30 May - 5 June 2014 #709

Climbers’ cough

Dhanvantari by Buddha Basnyat, MD

Many of us clinicians spend our lives telling patients to take “lamo, lamo sas” (deep breaths) as we auscultate the chest. This is a wonderful feeling when you are fresh out of medical school, but after a while you get a bit weary of this exhortation. Lucky, then, is the young physician who early on realises that some medical research activity may rescue him from boredom. Ashish Lohani (pic, right) conducted a cough research almost three years ago at the Everest Base Camp in the Khumbu and is one of those fortunate physicians involved in research.

Amazingly, cough in the mountains is the single most common medical problem that trekkers and mountaineers face. Year after year for almost 10 years, reports from the Everest Base Camp Clinic reveal that hacking persistent cough is very common in climbers.  And despite the fact that this problem is rampant, not much is known about the mechanism and cause of this “Khumbu cough”. It seems that the higher you go the more you are likely to have persistent, disabling cough. Many climbers have had to give up their summit attempt because the cough makes them breathless and unable to ascend.

Most high altitude climbers breathe through the mouth out of necessity, thus bypassing the natural humidifying mechanism of the nose. This cold air may be triggering the cough by “roughing up” the mucosa lining the airways. This is why many people breathe through a silk scarf in the hope that when the atmospheric air enters the lungs, it is warm and will not trigger a cough. It could also be that asthma like mechanisms (brought on by the cold and exertion) are at work at high altitude which cause narrowing of the airways and cough. Finally, the low oxygen at high altitude could be a primary reason. Whatever the cause, there is no known effective treatment.

Lohani conducted an RCT (randomised controlled trial) to prove the efficacy of drugs in clinical practice. There were two parts in his study, a potentially useful drug method and a placebo method. For over two months for two seasons, he randomly enrolled patients in the highest terrestrial research station in the Himalaya at 5,300m and conscientiously charted his results to be analysed later.

Many climbers including our own Nepali civil servants who were climbing Mt Everest in the spring of 2011 wished Ashish well so that future climbers may be helped. Unfortunately, many of these enthusiastic, high-profile Nepali climbers had to say good bye to their summit bid due to hacking, persistent cough that almost caused rib fractures and punctured lungs.

Although Ashish had hypothesised that the drugs method would prove to be effective in the treatment of high altitude cough, it did not prove to be so. In fact there was no difference in outcome between drug (inhaled combination of a steroid and a smooth muscle relaxant) and the placebo.

There was however an important limitation in his study. Most of the climbers who had severe cough were unwilling to enroll in the study because they felt certain that the combination drug worked and were reluctant to receive a placebo, and hence could not be randomised in the trial. Nonetheless, in those people with mild to moderate cough at high altitude, steroid spray and a smooth muscle relaxant drug do not seem to be effective.

Even negative findings are important in medical studies so that people do not use drugs unnecessarily just based on “gut” feeling. Intuition has to stand up to scientific reckoning.

Read also:

The Khumbu cough