Children in the mountains

High mountain trekking holidays are best avoided for the very young.

Editorial p 873

High altitude areas of the world were once visited only by a privileged minority. Now the great mountain ranges have become popular tourist destinations. An increasing number of children accompany their parents on such journeys, but little consideration has been paid to the potential risks of exposing young children to high altitudes. We are aware of ascents in Nepal where infants have been carried to over 6000 m on mountains requiring technical snow mountaineering expertise.

About half the adult tourists on the popular trekking routes in Nepal develop acute mountain sickness,1-3 a disorder characterised by headache, nausea, vomiting, anorexia, fatigue, dizziness, and sleep disturbance that is particularly common above 2500 m, especially when ascent is rapid.4 Although acute mountain sickness is generally benign, it may progress to life threatening high altitude cerebral or pulmonary oedema. Little information exists about altitude illness in children. Wu studied 464 children travelling across the Tibetan plateau at 4550 m and found incidences of acute mountain sickness and high altitude pulmonary oedema of 34% and 1.5% respectively on the basis of symptoms, physical examination, chest radiography, and relief of symptoms after oxygen therapy.5 These were almost identical to the corresponding incidences for 5355 adults who were also studied.

Similarly, Theis et al surveyed 558 children aged 9-14 years at 2835 m in Colorado and found that 28% reported symptoms of acute mountain sickness.6 However, it is unclear whether these symptoms were related to altitude or to travel itself, as 21% of a control group at sea level also reported similar symptoms. Yaron et al recently attempted to examine the incidence of acute mountain sickness in children aged under 37 using a behavioural score based on the standard adult mountain sickness symptom questionnaire.8 In 14 children aged 3-36 months ascending from 1609 m to 3488 m there was an incidence of mountain sickness of 22% (compared with 20% in 45 adults on the conventional scoring system). Pulmonary oedema seems to develop more often in children who have had recent upper respiratory tract infections.9

While this limited information suggests that children are no more likely to develop acute mountain sickness than adults, it is harder to recognise the condition in children. Headache, nausea, fatigue, anorexia, dizziness, and sleep disturbance are rarely reported by children under 5 years, in whom non-specific symptoms such as lethargy, food refusal, irritability, and excessive crying may be the only indication of the condition. Unfortunately, these symptoms can be attributed to changes in routine or diet associated with remote travel, or to intercurrent illness.

Since acute mountain sickness and the onset of high altitude pulmonary or cerebral oedema can be easily overlooked in young children, the diagnosis should always be assumed when a child becomes unwell above 2500 m and descent should start immediately. Rapid descent will usually relieve the symptoms of acute mountain sickness, may be lifesaving when high altitude pulmonary and cerebral oedema are present, and is the only definitive treatment for all forms of altitude illness. There is no place for a “wait and see” approach when children have acute mountain sickness.

Pharmacological treatment for altitude illness has not been studied in children, but in life threatening situations paediatric doses of drugs proved effective in adults should be used.4 When cerebral oedema or severe acute mountain sickness is suspected oxygen and dexamethasone (0.15 mg/kg/dose 4 hourly) should be given in combination with immediate descent. Pulmonary oedema also responds well to descent and oxygen therapy and, although systemic hypotension could be a problem, nifedipine (0.5 mg/kg/dose 8 hourly, maximum 20 mg for capsules and 40 mg for tablets) will lower pulmonary arterial pressure and relieve symptoms.

Prolonged exposure to high altitude should be avoided in infants aged under 1 year because of the risk of subacute infantile mountain sickness.10 This condition is characterised by pulmonary hypertension and consequent fatal right heart failure and occurs in up to 1% of infants of lowland parents who are born at 3000-5000 m or arrive there shortly after birth. It was first described in Tibet, where it almost exclusively affects infants of Han Chinese origin who have recently migrated from low altitude areas.

Travelling with children can be a valuable experience, but these valuable insights must always be balanced against the risks of serious illness and death from exposure to environmental hazards such as hypoxia and cold. In most cases there is little justification in taking young children to high altitude. Most positive outdoor experiences can be gained at modest elevations, where there is plenty of oxygen and more warmth. Slow ascent is recommended, regardless of the altitude. Additional caution is required when the child has recently had a respiratory tract infection, as this increases the risk of pulmonary oedema.9

Until further information suggests otherwise, when trekking in a remote setting a conservative approach would be to sleep no higher than 2000 m for children aged under 2 and no higher than 3000 m for children aged 2-10 years. High treks are no place for little children.