Medical illness, traumatic brain injury, alcohol intoxication, drugs, and poisonings may all lead to aberrations in a patient's neurological and physiological status in ways that cause an abnormal level of consciousness. AVPU is a straightforward scale that is useful to rapidly grade a patient's gross level of consciousness, responsiveness, or mental status. It comes into play during pre-hospital care, emergency rooms, general hospital wards, and intensive care unit (ICU) settings.
The basis of the AVPU scale is on the following criterion:
Comparison with other scales of Mental Status
Other scales for assessing mental status exist and may be superior to AVPU in specific settings.
The Glasgow Coma Scale (GCS) and the Richmond Sedation and Agitation Scale (RASS) are two scales used for assessing mental status. One study showed that in admitted patients, both GCS and RASS were significantly more accurate predictors of mortality then AVPU. Further, the routine tracking of GCS and/or RASS on the wards may improve the accuracy of detecting patients with deteriorating clinical status.
The ACDU Scale (alertness, confusion, drowsiness, and unresponsiveness) is another 4-point scale similar to AVPU. One study showed that ACDU might be superior for the simple ward assessment of seriously ill patients compared to AVPU. Additionally, median GCS scores associated with ACDU were 15, 13, 10, and 6. The median values of ACDU were more evenly distributed than AVPU when researchers compared both scales to GCS. This even distribution may indicate that ACDU is superior at identifying early deteriorations in the conscious level when they occur in critically ill ward patients compared to AVPU.
The Simplified Motor Score (SMS) categorizes and scores patients in the following three categories: obeys commands, localizes pain, and withdraws to pain or worse. It is useful in evaluating patients in the pre-hospital and acute care setting for possible traumatic brain injury. One study has shown it to have the best interrater reliability for assessing the altered loss of consciousness (LOC) of traumatic and non-traumatic cause among AVPU, GCS, and ACDU.
Utility in First Aid, Pre-Hospital Care, and Emergency Care
The AVPU scale is a quick and simple way of detecting altered mental status (AMS) in a patient. No formal training is necessary to use this score. It can be utilized during first aid and in the pre-hospital setting as any score lower than an "A" is considered abnormal until proven otherwise. This result should prompt the examiner to conduct additional assessments or begin more definitive care. EMS crews may begin with AVPU, to be followed by a GCS assessment if the AVPU score is below "A." AVPU is less detailed than the Glasgow Coma Scale, but it is performable more quickly. AVPU was initially used in the primary survey of trauma patients, as a decreased mental status could indicate inadequate circulation of oxygenated blood to the brain.
Utility in Hospital Care and Long Term Healthcare Facilities
AMS is one of the strongest predictors of death on the wards, and health care professionals within a hospital utilize this scale during patient assessment for any patients who are at risk of having an abnormal level of consciousness. It plays a role in Rapid Response Activation Criterion and Early Warning Scores to detect changes in a patient's physiologic status in hopes of becoming aware of and correcting any potentially life-threatening issues that could have arisen during a patients hospital stay. Select patients, such as those in long term health facilities or nursing homes, may have an AVPU score of less than A, which is considered to be the patient's baseline. The AVPU scale is not intended for long-term neurological observation of the patient.
Correlation to the Glasgow Coma Scale and Airway Protection
Similarly to GCS, where a score of 8 or lower prompts health care providers to consider the need for airway protection, the AVPU scale also addresses airway management and aspiration risks. Patients scoring "P" or "U" may have decreased or absent gag reflexes and thus are unable to maintain a patent airway. This status should prompt the healthcare provider to consider initiating a means of airway protection to avoid airway compromise or aspiration.
The nurses looking after the patient should be knowledgeable about the AVPU scoring system if they are using it frequently. A drop in score should immediately be alerted to the doctor.
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