Level of Consciousness 101

As medical providers, the most important thing we do is patient assessment.  Patient assessment alerts us to life-threatening and not-so-life-threatening injuries and illnesses, and allows us to see changes in patient status over time.  Because our assessment skills are so important, we must continually refine and practice them.

The AVPU Scale

With this in mind, I’m going to spend a few minutes talking about assessing a patient’s level of consciousness, or LOC.  You may have also heard this called level of responsiveness, or LOR.  Either work.  Level of consciousness measures how aware the patient is of his or her surroundings, which gives you an idea of how the patient’s brain is operating.

We measure LOC in two steps; first, we use the AVPU Scale (frequently pronounced “Av-poo”) to determine what the patient reacts to.  AVPU stands for “Alert, Verbal, Pain, and Unresponsive,” and each point stands for a type of stimuli.  Each step down the AVPU scale represents a lower level of responsiveness, and is an increasingly serious finding.

  • Alert:  If the patient is looking around, and is generally interacting with his or her environment in a normal manner, we say the patient is alert.
  • Verbal:  If the patient is conscious, but only responds when spoken to, we say the patient is responsive to verbal stimuli.  This patient is impaired, but there is some variation within this category.  Some patients who are alert to verbal stimuli will speak when spoken to, others may just open their eyes.
  • Pain:  If the patient will only respond when touched, poked, or pinched, we say the patient is responsive to painful stimuli.  The patient may open their eyes, or the patient may try to pull away, moan, or wince.
  • Unresponsive:  If the patient does not respond to verbal or painful stimuli, we say the patient is unresponsive.

If the patent is alert, we proceed to the second step and measure how alert they are.  For this, we use the alert and oriented scale.  Basically, we ask the patient a series of

AO x 4
The A and O Scale

questions; “Who are you?  Where are you?  What day is it?  What happened?”  These questions test to make sure the pt’s brain is operating correctly.  A patient who is able to answer all four questions correctly is said to be AO x 4, or fully responsive.  Sometimes patients are able to answer some questions, but not others.  If the patient is unable to answer all four questions, we say they’re AO x 3, 2 or 1, and this implies that their brain isn’t working as well as it could.  Usually the last memory to be lost is personal identity, so many patients will be able to say who they are, but not where they are, what day it is, or what happened to them.  Patients who are AO x 1 are frequently called “oriented to self.”

Causes of AMS

Patients who are less than AO x 4 (So, AO x 1, 2, or 3, or responsive to just verbal and painful stimuli, or are unresponsive) are said to have altered mental status, or AMS.  Another term that is frequently used to describe this condition is altered level of consciousness, or ALOC.  AMS has many causes, both traumatic and medical, and is a symptom of a larger problem.  Once you determine that a patient has AMS, its important to try to determine what is causing the AMS.  Some causes of AMS can be fixed in the field, while others will require a hospital.  Since AMS is a symptom of a larger problem, if you can fix the problem causing the AMS the patient will usually improve.

The patient’s mental status should be frequently re-assessed with vital signs, and trends should be watched over time.  If the patient’s mental status declines, this frequently suggests the patient is getting worse.


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