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LONG-TERM AMBULATORY MONITORING OF BLADDER TEMPERATURE IN OLDER PEOPLE: A PILOT STUDY

1998; Wiley; Volume: 46; Issue: 12 Linguagem: Inglês

10.1111/j.1532-5415.1998.tb01552.x

1532-5415

DG Roos‐van Eijndhoven, H.A.M. Middelkoop, HJM Cools,

Thermal Regulation in Medicine

To the Editor: Body temperature is usually sampled in the rectum, axilla, mouth, or ear. Other recording sites, e.g., urinary bladder, are rarely used.1 Bladder temperature measurement is considered reliable, safe, convenient, and accurate for monitoring persons with a urinary catheter.1-5 It yields values nearly identical to pulmonary artery and rectal temperatures.5,6 Thermistor-tipped urinary catheters used for monitoring bladder temperature have been applied continuously for 5 days only in a hospital setting.5 We connected a thermistor-tipped catheter to a digital datalogger (DT-Cath). The aim of our pilot study was to assess the clinical validity and practical applicability of the device in a nursing home setting and to assess body temperature fluctuations missed by twice daily rectal measurement. Excluded were patients with unstablized disorders, contraindication for rectal temperature measurement, use of antipyretic medication, and the need for bladder irrigation. Measurements were performed in three patients: Patient A: A wheel chair-bound, 76-year-old, nondemented woman with hypertension, diabetes mellitus, total urine incontinence, decubitus, cerebral infarction with hemiplegia, and amputation of both legs had had a urinary catheter for several months because of worsening sacral decubitus. Patient B: A nonambulatory, 1O2-year-old man, severely demented, with cerebral infarction, very low vision, and presbyacusis had had a urinary catheter for several years because of prostate hypertrophy. Patient C: An ambulatory, 91-year-old, nondemented man with cerebral infarction, cardiac arrhythmias, and prostate hypertrophy had a urinary catheter because of urine retention. Both patients A and C and the legal representative of patient B gave informed consent. A thermistor-tipped urinary catheter (Bardex Lubricath, temperature sensing urotrack plus Foley catheter, Charrière 16, 5cc balloon, Bard Benelux NV, Nieuwegein) was connected to a commercially available digital datalogger (SR 008, 32 kB RAM, Askey, Leiderdorp). The patients were wearing the datalogger in a waistbag. To ensure comparability within and among DTCaths, the in vitro intra- and intersensor sensitivity was compared in a standardized manner with a calibrated digital thermometer (DM 852, Ellab, Kopenhagen), which was the gold standard. To assess the clinical validity of the device, the in vivo bladder temperature measured by DTCath every 5 minutes was compared with the rectal temperature measured by a calibrated mercury thermometer twice a day at various moments. The correlation between the synchronized DTCath temperature and the rectal temperature was computed. Patients and nurses were asked if the device and the recording procedure were causing any discomfort. Bladder temperature was monitored continuously for a 42-day period in Patients A and C and for 26 days in Patient B, who died suddenly of septicemia. In vitro, the mean (SD) difference between the calibrated digital thermometer and the DTCath output over the range 36.0 to 41.0° C was –.16 (0.07° C), with correlation coefficients ranging from .99 to 1.00. In the subsequent analyses, DTCath data were corrected according to the results of the in vitro experiment. The correlation between rectal and bladder temperature was: Patient A: R = .74 (P < .001; n = 60 rectal measurements) Patient B: R = .96 (P < .001; n = 33) Patient C: R = .45 (P < .001; n = 78) The total period of elevated bladder temperature (>38° C) was 6 hours 5 minutes (0.6%) in Patient A, 123 hours 37 minutes (19.8%) in Patient B, and 11 hours 51 minutes (1.1%) in Patient C. In Patients A and C, all periods of raised bladder temperature were missed with the rectal measurements. No signs of increased temperature were noted in these two patients. In Patient B only 14% was missed. No restriction or inconvenience was reported during use of the DTCath. In conclusion, long-term ambulatory body temperature monitoring by thermistor-tipped catheters in nursing home patients is possible. Despite twice daily rectal measurements, several periods of elevated temperature were missed. This suggests that fever is underdiagnosed in catheterized patients. However, our results are derived from only three patients. Therefore, the conclusion must be verified in a larger sample of patients. To increase its clinical value, however, the device should signal temperatures above 38.0°C.