High Altitude Mountaineering Seminar 2013 - 10.16.13   High Altitude Medicine
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High Altitude Mountaineering Seminar 2013 - 10.16.13 High Altitude Medicine

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High Altitude Mountaineering Seminar 2013 - 10.16.13   High Altitude Medicine High Altitude Mountaineering Seminar 2013 - 10.16.13 High Altitude Medicine Presentation Transcript

  • High Altitude Medicine Scott R Valent MD
  • High Altitude Medicine ● University of Vermont College of Medicine ● Multiple high altitude treks in Nepal, Pakistan, Tibet ● Travels in Peru, Ecuador, Argentina, Bolivia ● Aconcagua ● Cardiologist
  • Highest cities in the world ● ● ● ● ● ● ● ● ● Lhasa, Tibet La Paz, Bolivia Cuzco, Peru Sucre, Bolivia Quito, Ecuador Toluca, Mexico Bogota, Columbia Addis Ababa, Ethiopia Asmara, Ethiopia 12,000 ft 11,910 ft 11,152 ft 9,331 ft 9,249 ft. 8,793 ft. 8,675 ft. 7,900 ft. 7,789 ft.
  • Altitude Facts ● The percentage of oxygen at altitude is the same as sea level, approximately 21% ● Atmospheric and partial pressure decrease with altitude, allowing less oxygen availability ● Barometric pressure 760mmHg sea level ● Barometric pressure 253mmHg Mt Everest ● Pressure 222mmHg at 67 degrees N lat.
  • Altitude sickness Anyone traveling to high altitude may be at risk for developing altitude sickness ● AMS ● HAPE ● HACE
  • Physiology at altitude ●
  • Physiologic effects of altitude High altitude 5,000-11,500 ft. (1,500-3,500m) ● AMS common with rapid ascent ● Decreased exercise capacity ● Pulse oximetry pOx>90%
  • Physiologic effects of altitude Very High Altitude 11,500-18,045 ft (3500-5500m) ● Most common range for severe high altitude illness ● Abrupt ascent dangerous ● Pulse Oximetry 75-85% ● Extreme hypoxia may occur during sleep, exercise and high-altitude illness
  • Physiologic effects of altitude Extreme altitude 18,000-29,035 (5500-8850m) ● Progressive deterioration outstrips acclimatization ● Humans cannot permanently live at these altitudes ● High likelihood of severe high-altitude illness with rapid ascent ● Pulse oximetry 58-75%
  • Acclimatization ● ● ● ● ● ● Immediate: Rapid breathing and HR Increased catecholamines Dehydration Pulmonary artery pressure increases Increase in hematocrit within 4 days Increase in 2,3-DPG
  • Cheyne-Stokes Breathing ● “Hey, my tentmate stopped breathing” ● The respiratory drive, particularly while sleeping is primarily driven by CO2 ● At altitude CO2 levels are typically lower and breathing may be initiated by decreased O2. ● This leads to erractic breating, with long, frightening pauses.
  • Risk categories for acute mountain sickness Risk category Description Prophylaxis recommendation LOW People with no prior history of altitude illness and ascending to <9,000ft. People taking >2 days to arrive at 8,000-9,000feet with subsequent increases in sleeping elevation <1, 600 feet/dy, and an extra day for acclimatization every 3,200 feet Acetazolamide prophylaxis is generally not indicated MODERATE People with prior history of AMS and ascending 8,000-9,000 feet in one day No history of AMS and ascending to >9,000 feet in 1 day All people ascending >1,600 ft per day at altitudes above 9,000 ft., but with an extra day for acclimatization every 3,200 feet Acetazolamide prophylaxis would be beneficial and should be considered HIGH History of AMS and ascending to >9,000 feet in 1 day All people with a prior history of HACE or HAPE All people ascending to >11,400 feet in one day All people ascending to >1,600 feet per day above 9,000 feet, without extra days for acclimatization Very rapid ascents (such as <7 day ascents of Mount Kilimanjaro Acetazolamide prophylaxis strongly recommended Hackett, P.H. Altitude illness, 2014 yellow book
  • Acute Mountain Sickness(AMS) ● Very common ○ 15-30% of colorado resort skiers ○ 50% of Mt. McKinley climbers ○ 70% of Mt. Ranier climbers
  • Lake Louise Criteria Acute Mountain sickness ● Headache plus at least one of the following: ○ fatigue or weakness ○ nausea,vomiting, anorexia ○ dizziness, lightheadedness, insomnia
  • HAPE Definition: Accumulation of fluid in the lungs leading to hypoxia Unrelated to AMS ● Incidence: 0.1-5% ● Often manifests at night, frequently the second night ● Can progress rapidly ● May lead to HACE
  • Lake Louise Criteria HAPE ● At least two of the following symptoms: ○ Dyspnea at rest ○ Cough ○ weakness or decreased exercise performance ○ Chest tightness or congestion
  • Lake Louise Criteria HAPE ● At least two of the following signs: ○ ○ ○ ○ Central cyanosis rales or wheezing Tachypnea Tachycardia
  • HAPE Risk Factors ● Young, fit males ● Exertion ● Cold
  • HAPE-Treatment ● Treatment of choice is descent (2,000 feet) ● Oxygen ● Nifedipine, Sildenafil ● Gamow Bag ● Mortality rate for untreated HAPE may be up to 44%
  • HACE ● ● ● ● ● Treatment Immediate descent Oxygen Steroids-Decadron Gamow bag
  • Treatment
  • Gamow bag
  • Gamow bag
  • Golden rules of high altitude medicine ● If you are sick at high altitude, it is altitude sickness until proven otherwise ● Never ascend with symptoms of AMS ● If you are deteriorating or have signs or symptoms of HAPE or HACE, descend immediately
  • Medications/Dosages Acetazolamide/Diamox Indication Route Dose AMS, HACE prevention oral 125mg twice a day 250mg twice a day if over 100KG AMS treatment Oral 250mg twice a day Hackett, P.H. Altitude illness, 2014 yellow book
  • Medications/Dosages Dexamethasone Indication Route Dose AMS, HACE prevention oral 2mg every 6 hours, or 4mg every 12 hrs AMS, HACE treatment oral, iv, im AMS: 4mg every 6 hrs. HACE: 8mg once, then 4mg every 6 hrs. Hackett, P.H. Altitude illness, 2014 yellow book
  • Medications/Dosages Nifedepine Indication Route Dose HAPE prevention oral 30mg SR (slow release) every 12 hrs or 20mg SR every 8hrs HAPE treatment oral 30mg SR every 12 hrs. or 20mgSR every 8 hrs. Hackett, P.H. Altitude illness, 2014 yellow book
  • Medications/Dosages Sildenafil (Viagra) Indication Route Dose HAPE prevention oral 50mg every 8 hrs. Hackett, P.H. Altitude illness, 2014 yellow book
  • Prevention ● One night at an altitude slightly below 10,000 feet ● At altitudes above 10,000 feet, increase sleeping altitude by only 1,000-1,500 feet per night ● Spend a second night at the same altitude for every increase of 3,000 ft. ● Example : Aconcagua:with a generous 1,500 foot per night increase, plus several rest and weather days, expect 9-10 days prior to summit night at 20,000+ feet
  • Prevention Acetazolamide ● Diuretic used to help hasten acclimatization ● 250-1,000 mg daily ● Mechanism: During initial time at altitude rapid breathing decreases CO2 and decreases acidity of blood ● Acetazolamide helps acidify blood ● Improves symptom scores for AMS ● may improve sleep ● Does not protect against AMS with ascent
  • Other hazards at altitude
  • Bronchitis/chronic cough ● Cool extremely dry airhyperventilation, mouth breathing ● Cough ● Broken ribs ● Can mimic HAPE
  • Sunburn ● UV intensity increases 4% per 1,000 feet ● at 18,000 feet 72% more sun exposure, not including snow reflection
  • Ultraviolet Keratitis ● ● ● ● Snow blindness Corneal damage from UV light Damage can occur in one hour Symptoms may not develop for 6-12 hours ● PREVENTION
  • Frostbite
  • Summary ● ● ● ● Prevention is critical Golden rules Early diagnosis and descent As one travels higher the margin for error decreases significantly
  • Questions?
  • Recommended websites ● Altitude.org ● BasecampMD.com ● http://www.high-altitude-medicine.com/ ● CDC chapter by Peter Hackett: http://wwwnc. cdc.gov/travel/yellowbook/2014/chapter-2-thepre-travel-consultation/altitude-illnesshttp://wwwnc. cdc.gov/travel/yellowbook/2014/chapter-2-the-pre-travel-consultation/altitude-illness