#Nocturnal cough guidelines free#

studied nocturnal cough frequency and citric acid cough threshold over the 40-day period of the study. In the next major hypobaric chamber study, Operation Everest III, during which 8 subjects again underwent a simulated ascent of Mount Everest, Mason et al. This brought into question the widely held view that cough at high altitude was due to the inspiration of dry, cold air. At altitudes above 7000 m the majority of the subjects developed pain and dryness in the throat and an irritating cough, despite the chamber being maintained at a relative humidity of between 72 and 82% and a temperature of 23☌. During Operation Everest II eight subjects who underwent a simulated ascent of Mount Everest in a hypobaric chamber were decompressed over a 40 day period to a barometric pressure of 253 mm Hg (33.7 kPa) equivalent to the summit of Everest (8848 m). Interestingly however, the author is not aware of any similar reports in the polar exploration literature where exercising explorers are exposed to a similar environment of cold, dry air, but often at a considerably lower altitude. Despite both anecdotal and observational evidence of an increase in cough with altitude, and a demonstrated change in citric acid cough threshold, the aetiology of altitude-related cough is poorly understood and treatment remains unsatisfactory.Īltitude-related cough has traditionally been attributed to the inspiration of the cold, dry air which characterises the high altitude mountain environment. Citric acid cough threshold was unchanged on arrival at Base Camp compared with sea level but was significantly reduced on the second visit to Base Camp compared with both the sea level and first visit to Base Camp measurements. As part of the same study citric acid cough threshold was measured in 42 subjects at sea level and on arrival at Base Camp at 5300 m and again at Base Camp in 23 of these same subjects after they had spent at least 9 days at or above 5000 m. In three climbers in whom recordings were made at 7000 m on Everest there was a massive increase in nocturnal cough frequency (Figure 1). Nocturnal cough frequency increased with increasing altitude. The first formal study of cough at high altitude took place during the 1994 British Mount Everest Expedition when 10 subjects trekking from 2800 m to Everest Base Camp at 5300 m underwent nocturnal cough frequency monitoring. In a survey of 283 trekkers walking in the Everest region of Nepal, 42% suffered from cough while in another study, again in the Everest region of Nepal, the prevalence of cough was found to be 22% between 42 m. Four members of the 1971 International Himalayan Expedition to Mount Everest suffered rib fractures as a result of coughing and other similar accounts of cough-related rib fractures at high altitude exist. This description by the late Joe Tasker is typical of the debilitating, paroxysmal cough that is well known within the mountaineering community to effect visitors to high altitude. The nights at base camp as well as on the mountain were often punctuated by staccato bursts of noise disturbing the sleep of the sufferer and all those around’.

#Nocturnal cough guidelines free#

The cold dry air compounded the irritation in the throat and the victim’s body would be shaken by the hacking cough until randomly flung free of its spell. ‘Alan was still racked by frequent coughs, and periodically, as if by auto-suggestion, I found that I too was succumbing to a bout.