Core temperature monitoring with new ventilatory devices

Widespread use of new airway devices, such as the laryngeal mask airway (LMA) and the cuffed oropharyngeal airway (COPA), preclude measuring core temperature in the distal esophagus. Therefore, we tested the hypothesis that core temperature measured with a thermocouple positioned on a LMA or COPA is sufficiently accurate and precise for clinical use. Temperatures were recorded from thermocouples positioned on the cuffs of LMAs or COPAs in 36 patients scheduled for prolonged orthopedic surgery or therapeutic hyperthermia for cancer. These temperatures, recorded at 15-min intervals, were compared with simultaneously obtained nasopharynx and tympanic membrane temperatures. Data were compared by linear regression and the bias calculated. Temperatures measured on the LMA correlated well with both nasopharyngeal (r(2) = 0.94) and tympanic membrane (r(2) = 0.94) temperatures. Temperatures measured on the COPA also correlated well with those on the nasopharynx (r(2) = 0.97) and tympanic membrane (r(2) = 0.96). The fraction of temperatures that differed from nasopharynx temperature by more than +/-0.5 degrees C was 8% with LMA and 11% with COPA; the fraction of temperatures that differed from tympanic temperature by more than +/-0.5 degrees C was 7% with LMA and 10% with COPA. These results suggest that body temperature measured from the cuffs of COPA or LMAs is sufficiently accurate for routine clinical use.

Temperatures measured on airway devices correlated well with independent measurements of core body temperature. Thus, body temperature measured on the cuffs of airway devices is sufficiently accurate for routine use.