From the Guidelines
A patient is considered to be in a coma when their total Glasgow Coma Scale (GCS) score is 8 or less out of the possible 15 points. This definition is based on the most recent and highest quality study available, which emphasizes the importance of the GCS in assessing the severity of traumatic brain injury 1. The GCS evaluates three components: eye opening (scored 1-4), verbal response (scored 1-5), and motor response (scored 1-6). A comatose patient typically cannot open their eyes spontaneously, cannot follow commands, and produces no meaningful verbal output.
When assessing a patient with a GCS of 8 or below, immediate airway management should be considered as these patients often cannot protect their airway, putting them at risk for aspiration. The physiological basis for coma involves dysfunction of either both cerebral hemispheres or the reticular activating system in the brainstem, which regulates arousal and consciousness. This dysfunction can result from various causes including traumatic brain injury, metabolic disorders, infections, stroke, or toxic exposures.
Key points to consider in the management of comatose patients include:
- Regular reassessment of GCS scores to monitor changes in neurological status and guide treatment decisions
- Immediate airway management for patients with a GCS of 8 or below
- Consideration of the underlying cause of the coma, such as traumatic brain injury or metabolic disorders, to guide treatment
- The use of the GCS as a tool for serial evaluations by relatively inexperienced care providers and to facilitate communication between care providers on rotating shifts, as originally intended by Teasdale and Jennett in 1974 1.
It is essential to note that while the GCS is a valuable tool for assessing the severity of traumatic brain injury, it has limitations, particularly in patients with mild or moderate TBI, where a single GCS score may not be sufficient to determine the degree of parenchymal injury after trauma 1. However, in the context of coma, a GCS score of 8 or less is a widely accepted threshold for indicating a significant impairment in consciousness.
From the Research
Definition of Coma in GCS
- A patient is considered to be in a coma when their Glasgow Coma Scale (GCS) score is 3 or less, indicating a severe impairment of consciousness 2.
- The GCS score is calculated based on three components: eye opening, verbal response, and motor response, with lower scores indicating more severe impairment 3.
GCS Scores and Coma
- A GCS score of 3 is considered to be the lowest score, indicating no eye opening, no verbal response, and no motor response 2.
- Patients with a GCS score of 3 are considered to be in a deep coma and have a poor prognosis 2.
- The GCS score is widely used to assess the level of consciousness in patients with brain injury and is a reliable indicator of coma 4, 5.
Clinical Use of GCS
- The GCS is used in clinical practice to assess the level of consciousness in patients with brain injury and to monitor their progress over time 3.
- The GCS score is also used to guide treatment decisions, such as the use of hyperosmolar therapy to reduce intracranial pressure 5, 6.
- The GCS score has been shown to be a reliable predictor of outcome in patients with brain injury, with lower scores indicating a poorer prognosis 2.