Articles from Anesthesia and analgesia 1999 October

Anesthesia and analgesia · Oct 1999

Low-flow anesthesia and reduced animal size increase carboxyhemoglobin levels in swine during desflurane and isoflurane breakdown in dried soda lime.

After institutional approval, we studied the effect of animal size, anesthetic concentration, and fresh gas flow (FGF) rate on inspired carbon monoxide (CO) and carboxyhemoglobin (COHb) during anesthesia in swine, using soda lime previously dried to 1 +/- 0.1% water content. To ascertain the effect of anesthesia, eight adult pigs were anesthetized with either 1 minimum alveolar anesthetic concentration (MAC) desflurane or isoflurane and, to characterize the effect of the FGF rate, it was doubled in four pigs. To determine the effect of animal size, four small and four large pigs received 1 MAC desflurane or isoflurane, and to determine the effect of the anesthetic concentration, a group of four swine was exposed to 0.5 MAC. CO and COHb concentrations were larger with desflurane (5500 +/- 980 ppm and 57.90% +/- 0.50%, respectively) than with isoflurane (800 ppm and 17.8% +/- 2.14%, respectively), especially in the small animals. Increasing the FGF rate significantly reduced peak CO and COHb concentrations resulting from both anesthetics; however, when each anesthetic was reduced to 0.5 MAC, the concentrations obtained were similar. We conclude that CO intoxication is more severe with desflurane than with isoflurane, that small animals are at higher risk for CO poisoning, and that low FGF can increase COHb concentrations. ⋯ The present study shows that the use of desflurane with desiccated carbon dioxide absorbents in pediatric anesthesia can produce a dangerous carbon dioxide intoxication, especially with low-flow anesthesia.

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Anesthesia and analgesia · Oct 1999

Comparative Study

A strategy for deciding operating room assignments for second-shift anesthetists.

We developed a relief strategy for assigning second-shift anesthetists to late-running operating rooms. The strategy relies on a statistical method which analyzes historical case durations available from surgical services information systems to estimate the expected (mean) remaining hours in cases after they have begun. We tested our relief strategy by comparing the number of hours that first-shift anesthetists would work overtime if second-shift anesthetists were assigned using our strategy versus if the anesthesia coordinator knew in advance the exact amount of time remaining in each case. Our relief strategy resulted in 3.4% to 4.9% more overtime hours for first-shift anesthetists than the theoretical minimum, as would have been obtained had perfect retrospective knowledge been available. Few additional staff hours would have been saved by supplementing our relief strategy with other methods to monitor case durations (e.g., real-time patient tracking systems or closed circuit cameras in operating rooms). ⋯ A relief strategy that relies only on analyzing historical case durations from an operating room information system to predict the time remaining in cases performs well at minimizing anesthetist staffing costs.