Wilderness and Rescue Medicine 8th Edition

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Section V: Environmental Medicine

General Principles

High - Altitude Pulmonary Edema

HAPE Medications

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Nifedipine (Procardia, Adalat): • 30 mg XR po for emergency treatment of moderate and severe sx • 30 mg q12h for prophylaxis Oxygen: • Titrate to patient response, 1 – 4 L /m may suffice • High flow may be necessary in severe cases • CPAP is ideal for emergency treatment Acetazolamide: • Prophylaxis, not treatment • 125mg q12h (5mg/kg/day in 2 divided doses for kids)

Normal Chest X -ray

Severe HAPE

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Emergency medications for HAPE include oral nifedipine, a smooth muscle relaxer that is nor- mally used to treat high blood pressure. It seems to ease the pulmonary hypertension that is forcing fluid to leak into the alveolar space. Nifedipine is a prescription medication in the United States. Other prescription medications like acetazol- amide, tadalafil, sildenafil, and dexamethasone may prevent HAPE in people with a past history of it, although the place for these drugs in emer- gency treatment is not clear.

Other Altitude Illnesses Although HACE and HAPE are the most dan- gerous forms of altitude illness, they are not the only manifestation. Capillary dilation and leakage can produce edema anywhere in the body. People traveling at altitude can end up with edematous hands and feet. Swelling in the gut can produce diarrhea. Edema in the mucous membranes of the nose and sinuses can mimic the congestion of a cold or sinus infection. Altitude makes the symptoms of an existing illness worse. The reduc- tion in available oxygen as well as the reduced protective effects of the atmosphere predispose people to other problems as well. Sunburn at altitude can be quick and extreme due to the lower atmospheric density and less water vapor. The minimum erythematous dose (MED) for unprotected skin can be as little as 15 minutes at 3,000 meters. Many ski and climbing trips have been ruined by the first morning of sun. Apply sunblock early and often. Snow blindness (solar keratitis) can develop within just a few hours. This condition is not only painful, but results in a debilitating and danger- ous loss of vision in a high-risk environment. Treatment with complete shielding, lubricating eye drops, and pain medication usually results in a complete resolution within 2 or 3 days, but pre- vention of the problemwith high-quality goggles or sunglasses is a lot easier.

High - Altitude Pulmonary Edema

Treatment: • Mild HAPE – oxygen, rest day, hydration and food

• Moderate HAPE – immediate descent of 500 meters, consider nifedipine or CPAP

• Severe HAPE – CPAP, immediate descent of 500+ meters, nifedipine or PDE 5 inhibitor

Severe HAPE will ultimately result in respiratory failure and death. Emergency treatment includes positive pressure ventilation (PPV), oxygen, nife- dipine, and an immediate descent of at least 1,000 meters. Pulmonary edema may persist for several days after descent and require hospital observa- tion and treatment. Unlike HACE, severe HAPE can and does kill people at moderate altitudes.