Makindo Medical Notes

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

🏔️ Altitude Sickness (Acute Mountain Sickness, AMS) is a condition that can occur when individuals ascend too quickly above 8,000 ft (2,500 m). ⚠️ Complications: AMS, High Altitude Pulmonary Oedema (HAPE), and High Altitude Cerebral Oedema (HACE). 🩺 Management: Stop ascent, allow acclimatisation, rest, hydrate, and descend if severe.

ℹ️ About

• Occurs with rapid ascent above ⛰️ 2,500 m
• Hypoxia → pulmonary vasoconstriction
• Causes hypocarbia + alkalosis
• Severe cases → pulmonary & cerebral oedema

🗺️ Geography (Examples)

• 🇬🇧 Ben Nevis: 1,345 m (rare AMS)
• 🇨🇭 Matterhorn: 4,478 m
• 🇫🇷 Mont Blanc: 4,807 m
• 🌍 Kilimanjaro: 5,895 m
• 🇳🇵 Everest: 8,848 m

🧬 Aetiology

• Exaggerated vascular response to hypoxia
• Acclimatisation = adaptive molecular & cellular changes

⚠️ Severity Factors

• Rate of ascent ⏫
• Maximum altitude reached ⛰️
• Length of stay 🕒
• Physical exertion 💪

🔎 Risk Factors

• Rapid ascent, poor acclimatisation
• Altitude > 2,500 m
• 💧 Dehydration, ❄️ hypothermia
• 🍷 High alcohol intake
• 💪 Excess exertion in early days
• 📜 Hx anaemia, AMS, pulmonary/cardiac disease

🧪 Pathology

• HAPE: pulmonary oedema, alveolar haemorrhage
• HACE: cerebral oedema
• Retinal haemorrhages possible 👁️

🧾 Types

• HAPE 🫁: Breathlessness, pink frothy sputum, cyanosis
• HACE 🧠: Confusion, ataxia, coma
• AMS 🥴: Headache, nausea, dizziness, insomnia
• High altitude retinal haemorrhage 👁️: Blurred vision

🩺 Clinical Symptoms

• AMS: Headache, nausea, fatigue, insomnia, facial swelling, oliguria
• HAPE: Cough, haemoptysis, wheeze, cyanosis, basal crackles
• HACE: Severe headache, confusion, ataxia, seizures, coma

🔍 Investigations

• FBC: ↑ haematocrit / Hb
• ABG: ↓ O₂, ↓ CO₂
• ECG: sinus tachycardia ❤️
• CXR: pulmonary oedema

💊 Management

• Prevention / Avoidance ⛺:
  • First night < 2,400 m
  • Above 2,700 m → ascend ≤ 300 m/day
  • Sleep lower than day’s highest point
  • “Pole-pole” (slow pace) 🐢
  • Avoid alcohol, smoking, sedatives
  • Hydrate 3–4 L/day
  • 💊 Diamox (acetazolamide) prophylaxis
• AMS 🥴: Rest, descent, O₂, hyperbaric bag if no descent possible
• HAPE 🫁: Rapid descent, O₂, hyperbaric chamber; nifedipine/sildenafil may help
• HACE 🧠: High-flow O₂, descent, dexamethasone 8 mg QDS, acetazolamide

📚 Reference

• Prevention, Assessment, and Management of Altitude Sickness

🧑‍⚕️ Case Examples — Acute Mountain Sickness (AMS)

• Case 1 (Mild AMS — headache & nausea): 🏔️ A 26-year-old hiker ascends rapidly from sea level to 3,200 m in 24 hours. Within 12 hours, he develops a throbbing headache, nausea, and poor sleep. Analysis: Rapid ascent without acclimatisation → classic trigger. Diagnosis: Lake Louise criteria: headache + GI upset + sleep disturbance = mild AMS. Management: Rest at altitude, avoid further ascent, simple analgesia, antiemetic. Monitor closely; usually self-limiting.
• Case 2 (Moderate AMS — impaired function): ⛷️ A 34-year-old skier ascends to 3,800 m. After 24 hours, he reports severe headache, dizziness, anorexia, and difficulty walking straight. Analysis: Functional impairment = moderate AMS. Risk of progression to HACE/HAPE if ascent continues. Diagnosis: Clinical (Lake Louise score >5, impaired coordination). Management: Halt ascent, give supplemental oxygen if available, acetazolamide to hasten acclimatisation, consider descent if symptoms persist >24 hours.
• Case 3 (Severe AMS with HACE progression): 🚨 A 40-year-old climber at 4,500 m develops confusion, ataxia, and vomiting after 2 days of persistent headache and insomnia. Companions note he is disoriented. Analysis: AMS progressing to High-Altitude Cerebral Edema (HACE), a life-threatening emergency. Diagnosis: Severe AMS with neurological signs = HACE. Management: Immediate descent, high-flow oxygen, dexamethasone, hyperbaric bag if descent impossible. Evacuation to lower altitude hospital.