Cardiovascular effects of sevoflurane compared with those of isoflurane in volunteers.

BACKGROUND: Sevoflurane is a new inhalational anesthetic with desirable clinical properties. In some clinical situations, an understanding of the detailed cardiovascular properties of an anesthetic is important, so the authors evaluated the hemodynamic effects of sevoflurane in healthy volunteers not undergoing surgery. METHODS: Twenty-one subjects were randomized to receive sevoflurane, isoflurane, or sevoflurane: 60% N2O. Anesthesia was induced and maintained by inhalation of the designated anesthetic. Hemodynamic measurements were performed before anesthesia, during controlled ventilation, during spontaneous ventilation, and again during controlled ventilation after 5.5 h of anesthesia. RESULTS: A few subjects became excessively hypotensive at high anesthetic concentrations (2.0 minimum alveolar concentration [MAC] sevoflurane, 1.5 and 2.0 MAC isoflurane), preventing data collection. Sevoflurane did not alter heart rate, but decreased mean arterial pressure and mean pulmonary artery pressure. Cardiac index decreased at 1.0 and 1.5 MAC, but in subjects with mean arterial pressure > or = 50 mmHg returned to baseline values at 2.0 MAC when systemic vascular resistance decreased. Sevoflurane did not alter echocardiographic indices of ventricular function, but did decrease an index of afterload. Sevoflurane caused a greater decrease in mean pulmonary artery pressure than did isoflurane, but the cardiovascular effects were otherwise similar. Administration of sevoflurane with 60% N2O, prolonged administration or spontaneous ventilation resulted in diminished cardiovascular depression. CONCLUSIONS: At 1.0 and 1.5 MAC, sevoflurane was well tolerated by healthy volunteers. At 2.0 MAC, in subjects with mean arterial pressure > or = 50 mmHg, no adverse cardiovascular properties were noted. Similar to other contemporary anesthetics, sevoflurane caused evidence of myocardial depression. Hemodynamic instability was noted in some subjects at high anesthetic concentrations in the absence of surgical stimulation. The incidence was similar to that with isoflurane. The cardiovascular effects of sevoflurane were similar to those of isoflurane, an anesthetic commonly used in clinical practice since 1981.

Prospective comparison of use of the laryngeal mask and endotracheal tube for ambulatory surgery.

We examined the response to the laryngeal mask (LM) compared to the endotracheal tube (ETT) in patients undergoing ambulatory anesthesia. The differences in management by the anesthesiologists for these two airways were also examined. Peripheral orthopedic procedures were studied in 44 outpatients randomized to receive a LM or ETT, and either spontaneous or controlled ventilation. Anesthesia was induced with propofol and succinylcholine intravenously (i.v.) and maintained with N2O and isoflurane. Anesthesiologists were allowed to determine ventilatory variables and anesthetic concentration. Hemodynamic and ventilatory measurements were made during the anesthesia. Barium sulfate was poured into the oropharynx after the airway was secure. Fiberoptic examination through the LM was performed at the beginning and at the end of the administration of each anesthetic. Radiographs were taken at the end of the anesthetic administration before LM or ETT removal to look for barium in the trachea. After airway removal, presence of blood on the airway, sore throat, coughing, nausea, vomiting, shivering, and amount of morphine demanded during recovery were noted. No barium in the trachea or bronchial tree was seen in any of the radiographs. The ETT was associated with greater hemodynamic response not only to airway placement (P < 0.05), but also to surgical incision (P < 0.05) and airway removal (P < 0.05). Spontaneous or controlled ventilation favored neither airway, although the ETT was associated with increased work of inspiration with controlled ventilation (P < 0.05). Anesthesiologists tended to elect smaller tidal volumes, faster ventilation rates, and lower anesthetic concentrations for patients with the LM (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)