Factors influencing deviation from target temperature during targeted temperature management in postcardiac arrest patients

Abstract

Background: Targeted temperature management (TTM) is a recommended therapy for postcardiac arrest patients. Hyperthermia worsened the patient outcome, and overcooling increased the incidence of complications; therefore, a high-quality TTM is required. The target temperature tended to be modified worldwide after the TTM trial in 2013. Our institute modified the target temperature to 35°C in 2017. This study aimed to compare the conventional and modified protocols, assess the relationship between target temperature deviation and patient outcomes, and identify the factors influencing temperature deviation.

Methods: This single-centre, retrospective, observational study included adult out-of-hospital cardiac arrest patients who underwent TTM between April 2013 and October 2019. We compared the conventional and modified protocol groups to evaluate the difference in the background characteristics and details on TTM. Subsequently, we assessed the relationship of deviation (>±0.5°C, >37°C, or<33°C) rates from the target temperature with mortality and neurological outcomes. We assessed the factors that influenced the deviation from the target temperature.

Results: Temperature deviation was frequently observed in the conventional protocol group (p=0.012), and the modified protocol group required higher doses of neuromuscular blocking agents (NMBAs) during TTM (p=0.016). Other background data, completion of protocol, incidence of complications, mortality and rate of favourable neurological outcomes were not significantly different. The performance rate of TTM was significantly higher in the modified group than in the conventional protocol group (p<0.001). Temperature deviation did not have an impact on the outcomes. Age, sex, body surface area, NMBA doses and type of cooling device were the factors influencing temperature deviation.

Conclusions: A target temperature of 35°C might be acceptable and easily attainable if shivering of the patients was well controlled using NMBAs. Temperature deviation did not have an impact on outcomes. The identified factors influencing deviation from target temperature might be useful for ensuring a high-quality TTM.

Keywords: Death, Sudden, Cardiac; Epidemiology; Heart Arrest; Out-of-Hospital Cardiac Arrest.

Figure 1

Process of the inclusion and exclusion of patients. Among the 930 patients with OHCA who transferred to our institution during the study period, 97 underwent TTM. Overall, 55 (57.1%) patients in the conventional protocol group were compared with 41 (42.9%) patients in the modified protocol group. Ninety-four patients were assessed for temperature deviation after excluding those with missing data and those who used an unusual cooling device. OHCA, out-of-hospital cardiac arrest; TMDU, Tokyo Medical and Dental University; TTM, targeted temperature management.