Extreme Cooling Rates in Avalanche Victims: Case Report and Narrative Review

Abstract

Background: We report a 25-year-old female backcountry skier who was buried by an avalanche during ascent. A cooling rate of 8.5°C/h from burial to hospital is the fastest reported in a person with persistent circulation. Methods: A case report according to the CARE guidelines is presented. A literature search with the keywords ''avalanche'' AND ''hypothermia'' was performed and yielded 96 results, and the last update was on October 25, 2020. A narrative review complements this work. Results: A literature search revealed four avalanche patients with extreme cooling rates (>5°/h). References of included articles were searched for further relevant studies. Nineteen additional pertinent articles were included. Overall, 32 studies were included in this work. Discussion: An avalanche patient cools in different phases, and every phase may have different cooling rates:(1) during burial, (2) with postburial exposure on-site, and (3) during transport. It is important to measure the core temperature correctly, ideally with an esophageal probe. Contributing factors to fast cooling are sweating, impaired consciousness, no shivering, wearing thin monolayer clothing and head and hands uncovered, an air pocket, and development of hypercapnia, being slender. Conclusions: Rescuers should be prepared to encounter severely hypothermic subjects (<30°C) even after burials of <60 minutes. Subjects rescued from an avalanche may cool extremely fast the more contributing factors for rapid cooling exist. After avalanche burial ( ‡60 minutes) and unwitnessed cardiac arrest, chances of neurologically intact survival are small and depend on rapid cooling and onset of severe hypothermia (<30°C) before hypoxia-induced cardiac arrest.

Accidental Hypothermia: 2021 Update

“…Accidental hypothermia has been recognised since ancient times [ 6 ]. Throughout history, hypothermia has been a disease of war and disasters such as avalanches, earthquakes and tsunamis [ 7 , 8 , 9 ]. Nowadays in developed countries, primary hypothermia affects mainly people who live, work, and recreate outdoors putting themselves at risk in cold environments and homeless people.…”

“…The wind chill index describes the combined effect of ambient air temperature and wind speed on the skin surface temperature [ 32 ]. In avalanches, the cooling rate of buried victims may reach 9 °C/h [ 9 ]. The cooling rate of hyperthermic patients during immersion in water at 1–2 °C can reach 5 °C/10 min [ 33 ].…”

“…Additional factors that may contribute to rapid cooling are sweating, impaired consciousness, wearing only a single thin layer of clothing, failure to cover the head, and a slender body habitus with limited subcutaneous fat. During avalanche burial, the absence of an air pocket and development of hypercapnia can also lead to rapid cooling [ 9 ].…”

Effects of Carbon Dioxide and Temperature on the Oxygen-Hemoglobin Dissociation Curve of Human Blood: Implications for Avalanche Victims

“…Our study suggests that there can be an ODC shift to the left in spite of moderate elevated CO 2 level, due to hypothermia. Based on measured 2 levels from a human experimental study (4) and cooling rates from observational studies of avalanche victims (32)(33)(34), the expected P50s in avalanche-buried victims were simulated in a model (Table 3). The calculated P50 (Table 3, P50 at 36.4 • C and PCO 2 of 47 mmHg) suggests an increased tissue oxygen unloading that might contribute to outcome (e.g., better cerebral oxygenation).…”

On-Site Medical Management of Avalanche Victims—A Narrative Review

“…With cooling, there is a decrease in oxygen consumption of ~6% for every 1 °C reduction in core temperature [ 22 ]. A mean core cooling rate of 3 °C/h has been calculated for the entire time between avalanche burial and hospital admission [ 23 ], yet, the individual cooling rates during snow burial vary widely, from 0.1 °C/h to 9 °C/h [ 24 , 25 ]. It generally takes at least 60 min after avalanche burial to reach a core temperature <30 °C [ 20 ].…”