GCS in intubated patients

February 13, 2011 by  
Filed under All Updates, EMS, ICU, Resus, Trauma

We use the Glasgow Coma Score to describe conscious level, derived from eye opening, verbal response, and motor response.

One problem is that if your patient is intubated, there can’t be a verbal response. There are some ways round this. Imagine your intubated patient opens eys to a painful stimulus and withdraws his limb from one:

  • Just give him the lowest score (1) for the verbal component – E2M4V1
  • Write ‘V’ (ventilated) or ‘T’ (tube), eg. E2M4VT
  • Make it up, based on what you would expect the V score to be based on the E and M scores.

Weird as it sounds, there is a model for this, demonstrated in the paper abstracted below. The Derived Verbal Score = -0.3756 + Motor Score * (0.5713) + Eye Score * (0.4233).

Don’t worry…if you really want to use this, you don’t have to memorise that equation; there is an online calculator for it here and if you try it you’ll see this patient gets a derived verbal score of 2.3, and therefore a GCS of 7.3! Your decision now whether to round up or down. (In the meantime, I’ve given the patient a V of 1 and called it GCS E2M4VT=7.)

Alternatively, of course, you could try a better validated score that gives more information, the FOUR score, as validated here. The problem is, most people won’t know what you’re talking about.

The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores.
Meredith W, Rutledge R, Fakhry SM, Emery S, Kromhout-Schiro S.

BACKGROUND: The Glasgow Coma Scale (GCS), which is the foundation of the Trauma Score, Trauma and Injury Severity Score, and the Acute Physiology and Chronic Health Evaluation scoring systems, requires a verbal response. In some series, up to 50% of injured patients must be excluded from analysis because of lack of a verbal component for the GCS. The present study extends previous work evaluating derivation of the verbal score from the eye and motor components of the GCS.

METHODS: Data were obtained from a state trauma registry for 24,565 unintubated patients. The eye and motor scores were used in a previously published regression model to predict the verbal score: Derived Verbal Score = -0.3756 + Motor Score * (0.5713) + Eye Score * (0.4233). The correlation of the actual and derived verbal and GCS scales were assessed. In addition the ability of the actual and derived GCS to predict patient survival in a logistic regression model were analyzed using the PC SAS system for statistical analysis. The predictive power of the actual and the predicted GCS were compared using the area under the receiver operator characteristic curve and Hosmer-Lemeshow goodness-of-fit testing.

RESULTS: A total of 24,085 patients were available for analysis. The mean actual verbal score was 4.4 +/- 1.3 versus a predicted verbal score of 4.3 +/- 1.2 (r = 0.90, p = 0.0001). The actual GCS was 13.6 + 3.5 versus a predicted GCS of 13.7 +/- 3.4 (r = 0.97, p = 0.0001). The results of the comparison of the prediction of survival in patients based on the actual GCS and the derived GCS show that the mean actual GCS was 13.5 + 3.5 versus 13.7 + 3.4 in the regression predicted model. The area under the receiver operator characteristic curve for predicting survival of the two values was similar at 0.868 for the actual GCS compared with 0.850 for the predicted GCS.

CONCLUSIONS: The previously derived method of calculating the verbal score from the eye and motor scores is an excellent predictor of the actual verbal score. Furthermore, the derived GCS performed better than the actual GCS by several measures. The present study confirms previous work that a very accurate GCS can be derived in the absence of the verbal component.

The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores.
J Trauma. 1998 May;44(5):839-44 (if you have full text access to Journal of Trauma the best bit about this article is the discussion on pages 844-5 in which surgeons wrestle with the meaning of the word ‘conundrum’ and the spelling of ‘Glasgow’).

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  1. Tweets that mention GCS in intubated patients | Resus M.E! -- Topsy.com on February 13th, 2011 06:30

    […] This post was mentioned on Twitter by claudiaswilliam, Cliff Reid. Cliff Reid said: How do YOU document Glasgow Coma Score if your patient is intubated? http://tinyurl.com/gcs-tube […]