Tissue Plasminogen Activator in Out-of-Hospital Cardiac Arrest with Asystole

摘要

This study was conducted to determine whether administration of recombinant tissue plasminogen activator in out-of-hospital cardiac arrest with asystole as the initial rhythm improves post-resuscitation outcome. A retrospective chart review of 177 patients with out-of-hospital cardiac arrest who underwent attempted resuscitation by the emergency medical service was performed for a six-year observation period. A total of 34 patients received thrombolytic therapy during resuscitation and were compared to 102 controls, closely matched according to arrival status. Administration of thrombolytics was optional. Return of spontaneous circulation occurred in 23 patients in the treatment group (68% vs. 33% in controls; p=0.001). Ten patients survived the first 24 hours (29% vs. 14% in controls; p=0.038), while four survived more than ten days (12% vs. 5% in controls; p=0.163). Three patients from the treatment group were ultimately discharged from hospital (9% vs. 3% in controls; p=0.570). Generally, the outcome of patients with asystole as the initial rhythm in cardiac arrest is poor. Thrombolytic therapy, however, may substantially improve frequency of return of spontaneous circulation and increase 24-hour survival in patients with asystole in out-of hospital cardiac arrest. Introduction The survival rate for patients with out-of-hospital cardiac arrest (OHCA) is generally regarded to be very poor for patients with asystole as the initial rhythm [1,2]. Thrombolytic therapy during cardiopulmonary resuscitation (CPR) was reported to improve survival and stabilize patients with pulmonary embolism and myocardial infarction [3, 4]. Furthermore, thrombolysis after OHCA has beneficial effects on cerebral reperfusion and is associated with improved cerebral outcome [5, 6]. Presumptively, hemodynamic variables improve faster in the presence of thrombolysis due to reduced plasma viscosity and improved microcirculatory reperfusion [7]. These effects substantially determine the degree of derangement of vital organ function and possibly counteract reperfusion disorders and postischemic-anoxic encephalopathy [8].As the results of thrombolytic therapy during CPR of non-traumatic etiology are promising, we decided to investigate a subgroup of cardiac arrest patients with a known unfavorable outcome. This study was designed to evaluate the impact of thrombolytic therapy on return of spontaneous circulation (ROSC), duration of hospitalisation and outcome in patients with out-of-hospital resuscitation and asystole as the initial rhythm. Patients And Methods Study backgroundThe Emergency Medical Service (EMS) in Innsbruck, Austria, is an urban university-affiliated system, that serves a population of approximately 150 000 including semi-rural areas in the close vicinity. During the entire period of data collection, the EMS was two-tiered. In emergency cases the dispatcher immediately sent an ambulance with rescue personnel able to provide basic care including chest compression and bag ventilation with 100% oxygen. Simultaneously, he dispatched the Advanced Cardiac Life Support (ACLS) team, consisting of an emergency physician from the Department of Anaesthesia and Critical Care Medicine together with two emergency personnel trained in advanced emergency care. Evaluation of initial rhythm was performed by the emergency physician. All CPR patients underwent orotracheal intubation and mechanical ventilation. Peripheral intravenous access, preferably via the external jugular vein, was placed for drug administration. Study designA retrospective data analysis was conducted of 177 out-of-hospital cardiac arrests with asystole as the initial rhythm. Patients who underwent attempted resuscitation by the Emergency Medical Service (EMS) in Innsbruck, Austria, between 1 January 1993 and 31 December 1998, were the subjects of this investigation. Patients who received recombinant tissue plasminogen activator (rt-PA) during CPR were compared to controls, who were clos