Core temperature measurement in therapeutic hypothermia according to different phases: Comparison of bladder, rectal, and tympanic versus pulmonary artery methods

Abstract Purpose Comparisons of bladder, rectal and tympanic temperatures versus pulmonary artery (PA) temperature during different therapeutic hypothermia (TH) phases. Methods Twenty-one patients admitted to our emergency department (ED) after out-of-hospital cardiac arrests were included in this study. For comparison, the temperature of four different sites, urinary bladder (BL), rectal (RE), tympanic membrane (TM) digital thermometers, and a Swan–Ganz catheter were used during TH, which were controlled by a surface cooling method. TH is divided into three phases: induction, maintenance, and rewarming phase. Results In the induction phase, the mean differences between PA temperatures and those of the other methods studied were: BL (-0.24 ± 1.30 °C), RE (-0.52 ± 1.40 °C), and TM (1.11 ± 1.53 °C). The mean differences between PA temperatures and those of the other methods in the maintenance phase were BL (0.06 ± 0.79 °C), RE (-0.30 ± 1.16 °C), and TM (1.12 ± 1.29 °C); in the rewarming phase: BL (0.08 ± 0.86 °C), RE (-0.03 ± 1.71 °C), and TM (0.89 ± 1.62 °C); and in the total phase: BL (0.04 ± 0.90 °C), RE (-0.22 ± 1.44 °C), and TM (1.03 ± 1.47 °C). Conclusions The mean difference between BL and PA temperatures is lower than those in other sites during TH. On the contrary, there are larger differences between TM and PA temperatures when compared to other sites. The differences between RE and PA temperatures are comparatively less than those between TM and PA. However, RE temperature tends to be higher than the temperature recorded by a BL thermometer or Swan–Ganz catheter during the rapid induction phase.