Strength of Recommendations: Weak.
Quality of Evidence: Low, primarily from Class III studies and indirect evidence.

Adult

1. Prehospital measurement of the Glasgow Coma Scale (GCS) is a significant and reliable indicator of the severity of traumatic brain injury (TBI), and should be used repeatedly to identify improvement or deterioration over time.
2. The GCS must be obtained through interaction with the patient (i.e., by giving verbal directions or, for patients unable to follow commands, by applying a painful stimulus such as nail bed pressure or axillary pinch).
3. The GCS should be measured after airway, breathing, and circulation are assessed, after a clear airway is established, and after necessary ventilatory or circulatory resuscitation has been performed.
4. The GCS should be measured preferably prior to administering sedative or paralytic agents, or after these drugs have been metabolized.
5. The GCS should be measured by prehospital providers who are appropriately trained in how to administer the GCS.

Pediatrics

1. The GCS and the pediatric GCS (P-GCS, Table 1) are reliable indicators of the severity of TBI in children and should be used repeatedly to identify improvement or deterioration over time.
2. The adult protocol for standard GCS measurement should be followed in children over 2 years of age. In pre-verbal children, the P-GCS should be employed, with a full verbal score of 5 assigned to infants cooing or babbling.
3. Prehospital providers should determine the GCS or P-GCS after airway, breathing, and circulation are assessed and stabilized.
4. The GCS and P-GCS should be measured preferably prior to administering sedative or paralytic agents, or after these drugs have been metabolized.

Teasdale and Jennett17 developed the GCS in 1974 as an objective measure of the level of consciousness after TBI. It has since become the most widely-used clinical measure of the severity of TBI. The GCS permits a repetitive and moderately reliable standardized method of reporting and recording ongoing neurologic evaluations even when performed by a variety of health care providers. The GCS evaluates three independent responses: eye opening, motor response, and verbal response.

Authors stated that for patients unable to follow commands, the motor response is scored on the best observed response to a standardized stimulus.17 The stimulus can be blunt pressure applied to the nail bed using a pencil, or a pinch of the patient's anterior axillary skin.

The GCS score, however, can be affected by pre and post-traumatic factors that may impair neurologic response and that field providers can recognize and treat immediately. Reversible conditions such as hypoglycemia or narcotic overdose should be determined and treated with intravenous glucose or naloxone. Hypoxia and/or hypotension are common complications in trauma patients and have been shown to negatively affect GCSscoring. Therefore, the airway, breathing and circulation should be assessed and stabilized first prior to measuring the GCS or P-GCS.

Another GCS scoring difficulty involves preverbal children. The American College of Emergency Physicians, and the American Academy of Pediatrics in its 1998 publication APLS - The Pediatric Emergency Medicine Course,1 agreed that for children under the age of 2 years, a modified GCS that assigns a full verbal score (5) for crying after stimulation, is appropriate.

A number of studies confirmed a moderate degree of inter- and intra-rater reliability in scoring the GCS, including GCSscores that prehospital Emergency Medical Services providers obtain.4,6,13

For this update Medline was searched from 1996 through July 2006 using the search strategy for this question (see Appendix B), and results were supplemented with literature recommended by peers or identified from reference lists. For adult studies, of 105 potentially relevant publications, 4 were added to the existing table and used as evidence for this question. For pediatric studies, of 42 potentially relevant publications, 3 new studies were used as evidence for this question (see Evidence Tables).

Adult

1. Prehospital measurement of the Glasgow Coma Scale (GCS) is a significant and reliable indicator of the severity of traumatic brain injury (TBI), and should be used repeatedly to identify improvement or deterioration over time.
2. The GCS must be obtained through interaction with the patient (i.e., by giving verbal directions or, for patients unable to follow commands, by applying a painful stimulus such as nail bed pressure or axillary pinch).
3. The GCS should be measured after airway, breathing, and circulation are assessed, after a clear airwayis established, and after necessary ventilatory or circulatory resuscitation has been performed.
4. The GCS should be measured preferably prior to administering sedative or paralytic agents, or after these drugs have been metabolized.
5. The GCS should be measured by prehospital providers who are appropriately trained in how to administer the GCS.

Foundation. Baxt2 compared advanced prehospital care provided by aeromedical scene responders to ground transport providers using less sophisticated medical interventions. He obtained the mortality rates for GCS scores performed in the field by the flight team. The predictive value for mortality of a GCS of 3 to 5 was 50% and 61% for helicopter and ground transport patients, respectively. The predictive value for a GCS of 6 to 8 was 14.5% and 15.3% respectively. In addition, the predictive value for a bad outcome (dead, vegetative, or severely disabled) for GCS of 3 to 5 was 81.6% and 84% for helicopter and ground transported patients, respectively, and for a GCS of 6 to 8, it was 34.5% and 40.7%, respectively. The study is limited by the fact that the GCS for ground transported patients was not calculated in the field by the paramedics, but rather on arrival in the ED.

A retrospective study designed to evaluate the effect of endotracheal intubation on the outcome of patients with TBI provided overall mortality data stratified by initial field GCS score.19 Of 351 patients with isolated TBI, patients with a GCS score of 3 had a 54.5% mortality compared to 13.1% for those patients with a GCS score of 4-8. In addition, of those patients with a GCS score of 3, 35% were able to be discharged to home compared to 42% of patients with a GCS score of 4-8.

Horowitz et al8 performed a retrospective chart review to evaluate whether or not patients with a field GCS score of 14 or 15 and a history of loss of consciousness after trauma required transport to a trauma center, based upon meeting any one of the following criteria: admission to a surgical or neurosurgical ICU, positive CT scan, hospital length of stay greater than 3 days, or need for non-orthopedic emergency surgery within 6 hours of hospital arrival. Of 655 patients included in the study, 19 (2.9%) met the criteria and one patient (0.2%) required emergent neurosurgical intervention. The authors suggested that patients with a brief loss of consciousness who have a GCS score in the field of 14 or 15 do not need transport directly to a trauma center but rather can be taken to a local facility with appropriate CT scan capabilities, and then undergo transfer to a trauma center if necessary.

Winkler20 evaluated 33 consecutive TBI patients, comparing the field GCS to the GCS score obtained on arrival in the emergency department (ED). Patients were grouped according to their final outcome (no deficits, minor deficits, major deficits, or dead). All four groups had similar GCS scores in the field. However, those who ultimately were discharged with no or minor deficits had significant improvements (> 2 points) in the GCS score at the time of their ED assessment. In contrast, those who had significant deficits or died showed little or no improvement in the GCSscore when assessed in the ED.

Servadei16 used change between the prehospital setting GCS score and the ED score as one criterion to determine the need for operative evacuation of posttraumatic subdural hematomas. For example, a patient whose GCS was unchanged or improved was often a candidate for nonoperative management. On the other hand, if the GCS score deteriorated from the field to the ED, there was a significant likelihood of the need for surgical intervention. Other criteria involved in the decision to operate included the size of the hematoma and the amount of midline shift. Patients treated surgically in this study had an average 2 point decrease in the GCS, whereas those treated expectantly did not change significantly.

Many emergency medical systems often do not record the GCS in TBI patients.15 This may explain the dearth of prehospital studies on the use of the GCS in the field setting and its correlation to patient outcome. Despite the paucity of prehospital data, the GCS measured in the hospital has been shown to have a significant correlation with patient outcome following severe TBI, either as a sum score or simply the motor component. In a prospective study by Narayan,14 a positive predictive value of 77% for a poor outcome (dead, vegetative, or severely disabled) was measured for patients with a GCS of 3 to 5 and 26% for those with a GCS of 6 to 8. In a study from Australia5, a significant inverse correlation was found between the initial GCS in the hospital (obtained 6-48 hours after injury) and mortality.

In another series of patients with TBI entered into the U.S. Traumatic Coma Data Bank, mortality rates for patients with initial GCS scores of 3, 4, or 5 were 78.4%, 55.9%, and 40.2%, respectively.16 Of note, however, is that 4.1%, 6.3%, and 12.2% of the three groups, respectively, had good outcome.

The ability of Emergency Medical Care providers to obtain the GCS score reliably was evaluated by Menegazzi13 who used videotaped scenarios of patients with severe, moderate, and mild/no alteration of level of consciousness in a classroom setting to compare the inter- and intra-rater GCS scoring reliability of paramedics and emergency physicians. He demonstrated moderate agreement between physicians and paramedics in measuring the GCS score.

In a similar fashion, Lane et al10 conducted a prospective study of 75 EMS providers of all levels (EMT-B, EMT-I, EMT-P, RN) who were asked to calculate the GCS of 4 scripted TBI patient scenarios. Prior to viewing the video, 14.7% of participants correctly scored all 4 cases. By comparison, 64% correctly scored the cases after reviewing a training video.

In a followup study, 46 EMT-B providers were randomly divided into two groups. One group one received a standard GCS scoring reference card, the other did not. Both groups received standardized video training. Of those EMTs using a reference card, 50% scored all 4 cases correctly prior to training and 100% scored them all correctly after the training.Without a reference card, 8% of the providers scored the cases correctly before the training, compared to 77%after the training. Although this study did not examine long-term retention of GCS scoring, formal training improved the overall scoring by EMS providers of all types.

Bazarian et al3 conducted a prospective observational study involving 60 patients with TBI and a field GCS score of 8-13 in which he compared the field score to the score obtained by emergency physicians upon arrival of the patient to the hospital. The authors documented that there is a significant linear relationship between the field GCS score and the emergency physician score. However the field GCS scores were usually approximately 2 points lower than the emergency physician score. The linear relationship suggests that, assuming most GCS scores improve from field to ED, there is concordance between EMS and physicians in assessment of TBI patients using the GCS.

Pediatrics

1. The GCS and the pediatric GCS (P-GCS, Table 1) are reliable indicators of the severity of TBI in children and should be used repeatedly to identify improvement or deterioration over time.
2. The adult protocol for standard GCS measurement should be followed in children over 2 years of age. In pre-verbal children, the P-GCS should be employed, with a full verbal score of 5 assigned to infants cooing or babbling.
3. Prehospital providers should determine the GCS or P-GCS after airway, breathing, and circulation are assessed and stabilized.
4. The GCS and P-GCS should be measured preferably prior to administering sedative or paralytic agents, or after these drugs have been metabolized.

Foundation. A GCS score of 12-15 reflects the presence of higher integrative brain function. These higher functions are difficult to assess in the young child due to central nervous system immaturity. Maturation of the central nervous system is a continuum from intrauterine development to adolescence. Therefore, especially in young children, the GCS should reflect the expected normal verbal and motor responses for developmental stage. The GCS in its standard form is not applicable to infants and preverbal children. As stated earlier, the American College of Emergency Physicians and the American Academy of Pediatrics in its 1998 publication APLS - The Pediatric Emergency Medicine Course agreed that for preverbal children, a modified GCS (Pediatric Glasgow Coma Scale) that assigns a full verbal score (5) for spontaneous cooing should be used.

The relationship of outcome to GCS has also been demonstrated in children in hospital-based studies. In a study of 109 children who sustained TBI, Massagli, using only the motor component of the GCS and a dichotomized outcome of good (moderate, no disability) vs. bad (dead, vegetative, or severely disabled), revealed that the GCS motor component alone was indicative of outcome.12

White examined survival among 137 children with severe TBI. A higher GCS at 6 hours after admission to the pediatric intensive care unit was a better predictor of survival (odds ratio 4.6 and 95% CI 2.06,11.9). All patients with a GCS > 8 at 6 hours survived.18

Johnson compared mortality rate among 98 children with severe TBI; 56 children were transferred directly from the scene and 42 were transferred between facilities.9 Mortality rates were significantly higher (50%) in children with a GCS between 3 and 8 when they were transferred from other facilities, compared to 27% for patients transported from the field.

The basic principle for measuring the pediatric GCS follows the same guidelines as adults. Holmes and colleagues evaluated 2,043 children with TBI, 16% of whom were under 2 years of age.7 The pediatric GCS accurately predicted 97% of these infants needing acute intervention. Acute intervention was defined as one of the following proximal outcomes: need for a neurosurgical procedure, requiring an anticonvulsant medication for more than one week, longer than 2 days of hospitalization, or having a persistent neurological deficit until hospital discharge.

The following questions require study to evaluate the role of the GCS score in the prehospital setting:

1. What is the ability of the initial field GCS score to predict outcome, compared with the postresuscitation score, or compared with any improvement or deterioration in score during the prehospital phase?
2. How does the presence of central nervous system depressants affect the field measurement of the GCS and its predictive value?
3. Is the motor score alone, obtained in the prehospital setting, a reliable indicator and predictor of outcome?
4. What mechanisms, such as training or educational programs, improve the reliability of GCS scoring?
5. What is the appropriate coma scale to be used by prehospital providers in pre-verbal children?
6. What is the reliability/validity of GCS/Pediatric GCS (PGCS) as measured by prehospital providers?
7. What is the correlation between the initial field GCS/PGCS and the emergency department GCS/PGCS?
8. What is the impact of prehospital interventions on the GCS/PGCS and outcome?
9. What strategies can be employed to improve prehospital documentation of the GCS?