Wilderness and Rescue Medicine 7th Edition Jeffrey Isaac, PA-C and David E. Johnson, MD

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Section II: Critical Body Systems

Assessing the Level of Consciousness

Differential Diagnosis of Brain Failure The term differential diagnosis describes a list of the possible causes of a condition or problem. The most common causes of impaired brain function can be summarized as a simple differential diag- nosis with the acronym STOPEATS. STOPEATS can be a handy diagnostic tool when you are evaluating mental status changes in the presence of a mixed or uncertain mechanism of injury. While reviewing the mnemonic, you will usually be able to eliminate some possible causes in your scene size-up and patient assess- ment. Other possibilities will have to remain on your problem list until they can be ruled out or confirmed over time. Imagine caring for the subject of a success- ful 48-hour backcountry search. Your patient is found curled up under a spruce tree in a level area of forest at 950 meters in elevation. The weather is cool and wet without thunderstorm activity. He is V on the AVPU scale and shivering. There is no evidence of trauma.

For field purposes, we describe brain function by using a scale abbreviated AVPU. This simple assessment tool is familiar to most emergency care providers. More complex evaluation tools, such as the Glasgow Coma Scale, are generally not necessary or useful in field medicine. In the emergency medical services (EMS), normal mental status in the awake patient is often abbreviated A&O × 4. This means that the patient is awake and oriented to person, place, time, and event. Using this phrase to describe nor- mal mental status is fine if everyone knows what this expression means. This description becomes confusing when the patient’s mental status is not normal. Reporting a patient as A&O × 2 gives little useful information. When describing mental status, plain language is usually better in a wilderness rescue or disaster settings that may involve multiple agencies and medical personnel at various levels of training.

Describing Brain Function

General Principles

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Brain Failure

General Principles

AVPU: A – Awake (describe mental status – oriented,

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Mechanisms: S – Sugar T – Temperature

confused, anxious, combative, lethargic, etc.)

V – Verbal P – Pain U – Unresponsive

O – Oxygen P – Pressure E – Electricity A – Altitude T – Toxins S – Salts

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“The numerous causes of impaired brain function can be summarized … with the mnemonic STOPEATS .”

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“In describing mental status, plain language is usually better…”

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Describing your patient as “awake, knows her name and where she is, but not sure how she got here or what day of the week it is,” may seem cumbersome, but everyone involved in her care and transport will understand it. Furthermore, improvement or decay in mental status will be more easily detected.

©2018WMA

Based on your survey of the scene and the patient, you can eliminate problems with pres- sure, electricity, oxygen, and altitude from your problem list. Even though you are fairly certain that his problem is hypothermia, the mnemonic reminds you to also consider blood sugar, toxins, and salts as possible contributing factors. Time and response to treatment may allow you to refine your problem list further in the field, or you may have to keep a potential problem on the