Blood flow and perfusion pressure during open-chest versus closed-chest cardiopulmonary resuscitation in pigs.

• OBJECTIVE: To evaluate the blood flow and perfusion pressure differences observed during open- vs. closed-chest cardiopulmonary resuscitation (CPR), including the effects of epinephrine and sodium bicarbonate administration.DESIGN: Prospective, randomized, controlled trial.SETTING: Experimental animal laboratory in a university hospital.SUBJECTS: A total of 35 anesthetized piglets.INTERVENTIONS: After tracheostomy and insertion of arterial, right atrial, and pulmonary arterial catheters, thoracotomy was performed with placement of a pulmonary arterial flow probe and left atrial catheter. Ventricular fibrillation was induced and followed by 15 mins of either open-chest (n = 14) or closed-chest (n = 21) CPR. A 4-min infusion of 50 mmol of sodium bicarbonate or saline was added at the start of CPR. After 8 mins of CPR, 0.5 mg of epinephrine was given intravenously, and after 15 mins, direct current (DC) shocks were used to revert the heart to sinus rhythm.MEASUREMENTS AND MAIN RESULTS: Blood flow was studied using transit-time ultrasound flowmetry. In an extended group, intrathoracic pressure was measured for calculation of transmural pressure. Before epinephrine administration, mean pulmonary arterial flow (cardiac output) was reduced: a) during closed-chest CPR relatively more than pulmonary perfusion pressure but in proportion to systemic perfusion pressure; b) during open-chest CPR relatively less than pulmonary perfusion pressure but still in proportion to systemic perfusion pressure. Epinephrine administration temporarily increased systemic perfusion pressure during both closed- and open-chest CPR but temporarily decreased pulmonary perfusion pressure only during closed-chest CPR. After epinephrine administration, cardiac output temporarily decreased during both closed-and open-chest CPR.CONCLUSIONS: Open-chest CPR resulted in better cardiac output and systemic perfusion pressure than closed-chest CPR. However, cardiac output values obtained with both methods were much lower than previously reported. After epinephrine administration, cardiac output became extremely low with both methods.

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