Ocular ultrasound to detect intracranial hypertension in trauma patients.

BACKGROUND: Increases in intracranial pressure (ICP) after head trauma require a rapid recognition to allow for adequate treatments. The aim of this study was to determine whether dilation of the optic nerve sheath, as detected by ocular ultrasound at the bedside, could reliably identify increases in ICP assessed with an intraparenchymal probe in adult head trauma patients.
METHODS: Eleven head trauma injured adult patients admitted to the intensive care unit with a Glasgow Coma Scale score ≤8, with cerebral contusion confirmed by computed tomography scan, and that required invasive ICP monitoring, were enrolled in the study. ICP values ≤20 mm Hg were considered as normal. Patients with acute or chronic ocular lesion were excluded. Ten nontrauma intensive care unit patients, with no ICP monitoring, were enrolled as control group. Invasive arterial pressure was monitored, and optic nerve sheath diameter (ONSD) was assessed by ocular ultrasound in all the patients.
RESULTS: Head trauma patients without intracranial hypertension had ONSD values, assessed by ultrasound, equivalent to those measured in control patients (5.52 mm ± 0.36 mm vs. 5.51 mm ± 0.32 mm). ONSD, instead, significantly increased to 7.0 mm ± 0.58 mm, when ICP rose in value to >20 mm Hg (p < 0.0001 vs. normal ICP and control). ONSD values were significantly correlated to ICP values (r = 0.74, p < 0.001).
CONCLUSIONS: When ICP was higher than 20 mm Hg, the ONSD diameter increased, whereas when the ICP was below 20 mm Hg, the ONSD returned to values equivalent to those assessed in control nontrauma patients. Accordingly, ocular ultrasound may be considered as a good alternative for a rapid indirect evaluation of head trauma patients' ICP.