SYSTEMIC PERFUSION-PRESSURE AND BLOOD-FLOW BEFORE AND AFTER ADMINISTRATION OF EPINEPHRINE DURING EXPERIMENTAL CARDIOPULMONARY-RESUSCITATION

Objectives: To evaluate instantaneous blood flow variations in the com pression and relaxation phases of cardiopulmonary resuscitation (CPR) and the effect of epinephrine administration. Design: Prospective, ran domized, controlled trial. Setting: Experimental laboratory in a unive rsity hospital. Subjects: Twenty-two anesthetized piglets. Interventio ns: A tracheostomy was performed and arterial, central venous, and pul monary arterial catheters were inserted, followed by thoracotomy with placement of pulmonary arterial, aortic, and left anterior descending coronary arterial (extended study group) flow probes and a left atrial catheter. Ventricular fibrillation for 2 mins was followed by 10 mins of either open-chest (n = 10) or closed-chest (n = 12) CPR. Seven min utes after the initiation of CPR, all piglets received 0.5 mg of epine phrine iv; at 12 mins, direct current shocks were applied. Measurement s and Main Results: Open-chest CPR generated greater systemic perfusio n pressure than closed-chest CPR, especially during the relaxation pha se, resulting in greater mean blood flow. With both open- and closed-c hest CPR, antegrade pulmonary arterial and aortic blood flow occurred during compression, whereas antegrade left anterior descending coronar y arterial blood flow occurred during relaxation. During relaxation, r etrograde flow was found in the pulmonary artery and aorta. During com pression, retrograde flow was found in the left anterior descending co ronary artery. The administration of epinephrine had the following eff ects: a) increased the systemic perfusion pressure more during open- t han closed-chest CPR; b) increased the systemic relaxation perfusion p ressure more than the compression perfusion pressure; c) decreased mea n pulmonary arterial and aortic blood flow, but substantially increase d the mean left anterior descending coronary artery blood flow; and d) reduced the retrograde flow in the left anterior descending coronary artery. Conclusions: Open-chest CPR generated greater systemic perfusi on pressure and blood flow than closed-chest CPR. Epinephrine increase d left anterior descending coronary artery blood flow but decreased to tal cardiac output, such that cerebral perfusion might be endangered. This problem will be studied separately.