The GCS, first published by Teasdale and Jennett ([196]), is a widely used tool for assessing level of consciousness and should be employed to assess all patients with head injuries (NICE [139]). It forms a quick, objective and easily interpreted mode of neurological assessment (Braine and Cook [26]). The GCS measures arousal and awareness by assessing three areas of the patient's behaviour: eye opening, verbal response and motor response (Wilkinson et al. [215]). Each area is allocated a score, enabling objectivity, ease of recording and comparison between recordings (Baumann [16]). The sum provides a score out of 15, where a score of 15 indicates a fully alert and responsive patient and a score of 3 (the lowest possible score) indicates unconsciousness (Adam et al. [2]). When used consistently, the GCS provides a graphical representation that shows any improvement or deterioration of the patient's consciousness level at a glance (Figure 14.51; Table 14.21) (Adam et al. [2], Brain Trauma Foundation [25], Braine and Cook [26]). However, a thoughtful, educated approach is essential to enhance its coherency and practicality (Braine and Cook [26]).

A limitation in the use of the GCS is that most healthcare professions will require the scale to be available for review in order to score a patient's consciousness level (as very few healthcare professions have memorized the scores for each area of assessment) (Reith et al. [174]). In an urgent or highly acute situation, this may not be possible, in which case the AVPU method may be more appropriate (see below) (RCUK [173]).

Assessment using the GCS involves three phases (Baumann [16]):

Eye opening indicates that the arousal mechanism in the brain is active (Fuller [66]). Eye opening may occur spontaneously, in response to speech, in response to a painful stimulus or not at all (Baumann [16]). Arousal (eye opening) is always the first measurement undertaken when performing the GCS, as without arousal, cognition cannot occur (Baumann [16], Brunker and Harris [32]). Eye opening is scored as follows:

A patient with flaccid ocular muscles may lie with their eyes open all the time; this is not a true arousal response and should be recorded as ‘none’ (Fuller [66]). If a patient's eyes are closed as a result of swelling or facial fractures, eye opening cannot be used to determine a falling consciousnes level; this should be recorded as a ‘C’ (closed) on the chart (Brunker and Harris [32], Fuller [66]).

Verbal response is scored as follows:

The absence of speech may not always indicate a falling level of consciousness; for example, the patient may not speak English but may still be able to speak. A patient with a tracheostomy or endotracheal tube should be recorded as ‘T’ on the chart under no response and allocated a score of 1 (Baumann [16]). Likewise, if the patient is dysphasic, the best verbal response cannot be determined accurately. The patient may have a motor (expressive) dysphasia and therefore be able to understand but be unable to find the right word, or a sensory (receptive) dysphasia, which means they will be unable to comprehend what is being said to them (Fuller [66]). At times, patients with expressive dysphasia may also have receptive problems; therefore, it is important to make an early referral to a speech and language therapist. This should be recorded as a ‘D’ on the chart under no response and allocated a score of 1 (Baumann [16]).

If a patient cannot follow an instruction due to a language barrier or unconsciousness, observe their spontaneous movements and note how strong they appear to be (Adam et al. [2]). Then, if necessary, apply painful stimuli (Fuller [66]). The nurse should also consider that some patients may need a lot of stimulation to maintain their concentration to answer questions, even though they can answer them correctly (Brunker and Harris [32]). It is therefore important to note the amount of stimulation that the patient required as part of the baseline assessment (Baumann [16]).

Motor response is the most important prognostic aspect of the GCS after traumatic brain injury (Adam et al. [2]). To obtain an accurate picture of brain function, motor response is tested by using the upper limbs because responses in the lower limbs reflect spinal function (Adam et al. [2]). The patient should be asked to obey a couple of simple commands; for example, they can be asked to squeeze the nurses hands (both sides). The nurse should note the power in the hands and the patient's ability to release the grip in order to discount a reflex action (Brain Trauma Foundation [25]). In addition, the patient should be asked to raise their eyebrows or stick out their tongue, and the best motor response should be recorded (Bickley [18]). If movement is spontaneous, the nurse should note which limbs move and whether the movement is purposeful (Fuller [66]). If the patient is able to obey commands, they should be allocated a score of 6 (Baumann [16]).

If the patient is unresponsive to simple commands, their response to painful stimuli should be assessed. This may be:

The AVPU scale is a simple, rapid and effective method for assessing consciousness and forms part of the National Early Warning Score 2 (NEWS2) (RCP [172]). It is particularly useful during the rapid assessment of an acutely unwell patient (RCUK [173]).

AVPU is a mnemonic for a neurological scoring system that quantifies the patient's response to stimulation and assesses their level of consciousness (Brunker and Harris [32]). It stands for Alert, response to Voice, response to Pain or Unresponsive. Assessment using the AVPU method is done in sequence and only one outcome is recorded; for example, if the patient responds to voice, it is not necessary to assess the response to pain (Wilkinson et al. [215]):