Prolonged isoflurane sedation of intensive care unit patients with the Anesthetic Conserving Device.

Objective: To test the efficacy and patient safety of a new method for administering isoflurane for prolonged sedation in the intensive care unit.
Design: Randomized controlled trial.
Setting: Multidisciplinary university intensive care unit, January 2002 to July 2003.
Patients: Forty ventilator-dependent intensive care unit patients 18-80 yrs old, expected to need >12 hrs sedation.
Interventions: Patients were randomized to sedation with inhaled isoflurane via the Anesthetic Conserving Device or intravenous midazolam infusion. Study duration was 96 hrs or until extubation.
Measurements and Main Results: Primary end points were wake-up times from termination of sedative administration and proportion of time within a predefined desired interval on a sedation scale (Bloomsbury Sedation Score). Practical and patient-related complications with the Anesthetic Conserving Device were noted. Hemodynamic, hepatic, and renal side effects were monitored. Wake-up times were significantly shorter in the isoflurane group than in the control group (time to extubation [mean +/- sd] 10 +/- 5 vs. 252 +/- 271 mins, time to follow verbal command 10 +/- 8 vs. 110 +/- 132 mins). Proportion of time within the desired sedation interval was comparable between groups (isoflurane 54%, midazolam 59% of sedation time). Few minor practical problems with this new method for isoflurane administration were noted. No serious complications related to either sedative drug occurred. We found no hemodynamic, hepatic, or renal adverse effects related to either sedative protocol.
Conclusions: Isoflurane via the Anesthetic Conserving Device is a safe and efficacious method for sedation in the intensive care unit, with short wake-up times after termination of administration. The Anesthetic Conserving Device allows easily titratable administration of isoflurane without costly equipment and can be safely managed by nursing staff.