Travel- skiing: Up where we belong?

It affects many skiers and may simply feel like the onset of flu - but it can kill. So how do you prevent altitude sickness?

The first time it happened was at the Italian resort of Sestriere, two seasons ago. I was skiing more clumsily than usual one afternoon, and had a slight headache; by the end of the day I felt much worse, nauseous and slightly dizzy. I drove back to the friends in whose house I was staying and announced that I would not be taking them out to dinner; rather, I would be retiring to my bedroom, probably to re-emerge two days later after a heavy bout of flu.

In fact I got up after a couple of hours sleep, feeling surprisingly better. We went out to dinner.

Another such episode occurred early the following season; again I thought little of it, apart from relief that the flu lasted no longer than an evening. It was only last April, at the high-altitude resorts of Vail and Beaver Creek in Colorado, where the symptoms recurred on successive days, that I began to put two and two together. They finally made four when, at the beginning of this season, I saw a small ad in a US skiing magazine.

The advert was for Diamox, the brand-name under which the drug acetazolamide is sold. It recommended taking a course of the drug, as a precaution against altitude sickness, before travelling to high-level ski resorts. Altitude sickness? This seemed a promising preliminary diagnosis of my recurrent condition.

I sought professional advice. After a couple of phone calls - during which I learned that the medical term for altitude sickness is actually acute mountain sickness, or AMS - I found myself talking to a doctor who, it transpired, was involved in the first clinical trials of acetazolamide for the treatment of AMS. I recounted my symptoms to Dr Jo Bradwell, chairman of the Birmingham Medical Research Expeditionary Society. He sounded almost triumphant: "Yes, that's AMS - you had AMS!"

AMS takes three forms. The two extreme conditions, high-altitude pulmonary and cerebral oedema (HAPO and HACO), are life-threatening and usually only affect trekkers and climbers who make progressive ascents on successive days, sleeping high on the mountain; and - for obvious reasons - they are the main focus of medical research. The mild form, commonly referred to simply as AMS, causes no more than physical discomfort, unless the sufferer ignores the symptoms (or treats them with painkillers) and pushes on to higher altitudes, where the condition can develop into HAPO and HACO.

In normal circumstances, skiers are affected only by mild AMS, and even then only if they go beyond the benchmark level of 3,000 metres. However susceptibility is variable - my first bout of AMS at Sestriere occurred below 2,500 metres, while at other times I have been unaffected by greater altitudes - for reasons that remain unclear. The research is short on consistent rules (except that physical fitness offers no protection against the condition), long on inconsistencies. For example, a study by Dr Peter Forster at the 4,200-metre-high Mauna Kea telescopes in Hawaii, to which staff often commute by road from sea level, revealed that one astronomer had worked there for two years before suddenly suffering from HAPO, and then remained unaffected for the remaining three years of the study.

What causes AMS? Put simply, the thin air at high altitude can cause a person who is not acclimatised to "over-breathe" but a chemical reaction in the body associated with the increased exhalation of carbon dioxide - it's called respiratory alkalosis - acts to suppress this overbreathing, leaving the system short of oxygen. During the skiing day, exertion naturally induces heavy breathing, and the problem may be masked. Thereafter, the respiratory alkalosis can cause an oxygen debt, an effect exacerbated if the sufferer also spends the night at high altitude or takes alcohol or sleeping pills - since both sleep and sedatives cause shallower breathing.

Normally, the symptoms of AMS arise after about six hours at altitude; and, provided the sufferer does not ascend further, they disappear after a few days, when the body acclimatises. But a low dose of acetazolamide, taken before and during the ascent to high altitude, prevents the condition from occurring. The drug was originally developed as a diuretic, and used particularly in the treatment of glaucoma; but its chemical properties also neutralise respiratory alkalosis, allowing the body to over-breathe and ensuring an adequate supply of oxygen. (Its only side-effect is a tingling sensation in fingers and toes, and - bad news for those who like a beer - to make fizzy drinks taste odd.)

Do many skiers, like me, suffer from AMS? I consulted Dr Dave Wilkinson at the Routt Memorial Hospital in Steamboat, Colorado - an unwise choice, he pointed out, because although Steamboat's ski area rises to 3,170 metres, the resort is relatively low, at 2,100 metres. "We don't see a lot of it here, because the tendency to under- breathe is much greater during sleep," he said. "At Breckenridge they have far more cases of AMS, because the resort base is at 2,927 metres." Never- theless, his hospital sees two or three cases a year of the serious HAPO condition ("We're always curious as to why those particular people develop the problem," he said), and Dr Wilkinson regularly treats skiers suffering from mild AMS.

From 17 years' experience at Steamboat, he says they fall into three groups of comparable size. "First, there are the people who think they have flu. Then there are those who know they have AMS, and want a prescription for acetazolamide. Finally, there's a group that doesn't know what the hell is going on." Dr Wilkinson's regular advice for sufferers is to stay hydrated, and to avoid sedatives. In place of the latter he prescribes "a Coke or a spot of coffee at bed-time" (presumably a weak American filter coffee would work more effectively than a double espresso).

But for British skiers heading for Colorado's slopes who are susceptible to AMS, he suggests a precautionary course of acetazolamide: "Take it the day before you leave, on arrival, and on the first day of skiing, and you should be alright," he says. I'll try that next time.

Acetazolamide is available only on prescription, through a GP or travel medicine specialist.

Skiing in Sarajevo: there is a different number for the ski operator based in the Bosnia capital that I mentioned last Saturday; call Harlequin Leisure on 00 387 71 214 788.