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High Altitude Illness

High Altitude Illness. Richard Dionne MD Emergency Medicine – University of Ottawa March 2013. High Altitude Illness. Goals & Objectives Understand the principles of acclimatization Discuss the clinical presentation, prevention and interventions for Acute Mountain Sickness

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High Altitude Illness

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  1. High Altitude Illness Richard Dionne MD Emergency Medicine – University of Ottawa March 2013

  2. High Altitude Illness • Goals & Objectives • Understand the principles of acclimatization • Discuss the clinical presentation, prevention and interventions for Acute Mountain Sickness • Discuss the clinical presentation, prevention and interventions for High Altitude Pulmonary Edema (HAPE) • Discuss the clinical presentation, prevention and interventions for High Altitude Cerebral Edema (HACE)

  3. Case You are going on a skiing vacation at Vail, Colorado. On day 2 you feel tired, lightheaded and a mild headache. You attribute it to accumulated stress and fatigue that is getting back at you. Could it be all the partying ???

  4. Acute Mountain Sickness« A.M.S.» • Rapid ascension & non-acclimatized • Feels like «Hangover» & «viral illness» • Close to 25% visitors to Colorado • Better in 2 - 7 days • Danger : « H.A.P.E. » / « H.A.C.E. » • Altitude ... • Moderate > 8000 feet (> 2500 m) • High > 10 000 feet (> 3000 m) • Extrême > 18 000 feet (> 5500 m)

  5. A.M.S. Physiology • Hypobaric Hypoxia • FiO2 = Oxygen tension … • 160 mmHg … sea level • 130 mmHg … 1500 m (commercial plane) • 120 mmHg … 2500 m • 80 mmHg … 5500 m • 40 mmHg … Everest 8848 m

  6. Video

  7. Prevention of A.M.S. • Staged ascent • No alcohol & tobacco • Normal Hydration • High carbohydrate diet • Diamox prophylaxis

  8. Staged Ascent • Recommended > 8000 feet (2500 m) Above 3000 m … • Do not sleep higher than 1000 feet (300 m) from previous night … • Suggest one day ( 2 nights ) extra of acclimatisation at every 3000 feet (1000 m) … thereafter

  9. Diamox • Anhydrase carbonate inhibitor • Induces HCO3 diuresis causing a metabolic acidosis •  Reflex Ventilation & Oxygenation … simulates : HVR « Hypoxic Ventilatory Response »

  10. Case You and 3 of your friends decide to ascend Mont Aconcagua in Argentina. Your altitude is now 14000 feet, (4200 m) on your 6th day. For the last 2 days you ’ve started a dry cough, that is getting worse as the day progresses.

  11. High Altitude Pulmonary Edema« H.A.P.E. » • 1-2% when > 12 000 feet • Diagnosis … • cough / dyspnea / bronchospasm /  performance / pulmonary edema … • usually day 2 … • Non-cardiogenic pulmonary edema: •  pulmonary artery pressure ( P.A.P.) but • normal wedge & L.V.E.F.

  12. «H.A.P.E.» • Patchy infiltrates ? • Uneven distribution of pulmonary vasoconstriction that causes overperfusion, distention and leakage in remaining vessels … • Membrane protein permeability is  secondary to inflammation ?

  13. Treatment • Reheat victim « P.A.P.» • Oxygen « SaO2 &  P.A.P. » • Descent : 1500-3000 feet / Hyperbaric ? • C-Pap ? • Medication … • Nifedipine (Adalat) • 10 mg, then 30 mg SR Bid … « PAP 30-50%» • +/- Diamox • Lasix & Morphine ? (non-cardiogenic)

  14. Case Having decided to go down, you are still in contact with your friends that are now at 16 000 feet, they plan to summit tomorrow am … One of your teamates as been having an increasing headache and feels unsteady, he may not try to summit but wants to wait for their return ???

  15. High Altitude Cerebral Edema«H.A.C.E» • Usually > 12 000 feet • Usually takes 1-3 days • Ataxia / headache / N° V° / seizures • Mecanism • Vasogenic edema : « capillary leak syndrome » • Cytotoxic edema : ( Secondary ) « sodium - potassium pump failure »

  16. «H.A.C.E» M.R.I. • Increase in white matter signal showing edema. Consistant with vasogenic edema hypothesis … • Increase T2 signal in the white matter and the corpum callosum...

  17. «H.A.C.E.»Predisposing factors 1- Rapid ascent : acclimatisation 2- Hypoventilation 3- Gas exchange alterations 4- Fluid retention 5- Individual disposition

  18. 1- Acclimatisation Hypobaric hypoxemia Alveolar hypoxemia Arterial hypoxemia • Directly related to speed of ascent...

  19. 2- Hypoventilation • Hypoxic Ventilatory Response «H.V.R.» • Initially… •  Ventilation /  Oxygenation &  PaO2 • Counter balanced… • renal excretion of HCO3 in response to hypocapnia & alcalosis of hyperventilation • H.V.R.= acclimatisation determinant factor

  20. 3- Gas exchange alterations • Blood adaptation… •  erythropoietin /  RBC ’s (4-5-days) •  2,3-DPG = right shift oxyhemoglobin curve • Resp. alkalosis = left shift oxyhemoglobin curve • Interstitial Pulmonary edema... •  A-a gradient & hypoxemia • In consequence … • Vital Capacity … diminished • Diffusion capacity … diminished • V/Q mismatch … elevated • Pulm. Artery Press. … elevated • Pulm. Vasc. Resistance … elevated

  21. 4- Fluid retention • Acclimatised • « reset » of osmolar neurocenter … • ADH suppression & Aldosterone … • 25%  diastolic volume •  circulating endogenous norepinephrine • Non-acclimatized • antidiuresis with ADH & Aldosterone still elevated • fluid retention and cerebral edema ...

  22. 5- Individual predisposition • Cannot predict • Controversial ... • hability to accomodate an  brain volume & CSF within the cranial box & spinal canal...

  23. Treatment 1-  Hypoxemia /  Oxygenation 2- Control Acclimatisation 3-  Cerebral edema • « capillary leak syndrome » 4- Symptomatic relief

  24. Treatment1-  Hypoxemia &  Oxygenation • Minimum descent 1500-3000 feet • as much as needed • Oxygen 100% • Hyperbaric Chamber • portable Gamow / Zertec / P-portable • can generate pressures 200mmHg (7000 feet / 2000 m descent)...

  25. « Gamow Hyperbaric Chamber »

  26. Treatment2- Controlled Acclimatisation • Acetazolamide ( Diamox) • 125-250 mg q 12h (2,5mg/Kg) •  diuresis /  CSF • stimulated « H.V.R.» (  ventilation ) • Start 1-2 days before ascent & continue for 48h … • Gives paresthesias ++ / sulpha allergy

  27. Treatment3-  Cerebral Edema • Dexamethasone • 4-8 mg stat, then 4 mg po / IM / IV q 6h • no role in acclimatisation • Diuretics • Acetazolamide (Diamox) • Furosémide (Lasix) • Mannitol & Hyperventilation • exceptionnaly if severe

  28. Treatment4- Symptomatic relief • Analgesic • acetaminophen / ASA / codeine ? • Anti-emetics • prochlorperazine (Stemetil) •  HVR ? • Ginko Biloba as prophylaxis ???

  29. Take Home ... • A.M.S. : can ressemble viral illness... • H.V.R. : determinant factor for acclimatisation ... • H.A.P.E. : non-cardiogenic pulmonary edema / treatment = descent & O2... • H.A.C.E. : subtil cerebellar ataxia … • the cerebellum is very sensitive to hypoxia ...

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