Cardiovascular and Metabolic Effects of Halothane and Enflurane Anesthesia in the Geriatric Patient

The hemodynamic and metabolic effects of halothane and enflurane anesthesia during mechanical ventilation in geriatric patients (n = 16, mean age 83 years) with hip fractures were studied before premedication, at the end of operation and 15 min and 2 h after the end of anesthesia. During anesthesia and surgery. systolic arterial blood pressure (SAP), cardiac index (CI), left ventricular stroke work index (LVSWI) and oxygen consumption (V̇O2) decreased to a similar extent in both groups, while systemic vascular resistance index (SVRI) remained unchanged. Fifteen minutes after the end of anesthesia SAP, CI and LVSWI had returned to preoperative levels but SVRI was decreased in both groups. Pulmonary systolic and diastolic pressures were unchanged during anesthesia but slightly increased 15 min after the end of anesthesia. No change was seen in venous admixture. In the halothane group, a significant increase in V̇O2 occurred in the postanesthetic period due to shivering. During anesthesia and surgery, arterial oxygen tension and arterial pH increased but arterial carbon dioxide tension decreased in both groups due to hyperventilation with the oxygen‐enriched gas mixture (N2O:O2 = 1:1). A similar increase in blood glucose, lactate and pyruvate levels was seen in both groups in the per‐ and postanesthetic periods, but there was no excess lactate production. In skeletal muscle, glucose and lactate levels were increased 15 min after the end of anesthesia but no changes were seen in the high energy phosphagen levels. It may thus be concluded that both halothane and enflurane had similar hemodynamic and metabolic effects in the geriatric patient. Both agents induced a myocardial depression and a decrease in whole body oxygen consumption. The effects on tissue metabolism were small and seem to be mainly due to an increased sympathetic activity caused by surgical stimuli.