Hypothermia in Trauma PDF 2021

International Journal of Environmental Research and Public Health Viewpoint Hypothermia in Trauma Michiel J. van Veelen 1, * and Monika Brodmann Maeder 1,2 1 Eurac Research, Institute of Mountain Emergency Med...

International Journal of Environmental Research and Public Health Viewpoint Hypothermia in Trauma Michiel J. van Veelen 1, * and Monika Brodmann Maeder 1,2 1 Eurac Research, Institute of Mountain Emergency Medicine, 39100 Bolzano, Italy; [email protected] 2 Department of Emergency Medicine, University Hospital Bern and Bern University, 3010 Bern, Switzerland * Correspondence: [email protected] Abstract: Hypothermia in trauma patients is a common condition. It is aggravated by traumatic hemorrhage, which leads to hypovolemic shock. This hypovolemic shock results in a lethal triad of hypothermia, coagulopathy, and acidosis, leading to ongoing bleeding. Additionally, hypothermia in trauma patients can deepen through environmental exposure on the scene or during transport and medical procedures such as infusions and airway management. This vicious circle has a detrimental effect on the outcome of major trauma patients. This narrative review describes the main factors to consider in the co-existing condition of trauma and hypothermia from a prehospital and emergency medical perspective. Early prehospital recognition and staging of hypothermia are crucial to triage to proper care to improve survival. Treatment of hypothermia should start in an early stage, especially the prevention of further cooling in the prehospital setting and during the primary assessment. On the one hand, active rewarming is the treatment of choice of hypothermia-induced coagulation disorder in trauma patients; on the other hand, accidental or clinically induced hypothermia might improve outcomes by protecting against the effects of hypoperfusion and hypoxic injury in selected cases such as patients suffering from traumatic brain injury (TBI) or traumatic cardiac arrest.



 Keywords: hypothermia; trauma; hemorrhage; lethal triad; coagulation; traumatic brain injury; Citation: van Veelen, M.J.; cardiac arrest; extracorporeal life support; ECLS; emergency preservation resuscitation Brodmann Maeder, M. Hypothermia in Trauma. Int. J. Environ. Res. Public Health 2021, 18, 8719. https://doi.org/10.3390/ 1. Introduction ijerph18168719 Major trauma, defined as an Injury Severity Score (ISS) of 15 or greater, accounts for 10% of all deaths worldwide. Hypothermia, defined as a body temperature of 35 ◦ C Academic Editor: Paul B. Tchounwou or less, is present in up to two-thirds of these patients upon admission to the emergency department (ED). Hypothermia is currently estimated to occur less frequently with Received: 2 August 2021 Accepted: 18 August 2021 modern hemostatic, goal-directed resuscitation with warm fluids. Risk factors for Published: 18 August 2021 hypothermia in trauma include the severity of injury, (prehospital) anesthesia or intubation, low environmental temperature or wet clothing, and administration of cold fluids [4,5]. Publisher’s Note: MDPI stays neutral Therefore, hypothermia in trauma patients can result from environmental exposure, the with regard to jurisdictional claims in injuries sustained leading to hypovolemic shock due to hemorrhage, or medical interven- published maps and institutional affil- tions, and it is often the result of a combination of these factors. Hypothermia in trauma iations. patients leads to higher in-hospital mortality, higher transfusion requirements, and longer length of stay [6–8]. Mortality increases with the degree of hypothermia in severely injured patients [6,8]. Since the late 1970s, studies have demonstrated a relationship between hypothermia and coagulation [9,10], but only in 1999 did the expression of the “lethal or Copyright: © 2021 by the authors. trauma triad of death” appear in scientific articles. It describes the combination of Licensee MDPI, Basel, Switzerland. acidosis, hypothermia, and coagulopathy, which is a condition that causes a substantial This article is an open access article rise in mortality in severe trauma. This report will overview the physiological process distributed under the terms and in hypothermic trauma patients focusing on the lethal triad of coagulopathy, hypothermia, conditions of the Creative Commons and acidosis. Furthermore, it will describe hypothermia staging, its implications, and treat- Attribution (CC BY) license (https:// ment options. It also describes the effect of hypothermia on clinical outcomes in trauma creativecommons.org/licenses/by/ patients and patients with traumatic brain (TBI) injury. Additionally, it further explains the 4.0/). role of clinically induced hypothermia in traumatic cardiac arrest. Int. J. Environ. Res. Public Health 2021, 18, 8719. https://doi.org/10.3390/ijerph18168719 https://www.mdpi.com/journal/ijerph Int. J. Environ. Res. Public Health 2021, 18, 8719 2 of 7 2. Coagulation The combination of hypothermia, acidosis, and coagulopathy has become well-known as the trauma triad of death, diminishing the chances of survival in severely injured pa- tients [11,12]. The three factors are highly interrelated and create a vicious circle if not addressed in a very early stage of trauma management. Acidosis is usually caused by diminished organ perfusion in shock, primarily hemorrhagic shock in trauma. It directly influences thrombin generation, which results in impaired coagulation function. Hy- pothermia is the next factor that affects blood clotting in different ways. All chemical reactions are temperature-dependent. This is also the case with blood clotting. Therefore, it seems evident that the function of the humoral coagulation cascade deteriorates with decreasing temperatures. However, several studies have also shown that platelet function is influenced by temperature [14,15]. Thrombin seems to play a major role in platelet dysfunction through a platelet adhesion defect in the presence of hypothermia [16,17]. Fibrinolysis appears to play a minor role in the development of coagulopathy. Unfor- tunately, all lab tests assessing coagulation are performed in normothermia. A correction in the presence of hypothermia is made purely by calculation and therefore does not neces- sarily correspond to the actual coagulation function [17,18]. As early as the 1990s, it was proposed to use viscoelastic hemostatic assays (VHA) such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM) to evaluate the entire coagulation system. Unfortunately, it did not lead to a breakthrough in the diagnosis of coagulation disorders in the presence of hypothermia [20,21]. 3. Clinical Management 3.1. Staging Prehospital staging of hypothermia is based on clinical status, the presence of vital signs and, if available, body temperature measurement. The Swiss staging model describes stages I–IV with ranges of stage 1 from