A CLINICAL-ASSESSMENT OF DESFLURANE ANESTHESIA AND COMPARISON WITH ISOFLURANE

In 48 randomly assigned ASA I adult patients undergoing elective ortho paedic procedures, we compared the pharmacodynamics of desflurane (DF) and isoflurane (IF), and their pharmacokinetics during rapid inductio n of deep anaesthesia (via face mask, to 1.5-2 MAC, after thiopentone) , maintenance of anaesthesia at 1.25 MAC, and emergence therefrom. Dur ing induction, laryngeal reactions ranging from mild crowing to laryng ospasm occurred more frequently with DF than with IF (15/24 DF 5/24 IF , P < 0.05) and was more severe (9/24 DF, 1/24 IF, excluding the milde st form, P < 0.05). As a result, induction of anaesthesia was not acco mplished faster with DF, in spite of a faster equilibration between ex haled and inhaled concentrations Emergence from DF was more rapid and less complicated by delirium. Pharmacokinetically, the exhaled concent ration of DF reached 90% of the inhaled concentration within five minu tes of induction, whereas that of IF lagged behind and remained 25% be low the inhaled concentration (1 vs 1.34 +/- 0.05) even one hour after induction. Premature ventricular contractions did not occur in any pa tient even during periods of difficulty with the airway and oxygen des aturation. It is concluded that DF is a safe anaesthetic, pharmacokine tically superior to IF but clinically inferior for induction of anaest hesia via a face mask. Because of the fast equilibration, the exhaled concentration of DF ran be controlled more precisely by the dial setti ng of the vaporiser.