Too Hot, Too Cold OHSUEffects of Temperature on Human Physiology Jenna M. Wiley, MD Wilderness Medicine Fellow Oregon Health and Science University September 18, 2020 Outline • • • • Pernio • Cold Urticaria Thermoregulatory Physiology

• Heat Rash, Edema, Cramps, & OHSU• Heat Exhaustion • OHSUPathophysiology

Source: Medical News Today OHSU

Source: http://sportmedschool.com/heat-related-illness/ OHSU

Source: Dupont et al, JEMS 2017 OHSU Heat Stress Protein denaturation -> neuronal cell death

Demand ischemia (massively increased CO) -> cell death -> hyperkalemia

Hyperventilation, hyperpnea, pulmonary vasodilation -> ARDS

High vascular permeability -> GI bleeding Ischemia -> liver cell apoptosis -> cytokine release

Source: https://insideclimatene -> hypoperfusion -> acute renal failure ws.org/content/infogra OHSUphic-what-heat-stroke- can-do-human-body

Protein denaturation -> DIC, coagulopathy, embolic events Heat Injury

Hyperthermia: elevated body temperature due to failed thermoregulation that occurs when a body produces or absorbs more heat than it dissipates OHSUSpectrum of Severity Source: http://sportmedschool.com/heat-related-illness/ Epidemiology

• 600 deaths annually • Leading cause of morbidity and mortality among U.S. high school athletes • Mortality of exertional heat OHSUstroke reaches 10%

Sources: denverhealth.org, dreamstime.com Heat Rash

• Management • Limb elevation • Bandages • Avoid high temperatures OHSU• Rehydrate

Source: osfhealthcare.org Heat Cramps

• Localized, painful, involuntary spasms of skeletal muscles

• Management • Oral salt solutions or electrolyte replacement OHSU• Passive stretching Source: slideshare.net Heat Edema

• Management • Limb elevation • Compression stockings • Avoid high temperatures • Rehydrate OHSUhttps://www.centerforvein.com/ Heat Syncope

• Management • Rule out other medical causes • Isotonic oral fluids • Rest in cool environment • Move extremities to prevent pooling of blood OHSU• Passive cooling Source: pixtastock.com Heat Exhaustion

• Management • Move to cool environment • Cease physical activity • Oral rehydration or isotonic fluids • If more severe -> IV fluids, evaporative and convective OHSUcooling

Source: medicalnewstoday.com Heat Stroke • 2 Types • Classic • Core temp above 40℃ (104℉) • Exertional with encephalopathy • Life threatening clinical syndrome • Loss of temperature OHSUregulation

Source: https://www.siumed.edu/ Heat Stroke

• Field Management • Hospital Management • Remove from heat source • ECG • Support ABCs • Chest x-ray • Labs (CBC, CMP, Mg, CK, UA) OHSU• Active cooling • Foley temperature probe • IV fluids • Continued active cooling • Evacuation Hypothermia

Definition: Unintentional drop in core temperature to 35℃ (95℉) OHSUor below OHSU

Source: Dupont et al, JEMS 2017 Classification

Standard Swiss Temperature Symptoms

Normal mental status Mild HT I 32 - 35℃ (90-95℉) +Shivering Difficulty caring for oneself

Altered mental status Moderate HT II 28 - 32℃ (82-90℉) No shivering Need external rewarming

Unconscious Severe HT III 24 - 28℃ (75-82℉) OHSUHigh risk of cardiac dysrhythmias or cardiac arrest HT IV Unconscious Profound < 24 ℃ (75℉) Vital signs absent – apparent death HT V Death due to irreversible hypothermia: <13.7°C Clinical Manifestations

Irritability, , poor memory, slurred speech, apathy, poor decision-making, lethargy,

Bradycardia -> reduced cardiac output Dysrhythmias

Decreased ventilatory response to CO2 -> hypoventilation and respiratory acidosis

OHSUCold-induced diuresis -> reduced circulating blood volume

Coagulopathy and hemoconcentration OHSU Management • Mild Hypothermia • Protect from further cooling • Seek shelter \ • Passive warming OHSU• Rest for at least 30 min

Source: https://www.pinterest.com/pin/525443481497961339/ Source: American Alpine Institute Management

• Moderate Hypothermia • Active external rewarming • Hypowrap • Warm IV fluids • IV or IO glucose • Handle gently and reassess often OHSU• No standing or walking Management

• Severe Hypothermia • Handle gently and keep horizontal • ABCs • CPR Considerations • Utility of Rescue • Active rewarming to core OHSU• Transport carefully Source: LiveScience.com Complications

• Afterdrop • Cold blood from extremities goes to core • Worsens effects of hypothermia on heart and brain • Affected by method of OHSUrewarming Source: https://openwaterswimming.com/ Complications

Source: https://openwaterswimming.com/

• Circumrescue collapse • Syncope or sudden death in victims of cold-water immersion just before, during or after rescue OHSUand removal from water Frostbite

Pathophysiology • Prefreeze • Freeze-thaw • Vascular stasis OHSU• Late ischemic Source: Sheridan R et al N Engl J Med 2009 Photo source: Auerbach’s Wilderness Medicine, 7th ed. Frostbite 2017

Frost nip • Superficial nonfreezing cold injury • Intense vasoconstriction • Numbness and pallor resolve after warming

Management • Avoid refreezing! Frost bite • Keep hydrated • Freezing of tissue • Ibuprofen OHSU• First through fourth degree • Remove jewelry • Splint extremity • Consider active rewarming Trench Foot

• Clinical Features • Management • Tingling, itching, prickliness • Apply warm packs or • Pain, swelling, numbness soaking in warm water for • Cold and blotchy skin approximately 5 min OHSU• Blisters may form

Source: postgraduate medical journal, BMP Pernio ()

• Clinical Features • Localized, inflammatory, bluish-red lesions • Management • Dry • Gentle massage • Avoid active rewarming above 30° C (86° F) OHSU• Nefidipine if severe

Source: Wikipedia CoLD Urticaria

• Clinical Features • Localized or generalized wheals, redness, swelling, itching • Management • Antihistamines OHSU• Corticosteroids, epi if severe

Source: Auerbach’s Wilderness Medicine 7th ed, 2017 Prevention is key

• Avoid dehydration • Acclimatization • Proper clothing OHSU• Fitness level Source: everydayhealth.com References

• Baumgartner EA, Belson M, Rubin C, et al. Hypothermia and other cold-related morbidity emergency department visits: United States, 1995- 2004. Wilderness Environ Med. 2008;19(4):233-237. • Bessen H, Ngo B: Hypothermia. In Tintinalli J, Stapczynski JS, Ma OJ, et al. (Eds.), Tintinalli’s emergency medicine: A comprehensive study guide. McGraw-Hill Education: New York, 2016. • Callaway CW, Donnino MW, Fink EL, et al. Part 8: Post-cardiac arrest care: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2015;132(18 Suppl 2):S465-S482. • CDC, C. f. (2010). Centers for Disease Control: among high school athletes – United States, 2005 – 2009. Atlanta, Georgia, USA: Morbidity and Mortality Weekly Report – CDC. • Charkoudian N and Crawhaw L. Thermoregulation. In Auerbach P (Ed.), Wilderness medicine, 7th edition. Mosby Elsevier: Philadelphia, pp. 120-134, 2017. • Danzl D, Huecker M. Accidental hypothermia. In Auerbach P (Ed.), Wilderness medicine, 7th edition. Mosby Elsevier: Philadelphia, pp. 135-162, 2017. • Dow J et al. Wilderness Medical Society Practice Guidelines for Out of Hospital Evaluation and Treatment of Accidental Hypothermia: 2019 Update. WEMJ. 2019; 30(4) S47-69. • Du Pont D, Dickinson E. Hypothermia. JEMS. 42(11); 2017. https://www.jems.com/2017/11/01/identifying-and-managing-accidental-hypothermia/ • Howe. (2007). Heat-Related Illness in Athletes. American Journal of Sport Medicine , 1384 -1395. • Leci E and Briscoe G. Heat Related Illness. Sport Med School. Feb 2020. http://sportmedschool.com/heat-related-illness/ • Leon, B. (2015). Heat Stroke. Comprehensive Physiology , Vol.5 (2) 611 – 647. • LipmanOHSU G et al. Wilderness Medical Society Practice Guidelines for Prevention and Treatment of Heat Illness: 2019 Update. WEMJ. 2019; 30(4): S33-46 • Osilla, a. S. (2019). Physiology, Temperature Regulation. Tampa, Florida, USA : StatPearls Publishing . • Toru Hifumi, Y. K. (2018). Heat stroke. Journal of Intensive Care , 320-328.