Relationship between blood, nasopharyngeal and urinary bladder temperature during intravascular cooling for therapeutic hypothermia after cardiac arrest.

OBJECTIVES: Therapeutic hypothermia improves survival and neurological outcome in patients successfully resuscitated after cardiac arrest. Accurate temperature control during cooling is essential to prevent cooling-related side effects. METHODS: Prospective observational study of 12 patients assessed during therapeutic hypothermia (32-34°C) achieved by intravascular cooling following cardiac arrest. Simultaneous temperature measurements were taken using a Swan-Ganz catheter (blood temperature BLT), nasopharyngeal probe (nasopharyngeal temperature NPT) and the urinary bladder catheter (urinary bladder temperature UBT). A total of 1728 measurements (144 measurements per patient) were recorded over a 48-h period and analyzed. Blood temperature was considered as the reference measurement. RESULTS: Temperature profiles obtained from BLT, NPT and UBT compared with the use of analysis of variance did not differ significantly. Pearson correlation revealed that the correlation between BLT and NPT as well as BLT and UBT was statistically significant (r=0.96, p<0.001 and r=0.95, p<0.001, respectively). Bland-Altman analysis proved that the agreement between all measurements was satisfactory and the differences were not clinically important. CONCLUSIONS: In 12 post-cardiac arrest patients undergoing intravascular cooling, both nasopharyngeal and urinary bladder temperature measurements were similar to blood temperatures measured using a pulmonary artery catheter.