Impact of rewarming rate on the mortality of patients with accidental hypothermia: analysis of data from the J-Point registry

Abstract

BackgroundAccidental hypothermia (AH) is defined as an involuntary decrease in core body temperature to < 35 °C. The management of AH has been progressing over the last few decades, and numerous techniques for rewarming have been validated. However, little is known about the association between rewarming rate (RR) and mortality in patients with AH.MethodThis was a multicentre chart review study of patients with AH visiting the emergency department of 12 institutions in Japan from April 2011 to March 2016 (Japanese accidental hypothermia network registry, J-Point registry). We retrospectively registered patients using the International Classification of Diseases, Tenth Revision code T68: ‘hypothermia’. We excluded patients whose body temperatures were unknown or ≥ 35 °C, who could not be rewarmed, whose rewarmed temperature or rewarming time was unknown, those aged < 18 years, or who or whose family members had refused to join the registry. RR was calculated based on the body temperature on arrival at the hospital, time of arrival at the hospital, the documented temperature during rewarming, and time of the temperature documentation. RR was classified into the following five groups: ≥2.0 °C/h, 1.5–< 2.0 °C/h, 1.0–< 1.5 °C/h, 0.5–< 1.0 °C/h, and < 0.5 °C/h. The primary outcome of this study was in-hospital mortality. The association between RR and in-hospital mortality was evaluated using multivariate logistic regression analysis.ResultDuring the study, 572 patients were registered in the J-Point registry, and 481 patients were included in the analysis. The median body temperature on arrival to the hospital was 30.7 °C (interquartile range [IQR], 28.2 °C–32.4 °C), and the median RR was 0.85 °C/h (IQR, 0.53 °C/h–1.31 °C/h). The in-hospital mortality rates were 19.3% (11/57), 11.1% (4/36), 14.4% (15/104), 20.1% (35/175), and 34.9% (38/109) in the ≥2.0 °C/h, 1.5–< 2.0 °C/h, 1.0–< 1.5 °C/h, 0.5–< 1.0 °C/h, and < 0.5 °C/h groups, respectively. Multivariate regression analysis revealed that in-hospital mortality rate increased with each 0.5 °C/h decrease in RR (adjusted odds ratio, 1.49; 95% confidence interval, 1.15–1.94; Ptrend < 0.01).ConclusionThis study showed that slower RR is independently associated with in-hospital mortality.

The Efficacy of Renal Replacement Therapy for Rewarming of Patients in Severe Accidental Hypothermia—Systematic Review of the Literature

“…However, the optimal rewarming rates are still unknown. In patients in accidental hypothermia, mortality increases for every 0.5 • C/h drop in rewarming rate below 2 • C/h, but higher values cause a significant increase of neuronal damage markers and thus indicate the possibility of central nervous system injury [26,27]. Moreover, the use of ECMO poses the risk of severe and potentially fatal complications, both associated with severe bleeding and thromboembolism, whose incidence reaches almost 30% [28].…”

Care at critical care medical centers is associated with improved outcomes in patients with accidental hypothermia: a historical cohort study from the J‐Point registry

“…Circulatory support such as ECMO for unstable patients often requires time-sensitive procedures and human or medical resources. 11,16 Indeed, severe hypothermic patients are more likely to have lower blood pressure. 1,10 However, unstable hemodynamic status could have greater impact on the outcomes of patients with AH than decreased body temperature itself.…”

“…In contrast, among patients with systolic blood pressure of <90 mmHg, care at the specialized centers had a positive association with improved outcome. Circulatory support such as ECMO for unstable patients often requires time‐sensitive procedures and human or medical resources 11,16 . Indeed, severe hypothermic patients are more likely to have lower blood pressure 1,10 .…”

“…Data regarding outcomes were in‐hospital death, and length of hospital and ICU stay. The detailed information was described in a previous study 9,11 …”

Bradycardia in Accidental Severe Hypothermia in a Newborn: Treat or Don’t Touch? A case report

“…12 Recent studies have shown a favorable outcome for hypothermic infants admitted to a well-equipped intensive care unit and treated with rapid external warming. 13,14…”