Does prolonged prone position affect intracranial pressure? prospective observational study employing Optic nerve sheath diameter measurements.

BACKGROUND: Our aim in this observational prospective study is to determine whether the prone position has an effect on intracranial pressure, by performing ultrasound-guided ONSD (Optic Nerve Sheath Diameter) measurements in patients with acute respiratory distress syndrome (ARDS) ventilated in the prone position. METHODS: Patients hospitalized in the intensive care unit with a diagnosis of ARDS who were placed in the prone position for 24 h during their treatment were included in the study. Standardized sedation and neuromuscular blockade were applied to all patients in the prone position. Mechanical ventilation settings were standardized. Demographic data and patients' pCO2, pO2, PaO2/FiO2, SpO2, right and left ONSD data, and complications were recorded at certain times over 24 h. RESULTS: The evaluation of 24-hour prone-position data of patients with ARDS showed no significant increase in ONSD. There was no significant difference in pCO2 values either. PaO2/FiO2 and pO2 values demonstrated significant cumulative increases at all times. Post-prone SPO2 values at the 8th hour and later were significantly higher when compared to baseline (p < 0.001). CONCLUSION: As a result of this study, it appears that the prone position does not increase intracranial pressure during the first 24 h and can be safely utilized, given the administration of appropriate sedation, neuromuscular blockade, and mechanical ventilation strategy. ONSD measurements may increase the safety of monitoring in patients ventilated in the prone position.

Optic Nerve Sheath Diameter, Intensive Care Unit admission & COVID-19-Related-In-hospital Mortality.

BACKGROUND: Hypoxia and hypercapnia due to acute pulmonary failure in patients with coronavirus disease 2019 (COVID-19) can increase the intracranial pressure (ICP). ICP correlated with the optic nerve sheath diameter (ONSD) on ultrasonography and is associated with a poor prognosis. AIM: We investigated the capability of ONSD measured during admission to the intensive care unit (ICU) in patients with critical COVID-19 in predicting in-hospital mortality. METHODS: A total of 91 patients enrolled in the study were divided into two groups: survivor (n = 48) and nonsurvivor (n = 43) groups. ONSD was measured by ultrasonography within the first 3 h of ICU admission. RESULTS: The median ONSD was higher in the nonsurvivor group than in the survivor group (5.95 mm vs. 4.15 mm, p < 0.001). The multivariate Cox proportional hazard regression analysis between ONSD and in-hospital mortality (contains 26 covariates) was significant (adjusted hazard ratio, 4.12; 95% confidence interval, 1.46-11.55; p = 0.007). The ONSD cutoff for predicting mortality during ICU admission was 5 mm (area under the curve, 0.985; sensitivity, 98%; and specificity, 90%). The median survival of patients with ONSD >5 mm (43%; n = 39) was lower than those with ONSD ≤ 5 mm (57%; n = 52) (11.5 days vs 13.2 days; log-rank test p = 0.001). CONCLUSIONS: ONSD ultrasonography during ICU admission may be an important, cheap, and easy-to-apply method that can be used to predict mortality in the early period in patients with critical COVID-19.

Measurement of Optic Nerve Sheath Diameter by Trans-Orbital Ultrasound to Detect Raised Intracranial Pressure in Children

Aims Raised Intracranial Pressure (ICP) is frequently encountered condition amongst children due to neurological and non-neurological etiologies. It contributes towards 20% of the admissions in our PICU at tertiary care institute of North India. Timely diagnosis of raised intracranial pressure is critical for appropriate management. Ultrasonographic measurement of optic nerve sheath diameter (ONSD) is non-invasive point of care tool to recognize raised intracranial pressure however there are very limited studies in pediatric population on this. Aim of this study was to measure the ONSD of children admitted in pediatric intensive care unit (PICU) to identify the difference in ONSD among the pediatric patients with normal and raised ICP and to achieve the cut-off value for diagnosing raised ICP. Methods A Hospital based observational comparative study conducted at PICU of a tertiary care institute of national importance in North India. ONSD measurement of all the patients aged 2-14 years admitted in pediatrics department for >48 hours was done in two phases due to COVID-19 related restrictions in routine admissions for some months. First phase was from 1st January 2020 to 31st March 2021 and second phase started from 15th January 2022. Complete enumeration technique was used for the study. Children receiving treatment for raised ICP based on clinical features (Muir's criteria) and neuroimaging were included in raised ICP group and they were compared with the patients without any signs of raised ICP. Optic nerve sheath diameter was measured in both the groups on Day 1 (i.e. within 24 hours of admission) and Day 2 of admission. Third and last ONSD measurement was done on any day between day 4 and day 7 of admission. On each day, 3 readings were taken from each eye and average of 3 readings was used for final statistical analysis for that particular day. Treating team was unaware of the USG findings throughout the stay of the patient in the department. Results Total 101 patients recruited, among them 16 patients had raised ICP and 85 patients had normal ICP. The mean optic nerve sheath diameter on day 1 was found to be higher in the patients with raised ICP (Mean ONSD = 4.955 +/- 0.80) as compared to those with normal ICP (Mean ONSD = 4.05 +/- 0.43). Their mean difference was 0.90 mm (95% CI 0.07-1.48 p value <0.01). Mean ONSD on day 2 also was higher in raised ICP patients (Mean ONSD = 4.82 +/- 0.73) in comparison to normal ICP patients (Mean ONSD = 4.06 +/- 0.47) which was statistically significant (p value = 0.001). The cut-off ONSD value for detecting the raised ICP was estimated to be 4.35 mm on ROC curve with area under the curve 0.862 (95% CI, 0.721-0.943), sensitivity of 75% and specificity of 76.5%. Conclusion Raised ICP is one of the important neurological entities in children contributing towards significant morbidity. Measurement of ONSD by trans-orbital ultrasound was able to detect raised ICP with excellent discriminatory performance.

Optic nerve sheath diameter measurement by ultrasound: Evaluation of a standardized protocol.

BACKGROUND AND PURPOSE: Treatment of elevated intracranial pressure (ICP) is central to neurocritical care, but not all patients are eligible for invasive ICP-monitoring. A promising noninvasive option is ultrasound measurement of the optic nerve sheath diameter (ONSD). However, meta-analyses of ONSD for elevated ICP show wide confidence intervals. This might be due to baseline variations, inter-rater variability, and varying measurement methods. No standardized protocol has been validated. Corrections for eyeball diameter (ED) and optic nerve diameter (OND) may compensate for baseline variations. We evaluated a protocol and compared two different measurement methods for ONSD ultrasound. METHODS: Two operators, blinded to each other's measurements, measured ONSD, ED, and OND twice in 20 patients. ONSD was measured with two different methods in use: internal (ONSDint) or external (ONSDext) of the dura mater. Intra-class correlation (ICC) was calculated for inter-rater and intra-rater reliability. RESULTS: ICCs for inter-rater reliability of ONSDext and ONSDint (95% confidence interval) were 0.96 (0.93, 0.98) and 0.88 (0.79, 0.94), respectively. ICCs for intra-rater reliability of ONSDext and ONSDint were 0.97 (0.94, 0.99) and 0.93 (0.87, 0.96), respectively. There was no significant bias or difference in intra-rater reliability between operators. CONCLUSIONS: ONSD can be measured with an excellent inter- and intra-rater reliability and low risk of inter-rater bias, when using this protocol. ONSDext yields a higher inter- and intra-rater reliability than ONSDint. Corrections for ED and OND can be performed reliably.