A common question we receive from our readers and patients is whether it is safe for patients with chronic lung disease to travel to higher elevations. For the sake of this discussion we will use 5,000 ft. or greater as high altitude. This is an important question since many of the tourist attractions are either at higher elevation or require driving across mountains that exceed 5000 ft.
High Altitude Physiology
The lungs have evolved to compensate for changes that occur as elevation increases. Above 5,000 ft. of elevation, there is less oxygen in the air. This triggers a response to breathe more (increased ventilation). The normal heart also pumps more blood to compensate for the reduced oxygen that is carried in the blood. Over time the body makes more red blood cells which helps increase the amount of oxygen that the blood can carry. The pulmonary arteries respond to high altitude by constricting or squeezing (vasoconstriction). This leads to the right side of the heart having to work harder. Additionally there is a tendency for the lungs to accumulate more water with ascent to higher altitude. This can further affect breathing.
These changes described above have important implications for patients with chronic lung disease. For example, patients with pulmonary hypertension may be particularly sensitive to the vasoconstriction (squeezing more tightly) that occurs. This leads to increased work for the right side of the heart. Many patients experience fluid retention and increased fatigue that can take several weeks to improve. Patients with pulmonary fibrosis (scarring in the lungs) may not be able to increase their breathing rate effectively and they may also experience worsening pulmonary hypertension.
Oxygen, Does it Help?
Many patients with chronic lung disease will need to wear oxygen when they travel to higher elevations. If you drop your oxygen saturation at night or during exercise at lower elevation then you will certainly benefit from oxygen at higher elevation. For patients who are borderline we have a high altitude simulation test (HAST) that can determine if you will need oxygen. Patients that do need oxygen with travel to higher elevation will still experience many of the physiologic changes of being at higher elevation. The 1-5 liters/min of oxygen delivered via nasal cannula can blunt the effects of elevation but does not completely reverse these changes. My advice to patients is to avoid higher elevations if at all possible. The more severe your lung disease the more important this is.