Anesthesiology
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The authors determined the efficacy of four postoperative warming devices by measuring cutaneous and tympanic membrane temperatures, and heat loss/gain using 11 thermocouples and ten thermal flux transducers in five healthy, unanesthetized volunteers. Overall thermal comfort was evaluated at 5-10 min intervals using a 10-cm visual analog scale. The warming devices were: 1) a pair of 250-W infrared heating lamps mounted 71 cm above the abdomen; 2) the Thermal Ceiling MTC XI UL (500 W) set on "high" and mounted 56 cm above the volunteer; 3) a 54-by-145-cm circulating-water blanket set to 40 degrees C placed over the volunteer; and 4) the Bair Hugger forced air warmer with an adult-sized cover set on "low" (approximately 33 degrees C), "medium" (approximately 38 degrees C), and "high" (approximately 43 degrees C). ⋯ Set on "high," the Bair Hugger increased skin-surface temperature more than the circulating-water blanket. The Bair Hugger (all settings) and the water blanket raised skin temperature more than the radiant heaters. The circulating-water blanket was the most effective device for heating an optimally placed transducer on the chest (directly under and parallel to the radiant heat sources, and touching the water and Bair Hugger blankets).(ABSTRACT TRUNCATED AT 250 WORDS)
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Development of an index of myocardial contractility that is both load independent and easily quantified in vivo has been a difficult task. Recently, three measures of contractile state have been advocated that appear to fulfill these requirements: the end-systolic pressure-length relationship (ESPLR), the ESPLR area, and regional preload recruitable stroke work (PRSW). Because the effects of halothane and isoflurane on these indices of contractility have yet to be studied, the purpose of this investigation was to compare the effects of these volatile anesthetics on contractile function as evaluated via these techniques in chronically instrumented dogs. ⋯ The PRSW slope also demonstrated a significant difference in depressed contractility when equianesthetic concentrations of halothane and isoflurane were compared (63 +/- 7% of control with halothane versus 86 +/- 4% of control with isoflurane at 1.5 MAC; 50 +/- 5% of control with halothane versus 70 +/- 6% of control with isoflurane at 2 MAC). The ESPLR area also accurately demonstrated the differential depression in contractile function suggested by recent in vitro studies when equianesthetic doses of halothane and isoflurane were compared in vivo. Therefore, while ESPLR slope and length intercept variables fail as indices of myocardial contractility, ESPLR area and regional PRSW slope were shown to be useful indicators of contractile state in the conscious and anesthetized dog.