An assessment of the LOC of the patient is vital for an accurate pain assessment and the administration of analgesia, and the subsequent assessment of its efficacy (Rose, et al. 2011). Regular evaluation of a patient’s LOC helps detect the onset of hypothermia and hypovolaemia. Muehlberger, et al. (2010) state that the development of pre-hospital hypothermia is a directly negative prognostic factor for burns patients.
The inclusion of LOC assessment for burns patients seems to be a recent development however, neither Allison & Porter (2004) nor Allison (2002) refer in any way to assessing a patient’s LOC in their work on standardising a pre-hospital approach to burns patient management.
A coma scale is a defined methodology by which neurological observations can be recorded in a standardised way by clinicians (Coyne, et al. 2010). Many different scales have been developed in an attempt to standardise the assessment of consciousness (Majerus, 2005).
In this essay I will discuss three main coma scales and examine their strengths and weaknesses. I will also briefly discuss a number of revisions to these scales.
Glasgow coma scale (GCS) and variations
The GCS is the most commonly used coma scale in the acute setting (Majerus, 2005) and its use is recommended by the National Institute for Health and Clinical Excellence (NICE, 2007). The scale was devised by Teasdale & Jennett based on their work in the neurosurgery department at the University of Glasgow. Their scale allows a clinician with minimal training to perform three basic assessments measuring the eye, verbal and motor responses against a set of criteria. The results for the three components are commonly totalled together to indicate the patient’s GCS ranging from 3 to 15, although the authors’ intent was that the three elements should be expressed separately (Teasdale, et al., 1983).
However, while the GCS works well for patients who can verbalise, typically over the age of five years, it has been found to be less effective at assessing younger children and infants (Coyne, 2010). Developmental changes and choosing not to speak, versus inability to speak, led to scores that were more subjective and prone to misinterpretation (Matis, 2008). To address this the scale was modified for use with children, this revision is known as the Paediatric Glasgow Coma Scale (PGCS) (Morray, et al. 1984).
Teasdale & Jennett tested the reliability of their scale when performed by different categories of clinician. The authors were confident that all assessors with the same basic training were able to score patients with a high degree of consistency. Subsequent analysis confirmed that only inexperienced or untrained staff produced inconsistent results (Rowley & Fielding, 1991). McNarry & Goldhill (2004) however, assert that a greater degree of skill is required to achieve consistency in scoring. While Kelly, et al. (2004) questioned the reliability of interrater scoring, finding that GCS scores calculated by clinicians only agreed in only 32% of cases.
A number of limitations were identified by Teasdale & Jennett themselves and relate to when elements of the scale are untestable, for example fractured or splinted limbs prevent mobilisation; a tracheotomy may prevent speech; or localised swelling or paralysis may make eye opening impossible.
Thirty years later Kelly, et al. (2004) concluded that the GCS was too complex for assessing intoxicated or uncooperative patients. They found that the verbal component was the main difficulty in determining an accurate GCS score....