Clinical paperCore temperature measurement in therapeutic hypothermia according to different phases: Comparison of bladder, rectal, and tympanic versus pulmonary artery methods?
Introduction
Therapeutic hypothermia (TH) is a key treatment modality in post cardiac arrest care.1 The target core temperature range for TH is 32–34 °C. However, the maintenance of the target core temperature during TH is very difficult either with or without an auto targeted temperature management system.2 If the core temperature during TH is maintained out of the target range (>34 °C or <32 °C), the effect of TH may be reduced, and complications of TH may occur.3 Therefore, the maintenance of core temperature may be cautiously monitored by temperature measurement at several sites, such as pulmonary artery (PA), esophagus, urinary bladder (BL), rectum (RE), and tympanic membrane (TM). The gold standard for the optimal site of core temperature is considered to be the PA using a Swan–Ganz catheter, yet, this measurement is very invasive and may induce fatal complications, such as dysrhythmia, injury of heart valve, bleeding, rupture of PA, and infection.4, 5, 6, 7, 8 The measurement of BL has been an accurate method of measuring the core temperature because of the quick and easy insertion of the probe and the low risk of dislocation.9, 10 However, the accuracy of BL temperature for the core temperature in a critically ill patient who has anuria or oliguria may be limited.3 The TM temperature is a very easy and non-invasive method and is recognized as an indirect measure of brain temperature.11, 12, 13 However, some studies have still not concurred on the reliability of TM temperature, particularly in critically ill patients.4, 14 The measurement of rectal temperature by the rectal temperature probe is a very easy and less invasive method in critically ill patients who are monitored in the emergency department (ED) and intensive care unit (ICU). However, the rectal temperature may be slow to respond to a change of temperature.3, 15 TH is composed of three phases, which include the initial rapid induction phase, maintenance phase, and slow rewarming phase. There were no previous studies as to the temperature being divided into these three phases. Typically, in the induction and rewarming phases, which are temperature change phases, the measurement of core temperature by RE, BL, and TM may be less accurate than during the maintenance phase.3 Thus, we have conducted a study comparing temperature measurement using the electronic probe in RE, BL, and TM sites versus PA core temperature during the three different TH phases.
Section snippets
Patients
This study was a prospective observational cohort study of mild TH after out-of-hospital cardiac arrests. It has been approved by the hospital's Ethics of Human Research Committee (Boramae Institutional Review Board), and informed consent was obtained from each patient's family or closest relatives.
From October 2009 to August 2011, all patients admitted to the ED of a tertiary, university-affiliated hospital in the Republic of Korea were eligible for inclusion criteria, which included adult age
Results
During the study period, 39 patients received post cardiac arrest care with TH after the return of spontaneous circulation. Among these patients, 18 of them were not enrolled in this study because they met the exclusion criteria, which were mainly not in agreement with the informed consent and delayed application of TH (>2 h). Therefore, 21 patients were enrolled in the study. Basal characteristics are shown in Table 1. All enrolled patients initially received TH in the ED. Core temperatures at
Discussion
In this study, we found that the mean difference between BL and PA temperatures is less than those of other sites during TH. The differences between RE and PA temperatures are comparatively less than those between TM and PA. However, RE temperature tends to be higher than the temperature recorded by a BL thermometer or Swan–Ganz catheter during the rapid induction phase.
The measured temperature of the ear canal near the tympanum was lower than the pulmonary artery temperature during all three
Conclusions
The mean difference between BL and PA temperatures is less than those in other sites during TH. On the contrary, there are more differences between TM and PA temperatures when compared to other sites. The differences between RE and PA temperatures are comparatively less than those between TM and PA. However, RE temperature tends to be higher than the temperature recorded by a BL thermometer or Swan–Ganz catheter during the rapid induction phase. A cautious approach is warranted in order not to
Conflict of interest statement
The authors have no relationships with organizations that could inappropriately influence their work. The manuscript, data, tables, and figures have not been submitted for publications elsewhere.
Acknowledgments
We want to thank the participating colleagues, nurses, and emergency medical technicians of the Department of Emergency Medicine for their enthusiastic support and facilitation of this study.
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2018, Anaesthesia Critical Care and Pain MedicineCitation Excerpt :Agreement between core body sites of measurement (lungs, oesophagus, bladder, and rectum) was correct. Correlation and agreement were poor for peripheral sites of measurement (skin and tympanic) [176–180]. A study reported a bias of 1 °C between core and tympanic temperature [178].
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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.12.023.