Lorazepam and High-Dose Fentanyl Anaesthesia: Effects on Haemodynamics and Oxygen Transportation in Patients Undergoing Coronary Revascularization

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Abstract
The effects of i.v. lorazepam (0.05 mg/kg) on hemodynamics and O2 transportation were studied in a group of 11 patients undergoing a coronary artery bypass grafting operation with high-dose fentanyl anesthesia and compared to the changes in another group of 11 patients receiving the same anesthesia, but saline instead of lorazepam. The measurements were made under stable hemodynamic conditions before the injection of lorazepam or saline, and repeated 5, 20 and 40 min after the injection. Lorazepam caused a slight decrease in the systemic and pulmonary arterial pressures and in the left ventricular stroke work index, as compared to the control group. The ECG or the rate-pressure product did not show changes indicative of myocardial O2 supply/demand imbalance in either group. There was a similar decrease in the systemic O2 transportation and an increase in the arterio-venous O2 content difference in both groups, but the unchanged systemic O2 consumption and arterial lactate levels suggest a well-maintained tissue oxygenation. Evidently, i.v. lorazepam does not cause important hemodynamic untoward effects as an adjunct to high-dose fentanyl anesthesia in patients undergoing coronary artery bypass grafting.