PRACTICING MEDICINE AT EXTREME HIGH ALTITUDE: Statistics, heuristics and logistics Emily E. Johnston, MD, FACEP, DiMM WMS Winter Conference 2021 We will cover: The most commonly encountered medical problems at extreme altitude A brief review of pertinent pathophysiology Extreme altitude statistics (as available) Decision making and practical logistics Heuristics A heuristic technique is any approach to problem solving or self-discovery that employs a practical method that is not guaranteed to be optimal, perfect, or rational, but is nevertheless sufficient for reaching an immediate, short-term goal or approximation. Medical problems at extreme altitude Cold injury Pre-existing medical conditions AMS/HAPE/HACE Exhaustion, Trauma dehydration Stress and anxiety Respiratory GI Skin Sudden cardiac Eyes death Cold injury – Hypothermia MS/LOC, shivering, performance, CV(blood pressure/rhythm) never for SEALs . ~32 C/89.6 F – exogenous heat needed ~30 C/95 F – cardiac changes WMS guidelines Figure 3 Wilderness & Environmental Medicine 2019 30S47-S69DOI: (10.1016/j.wem.2019.10.002) Copyright © 2019 Marketing EDGE.org. Cold injury – Hypothermia 31 yo OTW healthy male s/p ascent to 8848m/29,000+’, shortroping/lowering client from the yellow band attaches personal gear to ice screw,eventually taps out due to exhaustion and descends to 7200’/22,000’ alone. discovered hours later by teammate in tent at C3, AMS, not shivering. pt receives meds, rewarmed for hours. ultimately descends under his own power. Cold injury – Frostbite 30-35% of climbers at extreme altitude mostly face, fingers, toes. often delayed diagnosis due to: hypoxia sleep deprivation distraction Cold injury – Frostbite “I knew something was amiss with my left foot before reaching the summit - chose to ignore it and do as everyone else does and continue on up.” “by the time I finished messing around, achieving nothing, my hands were a tad chilly!” “Didn't think a big deal and made it back to C2 exhausted.” “Prior to heading to Everest I bought a set of heated (foot)warmers. carried them up to the South Col, still not using them. I didn't make the smart decision to actually connect them up. I left for the summit.... still without them installed.” Cold injury – Frostbite Frostbite management a variety of grading systems to rewarm or not? blister management oxygen Cold injury – Frostbite Day 3 Day 2 Day 6 Day 1 Cold injury – Frostbite Day 79 Day 10 Day 16 Day 83 Day 139 AMS/HAPE/HACE AMS – Acute Mountain Sickness don’t worry, it’s just brain swelling 15-40%+ of CO skiers (2500-4000m/8100-13,000’) 40% of Denali climbers about 70% above 3000m/10,000’ higher for those flown directly to 4200m/14,000’ decreased incidence in > 50 yo AMS/HAPE/HACE AMS diagnosis quandry exhaustion, dehydration, CO, stress, Covid-19 vitals/exam are not helpful oxygen? acetazolamide? ondansetron? graded trial of treatment depending on timeframe and resources AMS/HAPE/HACE HAPE – High Altitude Pulmonary Edema non-cardiogenic pulmonary edema hypoxic pulmonary vasoconstriction increased pressure risks: anything increasing risk of pulmonary hypertension prior HAPE, genetic predisposition pulmonary infection exertion and cold temps unusual below 3000m/9850’ AMS/HAPE/HACE HAPE 2% of Denali climbers 6190m/20,320’ 16% of Kilimanjaro climbers 5895m/19341’ 15% of people flown directly to 5500m/18,000’ 60% recurrence rate at 4500m/14,700’ 4500m – 0.2-6% 5500m – 2-15% AMS/HAPE/HACE HAPE SOB, cough is common at altitude 38% of medical pts at Everest ER - how do you know? oxygen is diagnostic and therapeutic orthopnea, dyspnea at rest, decreased exercise capacity frothy sputum is for Hollywood full court press ASAP descent and O2 and nifedipine, Gamow bag as needed AMS/HAPE/HACE HACE – High Altitude Cerebral Edema the vast majority with HACE have HAPE HAPE increases intra-thoracic pressure which contributes to cerebral venous congestion. on continuum with AMS vasogenic edema death by herniation AMS/HAPE/HACE HACE 0.5-1+% of travelers to high altitude 3-4% of AMS patients progress to HACE 13-20% of those with HAPE unusual below 3000m/9800ft mean altitude of onset 4730m/15,500ft Trauma Everest ER 14% trauma you fall off the mountain you fall into the mountain the mountain falls on you rockfall/people/objects avalanche/icefall extreme weather Stress and anxiety exacerbate other disorders precipitate formal and informal evacuations self-medication is not uncommon daily plan, structured time frequent one-on-one interactions eventually must let them go Gastrointestinal second most common complaint at Everest ER enteritis, gastroenteritis Nepal, Pakistan, Tibet, Ecuador, Mexico, Bolivia, Chile, Argentina, Canada, Alaska almost 30% of Denali climbers about 40% of med pts at EER, incidence likely 80%+ the fantastic combined effects of ondansetron! anorexia, malabsorption fat absorption decreases by up to 50% Sudden cardiac death etiology is often unknown stress on cardiovascular system due to physiology of altitude hypercoagulability hypoxic arrythmias pre-existing conditions Sudden cardiac death – CV stress Effect of altitude on VO₂ max Aviat Space Environ Med. 1998 Aug;69(8):793-801.Maximal and submaximal exercise performance at altitude C S Fulco , P B Rock, A Cymerman PMID: 971597 Sudden cardiac death - hypercoagulability risk of spontaneous vascular thrombosis increases 30 times with long stays at high and extreme altitude. DVT, PE, CVA, TIA, portal, splenic and superior mesenteric veins, arterial clots. hemoconcentration, vasoconstriction, stasis, possible changes in clotting cascade may unmask congenital predisposition typically above 4500m ASA use is not uncommon Sudden cardiac death – arrhythmias and pre-existing conditions many climbers chose to not disclose pre-existing conditions. hypoxia is arrhythmogenic, but what type of arrhythmias? significant increase in brady and tachyarrhythmias unclear data on ventricular arrhythmias overuse of azithromycin, ondansetron, other medications without medical oversight, is common. Sudden cardiac death -53 yo male, no known medical history at 6800m/22,300’ on Aconcagua -sits down at break, slumps over unresponsive. -CPR initiated, sat call. -climber had witheld hx of bovine aortic valve replacement. Logistics Resuscitation Decision-making Pre-existing medical conditions Dave Hahn: “Everything is worse at altitude” inherent physiologic stress, decreased buffer frequent nondisclosure awareness of subclinical disease asthma improvement is a silver lining no wheezing but everyone is breathless at altitude. Exhaustion, dehydration very, very common contribute to CV, pulmonary, emotional stress decreased immune function prevention is crucial nutrition morale clear intake goals Respiratory diagnostic quandry khumbu cough 38% of medical pts at Everest ER antibiotic stewardship stress and anxiety pulse oximetry Skin 56% of trauma at Everest ER was derm long periods of time in the same clothes poor hygiene dry and cold repetitive motion anorexia Eyes retinal hemorrhage ubiquitous but rarely symptomatic canary in the coal mine? snow blindness (UV uveitis) proparacaine Clarke C Neurology at high altitude Practical Neurology 2006;6:230-237. Logistics - medications the temperature inside tents is extreme difficult to tell if meds got too hot many meds are UV sensitive if capsules freeze they may crack and crumble if medication vials freeze: check for hairline cracks contain and gently melt many meds will lose efficacy Logistics - medications transporting medications split up and place in carry on bring twice as much as needed always have: a prescription in YOUR name a letter from the expedition physician (which may be you) on expedition letterhead Logistics – insulin insulin dependent diabetes: go low tech (syringes not pens) antiperspirant/sticky stuff/vet wrap at cannula site have a back-up cannula in place on high risk days keep insulin/strips at appropriate temp 14-30C (good for about 1 month) – carry a cold pack not too warm, not right next to the skin check/purge out air every 1000m be sure several people understand the system Logistics - general batteries will always die at the most inopportune moment anything ruined by water will get wet old transceiver bags wear well for temperature sensitive items be ready for creative problem solving under pressure understand the environment and resources at hand References Anand AC, Jha SK, Saha A, Sharma V, Adya CM. 2001. “Thrombosis as a complication of extended stay at high altitude.” Natl Med J India;14(4):197-201. Anand AC, Sashindran VK, Mohan L . 2006. “Gastrointestinal problems at high altitude.” Trop Gastroenterol 27(4):147-53. Bärtsch P, Gibbs JS. 2007. Effect of Altitude on the Heart and the Lungs”. Circulation;116:2191–2202. https://doi.org/10.1161/CIRCULATIONAHA.106.650796 Boos CJ , Holdsworth DA , Woods DR , O’Hara J , Brooks N , Macconnachie L , Bakker-Dyos J , Paisey J , Mellor A. 2017. “Assessment of Cardiac Arrhythmias at Extreme High Altitude Using an Implantable Cardiac Monitor. REVEAL HA Study (REVEAL High Altitude)”. Circulation;135:812–814 Boyer SJ, Blume FD. 1984. „Weight loss and changes in body composition at high altitude.”J appl physiol (11) 01. https://doi.org/10.1152/jappl.1984.57.5.1580 Clarke C. 2006. “Neurology at high altitude.” Practical Neurology. 6:230-237. Dow J, Giesbrecht GG, Danzl DF, Brugger H, Sagalyn EB, Walpoth