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hypothermia

A core temperature < 35 degrees C (95 degrees F). Etiology: 1) environmental exposure 2) drugs a) alcohol b) barbiturates c) phenothiazines d) opiates e) clonidine f) lithium g) benzodiazepines 3) metabolic (endocrine) disorders a) hypoglycemia b) hypothyroidism c) hypopituitarism d) adrenal insufficiency e) diabetic ketoacidosis 4) hypothalamic dysfunction 5) spinal cord transection (T1 of above) 6) skin disorders a) exfoliative dermatitis (toxic epidermal necrolysis) b) burns 7) general debilitation 8) episodic spontaneous hypothermia with hyperhidrosis 9) sepsis 10) uremia Epidemiology: - patients with impaired thermoregulation or perception of cold are at greatest risk a) elderly b) intoxicated persons [1] Clinical manifestations: 1) mild hypothermia (32-35 C or 89.6-95 F) a) shivering b) delirium, alert, poor judgement c) pulse may be normal or increased d) blood pressure may be normal or increased [1] 2) below 28-32 C (82.4-89.6 F) a) shivering ceases b) metabolism slows c) multiple organ system dysfunction occurs d) pulse, blood pressure & respirations decline e) consciousness progressively declines 3) below 28 C (82.4 F)* a) comatose b) pupils are fixed & dilated c) reflexes are absent d) hypotension e) pulse & respirations are barely detectable or absent * case report of 76 year old demented woman with core temperature of 26 C (78.8 F) [5] Laboratory: 1) arterial blood gas (ABG) - respiratory acidosis 2) complete blood count (CBC) a) elevated hematocrit from hemoconcentration b) leukopenia c) thrombocytopenia Special laboratory: Electrocardiogram (EKG): 1) atrial fibrillation 2) Osborne J wave* < 29 C [5] (image) * magnitude of the J waves may be associated with degree of hypothermia. but are not specific for hypothermia Management: 1) responsive patients a) warming with blankets b) warm, humidified air c) warm intravenous fluids d) shivering patients usually recover spontaneously if removed from cold environment & kept dry [1] 2) unresponsive patients (< 32 degrees C) a) during emergency care, aim for 32-36 degrees C & maintain temperature for at least 24 hours [3] b) active core warming with gastric, colonic or peritoneal lavage c) hemodialysis can be used for warming mostly for in conjunction with severe acid-base disturbances, not for core temperature < 28 C) [3] d) cardiopulmonary bypass [1] 3) patients should not be pronounced dead until they have been warmed to a core temperature of > 32 C (> 89.6 F) presumably for at least 24 hours [3]

Related

body temperature euthermia frostbite hyperthermia (pyrexia) hypothermic perfusion Osborne J wave

Specific

cold injury syndrome induced hypothermia; targetted temperature management

General

disorder of temperature regulation sign/symptom cold injury

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, 16, 17,18, 19. American College of Physicians, Philadelphia 1998, 2012, 2015, 2018, 2022
  2. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 98
  3. Physician's First Watch, Oct 20, 2015 David G. Fairchild, MD, MPH, Editor-in-Chief Massachusetts Medical Society http://www.jwatch.org - 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. (in 15 parts, see Table of Contents) Circulation November 3, 2015, Volume 132, Issue 18 suppl 2 http://circ.ahajournals.org/content/132/18_suppl_2.toc
  4. Brown DJ, Brugger H, Boyd J, Paal P Accidental hypothermia. N Engl J Med. 2012 Nov 15;367(20):1930-8. Review PMID: 23150960
  5. Kampouri E, Vaucher J. Electrocardiographic Changes in Hypothermia N Engl J Med 2018; 378:460. Feb 1, 2018 PMID: 29385369 http://www.nejm.org/doi/full/10.1056/NEJMicm1704534
  6. Hilmo J, Naesheim T, Gilbert M. "Nobody is dead until warm and dead": prolonged resuscitation is warranted in arrested hypothermic victims also in remote areas- a retrospective study from northern Norway. Resuscitation. 2014 Sep;85(9):1204-11. PMID: 24882104 Free Article