[Pollard AI, Murdoch DR, Bartsch P. Children in the mountains. BMI 1998; 316: 874-8751.

Acute mountain sickness occurs in more than 50% adult tourists trekking at a height of above 2500 m, especially when the ascent is rapid. Little data is available regarding the altitude sickness in children. Recently, attention has been drawn to the potential risks of exposing young children to high altitude areas of the world; even infants are reported being carried to over 6000 m on mountains in Nepal Himalayas. The present editorial reviews the existing data regarding health risks associated with high altitude trekking in young children in order to provide guidelines for parents travelling with their kids.

Existing data suggests that though children are not at increased risk of developing acute mountain sickness as. compared to adults; however, diagnosis of the condition is a major problem in children who are too young to express themselves clearly. Common symptoms such as headache, nausea, fatigue, anorexia, dizziness and sleep disturbance are rarely reported by the under fives. Presenting symptoms may comprise lethargy, food refusal, irritability, and excessive crying, which are too non specific and are easily attributed to changes in routine or diet associated with remote travel, or to intercurrent illness.

Since the diagnosis of acute mountain sickness and early stages of high altitude pulmonary and cerebral edema can be easily overlooked, a child becoming unwell above 2500 m should be presumed to have developed acute mountain sickness and therefore should be immediately brought down to lower altitude. The approach of wait and watch can be extremely dangerous in these situations.

Authors suggest that when trekking in a remote setting, a conservative approach should be adopted and children less than 2 years should not be allowed to sleep at altitudes in excess of 2000 m. Similarly, mountainous treks above 3000 m should be for- bidden for those aged 2-10 years.

Comments

Trekking and travelling in nature offers children life enhancing experiences that broaden them educationally, socially, and culturally, Although travel builds experiences that are usually beneficial, children are .at risk for serious health problems associated with altitude travel.

Acute Mountain Sickness (AMS) is defined as the presence of headache associated with any of the following symptoms: gastrointestinal upsets, nausea, vomiting, fatigue, dizziness or insomnia as a result of a recent increase in altitude and usually occurs at a height of greater than 2500 m (8200 ft). At least 25% of adults experience symptoms with ascent from sea level to 2000 m, 30% at exposure to 3000 m and about 75% at 4,500 m (14,80D ft). The most common range for serious altitude illness is between 3500 and 55.00 m; the PaO₂ at these elevations is less than 60 mm Hg with saturation of less than 90%. The incidence of AMS is unrelated to overall fitness, exercise training or gender. Symptoms of AMS  usually disappear within one week at the same altitude(1).

The common cause of death at high altitudes include high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). HAPE occurs within 6 hours to several days after rapid ascent to greater than 2500 m. HAPE is diagnosed in presence of at least two of the following symptoms and signs each in association with a recent gain in altitude; symptoms: orthopnea, cough, weakness, decreased exercise performance, chest tightness or congestion, signs: wheeze, cyanosis, tachycardia or tachypnea. The incidence of HAPE increases with the rate of ascent, exertion, final altitude and low ambient temperature. Children have a higher rate of HAPE(2).

HACE occurs when a person with both AMS and HAPE develops an altered level of consciousness. Hallucinations, ataxia, focal neurological signs, seizures, stupor and coma are the early presenting features(3).
Firm data on AMS is not available for children. below 10 years. The lack of information about altitude illness in young children trekking in Nepal is due to small number of lowland children coming for trekking in high altitude regions. The ad- vise given in the present paper though seemingly conservative, appears justified, given the lack of information at high altitude. Though it is totally agreeable that children under five are in no position to reliably communicate the symptoms of AMS to their guardians, even the 5-10 aged children may at times not able to express them- selves clearly, for they are not well versed with the dangers of AMS and are more likely to confuse fatigue symptoms with that of AMS. Himalayan Rescue Association, Nepal have also noted the difficulty faced by the parents in interpreting their child's behavior at high altitudes.

In older children, AMS can be pre- vented by adopting both non pharmacological and pharmacological measures. Non pharmacological measures include a gradual ascent 300 m/ day, to spend a few days at intermediate altitudes (2500-3000 m) before ascending further, ascend slowly at > 2500 m, spend an extra night for every 600-900 m if continuing to ascend and following the old saying of "climb high, sleep low". Pharmacological preventive main- stay is administration of acetazolamide. A pediatric dose of 2.5-5 mg/kg every 12 hourly upto 250 mg per day has been recommended but there have not been any studies in small children(4). Older children travelling in a group on a high altitude treck should not be allowed to travel with- out a physician well versed with the problems of high altitude.

It is important that those heading to high altitudes with children be cautioned about the warning signs of altitude sickness because they may easily be attributed to travel fatigue. If a child becomes ill at altitude, it should be presumed that the sick- ness is caused by the elevation. Stop ascent immediately, rest, descend down and seek medical advice. The wise idea is not to ex- pose young children to high altitude in a remote region when similar mountain holidays can be taken at low altitudes.

Piyush Gupta,
Associate Professor in Pediatrics,
B.P. Koirala Institute of Health Sciences,
Dharan,
Nepal.