PURPOSE: An external ventricular drain (EVD) is routinely placed to closely monitor intra-cranial pressure (ICP). Researchers have attempted to correlate optic nerve sheath diameter (ONSD) measurement with ICP by using multiple ultrasound modalities. A recent study demonstrated that there is a possible significant relationship between the largest measured ONSD and ICP at the time of admission (1). Our study attempts to analyze whether the changes in ONSD can predict changes in ICP in patients who are admitted with the diagnosis of intracranial hemorrhage (ICH).
METHODS: Patients with diagnosis of ICH and underwent EVD placements were enrolled in the study. ONSD were measured 3 mm sagittal behind the globe, using a GE-LOGIQBOOK-XP-handheld ultrasound. A high frequency linear transducer(10–13 MHz) was used. The ONSD measurements were obtained from each eye and averaged, every 4 to 6 hrs for a total of 5 measurements. ICP was measured by the nurses at the time of ONSD measurement. All investigators were blinded to the ICP readings and the nurses were blinded to the ONSD measurements. A linear regression analysis was applied to analyze the correlation between ONSD and ICP.
RESULTS: A total of 18 patients were enrolled. Eighty three percent were diagnosed with subarachnoid hemorrhage and 17% were diagnosed with intraparenchymal hemorrhage. A total of 82 measurements of ONSD and ICP were analyzed. There was no significant relationship between ONSD and ICP(r2=0.04). However, the mean ONSD in patients with increased ICP(ICP>20 cmH2O) was significantly higher than patients with normal ICP(6.2 mm vs. 5.7 mm,p<0.01).
CONCLUSION: ONSD does not appear to be an accurate predictor of ICP in patients with ICH. However, we found that patients with elevated ICP have significantly higher ONSD compared to the patients with normal ICP.
CLINICAL IMPLICATIONS: Based on our study, ONSD does not seem to be an adequate tool to assess ICP in patients with ICH.Reference:(1).Geeraerts T, et al. Ultrasonography of the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain injury. Intensive Care Medicine 2007;33:1704–1711.
DISCLOSURE: Naricha Chirakalwasan, No Financial Disclosure Information; No Product/Research Disclosure Information