CONSCIOUSNESS

Assessment of altered consciouslevel in clinical practiceRachel Palmer, Jessica Knight

The Glasgow Coma Scale (GCS) is an internationallyrecognized tool which assess the conscious level ofa patient. It is siuiple to use, with ;i high degree ofinter-rater reliability (Rowley and Fielding, 1991;

Harnihill, 1996; Fairley and Cosgrove, 1999; Heron et al,2(»(H: Teasdale, 2004). There are three components (eyeopening, best verbal and motor response) which collectivelycreate the GCS tool. These elements are considered tobe relevant to conscious level. However, in the authors'experience there is lack of fundamental knowledge of theanatomical and physiological components of conscious level.This incomplete knowledge base has the potential for theneurological assessment to be misinterpreted.

Healthcare professionals use a variety of assessment toolsin clinical practice. It should also be noted that GCS is theprimary tool used by healtli professionals to make repeated,rapid evaluations on the conscious level of the patient.One purpose of the GCS tool is to provide a commonlanguage for communication between nmltidisciplinarygroups (Jennett, 1986). It was designed to reduce observervariability and to give comparison, allowing for analysis oftrends over time. GCS is recognized as the *gold standard'assessment tool (Harrahill, 1996).

Patients in any clinical setting may require assessmentot conscious level for a number of reasons, e.g. falls,unresponsiveness, post-anaesthesia or new admissions.Alteration of consciousness level may result from intra- orextra-cranial causes (Table /). Conversely, an altered consciouslevel can be further complicated by secondary insultsto the central nervous system or from the deterioratinginfluences of extracranial factors listed in Table 1. Equally,impaired conscious level may compound many othermedical conditions.

History of GCSGCS is an objective clinical scoring system for assessingchanges in a patients' conscious level Quarez and Lyons,1995). It has developed from the Coma Index into the GCStool that is currently used in practice today (see Table 2).TheComa Index was developed as a research tool to monitor levelof consciousness in severe head injury and provide objectivemeasurement of function in comatose patients (Fischer andMathieson, 2001). Prior to this development there was nonational standardized assessment (Ingram, 1994).

The original GCS was published in 1974 as a 14-point scale(see Table 2) and then revised two years later in to the 15-pointsystem (Teasdale and Jennett, 1974; Teasdale, 1976; JennettandTeasdale, 1977), The main purpose of the GCS tool is to

AbstractThis article v«Il critically appraise the literature focusing on the useand application of the Glasgow Coma Scale (GCS). Historically theGCS tool was created in a 14-point format and later revised to a15-point format. Critical analysis of this potentially confusing aspectwiU be explored. The GCS tool enables the healthcare practitionerto effectively monitor the level of consciousness. The authorsbelieve that anatomical and physiological knowledge is requiredto competently interpret assessment of level of consciousness. Thearticle will review the anatomical basis of consciousness and considersome of the issues of application of GCS in practice, includingpainful stimuli.

Key words: Glasgow Coma Scale • Consciousness • Early warning score

provide a common language to improve communication inreporting neurological findings among healthcare profes.sionals(Fischer and Mathieson. 2001;Aird and Mclntosh, 2004). Itprovides a visual trend and concise information about thepatient's level of consciousness. The revised GCS (15 point)is the accepted version that has been conmionly utilized inpractice for the last 30 years (NICE, 2003; Wiese, 2003).

In the 15 GCS the additional point is from the inclusionof 'abnormal flexion' [Table 2). Teasdale (2004) neverintended the 15-point scale to be adopted into generaluse, due to the issue of recognizing abnormal flexion asa deteriorating physiological sign found between normalflexion (withdrawal) and extension. The distinction between"abnormal' and 'normal' flexion will only be made consistentlyby practitioners experienced in assessing neurological patients(Teasdale and Murray, 2000). However, the revised GCS hasbeen adopted into general use as evidenced by the AdvancedTrauma and Life Support (ATLS) protocols (AmericanCollege of Surgeons, 1993; NICE, 2003).

GCS is applicable for adolescents, as well as adults, and hasbeen adapted for use in paediatrics. Fischer and Mathieson(2001) recognize that it is not suitable for use in childrenunder the age of three years due to developmental issues.

Rachel Palmer is Lecturer Praitirioner and Jessica Kniglit is Lecturer itNursing, School of Nursing it Midwifery. University of Soucliaiiipcon& Wessex, Neurological Centre, Soudiampton University HospitalsNHS Trust

Accepted for publication: August 2006

BntisK journal of Nursing. 2(Hiii, Vol 15. No 22 1255

An alternative perspective, as researched by Wijdicks etal (1998). is chat alert patients can have subtle neurologicaldeterioration that may not be captured in current comascales. The authors have experienced this perspectivewithin the practice setting and agree that neurologicalpractitioners can 'pick up' the early subtle factors thatwould not change the GCS score on documentation, e.g.patient slower to respond.

The Importance of consciousnessMany health professionals do not have a good understandingof the underlying mechanisnLs tliat produce altered levelsof consciousness (Addison and Crawford, 1999; Shah, 1999;Waterhouse, 2005). There is confusion and ambiguity overthe use of the term consciousness, with descriptors using amultitude of verbs to define the continuum from consciousnessto coma, e.g. confusion, rousable, inattentiveness, delirium,clouding of consciousness, drowsiness, stupor, unrousable, flat,unconsciousness, obtundation, vegative state or coma (Victorand Ropper, 2001; Goetz, 2003; Hickey, 2003).

When asleep, there is a reduced level of consciousnessdue to the inhibition of direct perception of sensory stimuli.Sleep and coma can be differentiated by the fact that cerebraluptake does not decrease during sleep as it does in coma.Hence a sleeping person who is stimulated can be roused(Barker, 2002).

The GCS was developed to assess these componentsof consciousness (Teasdale and Murray. 2000). There arethree properties of consciousness which can be individuallyassessed and form the basis of the GCS. These are: best eyeopening (E), verbal (V) and motor (M) responses:• E: arousal or wakefulness (best eye opening)• V: alertness and awareness (orientation and verbal

communication)• M: motor activity, an aspect of arousal (e.g. obeying

commands).Consciousness can only be descriptively approached by

documentation of observations made at that point in time.Consciousness is subject to change; it can occur rapidlywithin seconds, minutes and hours or very slowly, over aperiod of days, weeks, months and years.

Consciousness can be described in many ways (see Table 3).Critically it should be noted that 'impaired consciousnessIS an expression of dysfunction in the brain as a whole'(Teasdale andjennett, 1974 p81).

A more creative description of consciousness is 'ourcontinuing stream of awareness of either our surroundingsor our consequential thoughts' (Guyton and Hall, 2006p723). Regardless of any number of philosophical andartistic interpretations of consciousness, the fact is, healthcarepractitioners have to be able to make a critical and functionalanalysis of consciousness.

Table 1. Causes of altered consciousness

These can easily be divided into intracranial and extracraniaand metabolic imbalances.

IntracranliilDirect destaiction oF the anatomical structures by a

disease or insultSpace-occupying lesions Include:Tumour, haematoma, contusion or abscess

which is literally taking up intracraniai spaceHead )n|uryHaemorrhagk events:

Cerebral haemorrhageSubarrachnoid haemorrhage (SAH)Extradural haemorrhage (EDH)Subdural haemorrhage (SDH)Cerebrovascular accident (CVA)

Seizures/epilepsyInfections

Inflammation of the brain tissue can becaused by bacteria, viruses or fungi

Degenerative conditionse.g. Alzheimers, demyelinatlon in multiple

sclerosisSecondary insults:

Cerebrai oedema/swellingRaised intracranial pressureIschaemia. infarction or vasospasmIncreases in cerebrospinal fluid causing

hydrocephalus

causes, or rather central nervous system structural abnormalities

ExtracranialThe most common metabolic causes of altered LOCseen in a hospitalized population are hypoxia.hypoglycemia. and sedative drug overdose' (Hickey,2003 pi62)Metabolic causes

Hypo/hyperglycaemiaFluid/electrolyte imbalanceAcid-base imbalance

Respiratory invoivementHypoxiaHypo/hypercapnia

Cardiovascular instabilityHypo/hypertension

Sepsis, shock, and traumaLiver, renal and endocrine dysfunctionPharmacologicai agents, e.g.:

Anaesthetic, sedatives and paralysing agentsOpiate analgesicsAnticonvulsantsAntidepressantsRecreational drugs and alcohol

Multi-organ dysfunction

(Teasdale and |ennett, 1974; |ennett and Teasdale. 1977; Fielding and Rowley. 1990; Edwards. 2001 ; Barker. 2002; Hickey. 2003:McLeod, 2004; Lewis, 2005)

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To do this the nurse needs to be aware that there aretwo distinct components: arousal and awareness. Althoughdistinct they should always be considered as united (Hickey,2003). As arousal and awareness are complex, a generalizedoverview follows.

The first step in a GCS assessment is to test arousal. Arousalis a state or appearance of being awake which reflects activityof the reticular activating system (RAS), colloquially knownas level of consciousness (LOG). It is often described asthe degree to which a person is able to interact with theirenvironment with a quality of vigilance (Barker, 2002;Goetz, 2003; Hickey, 2003). The RAS is part of the reticularformarion (RF) which is a group of interconnected neuronsthat runs through the brain stem (midbrain, pons and medullaoblongata) and into the thalamus, the relay station to thecerebral cortex. Disruption of these pathways will manifestin altered conscious level and the degree of dysfunction willbe reflected in the GSC score.

Arousal demonstrates interaction between the RF andcerebral hemispheres, e.g. motor response and speech. Lossof the midbrain component of RF results in loss of controlof the cortex, which cannot be altered by external orinternal stimuli (Goetz, 2003). The midbrain RAS receivesinput from every major somatic and sensory pathway. Thus,painful stimulus, as a last attempt, to arouse the patient isjustified. Impairment of arousal is thought to be attributedto the distortion of the normal anatomical relationships ofthe cortex, diencephalon and midbrain. This can be createdbecause of an interruption to the flow of informationbetween the midbrain and cerebral cortex.The diencephalonis a conduit, but Goetz (2003) proposes that it has a moreactive role in the control of arousal, especially within thenormal sleep-wake cycle.

Critically, when assessing the arousal component of GCSseveral other examinations should also be considered to givea full neurological assessment see Table 4.

Awareness refers to the content of consciousness, includingcognitive function and reflects the activity of the cerebralcortex. The changes in the person will be in their mentaland intellectual functions and in their emotional/mood state(Barker, 2002; Goetz, 2003; Hickey, 2003). There must beinteraction between the cerebral cortex and the RF for theindividual to be aware.

Discussion of theory/practice ImplicationsDuring neurological assessment, using the GCS tool, if averbal or tactile stimulus does not illicit a response fromthe patient, there will be a need to apply noxious or painfial

Table 2. Glasgow Coma Scale (GCS)

Table 3. Definitions of consciousness

1. A state of general awareness of oneself, as well as a stateof responsiveness to an environment with the ability toadapt to the external milieu (Barker. 2002)

2. A dynamic state, subject to change3. Resulting from integrated activities of numerous neural

structures including the reticular formation (Hickey. 2003;Bader and Littiejohns. 2004)

Best eyeopening

Best verbalresponse

Best motorresponse

14 point GCS(Teasdale & (ennett, 1974)

43215432154321

SpontaneouslyTo speechTo painNoneOrientatedConfusedInappropriateIncom prehensi bleNoneObeyingLocalizingFlexingExtendingNone

15 point GCSDennett & Teasdale, 1977)

432154321654321

SpontaneouslyTo speechTo painNoneOrientatedConfused conversationInappropriate wordsIncomprehensible soundsNoneObeysLocalizesWithdrawsAbnormal flexionExtendsNone

stimuli. This may be central or peripheral in nature and thereis much debate within the literature as to best practice.

Peripheral stitnuKA peripheral stimulus is interpreted via the peripheralnervous system (spinal nerves) and communicates withthe central nervous system via the spinal cord to the brain.However, reflex activity may be the response. A reflex can beinitiated when a stimulus is applied and sensory informationis interpreted at a spinal level resulting in a motor response, viathe reflex arc, e.g. knee jerk (Marieb, 2004). A reflex responsedoes not provide relevant information for assessment of LOC.Nail bed pressure is an example of a peripheral stimulus.Teasdale (1975, 2004) advocates that nail bed stimuli is lesspainful than sternal rub (central stimuli). Yet direct pressureover the nail bed can cause damage to the capillary networkunder the nail bed resulting in bruising and potential loss ofnail. Pressure can alternatively be applied to the side of thefmger nail distal to the last interphalangeal joint.

Central srimuliA central stimulus is applied to body areas where it is notpossible for a reflex response.This includes:• Trapezius muscle squeeze• Supraorbital notch pressure• Jaw angle pressure• Sternal rub

Sternal rub should be comidered with caution becausethis soft tissue area bruises easily. Commonly this stimulusis applied with the knuckles; trauma can be lessened byusing a flat open hand (barker, 2002). Clearly supraorbitaland jaw angle pressure may not be appropriate in thesuspected or proven facial trauma. Supraorbital pressure isalso contradicted in the presence of glaucoma and can alsoresult in bradycardia (Barker, 2002).

Response to noxious or painful stimuli implies that theneuronal pathways within the RAS connecting to sensoryand motor pathways are still functioning to some extent(Price, 2002; McLeod, 2004). A central stimulus is generally

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advocated in the first instance (Woodward, 1997; Addisonand Crawford. 1999; Shah. 1999; McLeod, 2004) as it canproduce an overall body responso (Barker, 2002). Bader andLitdejohns (2004) recognize that a central stimulus is morereliable than peripheral, A peripheral stimulus is useful inassessing individual limbs.

There is debate in the literature over best practice incentral stimulus, with sonic advocating cither a trapeziusmuscle squeeze, supraorbital pressure or jaw angle pressure(Woodward, 1997; Addison and Crawford, 1999; Shah,1999). Addison and Crawford (1999) argue that trapeziusmuscle squeeze is not a form of central stimulus as it maygenerate a spinal reflex. This is based upon the premisethat only the upper portion of the trapezius muscle isinnervated by the spinal accessory (cranial nerve XI). andthe lower portion via the cervical spinal nerves C3, 4. 5(Tortora and Grabowski, 1993; Nolan. 1996; Martini et al,2001). The physical response by the patient to the centralstimulus enables interpretation of the degree of neurologicaldysfunction and structures involved.

Trapezius squeeze may be more difficult to perform onlarge or obese patients (Barker, 2002). Painful stimuh appliedsupraorbitally or to the jaw angle may result in grimacingand eye closure as a natural response (Teasdale, 1974) andhence, not useful to demonstrating eye opening response.Anecdotally, the authors have beard of other inappropriatepainful stimuli, such as a nipple and testicular squeeze, whichis clearly not recommended for practice.

When a noxious or painful stimulus is applied to a patientwho subsequently responds, the patient is not comatose, as thisdemonstrates a degree of cortical funccion,The arousal responsecan be classified into physiological levels of dysflinction andare summarized in the motor components of the GCS (seeTable 2), Abnormal flexion and extension represent abnormalmovements/posturing. The terms decorticate and decerebraterigidity are also referred to in the literature. Decorticaterigidity is abnormal flexion and indicates interruption of the

Table 4. Anatomical basis of assessmentAssessments

Patient'sambient statePupillary sizeand responseto lightEye movements

Respirations

Motorexamination

Observations

e.g. awake, asieep

Constriction andconsensual response

Conjugation, both eyesmoving simultaneouslyand in the same directionBreathing patterns(rate, depth and rhythm)

Limb power:• Arms• Legs

Anatomical structures

Reticular activating system (RAS)

Occulomotor cranial nerve (CN III)

Occulomotor, abducens andtrochlear cranial nerves(CN III. IV and VI)Respiratory centres:

• The pons contains thepneumotaxic area (rate) andthe apneustic area (length ofrespiration)

• The medulla contains ventralrespiratory groups (rhythm)

Motor cortex in frontal lobe andefferent (motor) pathways

corticospinal tract in the brain stem. This motor posturingimplies malfunction, not necessarily destruction of these areas.Decerbrate rigidity is extension and retlects disturbance of themidbrain or pons (Bader and Litdejohns, 2004). Both reflectthe loss of higher motor control functions. As discussed earlier,this is due to the complex nature of defining normal/abnormalflexion and extension that a sound knowledge of anatomicaland physiological structures is required to accurately applyGCS assessment.

Inconsistency in ApplicationGCS can be used inappropriately and inconsistendy byhealthcare professionals and needs reinforcement (Rowley andFielding. 1991; Ellis and Cavanagh, t992;Teasdale and Murray.2000). "Consistency in the application of the GCS is foundto be essential to ensure that the tool is a valid indicator ofthe patient's clinical condition' (Fischer and Matbieson, 2001p53). It is recognized that education and training in the useof the GCS tool is required to ensure optimal neurologicalassessment. Bassi et al (1999) concluded that doctors havedifficulty utilizing the GCS when converting a patient'sclinical condition into a score. However inter-rater reliabilityis high in professionals who are experienced in assessingpatients with neurological deficits (Harrahill, 1996; Fairley andCosgrove, 1999; Heron et al. 2001;Teasdale 2004).

The GCS tool "claims to be valid and reliable in the repeatedobservations of the level of consciousness which can beaccurately recorded and universally understood' (Fairley andCosgrove, 1999 p 276), However Segatore and Way (1992)are in a minority who criticize the reliability and validityof the GCS tool and believe that it enjoys an unwarranteilprivileged position in a clinical context. Sternbach (2000)critically reviewed alternative tools and concluded thatalthough GCS has drawbacks, it remains the most universallyaccepted conscious level scale. GCS assessment, underpinsclinical decision making in regards to effective and promptinterventions in the patient with an altered conscious level.

Identification of the GCS tool and its format (14 or 15point) in clinical settings is critical to safe patient management,in reviewing the literature it is clear that the 15-point GCStool should be utilized,This may require some retraining, butalso the continuing education of all the multi-professionalteam to ensure its safe application and interpretation.

Assessment, application and training issuesIn the last decade alternative assessment tools have emerged,such as AVPU (alert, responds to voice, pain or unresponsive).This has been in response to the critical care agenda and therecognition of the 'at-risk patient' who may be acutely illor deteriorating. AVPU has a simple structure which is easyto apply and has been incorporated into the Early WarningScore (EWS), This is in recognition of the fact that alteredconscious levels are present in many deteriorating patients(Schein et al, 1990; Goldhill et al. 1999, 2001).

Healthcare professionals need to be confident in their abilityto assess and interpret results of a patient's level of consciousness.Practitioners should reniember the point made by McNarryand Goldhill (2004 ) that no other simple tool should replaceGCS in the evaluation of a critically ill patient.

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CONSCIOUSNESS

It should also be noted during a.ssessment of conscious level,that some other conditions, such as a spinal cord injury, mayskew or complicate the results. Clinical experience is clearly asignificant factor as is appropriate knowledge and training.

Training should include practice examples for interpretationand discussion, focusing on known ditTicult aspects ofassessment such as:• Verbal - misinterpretations can occur as some may assume

th.!t swearing could be considered as inappropriate words• Motor - as previously discussed, abnormal flexion and

extension are difficult for healthcarc professionals to recognizeif they have no experience of motor neurological deficits.Experienced observers may identify more subtle changes,

which may not alter the GCS score at the point ofassessment. At this point the healthcare professional shouldincrease the frequency of assessments and involve the widermuitidisciplinary team.

ConclusionHealthcare professionals require an understanding of theanatonucal and physiological basis of consciousness andpossible causes of altered level of consciousness. Level ofconsciousness can change rapidly within minutes or hours. Itshould be remembered that the GCS 15-point format, whilea simple and standardized system, is only one parameter; otherfactors such as vital signs, pupil size/response to light, andintracranial pressure, will be important in clinical decisions.

It is essential that appropriate observations are instigated,whether this is AVPU or GCS, to assess neurological trendswhich will inform clinical decisions. Practitioners mustrecognize when to escalate assessment from AVPU toGCS. Healthcare professionals develop an evolving 'indexof suspicion' based upon their knowledge and previousexperience. The experienced practitioner has a deeperunderstanding ot the neurological system based on practicalexperience coupled with further education and training.

It is the clinical and educational view of the authors thatassessment of conscious level should be used by all healthcareprotessionals as easily as routine vital signs observations. DB

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KEY POINTS

I Patients may present in a range of different settingsrequiring neurological assessment, commonly dueto extracranial causes.

I Practitioners require an understanding of the relatedanatomy and physiology to competently interpretGlasgow Coma Score assessment results.

I There are a range of different techniques for applyingpainful stimuli, the choice of which will depend uponthe response that you are trying to elicit.

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