Open-chest cardiac massage without major thoracotomy: metabolic indicators of coronary and cerebral perfusion

Abstract

Objective: to compare the coronary and cerebral perfusion achieved using a novel method of minimally-invasive, direct cardiac massage to that obtained using bimanual, open-chest cardiac massage. Design: prospective, controlled animal study with repeated measures. Setting: university research laboratory. Subjects: large domestic swine. Interventions: aortic, coronary sinus, jugular venous and pulmonary artery catheters were placed. Following an equilibration period, ventricular fibrillation was induced. After 4 min of untreated ventricular fibrillation, animals underwent bimanual, open-chest cardiac massage ( N=6) or minimally-invasive, direct cardiac massage using a novel device for direct cardiac compression ( N=6). Adrenaline was administered at a dose of 1 mg intravenously every 5 min. Measurements: systemic metabolic parameters, (arterial P O 2 , P CO 2 and lactate concentration) and coronary sinus and jugular venous metabolic parameters (pH, PV O 2 , SV O 2 , PV CO 2 and lactate concentration) were measured and calculated (coronary sinus/jugular-arterial SV O 2 , coronary sinus/jugular-arterial P CO 2 and lactate differences) at baseline and at 10, 20 and 30 min following induction of ventricular fibrillation. Animals were euthanised after 30 min with no attempt at defibrillation. Main Results: oxygen tension and oxygen saturation of coronary sinus blood declined significantly during the experimental period, but no differences were noted between treatment groups. The coronary sinus-arterial oxygen saturation difference increased during the study with no significant differences between groups. Coronary sinus P CO 2 and the coronary sinus-arterial P CO 2 difference increased significantly in both experimental groups during cardiac massage. No inter-group differences were noted. A similar relationship was noted in coronary sinus lactate values. The coronary sinus-arterial lactate difference displayed a positive balance at all intervals with no differences noted between group values. The oxygen tension and oxygen saturation of jugular venous blood, were reduced from baseline levels with both treatments. The jugular-arterial oxygen saturation difference increased in both groups compared to baseline values. Between group values were significantly different only at the 20 min interval. Both the jugular venous P CO 2 and the jugular-arterial P CO 2 gradient were elevated at all intervals, but no inter-group differences were noted. Jugular venous lactate concentration rose steadily with time in both groups. No significant increase in the jugular-arterial lactate gradient was noted at any time point. Conclusions: minimally-invasive, direct cardiac massage provides coronary and cerebral perfusion similar to that achieved using standard open-chest cardiac massage. This method may provide a more effective substitute for standard, closed-chest cardiac massage in cases of refractory cardiac arrest.