BACKGROUND:: Volatile anesthetic prices differ substantially. But differences in drug-acquisition cost would be inconsequential if hospitalization was prolonged by more soluble anesthetics. The authors tested the hypothesis that the duration of hospitalization is prolonged with isoflurane anesthesia.

METHODS:: Initially, the authors queried their electronic records and used propensity matching to generate homogeneous sets of adults having inpatient noncardiac surgery who were given desflurane, sevoflurane, and isoflurane. The authors then conducted a prospective alternating intervention trial in which adults (mostly having colorectal surgery) were assigned to isoflurane or sevoflurane, based on protocol.

RESULTS:: In the retrospective analysis, the authors identified 3,488 triplets matched on isoflurane, desflurane, or sevoflurane from among 43,352 adults. The adjusted geometric mean (95% CI) hospital length-of-stay for the isoflurane cases was 2.76 days (2.69-2.83); this was longer than that observed for both desflurane (2.56 [2.50-2.63]; P < 0.001) and sevoflurane (2.49 [2.43-2.56]; P < 0.0001). In the prospective trial (N = 1,584 operations), no difference was found; the adjusted ratio of means (95% CI) of hospital length-of-stay in patients receiving isoflurane versus sevoflurane was 0.98 (0.88-1.10), P = 0.77, with adjusted geometric means (95% CI) estimated at 4.1 (3.8-4.4) and 4.2 days (3.8-.5), respectively.

CONCLUSIONS:: Results of the propensity-matched retrospective analysis suggested that avoiding isoflurane significantly reduced the duration of hospitalization. In contrast, length-of-stay was comparable in our prospective trial. Volatile anesthetic choice should not be based on concerns about the duration of hospitalization. These studies illustrate the importance of following even the best retrospective analysis with a prospective trial.