Noninvasive assessment of cardiac performance of intravenous benzodiazepines by systolic time intervals

The effects of anesthetic induction by diazepam, flunitrazepam and midazolam on cardiac performance were evaluated in 33 ASA class I surgical patients (average age was 36 years). The patients were divided according to the 3 drug groups, and the effects of each drug assessed utilizing measurements of systolic time intervals. An increase in heart rate and decrease in blood pressure was observed following flunitrazepam and midazolam induction. There was no changes in PEPI (pre-ejection period index) and LVETI (left ventricular ejection time index) by benzodiazepines induction. The PEP/LVET ratio was increased by diazepam while the DPTI (diastolic pressure time index)/TTI (tension time index) was reduced by flunitrazepam and midazolam. However, these changes in PEP/LVET and DPTI/TTI were within normal limits. These data indicate that in healthy humans the induction dose of either diazepam, flunitrazepam or midazolam does not extremely influence either PEP/LVET for cardiac performance or DPTI/TTI for cardiac oxygen balance. The results also suggest that the simultaneous use of PEP/LVET and DPTI/TTI is more informative than any single variable for the evaluation of cardiac effects of anesthetics.