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dc.contributor.authorBjertnaes, Lars J.
dc.contributor.authorNæsheim, Torvind
dc.contributor.authorReierth, Eirik
dc.contributor.authorSuborov, Evgeny
dc.contributor.authorKirov, Mikhail
dc.contributor.authorLebedinskii, Konstantin M.
dc.contributor.authorTveita, Torkjel
dc.date.accessioned2022-09-09T11:56:09Z
dc.date.available2022-09-09T11:56:09Z
dc.date.issued2022-02-23
dc.description.abstractBackground: Accidental hypothermia (AH) is an unintended decrease in body core temperature (BCT) to below 35°C. We present an update on physiological/pathophysiological changes associated with AH and rewarming from hypothermic cardiac arrest (HCA).<p> <p>Temperature Regulation and Metabolism: Triggered by falling skin temperature, Thyrotropin-Releasing Hormone (TRH) from hypothalamus induces release of Thyroid-Stimulating Hormone (TSH) and Prolactin from pituitary gland anterior lobe that stimulate thyroid generation of triiodothyronine and thyroxine (T4). The latter act together with noradrenaline to induce heat production by binding to adrenergic β3-receptors in fat cells. Exposed to cold, noradrenaline prompts degradation of triglycerides from brown adipose tissue (BAT) into free fatty acids that uncouple metabolism to heat production, rather than generating adenosine triphosphate. If BAT is lacking, AH occurs more readily.<p> <p>Cardiac Output: Assuming a 7% drop in metabolism per °C, a BCT decrease of 10°C can reduce metabolism by 70% paralleled by a corresponding decline in CO. Consequently, it is possible to maintain adequate oxygen delivery provided correctly performed cardiopulmonary resuscitation (CPR), which might result in approximately 30% of CO generated at normal BCT.<p> <p>Liver and Coagulation: AH promotes coagulation disturbances following trauma and acidosis by reducing coagulation and platelet functions. Mean prothrombin and partial thromboplastin times might increase by 40–60% in moderate hypothermia. Rewarming might release tissue factor from damaged tissues, that triggers disseminated intravascular coagulation. Hypothermia might inhibit platelet aggregation and coagulation.<p> <p>Kidneys: Renal blood flow decreases due to vasoconstriction of afferent arterioles, electrolyte and fluid disturbances and increasing blood viscosity. Severely deranged renal function occurs particularly in the presence of rhabdomyolysis induced by severe AH combined with trauma.<p> <p>Conclusion: Metabolism drops 7% per °C fall in BCT, reducing CO correspondingly. Therefore, it is possible to maintain adequate oxygen delivery after 10°C drop in BCT provided correctly performed CPR. Hypothermia may facilitate rhabdomyolysis in traumatized patients. Victims suspected of HCA should be rewarmed before being pronounced dead. Rewarming avalanche victims of HCA with serum potassium > 12 mmol/L and a burial time >30 min with no air pocket, most probably be futile.en_US
dc.identifier.citationBjertnaes, Næsheim, Reierth, Suborov, Kirov, Lebedinskii, Tveita. Physiological Changes in Subjects Exposed to Accidental Hypothermia: An Update. Frontiers in medicine. 2022;9:1-17en_US
dc.identifier.cristinIDFRIDAID 2027378
dc.identifier.doi10.3389/fmed.2022.824395
dc.identifier.issn2296-858X
dc.identifier.urihttps://hdl.handle.net/10037/26752
dc.language.isoengen_US
dc.publisherFrontiers Mediaen_US
dc.relation.journalFrontiers in medicine
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2022 The Author(s)en_US
dc.titlePhysiological Changes in Subjects Exposed to Accidental Hypothermia: An Updateen_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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