PULMONARY EDEMA OF HIGH ALTITUDE

A FURTHER NOTE

The "Disease" called High Altitude Pulmonary Edema has become of increasing interest to doctors in the past few years and is doubtless of even greater interest and importance to climbers. Since publication of my first paper on the subject (New England Journal of Medicine, September 8, 1960) I have received correspondence on the subject from all over the world. Doctors and climbers from Japan, India, New Zealand and Europe have sent me case reports and many have included personal experiences.

Of even greater satisfaction to me have been letters from those planning expeditions who have written in advance for advice on prevention and treatment. Four of these men have written subsequently to describe cases they have diagnosed and treated successfully and I like to think that lives have been saved by this knowledge. The condition has been fatal as low as 9000 feet, and has occurred at 7500 feet, though it is more common above 15,000 feet.

A more complete paper appeared in Medicine for September 1961, written by Hultgren, Spickard, Hellriegel and myself, and those desiring full medical discussion of the condition should refer to this paper.

Two physicians skiing at Alta in the spring of 1961 fell victims to the disease; neither recognized it. Both were taken to Salt Lake City, critically ill and there treated by my friend Dr. Hans Hecht who has been of great help in studying the condition and who was able to diagnose and treat correctly at once. Complete investigation of these cases was done, thereby adding considerably to our knowledge. One of the men took a long pack trip in the high Sierra during the summer of 1961 and had a second severe attack; his life was saved by prompt recognition and by helicopter rescue. The other skied at Aspen in December 1961, allowing adequate time for acclimatization and had no difficulty.

The precise cause of the "disease” is still not clear, but it is probable that true heart failure occurs, with the accumulation of fluid in the lungs, even though the heart is normal. We are certain that the condition is brought on by oxygen lack; infection, though it may follow, is not a cause, nor are cold, fatigue or exertion—although each may contribute.

Many cases occur in residents at high altitude who descend to sea level and then return to their high altitude homes; the attack usually comes within one to three days. In these individuals one attack usually signals recurrences and more than half of the cases have had two or more attacks. Any age may be affected, the youngest patient in my collection being two years old. Even individuals who have never been to high altitude may be affected on their first trip, but almost invariably inadequate time for acclimatization may be blamed. The usual story is of a rapid trip by horse or car from sea level to the jumping-off place followed by several days of work and climbing to the higher camps; symptoms may appear during these working days.

Since the precise cause is not certain, prevention is not too certain either, but it is clear that individuals who allow too little time for full acclimatization run the greatest risk. It is not possible to set up a chart for optimum rate of ascent because of wide individual variation, but in general a person may go from sea level to 8000 feet in a few hours with no difficulty. Ten thousand feet may be reached in the next two days, and a thousand feet per day thereafter is tolerated by almost all. A rest period of two to five days at 15,000 feet is essential, and effective. Above 15,000 feet the old dictum of "Pack high and sleep low” applies and climbers should spend several days in packing to a higher camp before moving up. Each individual will have to modify this schedule judging from the way he feels. Curiously enough few cases have occurred above 22,000 feet— possibly because relatively few hardy souls venture that high.

The diagnosis can be made by an informed laymen without too great trouble. A day or two of fatigue and listlessness usually precede the major episode which begins with such shortness of breath that the climber can scarcely drag around. An irritating non-productive cough appears; sleep is broken and restless. Soon the individual must sit up to breathe, his cough becomes looser and he will raise a thin, frothy, sometimes pink sputum. The breath sounds are rattly and bubbling sounds may be heard either by the patient or by an observer listening with his ear against the bare chest. The pulse is usually rapid—but may be slow, and the temperature may be normal or high; he is obviously very ill and the apparent diagnosis would be pneumonia.

Treatment should be prompt and energetic. Because the layman may not be able to differentiate the condition from pneumonia, anti-biotics should be given early. Injectable penicillin (600,000 units every 12 hours) may be started at once—after being sure there is no history of allergy to this drug, or a broad spectrum anti-biotic such as Mysteclin, Achromycin or Chloromycetin (250 mg capsule every four hours day and night). Oxygen at a flow of 4 to 8 liters per minute should be given continuously while plans for descent are made. Digitalis should be given only by some one familiar with this powerful drug, and it is not believed to be very effective at that. Diuretic agents such as Diuril (500 mg every four to six hours) or injected Salyrgan (figure 1 cc intramuscularly every twelve hours) may be very helpful in "squeezing” fluid out of the water logged lungs. Morphine is generally contraindicated because of the depression of respiration. More exotic treatments such as bleeding(!), aminophylline, TRIS, and the like should be reserved for use by doctors only.

SUMMARY

In the past few years acute pulmonary edema has emerged as a far from rare hazard for mountaineers. Many dozen cases have been reported to me from around the world and this "physiological disease” has caused many deaths or near deaths. It is probably a form of heart failure though the heart is normal, and it is brought on by exposure to high altitude oxygen lack. Cold, exertion, and infection may contribute but are not primary; infection may follow. It is usually confused with pneumonia. Prevention consists in awareness of the condition, slow ascent with adequate time for the full force of acclimatization, and probably avoidance of a great excess of salt. Though the condition occurs in all ages, and in residents at high altitude who return from a trip to sea level, it is most prevalent in climbers going high too rapidly from sea level. Treatment consists first in correct diagnosis, secondly in use of oxygen and descent to low altitude as soon as possible, administration of anti-biotics (to ward off secondary infection) and the use of diuretic agents. All mountain expeditions planning to climb above 12,000 feet should be aware of the condition and taught how to recognize and treat it.

Charles S. Houston, M.D., Aspen Clinic, Aspen, Colorado