IMPROVED REGIONAL BLOOD FLOW AND RESUSCIBILITY WITH INTRAPULMONARY EPINEPHRINE DURING PROLONGED CARDIOPULMONARY RESUSCITATION IN DOGS
Abstract
Survival following prolonged cardiopulmonary arrest is poor, despite the evolution of basic and advanced life support. Current surveys report that only about one third of the out-of-hospital victims respond to initial resuscitation efforts and less than one fifth survive long enough to leave the hospital. Since survival is inversely related to the duration of CPR, this study was conducted to determine the ability of CPR to provide adequate circulation to vital organs during prolonged arrest periods and to attempt intervention which might improve survival. The objectives of this study were to measure blood flow to vital organs during 20 minutes of ventricular fibrillation (VF) and cardiopulmonary resuscitation (CPR), to assess the relationship of organ blood flow to restoration of circulation after 20 minutes, and to evaluate organ flow and resuscibility with the addition of intrapulmonary epinephrine. Two groups of anesthetized dogs were studied (n = 15 per group). Group I received no additional treatment while Group II received epinephrine (0.1 mg/kg diluted in 10 ml saline) injected deep into the bronchial tree after 7 and 17 minutes of CPR. Regional blood flow and cardiac output were measured at five minute intervals during 20 minutes of VF and CPR using radioactively labelled microspheres. After the final microsphere injection, the ventricles were defibrillated electrically via transthoracic electrodes. Surviving animals were monitored until blood pressure and heart rate were stable for a period of at least 20 minutes. Cardiac output did not vary significantly throughout the 20 minutes of standard CPR. The addition of intrapulmonary epinephrine significantly increased blood flow to the myocardium, brain, and adrenal glands while significantly decreasing cardiac output. When mean mycardial blood flow was greater than 0.44 ml/min/g, defibrillation alone restored spontaneous circulation. These studies show that a critical level of myocardial blood flow is required to restore ability of the heart to function as a pump after prolonged CPR.
Degree
Ph.D.
Subject Area
Anatomy & physiology|Animals
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