Effect of morbid obesity on kinetic of desflurane: wash-in wash-out curves and recovery times

Aim. The aim of this paper was to compare wash-in and wash-out curves of desflurane in morbidly obese and nonobese patients. Methods. Fourteen patients (7 obese and 7 nonobese) were studied. In the nonobese patients, anaesthesia was started by administering 2 mg/kg propofol bolus and a target controlled effect site concentration of remifentanil set at 2.5 ng/mL. Obese patients were intubated using a flexible fiberoptic bronchoscopic technique facilitated by a target controlled effect site concentration of remifentanil set at 2.5 ng/mL. After endotracheal intubation, general anaesthesia was started by administering a 1.5 mg/kg propofol bolus dose. Ten minutes after induction of anaesthesia, 4% desflurane was administered for 30 min. Desflurane kinetics was determined by collecting end-tidal samples from first breaths at 1, 5, 10, 15, 20, 25 and 30 min. At last skin suture, the end-tidal concentration of desflurane was recorded from 5 consecutive breaths before their discontinuation, then the end-tidal samples of the inhalational agent were collected at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5 min after terminating its administration. The period of time from discontinuation of desflurane to opening eyes, squeezing the observer's hand, extubation, stating the patients' name and providing date of birth was also recorded. Results. The FA/FI ratio was higher in the nonobese group from the 10th to the 15th min. Wash-out curves of desflurane and recovery times were similar. Conclusion. Our results show that desflurane provides similar kinetic and recovery profiles in obese and nonobese patients.