Point of care ultrasound assessment of the optic nerve sheath diameter in critically ill children

Abstract

Background: Raised intracranial pressure (ICP) is a typical neurological problem in critically ill children, which is associated with poor clinical outcomes or even death. The purpose of the study was to evaluate the efficacy of optic nerve sheath diameter (ONSD) as a point-of-care testing in the pediatric intensive care units for early diagnosis of raised intracranial pressure and as a follow up tool for treatment response.

Method: A prospective observational study was conducted in the pediatric intensive care unit of a tertiary care children's hospital. Consecutive children aged one month to twelve years with Glasgow Coma Scale less than or equal to 8 were included. Brain CT was performed just before or within few hours of admission to identify raised ICP. Two trained examiners in the same work place, who were blinded to the clinical details of the patients, performed the ONSD sonography concurrently. The ONSD was measured in the left and right eyes on admission, after 1 h, after 12 h, and after 24 h.

Results: Forty-two patients were categorized into 29 children with raised ICP and 13 children with non-raised ICP. The ONSD was significantly higher in the raised ICP group at all times in both eyes. It showed a significant decrease over time in both groups. A cutoff value of ≥ 4.3 mm was found to be an acceptable discriminator of ICP with Area Under the ROC curve (AUC) = 0.788 (95% CI 0.740- 0.830) (p < 0.0001), sensitivity of 59.91% (95% CI: 53.30-66.27) and specificity of 83.65% (95% CI: 75.12-90.18).

Conclusions: In critically ill children with non-traumatic causes of raised ICP, point of care ultrasound of ONSD shows a good diagnostic test accuracy for early diagnosis of raised ICP as well as follow up tool of treatment response if used serially. In addition, it is very good at correctly identifying individuals who do not have raised ICP to avoid unnecessary interventions.

Keywords: Critically ill children; Intensive care unit; Intracranial pressure; Non-invasive monitoring; Optic nerve sheath diameter; Point-of- care ultrasound.

Fig. 1

Study technique, the device used and the image obtained. (These images were obtained after consent from the patient’s parents for publication)

Fig. 2

Flow diagram of the study

Fig. 3

Binocular correlation of ONSD at different times. (T1: on admission, T2: after 1 h, T3: after 12 h, T4: after 24 h of admission)

Fig. 4

Area under the ROC curve of Optic Nerve Sheath Diameter by Ultrasound as a discriminator for raised intracranial pressure confirmed by Computed Tomography