Full Outline of UnResponsiveness (FOUR) Score Calculator

How does the Full Outline of UnResponsiveness (FOUR) score calculator work?

The "Full Outline of UnResponsiveness" is a newly designed and clinically tested tool that assesses patients with impaired levels of consciousness. It was developed in the Neurocritical care unit at the Mayo Clinic in Rochester, Minnesota.

There are four parameters evaluated in order to cover domains of neurological function:

■ Eye response – evaluating eyelid response to different stimuli.

■ Motor response – evaluating ability to flex, extend, respond to pain or the generalized myoclonus status characterized by persistent, multisegmental, ar-rhythmic, jerklike movements.

■ Brainstem reflexes – covering pupil and cornea reflexes and cough.

■ Breathing pattern and ventilation – covering regular, Cheyne-Stokes (progressively deeper and faster breathing followed by apnea), irregular and apnea. Cheyne-Stokes respiration and irregular breathing can represent bi-hemispheric or lower brainstem dysfunction of respiratory control.

One of the main improvements brought by this tool is that it can be used in patients who are intubated (presence of endotracheal tube), unlike the Glasgow Coma Scale which cannot be used in such cases because it requires verbal responses. Also, this new assessment of critical patients is able to detect subtle changes in the neurological examination, especially in the case of traumatic head injuries.

Impaired consciousness is defined as disturbances of consciousness, close to coma, due to a dysfunction present in the cerebral hemispheres or in the reticular activating system. During this status, the ability to remain awake is impaired and this classes as medical emergency.

Levels of impaired consciousness include: confusion, disorientation, delirium, lethargy, stupor and coma.

Confusion is lack of clear thinking while disorientation is the inability to recognize places, objects, place oneself in time and other inaccuracies, some related to memory usage.

Delirium is characterized by confusion and lack of logic thinking while lethargy is decreased consciousness status and stupor is the deepest level of impaired consciousness, the stage before coma when there is also a partial lack of response to stimuli.

Score interpretation

The overall result from the Full Outline of UnResponsiveness (FOUR) score calculator is obtained by summing the scores assigned to each of the 4 parameters in the neurological assessment.

The minimum obtainable is 0 while the maximum is 16. Outcomes of the studies suggest that the lower the score, the greater the coma gravity.

There are several validation studies in different medical emergency rooms and intensive care units.

The FOUR grading scale is comparable in purpose and efficiency with other tools such as the GCS and AVPU in evaluating critically ill patients.

The comparison of the inter-observer reliability of the FOUR method and the GCS revealed that the former is comparable in efficiency and even carries an advantage in use.

For instance, the FOUR score performed better for exact inter-rater agreement, but not for the clinically more relevant agreement within the range of +/- 1 score point.

References

1) Wijdicks EF, Bamlet WR, Maramattom BV, Manno EM, McClelland RL. (2005) Validation of a new coma scale: The FOUR score. Ann Neurol; 58(4):585-93.

2) Iyer VN, Mandrekar JN, Danielson RD, Zubkov AY, Elmer JL, Wijdicks EF. (2009) Validity of the FOUR score coma scale in the medical intensive care unit. Mayo Clin Proc; 84(8):694-701.

3) Bruno MA, Ledoux D et al. (2011) Comparison of the Full Outline of UnResponsiveness and Glasgow Liege Scale/Glasgow Coma Scale in an intensive care unit population. Neurocrit Care; 15(3):447-53.

4) Fischer M, Rüegg S, Czaplinski A et al. (2010) Inter-rater reliability of the Full Outline of UnResponsiveness score and the Glasgow Coma Scale in critically ill patients: a prospective observational study.  Crit Care; 14(2):R64.