Subjects and Methods
From March 2015 to April 2015, 40 patients who underwent percutaneous nephrolithotomy were admitted to our department's intensive care unit, including 22 males and 18 females, aged 24-67 years old, with an average age of (47.7±11.6) years old. Their body temperature was normal before surgery and there was no fever. Inclusion criteria: Age ≥18 years old, stones located at the renal calyx, renal pelvis-ureter junction, no important organ damage or functional failure. Exclusion criteria: Axillary thermometer measured body temperature ≤35°C. During admission, catheter was already placed and the body temperature was high (axillary temperature ≥37°C).
Surgery type: 12 cases underwent micro-channel percutaneous nephrolithotomy and 28 cases underwent standard-channel percutaneous nephrolithotomy. All surgeries were successful.
Axillary temperature (AT) monitoring: Start recording axillary temperature when entering the intensive care unit, once every 4 hours, and record it accurately.
Urinary bladder temperature (UBT) monitoring: Choose a suitable (14F-18F) catheter according to the patient's individual situation. The catheter insertion process strictly follows the aseptic principle.
After successful catheterization, connect the temperature-measuring catheter to the corresponding interface of the monitor. After recording the axillary body temperature, record the bladder temperature on the monitor at that time on the body temperature sheet.
III. Statistical Processing
Use SPSS20.0 software to perform statistical analysis. Use Medcalc software to perform Bland-Altman analysis to compare the consistency of bladder temperature measured by temperature-measuring catheter and axillary temperature measured by thermometer.
During the observation period, a total of 217 axillary temperatures were measured. Due to the negligence of the duty nurse, 11 axillary temperatures were not measured on time. Due to incorrect measurement methods, 12 measurements were obviously inaccurate, so the proportion of invalid axillary temperature measurements reached 10.6%. 240 bladder temperatures were measured. Since 23 axillary temperature measurements were invalid, the corresponding bladder temperature measurement results were discarded.
1. Pearson correlation analysis showed that the axillary temperature measured by a mercury thermometer was highly positively correlated with the bladder temperature measured by a temperature-measuring catheter (r=0.861, P<0.01), and the scatter plot had a linear trend (Figure 1).
2. Bland-Altman analysis showed that the average difference between bladder temperature and axillary temperature was 0.5°C, and the 95% confidence interval was -0.2-1.2; 5.5% (12/217) of data was outside the 95% confidence interval. Within the consistency range, the maximum absolute value of the difference between bladder temperature and axillary temperature is 1.4, which is large. So it is unacceptable clinically for their poor consistency (Figure 2).
Patients undergoing percutaneous nephrolithotomy have a high chance of infection, and urosepsis caused by urinary tract infection is a complication with a high mortality rate. Because its characterization is fever, it is necessary to monitor body temperature after surgery. Some literature suggests that bladder temperature is closer to pulmonary artery temperature. Nierman found that bladder temperature can provide a continuous, reliable monitoring method closer to core body temperature when monitoring body temperature in critically ill patients in the intensive care unit. Placement of a thermistor in the pulmonary artery is the gold standard for measuring core temperature. However, this invasive monitoring is not suitable for patients after percutaneous nephrolithotomy. Compared with pulmonary artery temperature monitoring, bladder temperature monitoring is non-invasive, does not cause additional discomfort except for the insertion of a temperature-measuring catheter, and can continuously and stably monitor temperature changes.
This study shows that the consistency between axillary temperature and bladder temperature is poor. The average difference between axillary temperature and bladder temperature is 0.5°C. Within the consistency range, the maximum absolute value of the difference between bladder temperature and axillary temperature is 1.4. Therefore, axillary temperature cannot accurately and timely reflect changes in human body temperature. Frequent axillary body temperature monitoring of patients in clinical practice will increase the workload of nurses and is not conducive to timely detection of patient infection symptoms. This method allows medical personnels to observe the patient's bladder temperature in real-time, or take timely measures if necessary. However, bladder temperature monitoring requires the use of a multi-functional monitor, which is difficult to achieve outside of the operating room and intensive care unit. The additional medical expenses incurred by using this system are also a disadvantage. The results of bladder temperature measurement are affected by the patient's urine output, and its accuracy has been questioned for patients with oliguria or anuria. Moreover, it is mostly suitable for patients who need to have a catheter placed, but not for those who do not need a catheter.
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Author's unit: 430070 Guangzhou Military Region Wuhan General Hospital Urology Department
Editor: Xu Wendan