Effect of anesthetic drugs on myocardial performance in man.

All potent CNS depressant drugs can depress cardiac function in man in a dose-dependent manner. The dose-effect curve is considerably flatter with several drugs (diethyl ether, cyclopropane, fluroxene, isoflurane, and ketamine), presumably from sympathetic nervous-system activation. Potent analgesics and tranquilizers appear to produce less depression, but have been incompletely studied. Neuromuscular blocking drugs and regional anesthesia produce minimal effects on the heart in healthy people. However, not as much is known about diseased man. For instance, nitrous oxide produces more depression in "muscle" function in IHD patients (43), while diazepam (28) and morphine (44) do not adversely affect pump function in this class of patients. Fluroxene (45) is more depressant in VHD patients, but nitrous oxide (46), morphine (30), fetanyl (46), and droperidol-fentanyl (46) seem to have equivalent effects to those seen in health patients. In any given patient, therefore, accurate prediction of the effect of any anesthetic drug on cardiac performance is not possible. Adequate monitoring and careful titration of drug dose offer the safest method of assuring a satisfactory response.