Criteria

The Lake Louise Acute Mountain Sickness Scoring System[2]​​

Acute mountain sickness (AMS) can be assessed using either the Lake Louise score or the AMS-C score of the Environmental Symptom Questionnaire (ESQ).[2][72]​ The ESQ can also be used to assess high-altitude cerebral edema (HACE); the presence of ataxia and changes in mental state signify the presence of HACE.

The ESQ takes much longer to complete, and calculating the AMS-C score is difficult in the field setting. It consists of 67 questions, of which 11 are used to calculate the AMS-C score. An AMS-C score of 0.7 or more is accepted as a cut-off for AMS.

The Lake Louise score tends to be preferred as it is not only easier to use but it is also capable of recognising milder disease at an earlier stage. According to the Lake Louise scoring system, a score of 3 or more in the presence of a headache fulfils the diagnosis of AMS.[2]

Symptoms:

  • Headache

    • 0 = none

    • 1 = mild

    • 2 = moderate

    • 3 = severe and incapacitating

  • Gastrointestinal symptoms

    • 0 = good appetite

    • 1 = poor appetite or nausea

    • 2 = moderate nausea or vomiting

    • 3 = severe, incapacitating nausea and vomiting

  • Fatigue and/or weakness

    • 0 = none

    • 1 = mild

    • 2 = moderate

    • 3 = severe

  • Dizziness or light-headedness

    • 0 = none

    • 1 = mild

    • 2 = moderate

    • 3 = severe

No neurological findings are exhibited in AMS alone, and the condition is self-limited. However, a change in mental status and ataxia are the classic findings in HACE, which can onset following AMS.[2][29]

Children’s Lake Louise Score (CLLS)[46]

Used for assessing children <4 years old. According to the CLLS, AMS is present if there has been a recent gain in altitude and the CLLS is ≥7. Details of the scoring system are as follows:

  • Amount of unexplained fussiness: 0 (no fussiness) to 6 (constant fussiness when awake)

  • Intensity of fussiness: 0 (no fussiness) to 6 (severe fussiness when awake)

  • Appetite: 0 = normal, 1 = slightly less than normal, 2 = much less than normal, 3 = vomiting or not eating

  • Playfulness: 0 = normal, 1 = playing slightly less, 2 = playing much less than normal, 3 = not playing

  • Ability to sleep: 0 = normal, 1 = slightly less or more than normal, 2 = much less or more than normal, 3 = not able to sleep.

High-altitude pulmonary edema[53][57]

Grade 1: Mild

  • Minor symptoms with limitation of heavy effort only. Slight resting tachycardia and increased respiratory rate. No limitation of normal activities.

Grade 2: Moderate

  • Patient is ambulatory, but normal activities are reduced. Tachycardia and tachypnoea are present. Weakness, dyspnoea, and cough are evident to others. Rales may be present.

Grade 3: Serious

  • Symptoms are present at rest. The patient may be unable to walk and may prefer to rest. Simple tasks may be impossible. Senses may be dulled. Confusion and disorientation may be present. Tachycardia and tachypnoea are present. Rales are easily heard.

Grade 4: Severe

  • Patient is obtunded or comatose and cannot respond logically to questions or commands. Patient is unable to sit or stand. Exhibits noisy breathing with sounds of fluid in the airways. There is marked tachycardia and tachypnoea.

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