Introduction: In ideal operating room setting, the goal is to minimize emergence timing and post anaesthesia care unit (PACU) length of stay, thus reducing cost.1 With the routine use of shorter acting inhalational anaesthetic agent quicker emergence and shorter PACU length of stay seems to be possible. We therefore assessed the treatment difference of Isoflurane versus Sevoflurane on PACU length of stay and emergence timing.
Methods:We included 1498 adults from a previously conducted prospective alternating intervention trial2,  mostly having colorectal surgery, who were assigned to isoflurane or sevoflurane  based on protocol.  The PACU length of stay was defined as the time from entering to exiting PACU phase I. Emergence time was defined as the time from last 0.3 (or higher) MAC inhalational dose towards the end of the procedure to out of the operating room.   Treatment effect was assessed using Cox proportional hazards regression and adjusting for imbalanced baseline variables.  In a post-hoc analysis we compared the two anaesthetics by type of surgery. 
Results: PACU length of stay did not differ between groups, with a median [quartiles] of 158 [117, 216] minutes for isoflurane and 155 [118, 219] minutes for sevoflurane group; the adjusted hazard ratio for PACU discharge time was 1.03 (95% CI; 0.92, 1.16) (P=0.53). However, isoflurane did have shorter PACU length of stay for non-abdominal surgeries.   Emergence timing was longer for isoflurane, with median [quartiles] of 16 [12, 22] minutes versus 14 [11, 19] minutes for sevoflurane, with adjusted hazard ratio of 0.80 (95% CI: 0.72, 0.90), P<0.001. Figure-1, Table 1. 
Conclusion:Use of inhalational agent isoflurane versus sevoflurane had no effect on PACU length of stay. Emergence timing is on average about two minutes quicker with sevoflurane, which may be of limited clinical significance. Sevoflurane, per Minimum Alveolar Concentration (MAC) hour, is twelve times more expensive compared to isoflurane and thus offer no advantage with respect to PACU length of stay and emergence timing. 


03 / The effect of Sevoflurane vs. Isoflurane on Emergence Time and PACU Length of Stay