Altitude pulmonary oedema is another illness that can occur at altitudes as low as 2500 m. The term oedema refers to an accumulation of fluid. As the name suggests, this accumulation occurs in the lungs, more specifically in the alveoli. Gas exchange takes place in these alveoli. The oxygen from the inhaled air is absorbed into the alveoli and exchanged for the waste gas carbon dioxide. When the alveoli are full of fluid, this exchange cannot take place. Less oxygen can be taken in and less carbon dioxide can be excreted. And it is precisely oxygen that is so necessary for getting up the mountain, as the gas helps to release fuel for the muscles. When this fluid build-up increases, the problem becomes life-threatening.
Altitude pulmonary oedema, or in other words 'HAPE', is diagnosed when a person meets at least two of the following four symptoms:
- Shortness of breath at rest
- Reduced effort tolerance or general weakness
- Feeling of pressure in the chest or congestion (e.g. of the nasal passages)
and satisfies two of the following four phenomena:
- Crackling sound or squeaking heard when listening to the lungs
- Blueing of the face (e.g. lips)
- Accelerated breathing (normal is between twelve and twenty breaths per minute)
- Accelerated heartbeat (normal is between sixty and one hundred beats per minute)
HAPE is life-threatening, its severity being determined by the tightness in rest. Immediate descent is recommended (minimum 1000 m descent) in severe HAPE. The descent should be as uneventful as possible. In other words, with little or no pack, by helicopter or on the back of an animal (or fellow climber).
Supplementary oxygen therapy can be used as an alternative to descent. The aim should again be a saturation of >90%. Descent is then recommended if the symptoms do not improve. The use of a hyperbaric chamber is debatable as its effect on HAPE has not been clearly studied. In any case, it cannot do any harm. If an individual is symptom free and has a stable and good saturation at rest with mild activity, resumption of ascent may be considered.
When HAPE is diagnosed, it is possible to treat it with the medication Nifedipine. This medication should be used for four days if, after stabilisation, the recommended ascent rate is maintained. This can be extended by three days if the climber is unable to keep to this.
The following dosages are recommended:
- Nifedipine (of the delayed-release type): 30 mg - oral administration - every 12 hours or 20 mg - oral administration - every 8 hours
HAPE roadmap in brief: