Temperature measurements of a wearable and wireless axillary sensor iThermonitor but not a bladder probe represents the core temperature during laparoscopic rectal surgery

Objective To investigate whether the temperature recorded by an iThermonitor has better concordance with the core temperature than the bladder temperature recorded by a Foley catheter sensor in laparoscopic rectal surgery. Methods Eighty-two adults undergoing laparoscopic rectal surgery were enrolled. Temperatures were continuously measured by a distal oesophageal probe (the reference core temperature), axillary iThermonitor and Foley catheter sensor (bladder temperature) in each patient during surgery. Pairs of axillary and core temperatures or pairs of bladder temperature and core temperatures were compared and summarized using linear regression and the repeated-measured Bland-Altman method during the whole surgical period and pneumoperitoneum period. Results There were 3303 pairs of temperature measurements during the whole surgical period. The mean difference between iThermonitor and oesophageal was 0.05 degrees C ; the limits of agreement were - 0.48 to 0.56 degrees C. The mean difference between the oesophagus and bladder was 0.28 degrees C; the limits of agreement were - 0.39 to 0.94 degrees C (P < 0.001, F-test vs. iThermonitor). Ninety -five% of all iThermonitor values were within 0.5 degrees C of oesophageal temperature, whereas the proportion for oesophageal and bladder differences within 0.5 degrees C was only 84% (95% confidence interval 80-88%). Lin's CCC for the iThermonitor and bladder measurements were 0.842 (95%CI: 0.831-0.851) and 0.688 (95%CI: 0.673-0.703) respectively. Similar results were found during the pneumoperitoneum period. Conclusions The temperature recorded by iThermonitor has better concordance with the core temperature than the bladder temperature recorded by Foley catheter sensor in laparoscopic rectal surgery.