Article Sections

Introduction

High altitude illness encompasses 3 conditions that develop in climbers or travelers who ascend to high altitude (generally >2500 m [8000 ft]) without sufficient time for acclimatization.  They include:

  • Acute mountain sickness
  • High altitude cerebral edema (HACE)
  • High altitude pulmonary edema (HAPE)

In addition, chronic mountain sickness, a form of pulmonary hypertension with severe polycythemia, can develop in individuals residing permanently at high altitude.

Pathogenesis

Normal adaptation to altitude

Atmospheric pressure (and therefore partial pressure of inspired oxygen [PiO2]) decreases with increasing altitude, resulting in hypobaric hypoxemia ( Figure 1).  Normal physiologic responses include the following ( Table 1):

  • Brain:  Cerebral vasodilation results in mildly increased intracranial pressure.
  • Lungs:  Pulmonary vasoconstriction results in mildly increased pulmonary artery pressure.  An increased ventilatory drive also causes respiratory alkalosis (↓PaCO

Continue Learning with UWorld

Get the full High Altitude Illness article plus rich visuals, real-world cases, and in-depth insights from medical experts, all available through the UWorld Medical Library.

Figures

Figure 1
Figure 1
Figure 2
Figure 2
Figure 3
Figure 3
Figure 4
Figure 4

Tables

Table 1