Altitude Sickness

What is altitude sickness?

Altitude sickness occurs when you cannot get enough oxygen from the air at high altitudes above 3000meter/10,000ft. This causes symptoms such as a headache,  loss of appetite, and trouble sleeping. It happens most often when people who are not used to high altitudes go quickly from lower altitudes to 8000 ft (2438 m) or higher.

Mild altitude sickness is common. Experts do not know who will get it and who will not. Neither your fitness level nor being male or female plays a role in whether you get altitude sickness.

Altitude sickness can be dangerous.

 

What causes altitude sickness?

Air is “thinner” at high altitudes. When you go too high too fast, your body cannot get as much oxygen as it needs. So you need to breathe faster. This causes the headache and other symptoms of altitude sickness. As your body gets used to the altitude, the symptoms go away.

 

What are the symptoms?

The symptoms of altitude sickness include:

  • A headache, which is usually throbbing. It gets worse during the night and when you wake up.
  • Not feeling like eating.
  • Feeling sick to your stomach. You may vomit.
  • Feeling weak and tired. In severe cases, you do not have the energy to eat, dress yourself, or do anything.
  • Waking up during the night and not sleeping well.
  • Feeling dizzy.

Your symptoms may be mild to severe. They may not start until a day after you have been at a high altitude. Many people say altitude sickness feels like having a hangover.

Altitude sickness can affect your lungs and brain. When this happens, symptoms include being confused, not being able to walk straight (ataxia), feeling faint, and having blue or gray lips or fingernail. When you breathe, you may hear a sound like a paper bag being crumpled. These symptoms mean the condition is severe. It may be deadly.

 

Basic rule:

  • Never go higher with mild symptoms

If you find mild symptoms developing while walking, stop and relax with your head out of the sun and drink some fluids. If the symptoms do not go away completely then stay at same altitude. Or if symptoms get worse, GO DOWN. A small loss of elevation (100-300m/328-984ft) can make a big difference to how you feel and how you sleep – descend to the last place where you felt good. If symptoms develop at night then, unless they rapidly get worse, wait them out and see how you feel in the morning. If the symptoms have not gone after breakfast then have a rest day or descend. If they have gone, consider having a rest day or an easy days walking anyway.

Continued ascent is likely to bring back the symptoms. Altitude sickness should be reacted to, when symptoms are mild – going higher will definitely make it worse. You trek to enjoy, not to feel sick.

Note also that there is a time lag between arriving at altitude and the onset of symptoms and in fact it is common to suffer mild symptoms on the second night at a set altitude rather than the first night.

 

Serious Symptoms

– Persistent, severe headache

– Persistent vomiting

– Ataxia – loss of co-ordination, cannot walk in a straight line, looks drunk

– Losing consciousness – cannot stay awake or understand things very well

– Liquid sounds in the lungs

– Very persistent cough

– Real difficulty breathing

– Rapid breathing or feeling breathless at rest

– Coughing blood or pink goo or lots of clear fluid

– Marked blueness of face and lips

– High resting heart beat – over 120 beats per minute

– Severe lethargy and drowsiness

– Mild symptoms rapidly getting worse

Ataxia is the single most important sign for recognizing the progression from mild to severe. This is easily tested by trying to walking a straight line, heel to toe. Compare with somebody who has no symptoms. 24 hours after the onset of ataxia a coma is possible, followed by death, unless you descend.

 

  • Immediate Descent

Take as far down as possible, even if it is during the night. (In the Everest region: if you are above Pheriche, go down to the HRA post there. From Thorung Phedi or nearby: take to the Manang HRA post.) The patient must be supported by several people or carried by a porter – his/her condition may get worse before getting better. Later the patient must rest and see a doctor. People with severe symptoms may not be able to think for themselves and may say they feel OK. They are not.

 

Medical Conditions

  • High Altitude Cerebral Oedema (HACE) – this is a build-up of fluid around the brain. It causes the first 4 symptoms of the mild, and the severe symptom lists.

 

  • High Altitude Pulmonary Oedema (HAPE) – this is an accumulation of fluid in the lungs, and since you are not a fish, this is serious. It is responsible for all the other mild and serious symptoms.

 

  • Periodic Breathing – the altitude affects the body’s breathing mechanism. While at rest or sleeping your body feels the need to breathe less and less, to the point where suddenly you require some deep breaths to recover. This cycle can be a few breaths long, where after a couple breaths you miss a breath completely, to being a gradual cycle over a few minutes, appearing as if the breathing rate simply goes up and down regularly. It is experienced by most trekkers at Namche, although many people are unaware of it while sleeping. At 5000m/16,404ft virtually all trekkers experience it although it is troublesome only for a few. Studies have so far found no direct link to AMS.

 

  • Swelling of the hands, feet, face and lower abdomen – remove rings. An HRA study showed that about 18% of trekkers have some swelling, usually minor. Females are definitely more susceptible. It is not a cause for concern unless the swelling is severe, so continuing ascent is OK.

 

  • Altitude immune suppression – at base camp altitudes cuts and infections heal very slowly so for serious infections descent to Namche level is recommended. The reasons are not well understood.

 

  • HAPE – descend, Diamox 250mg 12 hourly, Nifed orally, 10mg 8 hourly and 2-4l/min O2 or a Gamow bag.

 

  • Oxygen – supplementary O2 does not immediately reverse all the symptoms although it does help significantly. Descent in conjunction with O2 is more effective.

 

  • Gamow bag/PAC bag/CERTEC bag – the latest devices to assist with severe AMS. Basically it is a plastic tube that the patient is zipped into. A pump is used to raise the pressure inside the bag simulating going to a lower altitude. It is very effective.

 

AMS practical

Rates of Acclimatization

Individual rates of acclimatization vary enormously but ascending very rapidly and staying there will ALWAYS result in problems. Even Sherpas who live in Kathmandu upon returning to the Khumbu occasionally get AMS. Studies have shown that people who live at moderate altitudes (1000-2000m/3281-6562ft are acclimatised to those altitudes. They are much less susceptible to AMS when ascending to around 3000m/9842ft (ie going to Namche).

However the benefits decrease once higher and they should follow the same acclimatization program as others. This has implications for people who have spent a week or two in Kathmandu (at an altitude of 1400m/4593ft): they are becoming acclimatized to that altitude. For trekkers that fly from sea level to Kathmandu then almost immediately walk to Namche, they have no advantage and are more likely to suffer AMS. Unfortunately it is usually these people who are in a hurry to go higher. This is perhaps why it appears that group trekkers are initially more susceptible to troublesome AMS than individual trekkers, who often walk from Jiri or spend time in Kathmandu beforehand.

 

The Acclimatization Process

In a matter of hours your body quickly realizes that there is less oxygen available and it first reaction is to breathe more – hyperventilate. This means more oxygen (O2) in but also more carbon dioxide (CO2) is breathed out and with the O2-CO2 balance upset the pH of the blood is altered.

Your body determines how deeply to breathe by the pH level (mainly the dissolved CO2 in your blood) – at sea level a high level of exertion means your muscles produce a lot of CO2 so you breathe hard and fast. While resting, your body is using little energy so little CO2 is produced, demonstrating that you only need to breathe shallowly.

The problem is at altitude this balance is upset and your body often believes that it can breathe less than its real requirements. Over several days your body tries to correct this imbalance by disposing of bicarbonate (CO2 in water) in the urine to compensate, hence the need to drink a lot because it is not very soluble. Diamox assists by allowing the kidneys to do this more efficiently therefore enhancing some peoples ability to acclimatize. In addition, after a day or two, the body moves some fluid out of the blood effectively increasing the hemoglobin concentration. After 4-5 days more new red blood cells are released than normal.

 

Individual rates of acclimatization are essentially dependent on how fast your body reacts to compensate the altered pH level of the blood. For slow starters Diamox can provide a kick-start but for people already adapting well the effect often less noticeable.

 

If you stay at altitude for several weeks there are more changes, your muscles’ mitochondria (the energy converters in the muscle) multiply, a denser network of capillaries develop and your maximum work rate increases slowly with these changes. Expeditions have often run medical programs with some interesting results.

 

Climbers who experience periodic breathing (the majority) at base camp never shake it off and have great difficulty maintaining their normal body weight. Muscles will strengthen and stamina is increased but not the muscle bulk. Interestingly Sherpas who have always lived at altitude, never experience periodic breathing and can actually put on weight with enough food.

 

How long does acclimatization last?

It varies, but if you were at altitude for a month or more your improved work rates can persist for weeks meaning you still feel fit upon returning to altitude. You still should not ascend faster than normal if you return to sea level for a few days, otherwise you are susceptible to HAPE.

If you have been to 5000m/16,404ft then go down to 3500m/11,483ft for a few days, returning rapidly to 5000m/16,404ft should cause no problems, i.e having been to Lobuche and Kala Pattar, and then rested for two days in Namche you should be able to ascend to Gokyo quickly without problems.

 

Sleeping at altitude

Many people have trouble sleeping in a new environment, especially if it changes every day. Altitude adds to the problems. The decrease of oxygen means that some people experience wild dreams with this often happening at around 3000m. Compound this with a few people suffering from headaches or nausea, a couple of toilet visits, a few snorers and periodic breathers, and it takes someone who sleeps like the proverbial log (or very tired trekker) to ignore all the goings on at night in a large dormitory. Smaller rooms are a definite improvement, and tents, although not soundproof are still manage to be relatively peaceful.

 

Appetite

Some people lose appetite and do not enjoy eating. Sometimes equally worrying, although it is a good sign is a huge appetite. Your energy consumption, even at rest is significantly higher than normal because your body is generating heat to combat the constant cold, especially while sleeping. Energetic trekkers, no matter how much they eat will often be unable to replace the huge quantities of energy used.

 

Day trips 

The normal accepted recommendations are to go high during the day and sleep low at night, the sleeping altitude being the most important. This is fine for trekkers experiencing no AMS symptoms whatsoever, and will probably aid the acclimatization process, for example in the Everest region, going up to Chukhung from Dingboche or Pheriche, or visiting  Khunde/Khumjung from Namche. However if you are experiencing mild or even very mild AMS then this is not the best advice. Instead your body is already having trouble coping so it doesn’t need the additional stress of more altitude. Instead stay at the same elevation. Mild exercise is considered beneficial, rather than being a total sloth but take it as a rest day.

If you have troublesome mild symptoms then descent for a few hours may even be more beneficial.