Wilderness Medicine
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Wilderness Medicine Howard Backer MD, MPH, FACEP, FAEMS, FAWM Director, California Emergency Medical Services Authority Past-president, Wilderness Medical Society Medical Advisor, Mountain Travel Sobek Objectives • Define and explain the field of wilderness medicine • Review some common risks of wilderness travel and field interventions for them • Discuss differences and overlap between Wilderness Medicine and EMS What is Wilderness Medicine? • Medicine in remote environments • Limited medical resources requiring improvisation Content includes • Problems caused by the environment • Dangerous fauna and flora – envenomation and toxicology, infectious diseases • Survival and wilderness search and rescue – prolonged operations and need for expanded scope Survival Wilderness Medicine Travel Medicine Military Medicine Medicine Sports Medicine Emergency Medicine and EMS Wilderness Events • Extreme event medicine: Any sporting event in a challenging environment that exceeds the capacity of local EMS systems either in transport time to definitive care or skills and equipment required for expedient extrication. • Wilderness event medicine: the healthcare response at any discrete event with more than 200 persons located more than 1 h from hospital • Injury/illness rates 1-10 per 1000 person-days of exposure – one order of magnitude greater for events that last many days or include extremes of environment (heat, altitude) Laskowski-Jones L, et al. Emerg Med J 2017;34:680–685 Adventure/Expedition Racing Teams of four M/F must stay together Multiple stages with different sports Hundreds of kilometers No marked route, only check stations Heat Illness 4 Desert Race Series 250 miles over 7 days • Increases heart rate • Decreases cardiac output • Decreases sweating • Reduces skin blood flow • Increases perceived exertion • Degrades aerobic performance Kenefick, RW • Reduces maximal U.S. Army Research intensity Institute of • Negates benefit of Environmental acclimatization Medicine WMS Desert Medicine Heat Acclimatization 39.5 180 1.5 Sweat loss 39 Rectal Kg / 70kg / hr 1.4 160 temp 38.5 1.3 140 Heart 38 rate 120 1.2 37.5 0 3 Day 6 9 Heat Illness in Grand Canyon 160 150 140 120 113 100 1993 80 1996 60 Total 37 40 15 22 20 7 1 3 4 0 Heat Exhaustion Hyponatremia Heat Stoke Backer HD, Shopes E, Collins SL, Barkan H: Exertional heat illness and hyponatremia in Grand Canyon hikers. American Journal Emergency Medicine 1999;17:532-539. iSTAT use at Extreme Temperatures Backer H, Collins C. Use of a Handheld, Battery-operated Chemistry Analyzer for Evaluation of Heat-related Symptoms in the Backcountry of Grand Canyon National Park: Ann Emerg Med April 1999;33:418-422 Radler D, et al: Improvised Method for Increasing the Temperature of an i-STAT Analyzer and Cartridge in Cold Environments. Wild Environ Med 2014 (letter) Symptoms in Grand Canyon Hikers with Hyponatremia and Heat Illness 100% 90% 80% 70% Hyponatremia n=7 60% Heat Exhaustion n=36 50% 40% 30% Hyponatremia serum 20% sodium < 130 10% 0% Backer HD, et. al: Exertional heat Chills Thirst illness and hyponatremia in Grand Nausea Cramps Tingling Canyon hikers. American Journal Vomiting Anorexia Emergency Medicine 1999;17:532- 539. Uncoordinated Field Evaluation of Heat Illness Collapse in heat during exercise Check Mental Status and temperature Altered Consciousness Normal or brief alteration May have mild hyperthermia Marked hyperthermia Normothermic Heat Exhaustion Late deterioration of mental status Heat Stroke Hyponatremia Nonexertional “Classic” Heat Stroke Hypothermia The Last Desert: 250km run in Antarctic in 7 stages Giesbrecht G Government of Canada Wilderness & BICO (Baby its Cold Environmental Outside) Rescue.com Medicine 2018; 29(4): 499-503 Cold Water Immersion 1 MINUTE to get control of your breathing 10 MINUTES of meaningful movement, 1 HOUR before you become unconscious due to hypothermia. Superficial frostbite Deep Frostbite Altitude Illness • Acute mountain sickness • High altitude pulmonary edema • High altitude cerebral edema Performance at altitude • Young and fit increases performance at altitude, but is not protective for altitude illness • Acclimatization is best prevention for altitude illness Change in Oxygen Concentrations with Altitude SaO2 PiO2 (%) 2 O a S . PaO2 Partial Pressure Oxygen (torr) . Altitude Trekking in Nepal Deaths while trekking in Nepal • 148,000 trekkers 1984-1987 • 23 deaths – Trauma 11 – Illness 8 (none cardiac) – AMS 3 • 111 helicopter rescues – AMS 38; Trauma 29; illness 29; ortho 11 • Risk of death from trekking: 15/100,000 Shlim DR and Houston R, 1989 Risk on Very High Peaks (>8,000 m) Deaths among foreigners climbing Himalayan peaks1984-7 2900/100000 (2.9%) Percent of deaths to persons summiting Everest 6.5% Annapurna 32% K-2 23% Expedition on Mt Everest Acetazolamide for AMS • Prevention – 125 mg twice daily (or 500 mg SR daily) start 12 hours before ascent continue first day at altitude • Treatment – 125 - 250 mg twice daily until improved • Sleep – 62.5 - 250 mg at dinner time Acetazolamide Decreases Periodic Breathing (A) Placebo Respiratory Pattern SaO2(%) (B) Acetazolamide Respiratory Pattern SaO2(%) Dexamethasone to prevent AMS • Indicated for those who can’t take acetazolamide or rapid brief ascent (rescue) • Also used in conjunction with acetazolamide for rapid ascent above 3000 meters (e.g. rescue) • Dose: 4 mg every 6 hours Hyperbaric bag for treatment of Altitude Illness Flora, Fauna, and Microbes Name the Disease • Exposure to contaminated water • ~ 100-200 cases are identified annually in the United States with about 50% of cases occurring in Hawaii. • Considered to be the most widespread zoonotic disease in the world. Clinical Syndrome • Incubation period usually 7 days, range 2-29 days Phase 1 - with fever, chills, headache, muscle aches, jaundice, anemia, vomiting, or diarrhea, the patient may recover for a time but become ill again. Phase 2 (Weil's disease) renal or liver failure, meningitis • Treatment Doxycycline Penicillin Leptosporosis Outbreaks from Sport Events Suspect or Location Activity confirmed cases Illinois (1998) 84 (11%) Triathalon MMWR. August 21, 1998 / Wisconsin (1998) 20 (5%) Triathalon 47(32);673-6 Clin Inf Dis 2010; 50:843– Florida (2005) 44/192 (23%) Adventure race 849 Emerg Inf Dis Vol. 9, No. Borneo (2000) 80/189 (42%) Eco-challenge 6, June 2003 Costa Rica 9/26 (34%) River rafting MMWR. 1997;46:577-579 (1996) J Appl Microbiol. 107 Ireland 6/62 (10%) River rafting (2009) 707–716 Tickborne Diseases Arboviruses • Lyme • Dengue • Rickettsiosis • Yellow fever • Tickborne typhus • Zika • RMSF (spotted fevers) • West Nile • Babesiosis • Encephalitis • Relapsing fever • Chikungunya • Ehrlichiosis Protozoa • Malaria Envenomation First Aid Measures • “The 3 Rs”: Rest, Reassurance, • and Rapid transportation • Get a picture of the snake • Remove potential tourniquets • Immobilize extremity (heart level) • Don’t cut it • Don’t suck it • Don’t freeze it • Don’t shock it Risk factors for envenomation • Unaware in snake habitat • Poor judgment, stupidity • Intoxication Expected outcome of normal, healthy adult stung by honey bees and without medical intervention • 6 Stings/lb -- Survival • 8 Stings/lb -- 50% chance of survival • 10 Stings/lb -- Death Emergency Notification Devices Wilderness EMS vs Recreational Wilderness Medicine • EMS--NASEMSO definition – Credentialed teams – Medical control or delegated practice – Use preset protocols – Provide care in specific jurisdiction • Wilderness medicine – Limited or no medical oversight – May have limited duty to act or Good Samaritan – Interventions contextual and relative – May teach more advanced procedures (e.g., realign/reduce) Common Wilderness Medicine Training Levels Wilderness Wild Emerg Wilderness Wilderness Outdoor First Aid Med First EMT (Winter) (WFA) Responder Responder (WEMT) Emerg Care (WEMR) (WFR) (OEC) 16 hours 48-60 hours 70 hours Average 4 weeks 80-120 hours 160+ hrs Public first aid Wilderness Guides EMS rescue, Ski patrol rescue outdoor professionals ARC, SOLO, Can be Consensus Hybrid WM and Owned/licensed Boy Scouts, Am combined with SOP; can EMS but no by NSP; No Acad Ortho DOT EMR combine with formal EMS formal bridge to EMR recognition; Can EMT sit for NREMT Wilderness EMT vs EMT-Basic: differences in scope • Extended management • Improvisation • Rescue / evacuation decisions • Additional medications (from EMT basic) • Advanced procedures – Relocation/ alignment of fractures – Catheterization • Environmental problems • Immobilization clearance • Field termination of CPR Comparison of EMT and OEC-T Constance, Auerbach, Johe. Wilderness Environ Med 2012 EMT but not OEC-T OEC-T but not EMT • Ambulance based care • Wilderness operations • ED exposure • In-depth environmental injuries • Mechanical Ventilator • Adaptation and improvisation • Automated monitoring equip • Snow sports pathology • Mechanical CPR • Backcountry extrication • Assist Ob delivery • Specific emergency medications • Infectious disease • Hematologic emergencies • Post cardiac resuscitation • Neonatal emergencies EMS and Ski Patrol • Ski patrol has established medical duty to act • Ski patrol is authorized under a federal charter – Does this exempt patrollers from state regulation? • Ski patrol has consistently opposed regulations or licensing efforts • NAEMSP/NASEMSO: Ski patrollers are operational EMS providers who “should function within not outside the healthcare system.” (i.e., with medical oversight of a state-sanctioned medical director, and within state EMS credentialing and licensure systems.) Hawkins S. WEM 23:106-111, 2012 (editorial) Wilderness Medical Society • Education • Conferences • Research • Adventure CME Combine your profession and your passion for the Outdoors https://wms.org/ .