Assessment of neurological functioning (ACVPU)

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Week 5

tab_thumb.png Context

 In the ABCDE assessment algorithm, D is for Disability. By this we mean issues related to neurological function, which in turn disable the patient in some way. Generally this relates to consciousness, and that will be the focus of this week. Consciousness is a state of general awareness of oneself and the environment. Changes in the level of consciousness is the earliest and most sensitive indicator of change in neurological status (Hickey, 2009). Although there are multiple ways of assessing neurological status, ACVPU is an essential part of the NEWS criteria, therefore this section will discuss ACVPU alone.

NEWS(2)  in 2017 , incorporates a new section for new confusion. - C. This would include disorientation, delirium or any acute reduction in a persons GCS.  

The next section looks at the revised Glasgow Coma Scale, another easy to perform grading system of a patient's level of consciousness. 

 

tab_thumb.png Content

The parts of the brain involved in consciousness

The major parts of the brain involved in conscious ness are:

  • Reticular Activating System (RAS) (Arousal)
  • Cerebral cortex (Cognition)

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The reticular activating system (RAS) arises from the medulla, proceeds through the pons midbrain and thalamus, before it innervates the cortex as a diffuse network of neurones. The functions of the reticular activating system are many and varied. Among other functions, it contributes to the control of sleep, walking, sex, eating, and elimination. Perhaps the most important function of the RAS is its control of consciousness; it is believed to control sleep, wakefulness, and the ability to consciously focus attention on something. In addition, the RAS acts as a filter, dampening down the effect of repeated stimuli such as loud noises, helping to prevent the senses from being overloaded.

Cognition requires functioning hemispheres (cerebral cortex ) and diencephalon. The cerebral cortex is divided into right and left hemispheres. It encompasses about two-thirds of the brain mass and lies over and around most of the structures of the brain. It is the most highly developed part of the human brain and is responsible for thinking, perceiving, producing and understanding language. 

Most of the actual information processing in the brain takes place in the cerebral cortex. The cerebral cortex is divided into lobes that each have a specific function. For example, there are specific areas involved in vision, hearing, touch, movement, and smell. Other areas are critical for thinking and reasoning. Although many functions, such as touch, are found in both the right and left cerebral hemispheres, some functions are found in only one cerebral hemisphere. For example, in most people, language abilities are found in the left hemisphere.

 

Causes of alterations in levels of consciousness

  • Direct destruction of the anatomical structures of consciousness by a disease process (eg. traumatic brain injury, cerebral vascular accident (CVA or stroke), neoplasms, and infection).
  • Alterations in the energy substrates necessary for function of the anatomical structures involved in consciousness (eg. metabolic causes,and  hypoxic-ischaemic injury).
  • Toxic effects of endogenous or exogenous substances on anatomical structures (eg. alcohol, drugs, poisonous gases).

 

Using ACVPU as an assessment tool

Neurological assessment is performed to assess a person’s neurological status and is appropriate whenever there is impaired consciousness, a history of loss of consciousness, or a risk that the level of consciousness might deteriorate. Neurological assessment consists of either a quick review of a patient’s neurological state using the ACVPU scale, or an evaluation of the level of consciousness using the Glasgow Coma Scale (see next module), pupil size and reaction, motor and sensory function and vital signs. 

When assessing any person in your care the first priorities are to check responsiveness, ensure the patient has an open airway, check breathing, and maintain an adequate circulation following the basic life-support algorithms (Resuscitation Council UK 2015). It should be quickly established whether the person lost consciousness at any stage and appears to be deteriorating, particularly following an accident (NICE 2007b). Thus the person and any bystanders should be asked about the incident. Witnesses to a cardiac or respiratory event can be a valuable source of information regarding a person’s condition (Resuscitation Council 2015). The onset and duration of signs and symptoms, previous medical history and any recent illnesses are all useful to note. 

 

ACVPU is a quick and easy way to assess a person's level of conciousness and features in the 'D' section of the ABCDE assessment. Steps to using the model are:

  • Gain informed consent
  • If fully awake and talking to you, they are 'A'
  • Is there signs of new confusion, disorientation, delerium or any acute reduction in the GCS. they are 'C'  
  • If the patient is not fully awake, check they respond to your voice, or by the use of touch- they are then 'V' 
  • If the patient does not respond to voice or touch, they you can apply painful stimulus (trapezius squeeze) - if there is a response, they are 'P'
  • Those patients who do not respond at all are 'U'

Ensure you record this on the patient's NEWS chart and consider a cause for the altered level of conciousness. 

 tab_thumb.png References and Further Reading

Hickey, J. (2009)  The Clinical Practice of Neurological and Neurosurgical Nursing. 6th Edition. Philadelphia: Lippincott, Williams & Wilkins

 Royal College of Physicians 2017  National early warning score NEWS (2) Standardising the assessment of acute illness severity in the NHS  December 2017  

NICE (2014)  Download Head injury: Triage, assessment, investigation and early management of head injury in children, young people and adults

. London: NICE

NICE (2012) The epilepsies: the diagnosis and management of the epilepsies in adults and children in primary and secondary care. Clinical guideline 137. London: NICE.

Resuscitation Council Guidelines (2015) www.resus.org.uk Links to an external site.