Avoiding Mountain Sickness

When an observing team came to Hawaii for an run of a few nights on the JCMT (or UKIRT), each member of that team MUST have participated in a pretty thorough medical examination designed to detect possible problems that may occur to the user when working in a hostile environment such as the summit of Mauna Kea.

The requirement to produce a valid medical certificate has now been reviewed and medical torture has been avoided for most observers. The move to a medical alert disclaimer form does not imply that the JAC believes Mauna Kea is now a safer place to visit. Rather it transfers the emphasis of awareness of the potential medical difficulties and their symptoms from the administration directly to the observers themselves. It is their responsibility to ensure they are sufficiently healthy to work on Mauna Kea.

The JAC still firmly believes that the summit of Mauna Kea is a hostile and potentially hazardous working environment. This is reflected by the fact that the JAC staff will still have to pass a strict medical examination in order to be allowed to work up at the telescopes.

The medical disclaimer form very concisely describes a variety of symptoms that a victim may experience at any time when at altitude. However in order to give a little more understanding of what observers are signing I have attempted below to describe some of the potential problems in more detail from a layman's viewpoint.

The general problem

Mountain sickness is primarily caused by a lack of oxygen (hypoxia). Lower levels of oxygen in the air lead to a variety of physiological changes. At the summit of Mauna Kea the oxygen content of the reduced atmosphere is a mere 60% of that at sea-level. This has been described as being at the point when the brain decides to go 'off-line'.

It is possible for the human body to acclimatise to these conditions if the reduction in oxygen level is met slowly. Visitors would not suffer many mountain sickness symptoms if they were issued with backpacks and maps and made to walk from Hilo to the summit.

There are 4 main categories of mountain sickness. These are not necessarily independent and one may develop into another at an alarming rate if the symptoms are left untreated.

The cure for all mountain sickness is an immediate descent to sea level.

Acute mountain sickness

Most, but not all, observers are likely to suffer some of the symptoms of acute mountain sickness. These are headaches, shortage of breath, nausea, fatigue, loss of memory, lack of concentration, lack of appetite and inability to get to sleep. It is estimated that about 20% of people are affected by the above and the usual cause is a climb to over 8,000 feet too rapidly.

The law-abiding JCMT/UKIRT observer takes about one hour to drive from Hilo to HP (at 9,300 feet) which comes into the category of 'too rapidly'. However it is a JAC policy that visitors remain at HP for at least 8 hours (and preferably the night before the observing run) before proceeding to the summit. During that time the body partially adjusts itself to the reduced atmosphere. Visitors are advised to drink plenty of liquids (avoid alcohol, carbonated drinks, tea and coffee — which does not leave a lot of option!).

Residual 'hangovers' may persist for a few days whilst observing but if any of these symptoms become debilitating, or cause constant dull pain, the TO should be informed immediately.

The JAC stated maximum stay at the summit is 14 hours in a 24 hour period for visitors and staff alike. Only in exceptional circumstances do staff remain for the full duration.

The best cure for acute mountain sickness is to descend to sea level, not just to HP but completely down to Hilo.

High-altitude pulmonary oedema

Pulmonary oedema refers to a build-up of fluid in the lungs due to inflammation. This results in symptoms similar to pneumonia. They are a more severe form of those for acute mountain sickness. Victims may suffer a severe migraine-like headache, shortage of breath when at rest, may have a raised temperature (fever) and feel lethargic. A hacking cough may develop often spitting frothy, bloody fluid.

This rarely affects people below 9,000 feet but such cases are not unheard of. It usually develops after a longer period at altitude (which in this case includes HP and above) of about 48 hours or more. Descent from the telescopes to HP will not immediately alleviate the symptoms and descent to Hilo is recommended.

High-altitude cerebral oedema

This is more common at altitudes over 10,000 feet but, like pulmonary oedema, can occur even below 9,000 feet. The 'cerebral' part implies this condition has symptoms relating to brain behaviour and in fact the central nervous system is affected. Symptoms such as confusion, hallucination, slurred speech, loss of balance, lack of hand co-ordination, difficulty in focusing and aggressiveness may occur which appear very similar to drunkenness.

In fact, one effect of drinking alcohol is a reduction in the oxygen-carrying capacity of the blood. Lack of oxygen is the air produces similar symptoms. Drinking of alcohol is forbidden on the summit of Mauna Kea and is definitely not recommended at HP.

The victim may be the last person to realise that they are suffering these symptoms. The Telescope Operators (and all JAC staff) undergo training to make them more aware of such illness. They also have sufficient authority to order visitors (and other staff) off the mountain should they feel the situation is dangerous.

If left untreated this stage can easily develop and cause death. The cure is descent to sea level and possible medical treatment.

Chronic mountain sickness

People who fail to acclimatise but ascend rapidly to altitude (usually above 11,000 feet) may well end up with a case of chronic mountain sickness. This is characterised by extreme tiredness, palpitations, swollen ankles, chest pain and in some cases heart failure and death. The symptoms can occur quite suddenly and develop rapidly. There are some people who are unable to acclimatise properly even if they stay for 24 hours at HP. Chronic mountain sickness is very rare.

JAC mountain staff receive training in First Aid and Cardio-Pulmonary Resuscitation (CPR). However it must be remembered that on Mauna Kea they too suffer from lack of oxygen and may have difficulty avoiding altitude sickness if they are trying to breathe for you or perform strenuous pumping exercises on your chest. This coupled with the long, bumpy drive from summit to Hilo makes the successful CPR on the summit unlikely.

And finally...

Now that you are no longer required to take a medical to use our telescopes please do not misuse the disclaimer form. It is much better to go to your own GP and have a check-up than it is to fall over on Mauna Kea and have JAC staff test out their emergency procedures.

1. Research has shown that every 1,000 foot increase in altitude reduces a person's work capacity by 3%. Therefore on top of Mauna Kea everybody is running at a mere 58% of their operating efficiency at sea level, which for some people may not be a large amount!

2. Above 10,000 feet the large supply of oxygen that the rods in the eye require is no longer available and as a result night vision is reduced by about 50%. Astronomers without night vision?

3. It is recommended not to ascend more than 2,000 feet per day when above 7,000 feet. A tent and a flask of hot water may be provided!

4. One suggested treatment for mountain sickness is to place the victim in a sealed bag that can be inflated to sea-level pressure. Maybe this should be imposed on all visitors as a precaution!

Houston C S; 1992, Scientific American 267, 58.

Gantenbein D; 1993, Discover 14, 114.