The Lake Louise Consensus on the Definition of Altitude Illness

AMS In the setting of a recent gain in altitude, the presence of headache and at least one of the following symptoms:
 
  • gastrointestinal (anorexia, nausea or vomiting)
  • fatigue or weakness
  • dizziness or lightheadedness
  • difficulty sleeping
HACE Can be considered "end stage" or severe AMS. In the setting of a recent gain in altitude, either:
 
  • the presence of a change in mental status and/or ataxia in a person with AMS
  • or, the presence of both mental status changes and ataxia in a person without AMS
HAPE In the setting of a recent gain in altitude, the presence of the following:
Symptoms: at least two of:
 
  • dyspnea at rest
  • cough
  • weakness or decreased exercise performance
  • chest tightness or congestion
Signs: at least two of:
 
  • crackles or wheezing in at least one lung field
  • central cyanosis
  • tachypnea
  • tachycardia

Reference: "The Lake Louise Consensus on the Definition and Quantification of Altitude Illness" in Sutton JR, Coates G, Houston CS (eds), Hypoxia and Mountain Medicine. Queen City Printers, Burlington, Vermont, 1992.