Waste gas monitor reduces wasted volatile anesthetic

Objective. The increasing focus on health care costs requires that all physicians evaluate practice behaviors. The primary emphasis in anesthesia has been limiting the use of expensive medications and interventions. Reducing waste is another approach, and volatile anesthetics are an appropriate target in that simple reduction of fresh gas flow (FGF) rates is effective. A monitor that measures and displays the cost of wasted volatile anesthetic was developed and used to determine if real-time display of the cost would result in decreased FGF rates, which, in turn, would decrease wasted anesthetic. Methods. The waste gas monitor (WGM) measures flow rate at the anesthesia machine's scavenger port, integrates this with agent concentration, and displays the calculated cost, real-time, on a portable computer screen. The WGM equipment was attached to the anesthesia machine in the gynecologic surgery operating room (OR) and those cases performed under general endotracheal anesthesia and lasting longer than one hour were eligible for inclusion. First year anesthesiology residents assigned to the study OR as part of a non-specialty rotation, were the subjects of the study. For each resident, after data were collected from at least two eligible baseline cases (Baseline Phase, WGM not visible and resident unaware of its presence), the monitor was introduced and data collection continued for at least three more eligible cases (Visible Phase). Results. Nine residents were initially enrolled, but due to scheduling difficulties only five residents completed the protocol. Data from cases using the WGM demonstrated a 50% decrease (3.58 ± 1.34 l/min vs. 1.78 ± 0.51 l/min (p = 0.009)) in the scavenger flow rates, which resulted in a 48% ($5.28 ± 0.68 vs. $2.72 ± 0.80 (p = 0.002)) decrease in hourly cost of wasted volatile anesthetic. There was no difference between the Baseline and Visible phases with regard to use of nitrous oxide or intravenous anesthetic agents. Conclusions. The WGM decreased wasted volatile anesthetic by encouraging decreased FGF rates.