Hemodynamics and myocardial metabolism under deliberate hypotension. An experimental study in dogs.

Coronary blood flow, cardiac work and metabolism were studied in dogs under sodium nitroprusside (SNP) and trimetaphan (TMP) deliberate hypotension (20% and 40% mean pressure decrease from baseline). Regarding the effects of drug-induced hypotension on coronary blood flow, aortic and coronary sinus metabolic data (pH, pO2, pCO2) we could confirm that nitroprusside hypotension could be safely used to 30% mean blood pressure decrease from control, trimetaphan hypotension to 20% mean blood pressure decrease. Cardiac work was significantly reduced during SNP hypotension. Myocardial O2 consumption and O2 availability were directly dependent on the coronary perfusion. Careful invasive monitoring of the blood pressure, blood gases and of the ECG ST-T segment is mandatory.