High Altitude Pulmonary Oedema: An Observational Study

High altitude pulmonary oedema (HAPO) is a potentially fatal, non-cardiogenic pulmonary oedema, which occurs in unacclimatized, susceptible individuals after rapid induction into a high altitude area.

Aims: An observational study of high altitude pulmonary oedema.

Methods and Material: Data was collected over a 3-year study period at a general hospital located in high altitude and catering to a population of over 100,000 people deployed at heights ranging from 3000m to 6000 m in the Himalayas. Prospective data collection was done of all patients received with a clinical diagnosis of HAPO.

Results: 686 cases of high altitude related illness namely acute mountain sickness (AMS), High Altitude pulmonary oedema (HAPO), high altitude cerebral oedema (HACO) and high altitude pulmonary arterial hypertension (HAPAH) were received and treated at this specialised centre. A total of 434 cases of HAPO were diagnosed during this period with maximum number of cases occurring in age group 21-25 years, predominantly affected Lowlanders, majority occurred within 24 h of induction to altitudes ranging from 3000m to 4500m. The clinical presentation included productive cough and dyspnoea with crepitations on auscultation and tachypneoa with majority having saturations less than 80%. Chest radiographs showed classical pulmonary infiltrates involving B/L lung zones in < 30%, right lower zone (RLZ) was the commonest.

Conclusion: High altitude pulmonary oedema is a significant and potentially serious health problem. Early diagnosis carries better prognosis. Greater understanding of the pathophysiology and strict adherence to acclimatisation schedule definitely reduces its incidence, mortality and morbidity.