In the Field
Altered mental status is the catch-all term for a patient who is not behaving normally cognitively. In trauma, it is one of the more important early indicators of serious injury, particularly head injury, hypoperfusion, and shock. It is also one of the harder things to assess in a tactical environment, because the threat itself produces anxiety, adrenaline, and behavior changes that can look like altered mental status without being injury-related. The skill is in recognizing the difference, and in tracking changes over time more than fixating on any single observation.
Common Mistake
Confusing threat-related stress responses (hyperalertness, fear, abnormal behavior under fire) with injury-related altered mental status
Technical Detail
Altered Mental Status (AMS) is a broad clinical term encompassing any deviation from the patient's normal cognitive state. The deviation can range from subtle (mild confusion, slowed responses) to profound (unresponsiveness, coma).
Common causes in trauma. Several traumatic and trauma-adjacent causes drive AMS:
Traumatic brain injury (TBI). Direct impact to the head, blast injury, or penetrating head trauma can produce AMS ranging from brief confusion to deep coma. AMS after head trauma should be assumed to indicate brain injury until proven otherwise.
Hypoperfusion and shock. As blood loss progresses, brain perfusion drops, producing anxiety, restlessness, confusion, lethargy, and ultimately unconsciousness. AMS is part of the standard hemorrhagic shock progression.
Hypoxia. Inadequate oxygenation from airway compromise, chest injury, or shock produces cognitive changes early.
Hypoglycemia, intoxication, and pre-existing medical conditions. These are causes more common in civilian medical scenarios than in trauma, but a tactical medic may encounter a casualty whose AMS predates the tactical event.
Hypothermia. Severe hypothermia produces mental status changes including confusion and lethargy.
Field assessment. AMS is assessed by comparison to the patient's known or presumed baseline. Standard field assessment tools include:
AVPU scale. A four-category quick assessment: Alert (responds spontaneously and appropriately to surroundings), Verbal (responds to verbal stimuli but not spontaneously alert), Painful (responds only to painful stimuli), Unresponsive (does not respond to verbal or painful stimuli). AVPU is widely used because it is fast, simple, and can be performed in any operational environment.
Glasgow Coma Scale (GCS). A more detailed 15-point scale assessing eye opening, verbal response, and motor response. More commonly used in formal documentation and during evacuation than at the point of injury.
Orientation questions. Asking the patient their name, location, the date, and what happened tests four standard domains of orientation. Useful when the patient is verbal but their cognitive function is in question.
The tactical environment confound. The greatest challenge in field AMS assessment is that the tactical environment itself produces behavioral changes that resemble AMS:
Adrenaline and threat response produce heightened alertness, narrowed attention, and altered perception of time and detail.
Fear and acute stress can produce difficulty processing complex information.
Communication may be impaired by hearing protection, comms equipment, or noise.
Training and discipline can produce minimal verbal responses that look like reduced awareness.
The skill is in distinguishing these threat-driven responses from injury-driven cognitive changes. Two principles help:
Trend over time matters more than a single observation. A patient who is initially alert and oriented and becomes progressively more confused is more concerning than a patient who is briefly disoriented in a chaotic environment.
Mechanism of injury frames interpretation. AMS in a patient with a head wound, significant blood loss, or known hypoxia is more likely injury-driven. AMS in a patient with no obvious injury but exposure to a stressful event may be threat-driven.
In MARCH. AMS is not a separate component of MARCH but factors into Airway (an unconscious patient cannot protect their own airway), Respiration (hypoxia produces AMS), and Circulation (hypoperfusion produces AMS) assessments.
