Letters to the Editor
To the Editor:
The desflurane vaporizer contains a heated and pressurized chamber . We measured the electrical requirements of the desflurane vaporizer and calculated its cost to our hospital.
A digital clamp meter was used to measure AC voltage from the outlet and AC current from one of the wires of an extension cord that had been interposed between the vaporizer's plug and the wall outlet. Current needs were measured for the vaporizer when it was turned off and when it delivered 6% and 12% desflurane with a 10-L/min oxygen flow. For a different vaporizer, current requirements were measured before and 7 and 15 min after 240 mL (one bottle) of room temperature desflurane was added to the vaporizer.
Because current flow to the vaporizer fluctuated, an average value for a given run was obtained from >80 consecutive readings. Current needs increased slightly with higher desflurane flows, and the addition of a room-temperature drug caused current consumption to be increased briefly (Figure 1). However, the baseline consumption of a vaporizer not delivering anesthetic was only approximately 0.2 A. On a 120-V line, this amounted to 24 W. With our rate of 7.5 cents per kW/h, our cost for not using a vaporizer would be <$16/yr, or approximately $500/yr for not using the 32 vaporizers in our operating room suites.
Evidently, the desflurane vaporizer uses minimal electricity, although the anesthetic inside is kept heated at all times. Therefore, energy use should not be a major factor in choosing desflurane over other anesthetics.
Evan J. Goodman, MD
Ida M. Hudson, DO
Allen Douglas, CRNA
Department of Anesthesiology; Case Western Reserve University; School of Medicine and University Hospitals of Cleveland; Cleveland, OH 44106
1. Tec 6 Vaporizer Operation Manual. Tewksbury, MA: North American Drager, 1993.