//fpnotebook.com/
High Altitude Sickness
Aka: High Altitude Sickness, Acute Mountain Sickness
- See Also
- High Altitude Related-Conditions
- High Altitude Cerebral Edema (HACE)
- High Altitude Pulmonary Edema (HAPE)
- Portable Hyperbaric Chamber (Gamow Bag)
- Lake Louise Acute Mountain Sickness Score
- Epidemiology: Prevalence
- Colorado ski resort: 25% of travelers
- Himalayas: 50% of travelers
- Background: Barometric Pressure
- Sea level: 760 mmHg
- Sante Fe, New Mexico (7200 feet or 2194 meters): 582 mmHg
- Risk of Altitude Sickness starts at (8200 feet or 2500 meters): 560 mmHg
- Ski altitude (10,000 feet or 3048 meters): 522 mmHg
- Kala Pattar (18,187 feet or 5543 meters) : 375 mmHg
- Mount Everest (29,035 feet or 8849 meters): 249 mmHg
- Pathophysiology: Mechanism
- Hypobaric Hypoxemia results in paradoxical and maladaptive fluid retention
- Contrast with non-affected persons at altitude who experience diuresis
- Changes at altitude that may exacerbate comorbid illness
- Low partial pressure of oxygen
- Increased sympathetic tone
- Pulmonary artery Vasoconstriction
- Increased systemic vascular resistance
- Risk Factors
- Rapid ascent
- Significant physical exertion
- Prior history of altitude sickness
- Traveling from low altitude
- Younger age
- Aside from comorbidity, older adults may be less affected by altitude
- Symptoms
- Common Symptoms
- Headache
- Malaise
- Anorexia
- Other Symptoms
- Fatigue
- Nausea or Vomiting
- Insomnia
- Dyspnea
- Dyspnea on Exertion
- Dry cough
- Irritable
- Decreased Urine Output
- Course
- Onset: 6-12 hours following high altitude ascent
- Diagnosis
- Headache and
- One or more of the following
- Fatigue or weakness
- Dizziness or light headedness
- Gastrointestinal distress (Nausea, Vomiting, Anorexia)
- Sleep disturbance
- Differential Diagnosis
- Viral illness
- Hangover
- Exhaustion
- Dehydration
- Hypothermia
- Hypoglycemia
- Hyponatremia
- Medication: Sedative or hypnotic
- Carbon Monoxide Poisoning (e.g. cooking in tent)
- Management
- Very mild symptoms may resolve spontaneously with acclimitization
- Immediate descent (at least 1000 feet or 300 meters) is most critical for moderate to severe symptoms
- Other measures for moderate to severe symptoms where descent is not immediately possible
- Supplemental Oxygen
- Acetazolamide 250 mg orally twice daily
- Dexamethasone 4 mg orally every 6 hours
- Gamow Bag (Portable Hyperbaric Chamber)
- Other measures
- Antiemetics (e.g. Zofran) for Nausea, Vomiting
- Acetaminophen or Ibuprofen for Headache
- Complications (0.1 to 4 percent Incidence)
- See Pathophysiology above
- Altitudes above 11,400 feet (3500 meters) are associated with a more complicated course
- High Altitude Pulmonary Edema (HAPE)
- High Altitude Cerebral Edema (HACE)
- Prevention
- Medication Prophylaxis
- Indications
- Travel to 11,000 feet in one day (or over 9,000 feet if history of prior altitude sickness)
- Acetazolamide (Diamox) 125 mg twice daily (FDA approved)
- Start 1 day or more before ascent
- Continue until acclimitization to the higheest sleeping altitude
- Up to 250 mg twice daily may be used (but 125 mg is typically sufficient)
- Dexamethasone 4 mg orally every 6-12 hours (not FDA approved)
- Alternative, in those who cannot take Acetazolamide
- Risk of rebound mountain sickness when discontinued
- Does not speed acclimitization, but does reduce symptoms
- General Pointers
- Recognize the symptoms of Acute Mountain Sickness
- Never ascend to sleep higher if you have symptoms
- Descend if symptoms do not resolve or worsen
- Never leave a person with altitude sickness alone
- Maintain hydration
- Avoid overexertion
- Avoid Alcohol and Sedatives
- For altitudes above 9800 feet
- Do not sleep >2000 feet (600 meters) higher than the night before
- Spend an additional day if ascent over 2000 feet
- Comorbid Conditions
- See Air Travel Restriction
- Patients with asymptomatic cardiopulmonary disease may ascend safely to at least 8200 feet (2500 meters)
- Conditions which absolutely contraindicate high altitude travel
- Severe Chronic Obstructive Pulmonary Disease (COPD)
- Uncontrolled Congestive Heart Failure (CHF)
- Conditions for which caution should be Exercised due to risk of exascerbation (emphasize acclimitization)
- Arrhythmias
- Coronary Artery Disease
- Hypertension
- Sickle Cell Anemia (splenic infarct risk increases above 4900 feet (1500 meters)
- Keep Supplemental Oxygen available
- References
- (2018) Presc Lett 25(2)
- Candy and Contant in Herbert (2020) EM:Rap 20(3): 3-4
- Basnyat (2003) Lancet 361(9373): 1967-74 [PubMed]
- Fiore (2010) Am Fam Physician 82(9): 1103-10 [PubMed]
- Hackett (2001) N Engl J Med 345(2): 107-14 [PubMed]