Robert J. Whitty, MBBCh, Gail K. Wong, MBBS,
Guy C. Petroz, MD, Carolyne Pehora, MN,
Mark W. Crawford, MBBS
Canadian Anesthesiologists’ Society 2009
In order to establish guidelines for the preparation of the Dra¨ger Fabius GSTM premium anesthetic workstation for malignant hyperthermia-susceptible patients, the authors evaluated the effect of the workstation’s exchangeable and autoclavable components on the washout of isoflurane.
A Draeger Fabius GS workstation was primed with 1.5% isoflurane, and exchangeable components were replaced as follows: Group 1: no replacement (control); Group 2: autoclaved ventilator diaphragm and ventilator hose; Group 3: flushed ventilator diaphragm and ventilator hose; Group 4: autoclaved compact breathing system. The fresh gas flow (FGF) was set at 10 L min-1, and the concentration of isoflurane in the inspiratory limb of the circle breathing circuit was recorded every minute until an endpoint of 5.0 parts per million (ppm) was achieved, at which time the FGF was reduced to 3 L min-1. Six experiments were conducted in each of the four groups.
The time to achieve an isoflurane concentration of 5.0 ppm decreased in the following order: Group 1 (151 ± 17 min)[Group 3 (137 ± 7 min)[Group 4 (122 ± 11 min)[Group 2 (42 ± 6 min) (P\0.01 vs control). Isoflurane concentration increased approximately fivefold when the FGF was reduced to 3 L min-1.
Anesthetic washout from the Draeger Fabius GS is relatively slow. Although washout was accelerated when the Draeger Fabius GS was equipped with autoclaved components, the reduction in washout time may be less than that required for this technique to be accepted into clinical practice. A dedicated vapor-free workstation may be preferable for rapid turnover between cases.