A Belfast doctor believes that drug induced headaches can predict climbers' health
Every researcher hopes to have at least one eureka moment. The breakthrough that sparked important work by Roger McMorrow, a Belfast doctor, on altitude sickness came to him in bed, as he pondered an unusual headache. Earlier that day the doctor, who was then working as a junior in a cardiology unit, had decided, on a whim, to give himself a small, harmless dose of glyceryltrinitrate. One common side effect of the drug, which is administered to angina sufferers, is a headache caused as blood vessels widen throughout the body, including in the head.
"There was something about this headache, something that was different," says the 26-year-old, a keen mountaineer who will lead an expedition to scale a previously unclimbed and as yet unnamed Himalayan peak in northern India in May. "It was bugging me all night, and at around two in the morning I realised that it was identical to the headache that I usually get at altitude."
Headaches are a symptom of acute mountain sickness and the even more serious high-altitude cerebral oedema - or brain swelling - that can occur at high altitudes because of the lack of oxygen in the air. The conditions can affect anyone, regardless of fitness. Nobody really knows why some people are more susceptible to them than others. One current hypothesis - the "tight fit" theory - suggests that people with smaller skull-to-brain ratios are more likely to be affected.
While fairly rare, high-altitude cerebral oedema is responsible for most altitude-sickness-related deaths; at the moment there is no test to detect the swelling, which is the result of water forming on the brain. McMorrow began to consider whether glyceryltrinitrate-induced headaches, in which dilating blood vessels in the head cause swelling, might be able to predict who is at risk of developing acute mountain sickness or high-altitude cerebral oedema.
Last year, on an expedition to Kilimanjaro, he completed a pilot study that involved administering the drug to nine climbers at a range of altitudes. After McMorrow sprayed the drug under their tongues, to produce mild, five- to 15-minute headaches, his guinea pigs rated the aches on a scale of one to 10. According to McMorrow's theory, the strength of the headaches will give a reasonable prediction of how sick people will be as they climb higher.
If a climber at high altitude had a very severe headache after taking glyceryltrinitrate, for example, it could suggest that further brain swelling caused by altitude sickness could be dangerous. Another climber might experience only a mild headache after being given the drug, indicating less risk of developing severe altitude sickness.
"I am hoping to design a simple test to detect brain swelling before the individual shows signs of it, a test that a GP on a trek can do on the people in the group," he says. "If 10 people are saying they have headaches, the test will be able to determine if they are normal acute-mountain-sickness-type headaches or just starting to become cerebral oedema. In that way, it can act as a predictor for both acute mountain sickness and high-altitude cerebral oedema, and we should be able to judge from the strength or weakness of the headache that results from glyceryltrinitrate whether it is safe for the person to climb higher."
Altitude sickness can affect anyone at a height of more than 6,000 feet, from Olympic athletes on the peaks of Salt Lake City to the most confirmed coach potato. Any rapid ascent to high altitude would be uncomfortable for most people and can result in loss of appetitite, dizziness and, in severe cases, hallucination.
An anaesthetist at Belfast City Hospital, McMorrow has already presented his findings at an international conference and hopes to pursue an academic career. But mountaineering remains a consuming passion. "It is an all-round sport," he says. "It is not just about the peak; it works on so many levels and takes you to places you would never otherwise see."
The other members of the May expedition to the virgin peak - which, in a reference to its height, is known only as Pk6044 - are Michael McCann, a chemical engineer from Northern Ireland; Gustau Catalan, a physicist from Spain; and Sara Spencer, who works in marketing, from Co Waterford. All they have is a photocopied photograph of the peak, which is four times as high as Carrauntoohil, and they have no idea of the level of difficulty or how long the climb will take.
A former president of Queen's University's mountaineering club, McMorrow will continue his research into high-altitude physiology on the trip. He is also looking for volunteers to join him on an expedition to Makula, in Nepal, next year. They will be given glyceryltrinitrate and their headaches monitored. On that trip, McMorrow intends to use ultrasound to examine blood flow in the head, which will further bolster the young doctor's research.
Keeping fit
Above 10,000 feet, ascend no more than 1,000 feet per day and take a rest day every third day.
Climb as high as you like but sleep low.
Drink plenty of fluids - but not alcohol.
Load up on carbohydrates and high-energy foods; avoid fatty meals.
Avoid heavy exercise.
Do not overdo it on your first day or two.
If in doubt, descend, descend, descend!
Peak health
Acute mountain sickness
Very common at altitude; causes nausea, headaches, loss of appetite and lethargy. About two-thirds of people will experience some form of it higher than 10,000 feet.
High-altitude cerebral oedema
Relatively rare condition that occurs when acute mountain sickness worsens and water forms on the brain.
High-altitude pulmonary oedema
Fluid on the lungs; also quite rare but potentially fatal.
Anyone interested in joining the expedition to Nepal, in spring 2003, should contact McMorrow at Roger_McMorrow@Bigfoot. com or Simon Currin at simon @medex.org.uk, or phone 00-44-1743-351664