field ECG (n = 34) versus no ECG (n = 37). Time on scene was 16.4 +/- 9.7 minutes for the ECG group versus 16.1 +/- 7.0 minutes for the non ECG group (difference not significant). Time of transport averaged 18.2 +/- 9.9 and 17.6 +/- 13.1 minutes, respectively (difference not significant). Six of 34 patients with in-field ECG showed acute myocardial infarction, qualified for and received thrombolytic therapy at 48 +/- 12 minutes after hospital arrival (range 30 to 60) compared with 103 +/- 44 minutes (p less than 0.01) for 51 historical control patients and 68 +/- 29 minutes for 6 concurrent control patients without in-field ECG. Thus, in-field ECG causes negligible delays in paramedic time, leads to significant decreases in time to in-hospital thrombolysis and may make in-field therapy feasible. In-field ECG may be an important addition to reperfusion strategies.

A pilot study of paramedic-administered, prehospital thrombolysis for acute myocardial infarction

We have implemented a pilot program of supervised paramedic administration of thrombolysis in the field. This program was begun on a small scale by training and equipping one paramedic service of one hospital. Four patients with acute myocardial infarction were rapidly and appropriately treated in the field. We compared these 4 patients with 21 patients who were brought to hospital by ambulance, but treated with thrombolysis conventionally in the emergency department. The patients in the field were treated an average of 86 minutes sooner than the patients treated in the emergency department.