What is the management approach for a patient with an altered level of consciousness, specifically regarding the use of the Glasgow Coma Scale (GCS)?

Glasgow Coma Scale: Clinical Application and Management

What is the GCS and How to Use It

The Glasgow Coma Scale is a 15-point clinical tool that assesses consciousness through three components: Eye Response (1-4 points), Motor Response (1-6 points), and Verbal Response (1-5 points), with scores ranging from 3 (deep coma) to 15 (normal consciousness). 1, 2

Scoring Components

• Eye Response (1-4 points): Assess from no eye opening (1) to spontaneous eye opening (4) 1
• Motor Response (1-6 points): Evaluate from no movement (1) to obeying commands (6), representing the most prognostically valuable component 1, 2
• Verbal Response (1-5 points): Measure from no sounds (1) to oriented conversation (5) 1

Critical Clinical Thresholds

• GCS <14: Requires immediate transport to a trauma center with mortality rates of 24.7% 1, 2, 3
• GCS 9-12: Indicates moderate traumatic brain injury requiring urgent CT imaging and neurosurgical consultation 3
• GCS ≤8: Defines severe traumatic brain injury, typically requiring intubation and intensive care 1

How to Properly Assess and Document

Always document individual component scores (E, V, M) rather than just the sum, as patients with identical total scores but different component profiles may have vastly different outcomes. 1, 3, 4

Serial Assessment Protocol

• Moderate TBI (GCS 9-12): Monitor every 15 minutes for first 2 hours, then hourly for 12 hours (Scandinavian protocol) 3
• Any head injury: Perform serial assessments as declining or persistently low scores indicate poorer prognosis 2, 4
• Red flag: A decrease of ≥2 points from baseline requires immediate repeat CT scanning and escalation of care 3

Essential Concurrent Assessments

Always assess pupillary size and reactivity alongside GCS, as these are independent predictors of outcome and critical for complete neurological evaluation. 1, 4

• Pupillary responses provide complementary prognostic information beyond GCS alone 1, 4
• In trauma triage, combine GCS <14 with pupillary assessment and vital signs (systolic BP <90 mmHg, respiratory rate <10 or >29) 1

Critical Limitations and Confounders

The GCS has significant limitations including confounding by sedation, intubation, facial trauma, intoxication, and was not designed for mild TBI assessment. 2, 4

Major Confounding Factors

• Sedation and analgesics: Significantly impair accurate GCS assessment 4
• Endotracheal intubation: Eliminates verbal component scoring 4, 5
• Intoxication: Particularly opioids and alcohol alter consciousness independent of structural brain injury 4
• Facial trauma: May prevent accurate eye response assessment 2

Interrater Reliability Issues

• Only 32% exact agreement for total GCS scores between experienced emergency physicians 6
• Component agreement ranges from 55-74%, with 6-17% of paired measures differing by ≥2 points 6
• The motor component shows highest reliability (72% agreement) compared to verbal (55%) 6
• Adequate training through simulations or preceptor practice is essential for accurate scoring 7

Clinical Decision-Making Applications

Trauma Triage

Transport to a trauma center is mandatory for any patient with GCS <14, as this represents a critical physiologic criterion indicating significant neurological compromise. 1, 2

• GCS <14 has sensitivity of 55.6-64.8% and specificity of 85.7% for severe injury 1
• Adults meeting this criterion at Level I trauma centers have reduced mortality (OR: 0.7; 95% CI 0.6-0.9) compared to lower-level facilities 1

ICU Management

• Patients with GCS >9 have increased risk of unplanned extubation (OR: 1.98; 95% CI 1.03-3.81) 1
• 90.5% of unplanned extubations occur in patients with GCS 9-12 1
• Higher consciousness levels require enhanced airway security measures and closer monitoring 1

Hepatic Encephalopathy

For patients with significantly altered consciousness from hepatic encephalopathy, use GCS rather than West Haven criteria, as GCS provides a more robust and operative description. 1

• GCS is particularly useful when orientation cannot be reliably assessed 1
• Always exclude other causes of altered mental status (medications, alcohol, hyponatremia, psychiatric disease) before attributing changes to hepatic encephalopathy 1

Key Clinical Pitfalls to Avoid

• Never rely on a single GCS determination: Serial assessments provide substantially more valuable prognostic information 2, 3, 4
• Don't ignore the motor component: It has the highest predictive value in severe TBI and remains assessable even in sedated patients 1, 2
• Avoid using GCS alone: Always integrate with pupillary responses, vital signs, and clinical context 1, 4
• Don't assume identical sum scores mean identical prognosis: Component profiles matter significantly 3, 4
• Never skip documentation of individual components: Recording only the sum loses critical prognostic information 1, 3