Canadian climber Peter Aghar struggled out of the Gamow Bag and said: “”That feels great.” It was the opposite of the rapture of hypoxia. The bag had been used to re-oxygenate his blood. The Gamow Bag is a tubular pump-up bag a bit bigger that a body and is used to give climbers precious time against altitude sickness. Altitude sickness is quite random. It can strike the fittest, youngest and healthiest while smokers, older people and those who succumb to the slightest head cold seem immune. There is only one cure _ to go down. And even then it can bee too late. The first symptom is headache, then nausea, disorientation and finally coma and death. Not a great deal is known about why it strikes some and not others. For example, Fabian Sada Sherpa (the guide on our Peregrine trek in the Himalayas) told of a marathon runner who has succumbed at 3400 metres.
Perhaps the lack of knowledge is due to altitude sickness _ which is invariably self-induced _ quite rightly not being high on the list of world public-health priorities. To get greater knowledge a Canadian group from Canadian Himalayan Expeditions with a couple of doctors was in the Himalayas earlier this month with a couple of gadgets to record what happens to human bodies of various shapes, sizes and fitness. I was lucky to catch up with them at Namche Bazar at 3446 metres and again a couple of days later at Thyangboche (3875m). For those who will never measure height above sea level in anything by feet, that is 11,306 feet and 12,713 feet, respectively. They were going to climb Island Peak (6360m, 21,000ft), recording data on what was happening to their bodies.
They had two critical gadgets: the Gamow Bag, or portable hyperbaric bag, and the pulse oximeter. The pulse oximeter is a very neat piece of work. It is about the size of a large portable phone. Attached to it by wire cord is an enclosed finger slot about half the size of a match box. You put you finger in the slot and the machine reads both your pulse and the percentage saturation of oxygen in the blood. At sea level it should be a tad under 100 per cent. The two readings are related. The heavier you breathe to compensate for the thin oxygen, the higher your pulse and the better your oxygen saturation. In the long term (several months) people at high altitudes produces a higher proportion of haemoglobin _ the oxygen bearing red cells in the blood. It works by a small infra-red beam measuring the redness of the blood which is an indicator of oxygen saturation. Dr Peter Penev of Toronto explained that of the percentage of oxygen saturation drops suddenly you are in trouble.
The pulse oximeter can detect this before symptoms appear and can help distinguish between your average “”not-tonight-dear” headache and what might be a “”never-again-dear”” headache that is the precursor to altitude sickness. Also if the percentage gets below the low 70s (however slowly it falls), you are also in real trouble. This is where the Gamow Bag comes in. It was invented by Dr Igor Gamow several years ago causing Dr Penev’s climbing companions to nick-name him Dr Igor. The air-tight bag is made from a tough nylon fabric. The sick climber is placed in the bag which is blown up with a foot pump.
A pressure gauge and release valve are attached, there is a clear plastic observation window and you can hear and talk through the nylon.. If the climber is well enough, he or she takes the pulse oximeter inside the bag. As the pressure increases so does the percentage of oxygen saturation in the blood. Dr Igor kindly gave me a turn in the bag after a grisly description of the worst of altitude sickness. “”After the headaches and disorientation you get pulmonary adaema _ fluid on the lung,” he said. The widening his eyes he continued: “”And you cough it up _ pink, frothy, bloody, sputum.” He added nonchalantly: “”If you get cerebral adema _ fluid on the brain _ it’s coma and you’re gone in 12 hours.
Unless you get down. And that can be quite a problem if you’re in a storm. So that’s why we’ve got the bag. Hop in.” At Namche Bazar (20kms from Mount Everest as the crows flies _ though there is no record of any crows having actually made to the top), I had an oxygen saturation of 90 per cent at a resting pulse of 66. By the time I got into the bag a Thyangboche 429 metres higher (and six kms closer to the Big E) it had fallen to 82 per cent, despite heavier breathing causing a higher pulse at 74. I was zipped up with the pulse oximeter and the pressure was applied by blowing air in with a foot pump. It can add pressure of about 110mm of mercury to the existing pressure (about a seventh of sea-level atmospheric pressure). It is the equivalent of taking someone down about 2500 metres. My ears popped furiously and I watched the gauge pulse oximeter. The bag worked very quickly. My oxygen saturation was up to 98 per cent within a couple of minutes _ from almost two Kosciuskos high to Canberra. If there is no helicopter or a storm prevents descent, it’s a lifesaver. Someone can even be carried down inside it. Otherwise it folds up to day-pack size.
The mystifying thing was that the Sherpas with our trek had worse oxygen readings than some of us not used to altitude, yet they seemed unaffected by being at 4000 metres. Some people also suggest that smokers (especially those that give up during a trek) seem less likely to get altitude sickness. My own crackpot theory is that, irrespective of the absolute oxygen saturation, these two groups are used to an environment of fluctuating oxygen _ they are acclimatised to acclimatising. They depressurised the bag. The air rushed through my ears and I struggled out of the bag. “”How do you feel?” Dr Igor asked from a great height.