A comparative study of enflurane and halothane using systolic time intervals.

The effects of enflurane and halothane anesthesia on systolic time intervals were studied in 12 healthy patients. Cardiovascular measurements were made at equipotent levels of anesthesia: enflurane 1.23% end-tidal and halothane 0.65% end-tidal. These agents were studied first with 50% N2O and then without N2O. Systolic, diastolic, and mean arterial blood pressure were decreased more by enflurane than by halothane (p less than 0.05). However, halothane caused significantly more myocardial depression than enflurane, as indicated by a larger preejection period (PEP) and preejection period/left ventricular ejection time (PEP/LVET) and a smaller 1/PEP2 and ejection fraction. When N2O was discontinued, both agents increased PEP and PEP/LVET and decreased 1/PEP2 and the ejection fraction.