Past occurrence of AMS/HACE strongest risk factor for recurrence
Current theories center on role of brain swelling at altitude and raised ICP
HIGH ALTITUDE PULMONARY EDEMA
High altitude disease that kill most people
Incidence: severe cases 1-5% but increase lung water seen in 75% of climbers
Early signs are weakness and shortness of breath that evolves in tachypnea, tachycardia, and severe hypoxia
1) Rapid Descent
2) Oxygen 4-6/l
3) Nifedepine 10 mg po then 30mgSR q12-24 hours
4) Portable hyperbaric chamber if descent not possible
5) Sildenafil (Viagra) 50 TID: Lowers pulmonary artery pressures and improves oxygenation without systemic hypotension
6) Increasing data that acetazolimide may also help HAPE
Patients who have suffered from HAPE are prone to recurrence
1) Slower ascent
2) Nifedipine 20-30 mg q12 hours
3) Increasing evidence that steroids may prevent HAPE
Patients prone to HAPE have exaggerated pulmonary artery pressure to hypoxia
Uneven blood flow to parts of the lung may lead to stress breakdown of endothelium and fluid leak
Sleep Problems at Altitude
Poor sleep common at altitude - increase incidence of Cheyne-stokes breathing
Therapy: acetazolamide 125 mg or zolpidem 10 mg qHS
High Altitude Retinopathy and Refractive Surgery
Incidence of hemorrhage 36-56% at altitudes 15,000ft
Rarely causes permanent damage
Patients with both RF can have dramatic vision changes with ascending to over 12,000ft. Vision returns to normal when descending to sea level. Increasing data to suggest LASIK does not cause significant vision changes at altitude.
High Altitude and Travel's Thrombosis
Multiple case reports of DVT, PE, and stroke at altitude
Hypoxia not associated with increase in coagulation
Most cases due to classic risk factors such as dehydration, immobilization, and genetic factors
Risk of thrombosis with air-travel increase 3-4 fold
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