[Myocardial metabolism, oxygen demand and oxygen supply during prostaglandin E1 induced hypotension]

The effects of hypotensive anesthesia induced by PGE1 on myocardial metabolism, oxygen demand and oxygen supply were studied. Nine mongrel dogs were anesthetized with pentobarbital and isoflurane. Mean blood pressure (MBP), cardiac output (CO), blood gases (BG), coronary blood flow (CBF), and myocardial tissue oxygen tension (MPO) were measured. Arterial and coronary venous lactate and pyruvate concentrations were also measured. We calculated myocardial oxygen consumption, L/P ratio, excess lactate, oxygen extraction ratio and lactate extraction ratio to estimate the adequacy of myocardial aerobic metabolism. CO and CBF decreased in accordance with MBP depression. Myocardial oxygen consumption decreased significantly with PGE1 administration. Lactate and pyruvate concentrations, L/P ratio, excess lactate and myocardial tissue oxygen tension were unchanged. These results suggest that PGE1 exerts no significant effect on myocardial metabolism during hypotensive anesthesia.