OBJECTIVE: This study investigates whether the site of abdominal surgery or the urine flow rate affects the accuracy of urinary bladder temperature monitoring. METHODS: After approval by the local ethics committee we studied 7 patients during upper abdominal and 10 patients during lower abdominal surgery. Temperatures were recorded with a Hi-Lo Temp Esophageal-Stethoscope (Mallinckrodt Medical) and a Foley Catheter Temperature Sensor FC400-18 (Respiratory Support Products, Mallinckrodt Medical). Each probe and its recording unit were calibrated over a range of 30-40 degrees C against a reference quartz thermometer (Hewlett Packard Model 2801 A) in a water bath before the investigation. Urine flow rate was measured using a urometer. Temperatures and urine flow rate were recorded every 30 min. Agreement between the methods of measurement was assessed as described by Bland and Altman. RESULTS: 124 measuring points could be analyzed. Bladder temperature had a bias (B) of -0.06 degree C compared to oesophageal temperature. Limits of agreement (LOA; +/- 2 s) were +/- 0.68 degree C. In upper abdominal surgery (B: 0.02 degree C; LOA: +/- 0.42 degree C) a higher precision of oesophageal temperature estimation could be demonstrated compared to lower abdominal surgery (B: -0.14 degree C; LOA: +/- 0.82 degree C). Lower urine flow rates generally increased the limits of agreement. Regarding lower abdominal surgery the bias additionally increased to -0.22 degree C. CONCLUSION: Urinary bladder temperature recording is a clinically acceptable method to measure core temperature during abdominal surgery. The accuracy during lower abdominal surgery is decreased compared to upper abdominal surgery, especially in case of a urine flow rate below 250 ml/h.
OBJECTIVE: This study investigates whether the site of abdominal surgery or the urine flow rate affects the accuracy of urinary bladder temperature monitoring. METHODS: After approval by the local ethics committee we studied 7 patients during upper abdominal and 10 patients during lower abdominal surgery. Temperatures were recorded with a Hi-Lo Temp Esophageal-Stethoscope (Mallinckrodt Medical) and a Foley Catheter Temperature Sensor FC400-18 (Respiratory Support Products, Mallinckrodt Medical). Each probe and its recording unit were calibrated over a range of 30-40 degrees C against a reference quartz thermometer (Hewlett Packard Model 2801 A) in a water bath before the investigation. Urine flow rate was measured using a urometer. Temperatures and urine flow rate were recorded every 30 min. Agreement between the methods of measurement was assessed as described by Bland and Altman. RESULTS: 124 measuring points could be analyzed. Bladder temperature had a bias (B) of -0.06 degree C compared to oesophageal temperature. Limits of agreement (LOA; +/- 2 s) were +/- 0.68 degree C. In upper abdominal surgery (B: 0.02 degree C; LOA: +/- 0.42 degree C) a higher precision of oesophageal temperature estimation could be demonstrated compared to lower abdominal surgery (B: -0.14 degree C; LOA: +/- 0.82 degree C). Lower urine flow rates generally increased the limits of agreement. Regarding lower abdominal surgery the bias additionally increased to -0.22 degree C. CONCLUSION: Urinary bladder temperature recording is a clinically acceptable method to measure core temperature during abdominal surgery. The accuracy during lower abdominal surgery is decreased compared to upper abdominal surgery, especially in case of a urine flow rate below 250 ml/h.