Median Optic Nerve Sheath Diameter Research Articles

Optic nerve sheath diameter and its association with brain swelling in pediatric cerebral malaria: a retrospective study.

Mortality in pediatric cerebral malaria (CM) in low- and middle-income countries (LMICs) is associated with brain swelling on magnetic resonance imaging (MRI); however, MRI is unavailable in most LMICs. Optic nerve sheath diameter (ONSD) measurement is an inexpensive method of detecting increased intracranial pressure compared with the invasive opening pressure (OP). Our primary objective was to determine if increased ONSD correlated with brain swelling on MRI in pediatric CM. Our secondary objective was to determine if increased ONSD correlated with increased OP and/or poor neurological outcome in pediatric CM. We hypothesized that increased ONSD would correlate with brain swelling on MRI and increased OP and that ONSD would be higher in survivors with sequelae and non-survivors. We performed a retrospective chart review of children aged 0-12 years in Blantyre, Malawi, from 2013 to 2022 with CM as defined by the World Health Organization. Brain swelling on admission MRI was characterized by brain volume scores (BVS); severe swelling was scored as 7-8, mild-to-moderate as 4-6, normal as 3. The admission ONSD was measured via ultrasound; it was defined as abnormal if it was >4.5 mm in children >1 year and >4 mm in children <1 year. Favorable outcome was defined as a normal neurological exam on discharge in survivors. The primary and secondary objectives were evaluated using Spearman's correlation; and the demographics were compared using chi-square and the Kruskal-Wallis test (Stata, College Station, TX, USA). Median age of the 207-patients cohort was 50 months [interquartile range (IQR) 35-75]; 49% (n = 102) were female. Of those, 73% (n = 152) had a favorable outcome, and 14% (n = 30) died. Twenty-nine (14%) had a normal BVS, 134 (65%) had mild-to-moderate swelling, and 44 (21%) had severe swelling. ONSD was elevated in 86% (n = 178) of patients, while 12% of patients had increased OP. There was a weakly positive correlation between BVS and ONSD (r = 0.14, p = 0.05). The median ONSD was not significantly different compared by discharge outcome (p = 0.11) or by BVS (p = 0.18). ONSD was not a reliable tool to correlate with BVS, neurological outcome, or OP in children with CM. Future studies to identify alternative methods of early identification of CM patients at highest risk for morbidity and mortality are urgently needed.

Transcranial ultrasonographic evaluation of effect of ventriculoperitoneal shunt on intracranial dynamics: A prospective observational study

BackgroundTranscranial sonographic (TCS) evaluation of optic nerve sheath diameter (ONSD), third ventricular diameter (TVD) and mean flow velocities (Vm) and pulsatility index (PI) of middle cerebral artery (MCA) can provide important insights to the change in intracranial dynamics following ventriculo-peritoneal (VP) shunt surgery. The primary objective of this study was to observe changes in ONSD values following VP shunt at 12 h, compared to pre-VP shunt values. MethodsAfter obtaining ethical approval, patients admitted with a diagnosis of hydrocephalus posted for a VP shunt surgery were prospectively enrolled. TCS evaluation was done before induction of anesthesia and 12-hour post-VP shunt surgery. We recorded the values of ONSD, TVD and Vm and PI MCA at both time points. ResultsThirty-four patients (19 male) were evaluated for ONSD and for the improvement of symptoms. Transtemporal window could not be obtained in six patients. At 12 h following VP shunt, bilateral median ONSD values reduced significantly from their pre-VP shunt values [right ONSD- 0.62 (0.59–0.64) to 0.53 (0.5–0.54) mm (p < 0.001); left ONSD- 0.62 (0.59–0.63) to 0.53 (0.5–0.54) mm (p < 0.001)]. Similarly, the median TVD at 12 h post-VP shunt reduced significantly from its pre-VP shunt measurements [0.97 (0.85–1.09) to 0.74 (0.7–0.84) cm]. PI MCA values reduced significantly, while Vm MCA values increased significantly from the pre-VP shunt values. ConclusionVP shunt reduced the ONSD, TVD, PI MCA and increased the Vm MCA after shunt surgery as early as 12hrs.

Bedside Ultrasonographic Assessment of the Optic Nerve Sheath Diameter to Assess Intracranial Pressure in Patients Given Ketamine in Emergency Department

Background: There is an ongoing debate if ketamine exerts any effect on intracranial pressure (ICP). ICP can be evaluated noninvasively by means of optic nerve sheath diameter (ONSD) measurement. In the present study, we aimed to determine if ketamine has any perceivable effect on ICP using ONSD.&#x0D; Material and Methods: In this single-center observational study, we prospectively enrolled patients who were admitted to the ED and received intravenous ketamine for induction, analgesia, procedural sedation for any procedure (ie, fracture reduction, laceration repair, pacemaker implantation). ONSD was used to rate ICP changes noninvasively both before and after ketamine application.&#x0D; Results: There were a total of 75 patients with a mean age of 59.8 ± 20.5 years. The majority of patients were applied Procedural Sedation (53.3%). In patients who were administered ketamine for induction, the median ONSD before and after ketamine were 5.10 (IQR: 1) mm and 5.00 (IQR: 1.30) mm, respectively. There occurred no significant diameter change (p=0.832). In patients who were administered ketamine for analgesia, the median ONSD 3.70 (IQR: 0.40) mm and 3.65 (IQR: 0.23) mm prior to and after the procedure, respectively. There occurred no significant diameter change (p=0.549). In patients who were administered ketamine for procedural sedation, the median ONSD before and after the procedure were 4.05 (IQR:0.67) mm and 3.97 (IQR: 0.69) mm, respectively. This time, however, ONSD was significantly reduced after ketamine administration (p=0.001).&#x0D; Conclusions: In this patient population, ketamine did not cause any incremental effect on ONSD, a surrogate marker of ICP.

Prognostic role of optic nerve sheath diameter in stroke in emergency department, A case control study.

Sonographic measurement of optic nerve sheath diameter (ONSD) can reflect intracranial pressure (ICP) indirectly and determine the neurology intensive care unit (NICU) requirement and mortality in acute ischemic stroke (AIS). To demonstrate the effectiveness of ONSD to determine mortality, morbidity, and NICU requirement on patients with the AIS. The sonographic ONSD measurements were performed on each patient with AIS, over 18 years old. All patients were categorized according to the Oxfordshire Community Stroke Project (OCSP) classification system. MRI images were examined for increased ICP, and the patients were categorized into two groups as increased ICP (i-ICP) and normal ICP. The ONSD results were evaluated in terms of classifications, outcomes, and prognosis of the patients. One hundred and five patients were included and 31 (35.2%) were in the i-ICP group. The median ONSDs were 5.26 mm in the i-ICP group and 4.62 mm in the normal ICP group (P < 0.001). The median ONSDs were 5.13 mm in the NICU group and 4.69 mm in the neurology ward (NW) group (P = 0.001). The total anterior circulation infarction (TACI) subgroup had higher ONSDs than the others (TACI: 5.27 mm; PACI: 4.73 mm; POCI: 4.77 mm; and LACI: 4.64 mm, P < 0.001). The NICU requirements were higher in the TACI subgroup. The median ONSD was 5.42 mm in the deceased group (survived: 4.77 mm, P < 0.001). ONSD may be favorable for predicting the increased ICP and the NICU requirement in OCSP subgroups. Moreover, ONSD can be used to foresee the mortality of AIS.

545: OPTIC NERVE SHEATH DIAMETER AS A PREDICTOR OF BRAIN SWELLING IN PEDIATRIC CEREBRAL MALARIA

Introduction: Cerebral malaria (CM) is an important cause of death in children in low-and-middle income countries (LMICs) with a case fatality rate of >15%. Brain swelling on magnetic resonance imaging (MRI) is associated with morbidity and mortality in CM; however, this modality is expensive and unavailable in many LMICs. Optic nerve sheath diameter (ONSD) measurement is an inexpensive, non-invasive method of detecting increased ICP in other neurocritical illnesses. We hypothesized that increased ONSD would correlate with brain swelling on MRI and would be higher in survivors with neurological sequelae and non-survivors. Methods: We performed a retrospective chart review of 207 children aged 0-12 years in Blantyre, Malawi from 2013-22 with CM as defined by the World Health Organization. Brain swelling on admission MRI was characterized by brain volume scores (BVS) assigned by two blinded pediatric neuroradiologists; severe swelling was defined as 7-8, mild-to-moderate as 4-6, normal as 3. Admission ONSD measurement was taken via portable ultrasound (GE Logiq e); normal was defined as < 4.5 mm. Favorable outcome in survivors was defined as a grossly normal neurological exam on discharge. Data were compared using Kruskall-Wallis and Pearson’s correlation tests utilizing Stata (College Station, TX). Results: Median age of the cohort was 50 months (IQR 40); 49% (n=102) were female. 73% (n=152) had a favorable outcome, 12% (n=25) an unfavorable outcome, and 14% (n=30) died. Twenty-nine (14%) had a normal BVS, 134 (65%) had mild-to-moderate swelling, and 44 (21%) had severe swelling. ONSD was elevated in 86% (n=178) of patients overall; when compared by BVS group, it was elevated in 79% (n=23) of normal, 87% (n=117) of mild-to-moderate, and 86% (n=38) of severe. There was a weakly positive correlation between BVS and ONSD (r=0.14, p=0.05). Median ONSD was not significantly different when compared by discharge outcome (p=0.11) or when compared by BVS (p=0.18). Conclusions: ONSD was not a reliable tool to identify increased brain swelling as detected on MRI in children with CM. This may be due to heterogenous mechanisms leading to abnormal MRI findings. Future studies to identify an alternative method of early identification of children with CM that are high risk for morbidity and mortality are urgently needed.

Optic nerve sheath diameter, intensive care unit admission and COVID-19-related-in-hospital mortality.

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. 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. 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. 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). 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.

Predictive Value of Optic Nerve Sheath Diameter for Diagnosis of Intracranial Hypertension in Children With Severe Brain Injury.

Background and AimsIntracranial Hypertension (ICH) is a life-threatening complication of brain injury. The invasive measurement of intracranial pressure (ICP) remains the gold standard to diagnose ICH. Measurement of Optic Nerve Sheath Diameter (ONSD) using ultrasonography is a non-invasive method for detecting ICH. However, data on paediatric brain injury are scarce. The aim of the study was to determine the performance of the initial ONSD measurement to predict ICH occurring in children with severe brain injury and to describe the ONSD values in a control group.MethodsIn this cross-sectional study, ONSD was measured in children aged 2 months-17 years old with invasive ICP monitoring: before placement of ICP probe and within the 60 min after, and then daily during 3 days. ONSD was also measured in a control group.ResultsNinety-nine patients were included, of whom 97 were analysed, with a median (IQR) age of 8.7 [2.3–13.6] years. The median (IQR) PIM 2 score was 6.6 [4.4–9.7] and the median (IQR) PELOD score was 21 [12–22]. Aetiologies of brain injury were trauma (n = 72), infection (n = 17) and stroke (n = 8). ICH occurred in 65 children. The median (IQR) ONSD was 5.58 mm [5.05–5.85]. ONSD performed poorly when it came to predicting ICH occurrence within the first 24 h (area under the curve, 0.58). There was no significant difference between the ONSD of children who presented with ICH within the first 24 h and the other children, with a median (IQR) of 5.6 mm [5.1–5.9] and 5.4 mm [4.9–5.8], respectively. Infants aged less than 2 years had a median (IQR) ONSD of 4.9 mm [4.5–5.2], significantly different from children aged more than 2 years, whose median ONSD was 5.6 mm [5.2–5.9]. Age, aetiology or ICP levels did not change the results. Thirty-one controls were included, with a median age of 3.7 (1.2–8.8) years. The median (IQR) of their ONSD measurement was 4.5 mm [4.1–4.8], significantly lower than the patient group.ConclusionIn a paediatric severe brain injury population, ONSD measurement could not predict the 24 h occurrence of ICH. Severity of patients, timing and conditions of measurements may possibly explain these results.

Determination of normal values of optic nerve sheath diameter in Turkish adult population using magnetic resonance imaging

The measurement of optic nerve sheath diameter (ONSD) is a reliable tool for the estimation of increased intracranial pressure (ICP). However, it is known that racial changes can occur in human anatomy. In the present study we aimed to determine the normal values of ONSD in Turkish adult population. This retrospective study involved the collection of data between June 1, 2015, and May 31, 2019, and was conducted on 291 adults known to have no increased cranial/intraocular pressure. The ONSD was measured at 3 mm posterior to the globe on MR images. 291 subjects were enrolled, 63.6% of whom were female. The total median ONSD was 4.40mm (4.20- 4.70). The median ONSD of the male participants was 4.50mm (4.25-4.75), of the female participants was 4.35mm (4.15-4.50) and the difference was statistically significant (p = 0.001). According to statistical analysis, it was found that only the presence of chronic renal failure altered the median of ONSD among the comorbid diseases (p = 0.042). Monitoring and treating increased ICP is crucial. Thanks to an ONSD with a known normal value, recognition and emergency management of this pathology would be easier. We think our study is noteworthy because it is the first study investigating the normal ONSD value in Turkish adult population.

Optic Nerve Sheath Ultrasound for the Detection and Monitoring of Raised Intracranial Pressure in Tuberculous Meningitis.

BackgroundNeurological complications of tuberculous meningitis (TBM) often lead to raised intracranial pressure (ICP) resulting in high morbidity and mortality. Measurement of optic nerve sheath diameter (ONSD) by point-of-care ultrasound may aid in the identification of raised ICP in TBM.MethodsFrom June 2017 to December 2019, 107 Vietnamese adults with TBM, enrolled in the ACT HIV or LAST ACT trials (NCT03092817, NCT03100786), underwent ONSD ultrasound at ≥1 of days 0, 3, 7, 14, 21, and day ±30 after enrollment. Demographic data, TBM severity grade, HIV coinfection status, and clinical endpoints by 3 months were recorded. ONSD values were correlated with disease severity, baseline brain imaging, cerebrospinal fluid parameters, and clinical endpoints.Results267 ONSD ultrasound scans were performed in 107 participants over the first 30 days of treatment, with measurements from 0.38–0.74 cm. Paired baseline ONSD and brain imaging were performed in 63 participants. Higher baseline ONSD was associated with more severe disease and abnormal brain imaging (abnormal imaging 0.55 cm vs 0.50 cm normal imaging, P = .01). Baseline median ONSD was significantly higher in participants who died by 3 months (0.56 cm [15/72]) versus participants who survived by 3 months (0.52 cm [57/72]) (P = .02). Median ONSD was higher at all follow-up times in participants who died by 3 months.ConclusionsHigher ONSD was associated with increased disease severity, brain imaging abnormalities, and increased death by 3 months. ONSD ultrasound has a potential role as a noninvasive, affordable bedside tool for predicting brain pathology and death in TBM.

The diagnostic and prognostic value of the optic nerve sheath diameter on CT for diagnosis spontaneous subarachnoid hemorrhage

IntroductionThe aim of this study was to investigate the relationship between the optic nerve sheath diameter (ONSD) measured on non-contrast head computed tomography (CT) and the diagnosis and prognosis of spontaneous subarachnoid hemorrhage (SAH) on emergency department (ED) patients. MethodWe used a matched control group of patients with the same age and gender who were diagnosed in the ED with spontaneous SAH and who admitted to the ED with headache. Four emergency medicine attending physicians made the ONSD measurements. For measurements, the 3-mm posterior location where the optic nerve enters the eyeball was used. ResultsThis study was done with 61 spontaneous SAHs with an equal number of control patients. The median ONSD for control and spontaneous SAH groups was 5.76 [interquartile range (IQR): 0.96] mm and 6.72 (IQR: 1.42) mm, respectively (p<0.001). The area under the receiver operating characteristic curve was determined as 0.791 (confidence interval 95% 0.710–0.872). At an ONSD threshold value of 6.1 mm, the sensitivity and specificity of SAH was 72%. There was no significant relationship between ONSD and in-hospital mortality in spontaneous SAH patients (p>0.05). The intra-class correlation coefficients for inter and intra-rater reliability were 0.84 and 0.95, respectively. ConclusionIn patients with spontaneous SAH, the ONSD measured in the orbital sections of a head CT is strongly correlated with a SAH diagnosis. Assessment of ONSD in head CTs taken with spontaneous SAH suspicion may contribute to the diagnoses of spontaneous SAH.

Inter-rater Reliability of Sonographic Optic Nerve Sheath Diameter Measurements by Emergency Medicine Physicians.

To compare the degree of agreement of sonographic optic nerve sheath diameter (ONSD) measurements by ultrasound fellowship-trained and resident emergency medicine (EM) physicians. Ten ultrasound fellowship-trained EM attending physicians from multiple institutions and 51 resident EM physicians at a single residency were enrolled to measure the ONSD using a computerized ruler on five separate still-frame sonograms of adult eyes that included the retrobulbar optic nerve. Descriptive and bivariate statistics for each ultrasound image were calculated to compare median ONSD measurements among groups. Intraclass correlation coefficients (ICCs) were calculated to estimate the inter-rater reliability. Although the median ONSD measurement of each image did not significantly differ between resident and ultrasound fellowship-trained EM physicians, we found greater variation in agreement of ONSD measurements by resident EM physicians (ICC 0.50; 95% confidence interval 0.25-0.89) than ultrasound fellowship-trained EM physicians (ICC 0.73; 95% confidence interval 0.44-0.96). Although both resident and ultrasound fellowship-trained EM physicians showed good inter-rater reliability of ONSD measurements, variation in agreement among ultrasound fellowship-trained EM physicians may be as wide as 0.44, suggesting that even in skilled hands, ultrasound measurement of the ONSD may not be as dependable a screening tool for elevated intracranial pressure as previously suggested in the literature.

Transorbital Sonography and Visual Outcome for the Diagnosis and Monitoring of Optic Neuritis.

Transorbital sonography (TOS) is a promising tool to support the clinical diagnosis of optic neuritis (ON) by showing thickening of optic nerve. In this study, we aimed to define its specific role in follow-up of ON patients. We measured ultrasonography parameters and visual acuity (VA) at presentation and after 1 year in 45 patients with newly diagnosed ON. Two vascular sonographers used B-mode TOS to evaluate mean optic nerve diameter (OND) and optic nerve sheath diameter (ONSD). Median ONSD values were significantly thicker in patients with ON in the affected eye (6.4 mm, interquartile range [IQR]: 6.0-6.9) at presentation compared with the nonaffected side (5.7 mm; IQR: 5.2-6.1) (P < .001). The median OND was not significantly thicker at presentation in the affected eye (3.0 mm; IQR: 2.9-3.4) compared with the fellow eye (2.9 mm; IQR: 2.8-3.2) (P = .09). Logarithmic VA was significantly compromised at presentation in the affected eye (.16; IQR: .00-.55) compared with fellow eye (.00; IQR: .00-.00) (P < .001). After 1 year, no significant difference (P ≥ .05) was found between ONSD or OND of the affected side compared with the nonaffected side. VA improved in most of the patients but remained significantly impaired in affected eye after 1 year. TOS is a useful tool to support diagnosis of ON. This technique seems to have less value to evaluate atrophy of the optic nerve after 12 months.

Transorbital sonographic evaluation of normal optic nerve sheath diameter in healthy Nepalese adults

Abstract Background: Sonographic evaluation of optic nerve sheath diameter (ONSD) is increasingly being used as a non-invasive technique for detecting raised intracranial pressure. Aims: The aim of this study is to find out the normal ONSD in healthy Nepalese adults. Settings and Design: It is a cross-sectional observational study. Subjects and Methods: ONSD was measured 3 mm behind the globe using 6–13 MHz linear probe. Subjects were examined in the supine position with their eyes closed and in neutral position. Transducer was placed horizontally and in each eye, an average of three readings were documented. Statistical Analysis Used: Data were represented as mean and standard deviation. Paired t-test was used to compare ONSD between the right and left eye. Independent t-test was used to compare ONSD between males and females. Pearson correlation coefficient was used to assess the correlation between age and ONSD. Results: Eighty-eight healthy subjects above 18 years of age were enrolled in the study. The median ONSD was 4.1 mm with 95% of subjects in the range of 3.1–4.6 mm. There was no significant difference in ONSD measurement between males and females (P = 0.09) and between the right and left eye (P = 0.72). There was no relationship between ONSD and age ( R2=0.06, P = 0.55). Conclusions: The range for normal ONSD in healthy adult Nepalese subjects is 3.1–4.6 mm with no significant relationship with gender, age and side of the body.

Transorbital sonography in acute optic neuritis: a case-control study.

Acute unilateral optic neuritis is associated with a thickening of the retrobulbar portion of the optic nerve as revealed by transorbital sonography, but no comparison has been made between nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis versus healthy controls. We evaluated optic nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis and healthy controls and compared optic nerve sheath diameter and optic nerve diameter with visual-evoked potentials in patients. A case-control study was performed in 2 centers. Twenty-one consecutive patients with onset of visual loss during the prior 10 days and established acute noncompressive unilateral optic neuritis were compared with 21 healthy controls, matched for sex and age (±5 years). Two experienced vascular sonographers performed the study by using B-mode transorbital sonography. Visual-evoked potentials were performed on the same day as the transorbital sonography and were evaluated by an expert neurophysiologist. Sonographers and the neurophysiologist were blinded to the status of the patient or control and to clinical information, including the side of the affected eye. The median optic nerve sheath diameter was thicker on the affected side (6.3 mm; interquartile range, 5.9-7.2 mm) compared with the nonaffected side (5.5 mm; interquartile range, 5.1-6.2 mm; P < .0001) and controls (5.2 mm; interquartile range, 4.8-5.5 mm; P < .0001). The median optic nerve diameter was 3.0 mm (range, 2.8-3.1 mm) on the affected side and 2.9 mm (range, 2.8-3.1 mm) on the nonaffected side (P = not significant.). Both sides were thicker than those in controls (2.7 mm; interquartile range, 2.5-2.8 mm; P = .001 and .009). No correlation was found between optic nerve sheath diameter and optic nerve diameter and amplitude and latency of visual-evoked potentials in patients with optic neuritis. Transorbital sonography is a promising tool to support the clinical diagnosis of acute optic neuritis. Further studies are needed to define its specific role in the diagnosis and follow-up of optic neuritis.

Transorbital Sonographic Evaluation of Normal Optic Nerve Sheath Diameter in Healthy Volunteers in Bangladesh

IntroductionMeasurement of optic nerve sheath diameter (ONSD) by ultrasound is increasingly used as a marker to detect raised intracranial pressure (ICP). ONSD varies with age and there is no clear consensus between studies for an upper limit of normal. Knowledge of normal ONSD in a healthy population is essential to interpret this measurement.MethodsIn a prospective observational study, ONSD was measured using a 15 MHz ultrasound probe in healthy volunteers in Chittagong, Bangladesh. The aims were to determine the normal range of ONSD in healthy Bangladeshi adults and children, compare measurements in males and females, horizontal and vertical beam orientations and left and right eyes in the same individual and to determine whether ONSD varies with head circumference independent of age.Results136 subjects were enrolled, 12.5% of whom were age 16 or under. Median ONSD was 4.41 mm with 95% of subjects in the range 4.25–4.75 mm. ONSD was bimodally distributed. There was no relationship between ONSD and age (≥4 years), gender, head circumference, and no difference in left vs right eye or horizontal vs vertical beam.ConclusionsUltrasonographic ONSD in Bangladeshi healthy volunteers has a narrow bimodal distribution independent of age (≥4 years), gender and head circumference. ONSD >4.75 mm in this population should be considered abnormal.

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Introduction: Increased intracranial pressure (ICP) leads to morbidity and mortality in patients with brain injury (stroke, head trauma, encephalopathy) and is an important cause of long-term neuro-cognitive deficit and death. While invasive monitoring techniques remain the diagnostic gold standard, potential bleeding and other complications pose a relevant risk and make them dangerous to apply routinely. Clinical deterioration can be an early indicator of increasing ICP, but is limited in its ability to accurately detect elevated intracranial pressures in this patient population due to fluctuations in mental status, sedation, other life-threatening injuries, and paralysis as part of the acute stabilization process. Measurement of ICP is critical during this early time period in order to optimize hemodynamics and prevent further brain injury. Optic ultrasound (OUS) is a non-invasive technique that can be used to measure the optic nerve sheath dimension providing valuable ICP monitoring data for physicians as they treat critically ill patients. Methods: In a prospective convenience sample study, 115 adult patients at risk for increased ICP (stroke, head trauma, encephalopathy) were enrolled at a tertiary care center. Patients with suspected ocular globe trauma were excluded from the study. OUS using a 7.5 MHz linear array transducer was performed on the first and second day of arrival to the emergency department (ED) or intensive care unit (ICU). Ocular ultrasound is performed non-invasively through placement of sterile conductive ultrasound gel on the eyelids with the eyes closed. Minimal pressure is applied on the eyelid with the ultrasound transducer touching the gel that has been placed on the eyelid (no direct contact with eye surface). The patient’s head position was not changed and was performed bedside with portable ultrasound machines. Due to fluid content in the eyeball and surrounding tissue, ocular structures are well visualized. The optic nerve sheath diameter (ONSD) was examined. A longitudinal and a transverse measurement were taken on both the left and right eye of each patient. Data analysis includes paired t-tests and Chi-Square to compare means and proportions as appropriate. Regression analysis assesses ONSD and patient outcomes relationships using -SAS v.9.3 statistical software. Results: There was no significant difference for measurements of lateral versus transverse measurements of each eye: right p=0.903 and left p=0.467. There was no significant difference for measurements of left versus right eye, for the longitudinal p=0.270 and transverse p=0.163, respectively. The median ONSD for those that died versus those that did not die was 0.60 (IQR 0.55, 0.67) and 0.55 (IQR 0.51, 0.61), respectively p= 0.005. For every 0.1 cm increase in ONSD, the odds of death increased 2.68 fold 95% CI (1.30, 5.51). Conclusions: ONSD measurements can be taken in either eye, in either orientation, with no significant difference in accuracy. Increased ONSD measurements were correlated with worsened short term outcomes (death). We expect that increased ONSD measurements will be correlated with worsened outcomes (Modified Rankin Scale analysis will be done at 6 months). OUS may be used as a screening tool to identify patients at risk for increased ICP. OUS will enable the treating physician to utilize a reliable non-invasive monitoring technique, and will improve patient care.

Optic Nerve Sheath Diameter Used as Ultrasonographic Assessment of the Incidence of Raised Intracranial Pressure in Preeclampsia

Dubost, Clément*; Le Gouez, Angès*; Jouffroy, Viridiana*; Roger-Christoph, Sandrine*; Benhamou, Dan†; Mercier, Frédéric J.*; Geeraerts, Thomas* Author Information

THIS MONTH IN Anesthesiology

The NLRP3 inflammasome is upregulated by mechanical ventilation in humans and is required for full expression of ventilator-induced lung injury in mice.Risperidone treatment of subsyndromal delirium was associated with reduced clinical delirium after cardiac surgery. See the accompanying Editorial View on page 975 Methylphenidate induces emergence from propofol anesthesia; further study is warranted to test this in humans. See the accompanying Editorial View on page 977 Sevoflurane–nitrous oxide anesthesia may provide a wider margin of safety against impaired cerebral oxygenation in these patients.Acute kidney injury leads to earlier onset of multiorgan dysfunction and increased mortality. Animal models suggest neutrophil migration, uncontrolled cytokine expression, and increased oxidative stress as factors in such organ dysfunction.The incidence of elevated intracranial pressure in preeclampsia is not known. A study was conducted to measure optic nerve sheath diameter (ONSD) in 51 preeclamptic and healthy pregnant women using ocular ultrasonography. At delivery, preeclamptic patients had significantly higher median ONSD values, and 19% had ONSD greater than 5.8 mm. Values were similar between groups by postpartum Day 7. This study suggests the potential utility of ocular ultrasonography to monitor intracranial pressure in preeclamptic patients. See the accompanying Editorial View on page 983 Mechanical ventilation using high tidal volumes is known to increase mortality in certain patients with comorbidities. The current study evaluated the impact of tidal volume on patients undergoing cardiac surgery. High, traditional, and low tidal volumes were used. Independent risk factors for high tidal volume included body mass index greater than 30 kg/m2, and female sex. Furthermore, high and traditional tidal volumes were found to be independent risk factors for poor outcomes including organ failure, multiple organ failure, and prolonged stay in the intensive care unit. This study confirmed the negative impact of mechanical ventilation with high tidal volumes on patients after cardiac surgery. See the accompanying Editorial View on page 985 Effective noninvasive and continuous blood pressure measurement using finger cuff technology would be beneficial in a multitude of surgeries. This study compared the precision of arterial pressure measured by Nexfin® (BMEYE, Amsterdam, The Netherlands), a noninvasive arterial pressure (NAP) device, with direct intraarterial pressure (IAP) in cardiothoracic surgery patients. Systolic, diastolic, mean arterial, and pulse pressure measurements all correlated between IAP and NAP techniques. NAP showed within-subject precision over a wide range of pressures. These results suggest that arterial blood pressure may be successfully measured noninvasively and continuously using such a device.

CaO + MgO + Al 2 O 3 + SiO 2 + H 2 O to 35 kb; amphibole, talc, and zoisite dehydration and melting reactions in the silica-excess part of the system and their possible significance in subduction zones, amphibolite melting, and magma fractionation

<h3>BACKGROUND AND PURPOSE:</h3> Acute unilateral optic neuritis is associated with a thickening of the retrobulbar portion of the optic nerve as revealed by transorbital sonography, but no comparison has been made between nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis versus healthy controls. We evaluated optic nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis and healthy controls and compared optic nerve sheath diameter and optic nerve diameter with visual-evoked potentials in patients. <h3>MATERIALS AND METHODS:</h3> A case-control study was performed in 2 centers. Twenty-one consecutive patients with onset of visual loss during the prior 10 days and established acute noncompressive unilateral optic neuritis were compared with 21 healthy controls, matched for sex and age (±5 years). Two experienced vascular sonographers performed the study by using B-mode transorbital sonography. Visual-evoked potentials were performed on the same day as the transorbital sonography and were evaluated by an expert neurophysiologist. Sonographers and the neurophysiologist were blinded to the status of the patient or control and to clinical information, including the side of the affected eye. <h3>RESULTS:</h3> The median optic nerve sheath diameter was thicker on the affected side (6.3 mm; interquartile range, 5.9–7.2 mm) compared with the nonaffected side (5.5 mm; interquartile range, 5.1–6.2 mm; <i>P</i> &lt; .0001) and controls (5.2 mm; interquartile range, 4.8–5.5 mm; <i>P</i> &lt; .0001). The median optic nerve diameter was 3.0 mm (range, 2.8–3.1 mm) on the affected side and 2.9 mm (range, 2.8–3.1 mm) on the nonaffected side (<i>P</i> = not significant.). Both sides were thicker than those in controls (2.7 mm; interquartile range, 2.5–2.8 mm; <i>P</i> = .001 and .009). No correlation was found between optic nerve sheath diameter and optic nerve diameter and amplitude and latency of visual-evoked potentials in patients with optic neuritis. <h3>CONCLUSIONS:</h3> Transorbital sonography is a promising tool to support the clinical diagnosis of acute optic neuritis. Further studies are needed to define its specific role in the diagnosis and follow-up of optic neuritis.