Makindo Medical Notes

Related Subjects: | Assessing Breathlessness | Respiratory Failure | Caisson Disease - Decompression Sickness | Altitude Sickness / Acute Mountain Sickness

Altitude Sickness, also known as Acute Mountain Sickness (AMS), is a condition that can affect individuals who ascend to high altitudes, typically above 8,000 feet (2,500 meters), too quickly. Complications include acute mountain sickness, high altitude pulmonary oedema, and high-altitude cerebral oedema. Management involves stopping ascent, allowing time for acclimatization, rest, and hydration.

About

• Occurs with rapid ascent to high altitudes above 2,500 meters.
• Increasing altitude leads to hypoxia and pulmonary vasoconstriction.
• Results in hypocarbia and alkalosis.
• Severe cases can develop into pulmonary and cerebral oedema.

Geography

• Ben Nevis, UK: 1,345 meters (Not typically seen)
• Matterhorn: 4,478 meters
• Mont Blanc: 4,807 meters
• Kilimanjaro: 5,895 meters
• Everest: 8,848 meters

Aetiology

• The physiological process underlying altitude sickness is an exaggerated vascular response to hypoxia.
• Acclimatization allows the body to make physiological adjustments at both the molecular and cellular levels.

Severity Factors

• Rate of ascent
• Height above sea level
• Length of stay at altitude
• Physical exertion at altitude

Risk Factors

• Rapid ascent and lack of acclimatization
• Altitude above 8,000 feet (2,500 meters)
• Dehydration and hypothermia
• High alcohol intake
• Excessive physical exertion in the first few days at altitude
• Previous history of anaemia, altitude sickness, or pulmonary/cardiac conditions

Pathology

• Pulmonary oedema
• Protein-rich exudate and alveolar hemorrhages
• Alveolar hyaline hemorrhage
• Cerebral oedema

Types of Altitude Sickness

• High Altitude Pulmonary Oedema (HAPE): Fluid accumulates in the lungs, causing extreme breathlessness, coughing (sometimes with pink, frothy sputum), and cyanosis (bluish skin).
• High Altitude Cerebral Oedema (HACE): Swelling of the brain, leading to confusion, loss of coordination, and potentially coma.

Clinical Symptoms

• Acute Mountain Sickness: Can range from mild to severe.
  • Headaches, nausea, vomiting, loss of appetite
  • Insomnia, dizziness, confusion
  • Fatigue, weakness, heavy legs
  • Swelling of hands and face
  • Breathlessness and irregular breathing
  • Reduced urine output
• High Altitude Pulmonary Oedema (HAPE):
  • Breathlessness, cough, haemoptysis, wheezing
  • Tachycardia, hypotension, cyanosis
  • Bilateral basal crackles on lung examination
• High Altitude Cerebral Oedema (HACE):
  • Severe headache, confusion, ataxia
  • Irritability, delirium, coma, seizures
• High Altitude Retinal Haemorrhage: Altered vision due to retinal bleeding.

Investigations

• FBC: Elevated haematocrit and hemoglobin
• ABG: Low oxygen levels (O₂) and low PCO₂
• ECG: Sinus tachycardia
• Chest X-ray (CXR): May show pulmonary oedema

Management

• Avoidance:
  • First night sleeping altitude should not exceed 2,400 meters.
  • Above 2,700 meters, limit daily ascent to 300 meters.
  • Descend to lower altitude for sleeping if you ascend higher during the day.
  • Move slowly ("pole-pole" technique on Kilimanjaro).
  • Avoid alcohol, smoking, and sleeping pills.
  • Drink 3-4 liters of water daily to prevent dehydration.
  • Keep daypacks light (10-12 kg).
  • Take Diamox (acetazolamide) after consulting a doctor.
  • Inform others if you feel unwell and descend if symptoms worsen.
• Acute Mountain Sickness (AMS): Descent to lower altitude is mandatory. If immediate descent is not possible, low-flow oxygen, a portable hyperbaric chamber, or drug therapy can help.
• HAPE: Rapid descent, oxygen therapy, or hyperbaric oxygen. Nifedipine and sildenafil may be used.
• HACE: High-flow oxygen, descent, dexamethasone 8 mg four times a day (QDS) for cerebral oedema, and acetazolamide.
• Hyperbaric Chambers: Portable hyperbaric chambers simulate descent by increasing atmospheric pressure, temporarily relieving symptoms while awaiting actual descent.

References

• Prevention, Assessment, and Management of Altitude Sickness