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Summary: Peri‐operative hypothermia is associated with significant morbidity, yet limitations exist regarding non‐invasive temperature assessment in the post‐anaesthesia care unit (PACU). In this prospective study of 100 patients, we aimed to determine the reliability of two commonly used temperature measurement devices, forehead temporal artery temperature and tympanic measurement, in addition to an indwelling urinary catheter with temperature probe, in comparison with the final nasopharyngeal core temperature at the end of surgery. Agreement of forehead measurement with nasopharyngeal temperature showed a mean bias (±95% limits of agreement) of 0.15 °C (±1.4 °C), with a steep slope of the relationship on the Bland–Altman plot of −0.8, indicating a tendency to normalise patient temperature readings to 36.4 °C. Only 54% of hypothermic cases were correctly detected by the forehead measurement device. Agreement of tympanic measurement with nasopharyngeal core temperature measurement was marginally improved with a mean bias of 0.13 °C (95% limits of agreement ±1.15 °C). In contrast, agreement of bladder temperature with nasopharyngeal temperature showed a mean (SD) bias of 0.19 (0.28) °C (95% limits of agreement ±0.54 °C), with a relatively flat line of best fit. We demonstrated that two commonly used temperature measurement devices, forehead temporal artery temperature and tympanic measurement, compared with nasopharyngeal core temperature, were imprecise and unreliable following major surgery. However, the indwelling catheter with temperature sensor was precise and acceptable for continuous core temperature measurement in the PACU. [ABSTRACT FROM AUTHOR]

Theoretical modelling predicts that the concentrating effect of nitrous oxide (N2O) uptake on alveolar oxygenation is a persisting phenomenon at typical levels of ventilation – perfusion (V/Q) inhomogeneity under anaesthesia. We sought clinical confirmation of this in 20 anaesthetised patients. Arterial oxygen pressure ( Pao2) was measured after a minimum of 30 min of relaxant general anaesthesia with an inspired oxygen ( FIo2) of 30%. Patients were randomly allocated to two groups. The intervention group had N2O introduced following baseline blood gas measurements, and the control group continued breathing an identical FIo2 in nitrogen (N2). The primary outcome variable was change in Pao2. Mean (SD) in Pao2 was increased by 1.80 (1.80) kPa after receiving a mean of 47.5 min of N2O compared with baseline conditions breathing O2/N2 (p = 0.01). This change was significantly greater (p = 0.03) than that in the control group: + 0.09 (1.37) kPa, p = 0.83 and confirms the presence of significant persisting concentrating and second gas effects. [ABSTRACT FROM AUTHOR]