Deaths at high altitude: Reducing the risk. A preliminary field study

Area of Science:

• Altitude medicine
• Cardiovascular physiology

Background:

• Limited clinical studies on altitude sickness and blood pressure in adventure travelers.
• Need for data to advise General Practitioners (GPs) on pre-trek medical advice.

Purpose of the Study:

• To investigate altitude sickness symptoms and systemic blood pressure changes in relation to altitude.
• To provide data for GPs advising patients undertaking adventure holidays at altitude.

Main Methods:

• 17 trekkers gradually ascended Mera Peak in the Himalayas.
• Daily measurements of heart rate, blood pressure, oxygen saturation, peak expiratory flow, and core temperature.
• Hourly altitude checks and 24-hour ambulatory blood pressure monitoring for two individuals.

Main Results:

• No altitude sickness symptoms below 4000m; unpredictable symptoms arose above 4500m.
• Significant fall in oxygen saturation (O2sat) between 3500-4000m.
• No altitude effect on blood pressure below 3500m; marked, asymptomatic rise above 5000m.

Conclusions:

• A critical altitude may exist requiring increased vigilance.
• Further research on blood pressure at extreme altitudes is warranted.