1-1-12 One-Step Wash-In Scheme for Desflurane-Nitrous Oxide Low-Flow Anesthesia : Rapid and Predictable Induction

Abstract EN

Background.

We propose a 1-1-12 wash-in scheme for desflurane-nitrous oxide (N2O) low-flow anesthesia.

The objective of our study was to determine the time to achieve alveolar concentration of desflurane (FAD) at 1, 2, 3, 4, 5, and 6%.

Methods.

We enrolled 106 patients scheduled for elective surgery under general anesthesia.

After induction and intubation, wash-in was started with a fresh gas flow (FGF) of N2O : O2 1 : 1 L min−1 and vaporizer concentration of desflurane (FD) of 12%.

Ventilation was controlled to maintain PACO2 at 30–35 mmHg.

Results.

The FAD rose rapidly from 0 to 4% in 2 min in a linear manner in 0.5 min increments.

An FAD of 6% was achieved in 4 min in a linear fashion from FAD of 4% but in 1 min increments.

An FAD of 1 to 6% occurred at 0.6, 1, 1.5, 2, 3, and 4 min.

Heart rate during wash-in showed a statistically, albeit not clinically, significant pattern of increase.

By contrast, blood pressure slightly decreased during this period.

Conclusions.

We developed a 1-1-12 wash-in scheme using a FGF of N2O : O2 1 : 1 L min−1 and FD of 12% for desflurane-nitrous oxide low-flow anesthesia.

A respective FAD of 1, 2, 3, 4, 5, and 6% can be expected at 0.6, 1, 1.5, 2, 3, and 4 min.