Fitness for Altitude and Diving

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Altitude Fitness Assessment - Summit Seekers' Screen

  • Core Evaluation:
    • History: Prior altitude illness (AMS, HAPE, HACE), comorbidities (cardiac, pulmonary).
    • Physical Exam: Focus on CVS & RS.
  • Key Indicators & Tests (Selective):
    • VO2 max: Aerobic fitness.
    • Spirometry: FEV1, FVC for lung function.
    • ECG/Echo: If cardiac concerns.
    • 📌 HVR (Hypoxic Ventilatory Response) test: Specialized.
  • High-Risk Factors:
    • Previous HAPE/HACE.
    • Severe cardiopulmonary disease (Pulmonary HTN, severe COPD).
    • Sickle cell disease.

    ⭐ History of HAPE/HACE significantly ↑ recurrence risk (e.g., HAPE up to 60% at >4500m).

  • Contraindications (Absolute/Relative): Unstable cardiac conditions, severe lung disease.

Pathophysiological Mechanisms in High Altitude Illnesses

Diving Fitness Assessment - Deep Dive Med Check

Crucial for preventing barotrauma, Decompression Illness (DCI), and other dive-related incidents. Aims to identify conditions exacerbated by hyperbaric environments.

  • Key Systems:
    • Cardiovascular: No uncontrolled HTN (>160/100 mmHg), arrhythmias, significant Coronary Artery Disease (CAD), Patent Foramen Ovale (PFO).
    • Respiratory: No active asthma, COPD, bullae/cysts, history of spontaneous pneumothorax. Spirometry FEV1/FVC >70%.
    • ENT: Patent Eustachian tubes, no chronic sinus infections.
    • Neurological: No epilepsy, unexplained Loss Of Consciousness (LOC).
    • Psychological: No severe claustrophobia or panic disorder.
  • 📌 Mnemonic: "EARS & LUNGS" - Ears (barotrauma), Airways (asthma), Respiratory (pneumothorax), Sinuses & Lungs (general fitness).

⭐ An absolute contraindication to diving is a history of spontaneous pneumothorax due to high risk of recurrence and tension pneumothorax under pressure.

Contraindications & Special Groups - No-Fly, No-Dive Zones

  • Absolute Contraindications (Flying/Diving):
    • Recent Pneumothorax (⚠️ critical)
    • Active, unstable asthma; Severe COPD/bullae
    • Inability to equalize pressure (ears/sinuses)
  • Primarily No-Fly (Altitude):
    • Sickle cell disease (unpressurized/hypobaric exposure)
    • Severe pulmonary hypertension
    • Recent CVA/MI (<6 weeks for commercial flights)
  • Primarily No-Dive (Diving):
    • Pregnancy (absolute)
    • Uncontrolled epilepsy
    • History of severe/recurrent Decompression Sickness (DCS)
    • Symptomatic Patent Foramen Ovale (PFO)
    • Active psychosis
  • Special Groups (Increased Risk):
    • Infants, young children (equalization, susceptibility)
    • Elderly with comorbidities
    • Obesity (↑DCS risk diving)

⭐ A recent spontaneous pneumothorax is an absolute contraindication to air travel for at least 1 week after radiological resolution (BTS guidelines); other guidelines suggest 2-3 weeks.

Prophylaxis & Safe Practices - Altitude & Abyss Armor

  • Altitude Acclimatization & Prophylaxis:
    • Gradual Ascent: Key. Limit gain to 300-500m/day above 2500m.
    • 📌 "Climb high, sleep low."
    • Pharmacoprophylaxis (if rapid ascent/prior AMS):
      • Acetazolamide: 125-250mg BD, 1-2 days before, continue for 48h at altitude.
      • Dexamethasone: Alternative if sulfa allergy; or for HACE/HAPE rescue.
    • Hydration, high-carbohydrate diet. Avoid alcohol, sedatives.
  • Diving Safety & DCS Prevention:
    • Controlled Ascent: Max 9-18 m/min (or per dive computer).
    • Safety Stops: e.g., 3-5 min at 5m.
    • Dive Planning: Use tables/computers; respect no-decompression limits (NDLs).
    • Fitness: Medical clearance, no acute illness.
    • Buddy System: Never dive alone.

    ⭐ Critical: No flying for 12h (single no-D dive) to 18-24h (multiple/decompression dives) post-diving to prevent DCS.

Altitude and Diving Physiology

High‑Yield Points - ⚡ Biggest Takeaways

  • Gradual ascent and acetazolamide aid altitude acclimatization, preventing Acute Mountain Sickness (AMS).
  • HAPE and HACE are life-threatening; immediate descent and oxygen are critical.
  • Absolute diving contraindications: history of spontaneous pneumothorax, epilepsy, severe lung disease.
  • Decompression Sickness (DCS) from rapid ascent requires 100% oxygen and recompression.
  • Nitrogen narcosis ("Martini effect") impairs judgment at depth; heliox for very deep dives.
  • Good cardiorespiratory fitness and normal Pulmonary Function Tests (PFTs) are essential for safe diving.
  • Avoid flying for 12-24 hours post-diving to prevent DCS.

Practice Questions: Fitness for Altitude and Diving

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Flashcards: Fitness for Altitude and Diving

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During acclimatization at higher altitude, the sensitivity of central and peripheral chemoreceptors _____creases

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During acclimatization at higher altitude, the sensitivity of central and peripheral chemoreceptors _____creases

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