Elevated intracranial pressure detected by bedside emergency ultrasonography of the optic nerve sheath

Effect of Target Temperature Management on Optic Nerve Sheath Diameter in Post-Cardiac Arrest Patients

Target Temperature Management (TTM) is a procedure used in post-cardiac arrest (CA) patients to reduce mortality and morbidity. The goal of this study was to investigate the link between intracranial pressure (ICP) and optic nerve sheath diameter (ONSD) in this patient group, which has a high mortality rate, despite TTM, and to see if ONSD may be used to predict mortality. The research was designed to be a retrospective observational study. The study comprised patients who were followed up on in a tertiary intensive care unit, had post-CA TTM, and had brain computed tomography (BCT) before and 0-6 hours after TTM. ONSD measurements were acquired from patients' BCT images recorded before and after TTM. The difference in pre-TTM ONSD and post-TTM ONSD measurements in all post-CA patients, as well as the difference in pre-TTM ONSD and post-TTM ONSD measurements in surviving and deceased patients, was compared. The study involved 33 participants. The patients' average age was 60.58-12.39 years, and 75.8% were male. Around 51.5% of the patients died. When the pre-TTM and post-TTM ONSDs of all patients were compared, there was no statistically significant difference (p = 0.856). When the percentage change (Δ) values between the post-TTM ONSD and pre-TTM ONSD and post-TTM ONSD measures of the surviving patients and the deceased patients were compared, a difference was observed (p < 0.01). Increased ICP in post-CA patients is a significant clinical issue associated with mortality and poor neurological prognosis. ONSD measurement may be useful in monitoring ICP, which may rise, despite TTM, and higher ONSD measurements may be used as an indicator for mortality in post-CA patients, who have received TTM.

Investigating the effects of tilting the postural drainage lithotripsy system on cerebral blood flow, intracranial pressure, heart rate, and blood pressure

PURPOSE

To investigate the effect of the postural drainage lithotripsy system developed by our experimental team on the vital signs of patient with urinary stones during the stone removal process.

METHODS

Four groups of 15 subjects (0°, 10°, 40°, and 70°) were subjected to different angles of head-down tilt to measure middle cerebral artery blood flow velocity (MCAv), cerebrovascular conductance coefficient (CVCi), intracranial pressure (nICP), heart rate (HR), and mean arterial blood pressure (MAP).

RESULTS

As the angle of HDT changed, MCAv values, nICP values, CVCi values, HR values, and MAP values changed significantly (all P ≤ 0.001), and the difference was statistically significant. During 10°HDT, despite a slight increase in nICP, the other measurements remained stable. During 40°HDT, only the MCAv values did not change significantly, whereas the rest of the measures were significantly altered. During 70°HDT, all indicators changed significantly.

CONCLUSIONS

The significant alterations in cerebral blood flow, intracranial pressure, and hemodynamics induced during the treatment of renal residual fragments with postural drainage should be used with caution in individuals with cerebrovascular accidents.

CHINA CLINICAL TRIALS REGISTRY

ChiCTR2300070671; Registration date: 2023-04-18.

Bedside ultrasonographic evaluation of optic nerve sheath diameter for monitoring of intracranial pressure in traumatic brain injury patients: a cross sectional study in level II trauma care center in India

BACKGROUND

Optic nerve sheath diameter (ONSD) is an emerging non-invasive, easily accessible, and possibly useful measurement for evaluating changes in intracranial pressure (ICP). The utilization of bedside ultrasonography (USG) to measure ONSD has garnered increased attention due to its portability, real-time capability, and lack of ionizing radiation. The primary aim of the study was to assess whether bedside USG-guided ONSD measurement can reliably predict increased ICP in traumatic brain injury (TBI) patients.

METHODS

A total of 95 patients admitted to the trauma intensive care unit was included in this cross sectional study. Patient brain computed tomography (CT) scans and Glasgow Coma Scale (GCS) scores were assessed at the time of admission. Bedside USG-guided binocular ONSD was measured and the mean ONSD was noted. Microsoft Excel was used for statistical analysis.

RESULTS

Patients with low GCS had higher mean ONSD values (6.4±1.0 mm). A highly significant association was found among the GCS, CT results, and ONSD measurements (P<0.001). Compared to CT scans, the bedside USG ONSD had 86.42% sensitivity and 64.29% specificity for detecting elevated ICP. The positive predictive value of ONSD to identify elevated ICP was 93.33%, and its negative predictive value was 45.00%. ONSD measurement accuracy was 83.16%.

CONCLUSIONS

Increased ICP can be accurately predicted by bedside USG measurement of ONSD and can be a valuable adjunctive tool in the management of TBI patients.

Effect of General Anesthesia on MR Optic Nerve Sheath Diameter in the Pediatric Population

BACKGROUND

Papilledema is thought to be the hallmark sign of increased intracranial pressure (ICP). Distension of the subarachnoid space within the optic nerve sheath is also commonly reported in MR studies as an indirect sign of increased ICP.

HYPOTHESIS

General anesthesia and positive pressure ventilation might result in changes in optic sheath diameter (OSD) observed on clinical brain MRI.

STUDY TYPE

Retrospective.

POPULATION

One hundred forty-five  patients (154 MRI scans, 7.3 years ± 5.1); 97 studies in the anesthesia group (4.4 years ± 3.4) of which 22 had papilledema, and 57 in the non-anesthesia group (12.3 years ± 3.2), of which 28 had papilledema.

FIELD STRENGTH/SEQUENCE

1.5T or 3.0T volumetric T2 images. T2 images were obtained from different vendors.

ASSESSMENT

OSD, optic nerve diameter (OND), and peri-optic cerebrospinal fluid (CSF) were measured manually on T2-weighted MR images for various population subgroups (with and without anesthesia; with or without papilledema). The correlation between these measurements and the clinical diagnosis of papilledema was evaluated via receiver operating characteristic (ROC) analysis.

STATISTICAL TESTS

Chi-square test; Mann-Whitney Test; Spearman's test and ROCs; Interclass correlation coefficient, P = 0.05.

RESULTS

General anesthesia resulted in significantly larger mean OSD in patients with or without papilledema (7.3 ± 1.0 mm vs. 6.1 ± 1.1 mm and 6.7 ± 1.0 mm vs. 5.4 ± 0.9 mm, respectively). In the non-anesthesia group, the average OSD values (6.1 ± 1.1 mm) were significantly higher in papilledema patients compared to non-papilledema patients (5.4 ± 0.9 mm), with larger peri-optic CSF rim (1.6 ± 0.4 mm vs. 1.3 ± 0.3 mm). In the anesthesia group, OND was significantly larger in papilledema patients (3.4 ± 0.4 mm vs. 3.1 ± 0.5 mm), though the average peri-optic CSF rim did not reach a significance in papilledema compared with non-papilledema patients (2.0 ± 0.3 mm vs. 1.8 ± 0.4 mm, P = 0.06). In patients with general anesthesia, peri-optic CSF rim had a limited correlation with increased ICP.

DATA CONCLUSION

In the pediatric population, imaging findings of increased OSD on brain MRI might be related to general anesthesia rather than increased ICP. The interpretation of optic nerve sheath distention should be reported cautiously in conjunction with anesthesia status, especially in the pediatric population.

EVIDENCE LEVEL

4 Technical Efficacy: 5.

The potential of point-of-care diagnostics to optimise prehospital trauma triage: a systematic review of literature

PURPOSE

In the prehospital care of potentially seriously injured patients resource allocation adapted to injury severity (triage) is a challenging. Insufficiently specified triage algorithms lead to the unnecessary activation of a trauma team (over-triage), resulting in ineffective consumption of economic and human resources. A prehospital trauma triage algorithm must reliably identify a patient bleeding or suffering from significant brain injuries. By supplementing the prehospital triage algorithm with in-hospital established point-of-care (POC) tools the sensitivity of the prehospital triage is potentially increased. Possible POC tools are lactate measurement and sonography of the thorax, the abdomen and the vena cava, the sonographic intracranial pressure measurement and the capnometry in the spontaneously breathing patient. The aim of this review was to assess the potential and to determine diagnostic cut-off values of selected instrument-based POC tools and the integration of these findings into a modified ABCDE based triage algorithm.

METHODS

A systemic search on MEDLINE via PubMed, LIVIVO and Embase was performed for patients in an acute setting on the topic of preclinical use of the selected POC tools to identify critical cranial and peripheral bleeding and the recognition of cerebral trauma sequelae. For the determination of the final cut-off values the selected papers were assessed with the Newcastle-Ottawa scale for determining the risk of bias and according to various quality criteria to subsequently be classified as suitable or unsuitable. PROSPERO Registration: CRD 42022339193.

RESULTS

267 papers were identified as potentially relevant and processed in full text form. 61 papers were selected for the final evaluation, of which 13 papers were decisive for determining the cut-off values. Findings illustrate that a preclinical use of point-of-care diagnostic is possible. These adjuncts can provide additional information about the expected long-term clinical course of patients. Clinical outcomes like mortality, need of emergency surgery, intensive care unit stay etc. were taken into account and a hypothetic cut-off value for trauma team activation could be determined for each adjunct. The cut-off values are as follows: end-expiratory CO2: < 30 mm/hg; sonography thorax + abdomen: abnormality detected; lactate measurement: > 2 mmol/L; optic nerve diameter in sonography: > 4.7 mm.

DISCUSSION

A preliminary version of a modified triage algorithm with hypothetic cut-off values for a trauma team activation was created. However, further studies should be conducted to optimize the final cut-off values in the future. Furthermore, studies need to evaluate the practical application of the modified algorithm in terms of feasibility (e.g. duration of application, technique, etc.) and the effects of the new algorithm on over-triage. Limiting factors are the restriction with the search and the heterogeneity between the studies (e.g. varying measurement devices, techniques etc.).

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.

Acil servise kafa travması ile başvuran hastaların yönetiminde optik sinir kılıf çapı ölçümünün değerlendirilmesi

Amaç: Literatürde ultrasonografik olarak optik sinir kılıf çapı ölçümünde saptanan değerler, kafa içi basınç artışı ile ilişkilendirilmektedir. Kafa içi basıncı ölçümü yapılan hastalar kritik alan ya da yoğun bakım hastalarıdır. Hafif ya da orta şiddette kafa travmasında patolojiyi ya da operasyona gidişi öngörmede ultrasonografi ile optik sinir kılıf çapı ölçümünün etkisi değerlendirilmemiştir. Çalışmamızda kafa travması ile başvuran hastaların, ultrasonografi ile optik sinir kılıf çapı ölçüm değerlerini, kraniyal tomografi bulguları ve hastaların klinik sonlanımları ile karşılaştırmayı hedefledik. Gereç ve Yöntem: Prospektif kesitsel planlanan çalışmada acil servise başvuran kafa travmalı hastalar hafif, orta ve şiddetli beyin hasarı olarak değerlendirildi. Çalışmaya dahil edilen hastaların ultrasonografi ile optik sinir kılıf çapları ölçüldü. Bulgular hastaların sonlanımları ve kraniyal tomografi özellikleri ile karşılaştırıldı. Bulgular: Acil servise kafa travması ile başvuran 58 hastanın incelemesinde en sık hafif şiddette travmatik beyin hasarına rastlandı. Hastaların %51,7 (30)’sinde yatış ya da operasyon ihtiyacı vardı. Optik sinir kılıf çapı ölçümlerinin ortalaması sağda 4,96±1,02 mm (3,1-7,3) solda ise 4,92±1,02 mm (3,3-7,8) olarak bulunmuştur. Optik sinir kılıf çapı ölçüm değerlerinin 5 mm ve üzerinde saptanması hastaneye yatışı öngörmede istatistiksel olarak anlamlı olarak saptandı (p

Ultrasonic optic disc height combined with the optic nerve sheath diameter as a promising non-invasive marker of elevated intracranial pressure

Background/aim: Patients with elevated intracranial pressure (ICP) tend to have optic disc edema and a thicker optic nerve sheath diameter (ONSD). However, the cut-off value of the optic disc height (ODH) for evaluating elevated ICP is not clear. This study was conducted to evaluate ultrasonic ODH and to investigate the reliability of ODH and ONSD for elevated ICP.

Methods: Patients suspected of having increased ICP and who underwent a lumbar puncture were recruited. ODH and ONSD were measured before lumbar puncture. Patients were divided according to elevated and normal ICP. We analyzed the correlations between ODH, ONSD, and ICP. ODH and ONSD cut-off points for the identification of elevated ICP were determined and compared.

Results: There were a total of 107 patients recruited for this study, 55 patients with elevated ICP and 52 with normal ICP. Both ODH and ONSD in the elevated ICP group were higher than in the normal group [ODH: median 0.81 (range 0.60–1.06) mm vs. 0.40 [0–0.60] mm, p &lt; 0.001; ONSD: 5.01 ± 0.37 mm vs. 4.20 ± 0.38 mm, p &lt; 0.001]. ICP was positively correlated with ODH (r = 0.613; p &lt; 0.001) and ONSD (r = 0.792; p &lt; 0.001). The cut-off values of ODH and ONSD for evaluating elevated ICP were 0.63 mm and 4.68 mm, respectively, with 73% and 84% sensitivity and 83% and 94% specificity, respectively. ODH combined with ONSD showed the highest value under the receiver operating characteristic curve of 0.965 with a sensitivity of 93% and a specificity of 92%.

Conclusion: Ultrasonic ODH combined with ONSD may help monitor elevated ICP non-invasively.

Ultrasonographic measurement of the optic nerve sheath diameter to detect intracranial hypertension: an observational study

OBJECTIVES

To evaluate the ultrasonographic measurement of optic nerve sheath diameter (ONSD) as a predictor of intracranial hypertension as compared to the invasive measurement of intracranial pressure (ICP).

DESIGN

Cross-sectional observational study.

SETTING

Intensive Care Unit (ICU) of two tertiary university hospitals in Montevideo, Uruguay.

PATIENTS

We included 56 adult patients, over 18 years of age, who required sedation, mechanical ventilation, and invasive ICP monitoring as a result of a severe acute neurologic injury (traumatic or non-traumatic) and had a Glascow Coma Score (GCS) equal to or less than 8 on admission to the ICU.

INTERVENTIONS

Ultrasonographic measurement of ONSD to detect intracranial hypertension.

MEASUREMENTS AND MAIN RESULTS

In our study, a logistic regression model was performed in which it was observed that the variable ONSD is statistically significant with a p value of 0.00803 (< 0.05). This model estimates and predicts the probability that a patient will have an ICP greater than 20 mmHg. From the analysis of the cut-off points, it is observed that a value of 5.7 mm of ONSD maximizes the sensitivity (92.9%) of the method (a greater number of individuals with ICP > 20 mmHg are correctly identified).

CONCLUSIONS

In sedated neurocritical patients, with structural Acute Brain Injury, the ONSD measurement correlates with the invasive measurement of ICP. It was observed that with ONSD values less than 5.7 mm, the probability of being in the presence of ICP above 20 mmHg is very low, while for ONSD values greater than 5.7 mm, said probability clearly increases.

Optic Nerve Changes Detected with Ocular Ultrasonography during Different Surgical Procedures: A Narrative Review

Ultrasonographic appraisal of the optic nerve sheath diameter has become popular in recent years as a useful diagnostic tool to detect intracranial pressure variations. Intracranial hypertension is a life-threatening disease with possible poor clinical outcomes and can be caused by a variety of neurological and non-neurological conditions. Considering the latter, increases in intracranial pressure have also been described during several surgical procedures. Ocular ultrasonography might be utilized to identify intracranial pressure increases by evaluating optic nerve sheath diameter variations. The aim of this review is to provide a wide overview on the use of the optic nerve ultrasound evaluation to detect intracranial pressure changes during surgical procedures, also discussing the pitfalls of the B-scan technique, the most widely used for such a purpose. PubMed medical database, Web of Science and Scopus were used to carry out this review. The present review showed that ocular ultrasonography could be considered a valuable diagnostic tool in the surgical setting to indirectly assess intracranial pressure. However, the use of the B-scan ultrasound should always be coupled with the standardized A-scan technique for a more accurate, precise and trustworthy ultrasound assessment.

Ultrasound Detection of Intracranial Hypertension in Brain Injuries

In recent years, the measurement of optic nerve sheath diameter with ultrasound to detect the presence of increased intracranial pressure has widely spread. It can be qualitatively and effectively used to identify intracranial hypertension. Intracranial pressure can rise due to acute injury, cerebral bleeding, hydrocephalus, brain tumors and other space-occupying abnormalities, and it is linked to a high death rate. The purpose of this review is to give a general overview of the most relevant scientific publications on ultrasonographic evaluation of the optic nerve in case of brain injuries published in the last 30 years, as well as to analyze the limits of the most extensively used B-scan approach. Fifty-two papers chosen from the PubMed medical database were analyzed in this review. Our findings revealed that ocular ultrasound is an useful diagnostic tool in the management of intracranial hypertension when it exceeds a certain value or after head trauma. As a result, an ultrasound of the optic nerve can be extremely helpful in guiding diagnosis and treatment. The blooming effect is one of the most critical restrictions to consider when using B-scan ultrasonography. Since amplitude-scan ultrasound, also known as A-scan, does not have this limit, these two diagnostic techniques should always be used together for a more full, accurate, and trustworthy ultrasound examination, ensuring more data objectivity.

Clinical Relevance of Transorbital Ultrasonographic Measurement of Optic Nerve Sheath Diameter (ONSD) for Estimation of Intracranial Pressure Following Cerebrospinal Fluid Diversion Surgery

Background and aim

Raised intracranial pressure (ICP) can be estimated by various invasive as well as non-invasive techniques. Optic nerve sheath diameter (ONSD ) is a bedside non-invasive technique for assessment of ICP as a regular follow-up tool and has added advantage over CT scan/MRI, which require patient transfer to the suite. Cerebrospinal fluid (CSF) diversion procedures such as a ventriculoperitoneal shunt or external ventricular drainage are commonly done to relieve symptoms of patients with raised ICP. Change in ICP measured through ONSD after CSF diversion procedures may guide the proper functioning of the shunt and immediate post-operative management. The present study was conducted to compare ONSD before and after CSF diversion procedures and correlate the ONSD with ICP. Our secondary objective was to determine the ONSD cutoff for the prediction of ICP >20mm Hg.

Setting, design, and methods

This prospective, comparative, and observational study was carried out at Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, India. The present study was conducted on 40 adult patients undergoing CSF diversion surgery under general anaesthesia. Ultrasonographic measurement of the ONSD was performed before induction, after induction, after endotracheal intubation, after completion of shunt surgery, and then every two hours for 12 hours. The direct ICP was measured by the neurosurgeon at the time of the initial ventricular puncture.

Statistical analysis

The Wilcoxon signed-rank test was used to compare pre and post variables. Qualitative variables were compared using the Chi-Square test/Fisher’s exact test as appropriate. Spearman's rho statistical measure of linear association was applied to measure the strength of linear association between parameters to show how close the points lie to a straight line. A p-value of <0.05 was considered statistically significant.

Results

The mean value of ONSD before induction and after induction was 6.36 ± 0.61 mm and 6.29 ±0.64 mm, respectively. After endotracheal intubation, ONSD slightly increased to 6.34 ±0.62mm, followed by a consistent decrease in ONSD values. The mean direct ICP recorded was 30.93±6.22 mmHg. Comparison of mean ONSD before induction, after induction, and after intubation with ONSD after surgery was statistically significant (p <0.001). We found a strong positive correlation between direct ICP and ONSD after intubation with a correlation coefficient of 0.969 (P <0.001). Receiver operating characteristic (ROC) curve analysis showed an ONSD cutoff of >5.85, predicted ICP>20 mmHg with a sensitivity of 92.3%, and specificity of 85.7%.

Conclusion

Measurement of ONSD by ultrasonography is an important and reliable tool in the assessment of normalization of ICP post CSF diversion procedure.

Accuracy of Optic Nerve Sheath Diameter Measurements in Pocket-Sized Ultrasound Devices in a Simulation Model

Introduction

Transorbital sonographic measurement of optic nerve sheath diameter (ONSD) is an emerging non-invasive technique for the identification and monitoring of intracranial hypertension. In recent years, new pocket ultrasound devices have become available, and it is uncertain if they have the resolution to measure such small structures appropriately as compared to their predecessors. In this study, we measure the performance of three ultrasound units on a simulation model to establish their precision and accuracy.

Methods

ONSD was measured by three expert point-of-care sonographers using ultrasound machines three times on each of seven discrete ONS model sizes ranging from 3.5 to 7.9 mm. Two pocket ultrasounds (IVIZ, Sonosite, and Lumify, Philips) and one standard-sized portable ultrasound (M-Turbo, Sonosite) were used. Measurements were analyzed for mean error and variance and tested for significance using blocked covariance matrix regression analyses.

Results

The devices differed in their variances (Lumify: 0.19 mm², M-Turbo: 0.26 mm², IVIZ: 0.34 mm²) and their mean error (Lumify: -0.05 mm, M-Turbo: 0.10 mm, IVIZ: -0.10 mm). The difference in mean error between users is not significant (p = 0.45), but there is a significant difference in mean error between devices (p = 0.02).

Conclusions

Accurate ONSD measurement is possible utilizing pocket-sized ultrasound, and in some cases, may be more accurate than larger portable ultrasound units. While the differences in these devices were statistically significant, all three were highly accurate, with one pocket device (Lumify) outperforming the rest. Further study in human subjects should be conducted prior to using pocket ultrasound devices for in vivo diagnosis of intracranial hypertension.

Optic Nerve Ultrasound Evaluation in Animals and Normal Subjects

In recent years, ultrasonographic measurement of the optic nerve sheath diameter (ONSD) has been widely used to identify the presence of increased intracranial pressure (ICP). Intracranial hypertension is a life-threatening condition that can be caused by various neurological and non-neurological disorders, and it is associated to poor clinical results. Ultrasonography could be used to qualitatively and efficiently detect ICP increases, but to reach this purpose, clear cut-off values are mandatory. The aim of this review is to provide a wide overview of the most important scientific publications on optic nerve ultrasound normal values assessment published in the last 30 years. A total of 42 articles selected from PubMed medical database was included in this review. Our analysis showed that ocular ultrasonography is considered to be a valuable diagnostic tool, especially when intracranial hypertension is suspected, but unfortunately this research provided conflicting results that could be due to the different ultrasound protocols. This is mainly caused by the use of B scan alone, which presents several limitations. The use of B-scan coupled with the standardized A-scan approach could give more accurate, and reliable ultrasound evaluation, assuring higher data objectivity.

Inter-rater reliability of optic nerve sheath diameter measurement using real-time ultrasonography

Objectives

Ultrasound measurement of the optic nerve sheath diameter (ONSD) is a rapid, non-invasive means to indirectly assess intracranial pressure. Previous research has demonstrated the ability of emergency physicians to measure ONSD accurately with bedside ultrasound when compared to CT scan or MRI, however the reliability of this measurement between two or more operators has been called into question (Hassen et al. in J Emerg Med 48:450–457, 2015; Shirodkar et al. in Ind J Crit Care Med 19:466–470, 2015). Given the need for accurate and precise measurement to use this as a screening exam, we sought to determine the inter-rater reliability between ONSD measurements obtained in real time by fellowship-trained emergency ultrasound physicians.

Methods

Three ultrasound fellowship-trained emergency physicians measured bilateral ONSD of 10 healthy volunteers using a high-frequency linear transducer. The physicians were blinded to the other scanners’ measurements, and no instructions were given other than to obtain the ONSD. Each sonographer measured the ONSD in real time and it was recorded by a research coordinator. All measurements were recorded in millimeters. Intraclass correlation coefficients (ICCs) were calculated to estimate the inter-rater reliability.

Results

A total of 60 measurements of ONSD were obtained. The average measurement was 4.3 mm (3.83–4.77). Very little variation was found between the three physicians, with a calculated ICC of 0.82 (95% confidence interval 0.63–0.92).

Conclusions

ONSD measurement obtained by ultrasound fellowship-trained emergency medicine physicians is a reliable measurement with a high degree of correlation between scanners.

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

BACKGROUND AND AIMS

Intracranial 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.

METHODS

In 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.

RESULTS

Ninety-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.

CONCLUSION

In 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.

Ultrasound measurement of the optic nerve sheath diameter in traumatic brain injury: a narrative review

Background : Raised intracranial pressure (ICP) needs to be investigated in various situations, especially in traumatic brain injury (TBI). Ultra-sonographic (US) measurement of the optic nerve sheath diameter (ONSD) is a promising noninvasive tool for assessing elevated ICP. Objectives : This narrative review aimed to explain the history of and indications forUS measurement of ONSD. We focused on the detection of elevated ICP after TBI and discussed the possible improvements in detection methods. Conclusions : US measurement of ONSD in TBI cases provides a qualitative but no quantitative assessment of ICP. Current studies usually calculate their own optimum cutoff value for detecting raised ICP based on the balance between sensitivity and specificity of the method when compared with invasive methods. There is no universally accepted threshold. We did not find any paper focusing on the prognosis of patients benefiting from it when compared with usual care. Another limitation is the lack of standardization. US measurement of ONSD cannot be used as the sole technique to detect elevated ICP and monitor its evolution, but it can be a useful tool in a multimodal protocol and it might help to determine the prognosis of patients in various situations.

Ultrasound of Optic Nerve Sheath Diameter and Stroke Outcomes

Supplemental Digital Content is available in the text.

We aimed at utilizing ocular ultrasound to determine its utility in predicting outcomes among stroke patients.

Comparative evaluation of optic nerve sheath diameter in patients undergoing laparoscopic cholecystectomy using low and standard pressures of gas insufflations

Background and Aims

Intra-abdominal insufflation of CO₂ is associated with an increase of intracranial pressure (ICP). We conducted this randomized control trial to compare the impact of low vs standard pressure pneumoperitoneum on ICP through the ultrasonographic estimation of the optic nerve sheath diameter (ONSD).

Material and Methods

Patients of age group 18-80 years planned for laparoscopic cholecystectomy were randomly allocated into two groups; group S (standard pressure of 12-16 mmHg) and group L (low pressure of 8-10 mmHg) on the basis of intra-abdominal pressures used for the surgery. All were administered general anesthesia and end-tidal carbon dioxide (ETCO₂) was maintained between 35 and 40 mmHg and peak airway pressures less than 35 cmH₂O. ONSD was measured in either eye at a point 3 mm posterior to the globe at following time intervals; baseline, 5 min after induction, 10 min after insufflation, 10 min after reverse Trendelenburg, intraoperatively during surgery and after exsufflation in the supine position.

Results

The demographic profile and operative times were comparable. ONSD was measured in 100 patients in each group for both the eyes and no patient had values above the cutoff value of 5.0 mm. No significant difference in the ONSD was observed at the above mentioned time intervals between the groups. There was a statistically significant lower value of the heart rate and mean arterial pressure in the low-pressure group.

Conclusion

Intra-abdominal insufflation of CO₂ at standard and low pressures does not increase ICP in short duration surgeries and thus both the pressures can be safely used in adult patients operated in reverse Trendelenburg position. Advantages of low pressure were limited to better hemodynamic control.

Point-of-care ultrasound in a pandemic: Practical guidance in COVID-19 units

The coronavirus disease 2019 (COVID-19) pandemic has stretched our healthcare system to the brink, highlighting the importance of efficient resource utilization without compromising healthcare provider safety. While advanced imaging is a great resource for diagnostic purposes, the risk of contamination and infection transmission is high and requires extensive logistical planning for intrahospital patient transport, healthcare provider safety, and post-imaging decontamination. This dilemma has necessitated the transition to more bedside imaging. More so than ever, during the current pandemic, the clinical utility and importance of point-of-care ultrasound (POCUS) cannot be overstressed. It allows for safe and efficient beside procedural guidance and provides front line providers with valuable diagnostic information that can be acted upon in real-time for immediate clinical decision-making. The authors have been routinely using POCUS for the management of COVID-19 patients both in the emergency department and in intensive care units turned into “COVID-units.” In this article, we review the nuances of using POCUS in a pandemic situation and maximizing diagnostic output from this bedside technology. Additionally, we review various methods and diagnostic uses of POCUS which can replace conventional imaging and bridge current literature and common clinical practices in critically ill patients. We discuss practical guidance and pertinent review of the literature for the most relevant procedural and diagnostic guidance of respiratory illness, hemodynamic decompensation, renal failure, and gastrointestinal disorders experienced by many patients admitted to COVID-units.

Mean value of B-mode optic nerve sheath diameter as an indicator of increased intracranial pressure: a systematic review and meta-analysis

Objectives

Timely diagnosis and treatment of increased intracranial pressure can decrease morbidity and prevent mortality. The present meta-analysis aims to determine the mean value of the ONSD measured in patients with various elevated ICP etiologies under different clinical settings, as well as comparing the value of ONSD between patients with and without elevated ICP.

Methods

This meta-analysis complied with the Preferred Reporting Items for Systematic Reviews and Meta-analysis Statement8. PubMed, Embase, and Cochrane Library were searched to identify ONSD measured by US for patients with increased ICP from establishment to October 2020.

Results

A total of 779 patients with elevated ICP among 22 studies were included in the present meta-analysis. Studies were published between 2003 and 2020. Eighteen were comparative (18/22, 81.8%), and four were single-armed study (4/22, 18.2%). Twenty were prospective studies (20/22, 90.9%). There was moderate-to-high heterogeneity based on the prediction ellipse area and variance logit of sensitivity and specificity.

Conclusions

The mean value of the ONSD among patients diagnosed with increased ICP was 5.82 mm (95% CI 5.58–6.06 mm). Variations were observed based on etiology of intracranial hypertension, clinical settings where ONSD was measured, and standards for diagnosing intracranial hypertension. The US-ONSD among patient with elevated ICP was significantly higher than the normal control. Although a cut-off value is not clearly determined, these mean values can be implemented to evaluate the sensitivity and specificity of US-ONSD in diagnosing intracranial hypertension in future studies.

The assessment of the effect of different intraabdominal pressures used for laparoscopic cholecystectomy surgery on optic nerve sheath diameter: a prospective observational cohort study

Background/aim

During laparoscopic cholecystectomy operations, increases in intraabdominal, intrathoracic, and intracranial pressures (ICP) can be seen after pneumoperitoneum created for surgical imaging. Orbital ultrasonography (USG), which has been developed in recent years, is a method that can evaluate the ICP by measuring the optic nerve sheath diameter (ONSD) from the eyeball. In our study, we aimed to evaluate whether different intraabdominal pressure values created during laparoscopic cholecystectomy operations correlate with ICP by measuring ONSD.

Materials and methods

The study included a total of 90 patients with American Society of Anesthesiologists (ASA) physical status classification I (ASA I) and II (ASA II) and ages from 18 to 65 years with laparoscopic cholecystectomy planned. After the patients were intubated, at the 5th min, bilateral ONSD measurements were performed. The same measurements were performed at the 15th and 30th min after CO2 insufflation and additionally 10 min after CO2 was released at the end of the operation. During intrabdominal CO2 insufflation, patients with 10 mmHg pressure applied comprised Group 1, patients with 12 mmHg pressure applied comprised Group 2, and patients with 14 mmHg pressure applied comprised Group 3.

Results

The study was completed with 89 patients, 51 female and 38 males. One patient was excluded from the study due to erroneous values. The variations in ONSD measured in the right-left eye before pneumoperitoneum and at the 15th and 30th min after abdominal CO2 insufflation were observed to be statistically significant (p < 0.01). In all three groups, the right and left eye ONSD values were not identified to be statistically significantly different (p > 0.01). A significant increase was observed in ONSD values in direct proportion to the increase in intraabdominal pressure in patients undergoing laparoscopic cholecystectomy surgery.

Conclusion

USG-guided ONSD measurements appear be a guide to ensure optimization of intraabdominal pressures and safe anesthesia administration for patients, especially those at risk of ICP increase, during laparoscopic surgery.

Real-time change of optic nerve sheath diameter after rebleeding of ruptured intracranial dissecting aneurysm

Ultrasonographic measurement of optic nerve sheath diameter (ONSD) has been validated to detect and monitor the increased intracranial pressure (IICP) in neurosurgical field. Especially, the ONSD has been known to reflect well the ICP in case of intracranial hemorrhage (ICH) occurring in the anterior circulation of intracranial vascular system, however it has not been well elucidated the role of ONSD in the posterior circulating vascular problems. A 43-year-old man presented with a subarachnoid hemorrhage with intraventricular hemorrhage due to rupture of dissecting aneurysm at right vertebral artery, and immediately performed the stent-assisted coil embolization. Two day after coil embolization, he became nearly alert without definite neurologic deficits. The ONSD was reduced from 5.8 mm to 5.5 mm. The 10^th postoperative days, the patient suddenly changed into stuporous mentality due to rebleeding of aneurysm. The ONSD was enlarged to 6.7 mm. We report a case of intimate relationship between ONSD and IICP after rupture of dissecting aneurysm located in posterior circulation.

Evaluation of Bedside Sonographic Measurement of Optic Nerve Sheath Diameter for Assessment of Raised Intracranial Pressure in Adult Head Trauma Patients

Aim:

The aim was to evaluate the use of bedside sonographic measurement of the optic nerve sheath diameter (ONSD) in the assessment of elevated intracranial pressure in patients with head injury coming to the emergency department (ED).

Methods:

A prospective study of ED patients presenting with a history of acute head injury, an ocular ultrasound was performed for ONSD measurement, followed by a computed tomography (CT) of the brain. Three measurements were taken for each eye, then, the mean binocular ONSD measurement for each patient was obtained to ensure accuracy. A mean bipolar ONSD >5 mm was considered abnormal.

Results:

A total of 175 patients were considered for the study. Of 175 patients, only 56 (32%) had intracranial pathology detected on CT brain with mean ONSD of 5.7 mm (standard deviation [SD]: 0.59). The mean ONSD for 119 (68%) patients, who had normal CT brain, was 4.5 mm (SD: 0.42). The mean ONSD measured for the right eye was 4.86 mm with SD 0.88, and the mean ONSD for the left eye was 4.90 mm with SD 0.85. When comparing ONSD measurement with CT findings of raised intracranial pressure, the ONSD sensitivity was 87.5% (95% confidence interval [CI]: 85%–96%) and specificity was 94.1% (95% CI: 85%–96%), with a positive predictive value of 87.5% and a negative predictive value of 94.1%. The area under the receiver operator characteristic curve obtained was 0.90 (95% CI: 0.85–0.96).

Conclusion:

The study has shown a bedside measurement of ONSD through sonography as an efficient tool to assess elevations in intracranial pressure in head injury patients.

Optic Nerve Sheath Diameter Measured by Point-of-Care Ultrasound and MRI

BACKGROUND AND PURPOSE

Ultrasound (US) measurement of the optic nerve sheath diameter (ONSD) and optic nerve diameter (OND) is a method frequently used to screen for an increased intracranial pressure. The aim of this study was to assess the accuracy of US measurements of ONSD and OND, when compared to magnetic resonance imaging (MRI) measurements as the criterion standard.

METHODS

In this prospective, single-institution study, orbital US was performed for those patients requiring an emergent brain MRI. ONSD and OND of both eyes were measured in the axial and coronal planes in straight gaze by US. ONSD and OND from brain and orbital MRI were measured by two neuroradiologists. Correlation and agreement between readings were assessed using Pearson's correlations.

RESULTS

Eighty-two patients met inclusion criteria. The mean axial and coronal ONSD in the MRI examinations was 5.6 and 5.7 mm at 3-5.9 mm behind the globe, respectively. The mean ONSD from the US measurements was 6.22 and 5.52 mm in the axial and coronal planes, respectively. The mean OND in US examinations was 4.31 mm (axial) and 3.68 mm (coronal). Axial versus coronal measurements of ONSD had a modest correlation in US assessment with an r² of .385 (P < .001) but there were no correlations between any of the US and MRI measurements.

CONCLUSIONS

In measuring ONSD and OND, US measurements showed a modest correlation between axial and coronal measurements, but no concordance was found between US and MRI in our setting.

Review: pathophysiology of intracranial hypertension and noninvasive intracranial pressure monitoring

Measurement of intracranial pressure (ICP) is crucial in the management of many neurological conditions. However, due to the invasiveness, high cost, and required expertise of available ICP monitoring techniques, many patients who could benefit from ICP monitoring do not receive it. As a result, there has been a substantial effort to explore and develop novel noninvasive ICP monitoring techniques to improve the overall clinical care of patients who may be suffering from ICP disorders. This review attempts to summarize the general pathophysiology of ICP, discuss the importance and current state of ICP monitoring, and describe the many methods that have been proposed for noninvasive ICP monitoring. These noninvasive methods can be broken down into four major categories: fluid dynamic, otic, ophthalmic, and electrophysiologic. Each category is discussed in detail along with its associated techniques and their advantages, disadvantages, and reported accuracy. A particular emphasis in this review will be dedicated to methods based on the use of transcranial Doppler ultrasound. At present, it appears that the available noninvasive methods are either not sufficiently accurate, reliable, or robust enough for widespread clinical adoption or require additional independent validation. However, several methods appear promising and through additional study and clinical validation, could eventually make their way into clinical practice.

Bedside Ultrasonographic Assessment of Optic Nerve Sheath Diameter As a Means of Detecting Raised Intracranial Pressure in Neuro-Trauma Patients: A Cross-Sectional Study

Background:

Optic nerve sheath diameter (ONSD) measurement is emerging as a noninvasive method to estimate raised ICP. It is helpful in situations where imaging of brain or direct ICP monitoring is not available or feasible. Use of ONSD is still limited, so this study was planned to determine whether the bedside sonographic measurement of ONSD can reliably predict elevated ICP in neuro-trauma patients.

Methodology:

After approval from Hospital Ethics Committee, this cross-sectional study was conducted in hundred traumatic brain injury (TBI) patients with suspected elevated ICP, admitted to neurosurgical ICU. The severity of brain injury was assessed according to Glasgow coma scale (GCS), initial CT scan findings, and revised trauma score (RTS). All patients underwent ONSD sonography of the eye and CT scan subsequently. ONSD of ≥5.0 mm was considered as a benchmark of raised ICP.

Results:

Mean ONSD of the study group with ONSD ≥5.0 mm was 5.6 ± 0.3 mm. ONSD was raised in 46% of patients, more so in patients with low GCS (3-6). The relationship of ONSD with GCS, CT scan findings, and RTS was highly significant. The sensitivity of the bedside sonographic measurement ONSD to detect raised ICP was 93.2% and specificity was 91.1% when compared with CT scan. Positive Predictive Value of the ONSD measurement was 89.1% and the negative predictive value was 94.4%.

Conclusion:

Ultrasonographic assessment of ONSD is a reliable modality to detect raised ICP in neurotrauma patients. It can be helpful in the early initiation of treatment of elevated ICP, thus preventing secondary brain damage.

Comparison of Two Techniques to Measure Optic Nerve Sheath Diameter in Patients at Risk for Increased Intracranial Pressure

OBJECTIVES

Intracranial pressure over 20 mm Hg is associated with poor neurologic prognosis, but measuring intracranial pressure directly requires an invasive procedure. Dilation of the optic nerve sheath on axial ultrasound of the eye has been correlated with elevated intracranial pressure, but optimal cutoffs have been inconsistent possibly related to the measurement technique. A coronal technique has been studied on healthy volunteers but not on patients with high intracranial pressure. We compared two measurement techniques (axial and coronal) in patients with suspected high intracranial pressure due to trauma, bleeding, tumor, or infection.

DESIGN

Prospective blinded observational study.

SETTING

Two tertiary referral center ICUs.

PATIENTS

Twenty adults admitted to the ICU at risk for increased intracranial pressure expected to receive invasive intracranial monitoring.

INTERVENTIONS

Ultrasound measurements of the optic nerve sheath in axial and coronal views either averaged between eyes or the highest in either eye.

MEASUREMENTS AND MAIN RESULTS

Coronal measurements showed less variability between each eye than axial measurements (mean difference 0.5 mm vs 1 mm; p = 0.03) and were associated with high intracranial pressure at first measurement and over 24 hours (area under the receiver operating characteristic range 0.7-0.8). Mean and highest axial measurements showed improved association with first (area under the receiver operating characteristic 0.87-0.94) and highest intracranial pressure measurement (area under the receiver operating characteristic 0.89-0.96) within 24 hours. A cutoff of highest axial measurement in either eye greater than 6.2 mm or mean axial measurement between eyes of 5.6 mm had a sensitivity of 100% in predicting high intracranial pressure over the following 24 hours.

CONCLUSIONS

The highest axial measurement of optic nerve sheath diameter in either eye is the most predictive of patients with high intracranial pressure in our population. This comparison of measurement techniques has not previously been described and should be further explored to set test cutoffs for ultrasound of the optic nerve sheath diameter.

OPTIC NERVE SHEATH SONOGRAPHY IS A PROMISING TOOL FOR ASSESSMENT OF RAISED INTRACRANIAL PRESSURE IN PATIENTS ADMITTED TO NEUROLOGICAL INTENSIVE CARE UNIT

Optic nerve sheath diameter (ONSD) enlargement is detectable in traumatic brain injury patients with raised intracranial pressure (ICP). The aim was to assess its value in neurological patients suspected to have increased ICP. Patient clinical imaging data and hospitalization outcome were analyzed. Patients were divided into groups according to brain pathology and level of consciousness with Glasgow Coma Score (GCS). Poor hospitalization outcome was assessed by modified Rankin scale (mRS) >3. Data obtained by ocular sonography performed in acute setting were compared with data of 100 control subjects. Data were expressed as mean ± SD. Intergroup comparison was performed by Student’s t-test. Data of 34 patients (63+16 years) were suitable for analysis, including 8 primary intracerebral hemorrhage (PICH), 8 subarachnoid hemorrhage (SAH), 12 PICH or SAH and intraventricular hemorrhage (IVH), 4 tumors and 2 ischemic strokes. The mean ONSD was 5.86+0.69 mm in patients versus 4.38+0.41 mm in controls (p<0.01). ONSD was 6.28+0.61 mm in patients with GCS <8 and 5.77+0.55 mm in other patients (p<0.05). ONSD was 5.72+0.59 mm in PICH versus 6.20+0.65 mm in PICH/SAH with IVH (p=0.1). ONSD was 5.73+0.38 mm in SAH in comparison to PICH/SAH with IVH (p=0.05). There was no statistically significant difference in optic nerve diameter between patients and controls (2.48+0.28 mm vs. 2.39+0.33 mm; p>0.05). Pronounced enlargement of ONSD was observed in patients with ICH or SAH with IVH, and in patients with GCS <8. Enlarged ONSD was associated with poor neurological outcome (mRS >3).

Role Of Point Of Care Ultrasound In The Diagnosis Of Retinal Detachment In The Emergency Department

Ocular complaints represent up to 3% of all emergency department (ED) visits. These presentations can result in permanent vision loss if not promptly diagnosed and treated. Recently, point of care ultrasound (POCUS) has been investigated for the evaluation of ocular pathology in the ED. Multiple studies have investigated the role that ultrasound may play in the early diagnosis of these patients. Ocular ultrasound can be used to visualize the structures of the eye and evaluate for pathology such as retinal detachment, vitreous hemorrhage and vitreous detachment. This comprehensive review aims to present current evidence for the efficacy and reliability of ED ocular ultrasound use in the detection of retinal detachment and additional ocular pathologies.

Association of optic nerve sheath diameter in ocular ultrasound with prognosis in patients presenting with acute stroke symptoms

Background

Measurement of optic nerve sheath diameter (ONSD) by means of ocular ultrasound (US), can diagnose elevated intracranial pressure (ICP). Stroke accompanied by elevated ICP might have a worse prognosis.

Objective

To determine the relationship of ONSD in ocular US with prognosis in acute stroke in the emergency department (ED).

Methods

Patients with acute presentations of stroke, presenting to the ED in 2017 (during six months), were enrolled in our study. US exam was performed on all of them and ONSD was determined in two longitudinal and transverse dimensions. Demographic data, rate of patients' admission in the ward or intensive care unit, one-month patients’ outcome and type of stroke were recorded. The relationship of mean ONSD was evaluated with study variables.

Results

In this study, 60 patients were enrolled. The mean ± SD ONSD in the deceased cases was 4.40 ± 0.64 mm and in the survived patients was 3.83 ± 0.56 mm. Youden index calculated ONSD>3.9 mm as the best cut-off point in mortality prognosis. It has a sensitivity of 83.3% and a specificity of 59.2%.

Conclusions

Increased ONSD had a direct relationship with mortality rate in acute stroke.

Neurocritical care monitoring of encephalopathic children with acute liver failure: A systematic review

Research on non-invasive neuromonitoring specific to PALF is limited. This systematic review identifies and synthesis the existing literature on non-invasive approaches to monitoring for neurological sequelae in patients with PALF. A series of literature searches were performed to identify all publications pertaining to five different non-invasive neuromonitoring modalities, in line with PRISMA guidelines. Each modality was selected on the basis of its potential for direct or indirect measurement of cerebral perfusion; studies on electroencephalographic monitoring were therefore not sought. Data were recorded on study design, patient population, comparator groups, and outcomes. A preponderance of observational studies was observed, most with a small sample size. Few incorporated direct comparisons of different modalities; in particular, comparison to invasive intracranial pressure monitoring was largely lacking. The integration of current evidence is considered in the context of the clinically significant distinctions between pediatric and adult ALF, as well as the implications for planning of future investigations to best support the evidence-based clinical care of these patients.

Role of Orbital Ultrasound in the Assessment of Clinically Detected Papilledema

BACKGROUND

Increased intracranial pressure (ICP) is frequently seen, and it is considered a serious problem that needs a careful assessment and management, especially by easy and least invasive modalities.

OBJECTIVE

The objective of the study is to assess the optic nerve sheath diameter (ONSD) using transorbital ultrasound (US) as a marker and indicator for diagnosing raised intracranial pressure.

PATIENTS AND METHODS

It is a prospective study that was carried out in Neurology and/or Ophthalmology Clinics, Baghdad Teaching Hospital in the Medical City Complex during the period from June 2016 to May 2017; in this study, 40 patients seeking medical help for other causes were considered to be a control group and the other 40 patients who were complaining of raised ICP symptoms and suggested of having optic disc swelling by ophthalmoscopy examination. All the patients and the control group were examined by transorbital US to measure the ONSD, and then, only the patients with symptoms of raised intracranial underwent a lumbar puncture (LP).

RESULTS

Pearson's correlation test was used, demonstrating a very significant correlation between the ultrasonographic ONSD and the measurements of LP (R > 0.9) and (P < 0.001). Transorbital US yielded high sensitivity (91.6%) with modest specificity (75%) and high accuracy (90.0%) of ONSD was considered the normal the cutoff value of (5 mm) obtained from the control group. The US also showed the crescent sign and the optic disc bulging with lower sensitivity than the ONSD (61.1% and 41.6%, respectively) but with very high specificity (100%) for both.

CONCLUSION

ONSD by transorbital ultrasonography is highly accurate, easily performed, and noninvasive procedure for the detection of raised ICP. Routine daily monitoring of ONSD could be of help in intensive care units when invasive ICP monitoring is not available or contraindicated; it also has a good role in early recognition of intracranial hypertension.

A noninvasive method for the estimation of increased intracranial pressure in patients with severe traumatic brain injury using optic nerve sheath diameter measured on computed tomography head

Background:

Measurement of optic nerve sheath diameter (ONSD) using ocular ultrasonography has shown a promise in predicting increased intracranial pressure (ICP). However, this method is dependent on operator technique and equipment availability. We propose an alternative method of measuring ONSD and Marshall score grading by utilizing initial computed tomography (CT) head obtained on admission. We believe that such a technique could help predict patients requiring an invasive ICP monitor on admission.

Methods:

Patients were retrospectively selected from the neurosurgery database of a level II trauma center. Control patients originated from a database of nontraumatic brain injury (TBI) patients with a negative CT head and no intracranial pathology. Study subjects included patients aged 18–90 years, who sustained a severe TBI requiring placement of an ICP monitor on admission. All patients had a non-contrast CT head before the placement of an ICP monitor. Patients receiving any intervention for decreasing suspected elevated ICPs and those with any documented orbital fractures before ICP monitor placement were excluded from the study. All measurements were performed by at least of two independent assessors.

Results:

A total of 242 patients were reviewed, of which 204 (100 control and 104 intervention) met inclusion criteria for this study. T he average age in the control group was 49.1 ± 22.9 years old while the average age of the intervention group was 36.9 ± 15.1 years (P < 0.0001). The average Glasgow Coma Scale was 7 in the intervention group. The average ONSD of the control group was 5.73 ± 0.58 mm compared to 6.76 ± 0.83 mm in the intervention group (P < 0.0001). Linear regression analysis demonstrated a statistically significant correlation between ONSD and opening ICP (r = 0.40, P < 0.001) and peak ICP (r = 0.31, P < 0.0001). An ONSD ≥6.0 mm + Marshall score ≥3 on initial CT head demonstrated a 92.5% sensitivity, 92.6% specificity, and 96.1% positive predictive value for developing an ICP ≥20 mmHg during hospitalization.

Conclusion:

Utilizing ONSD in combination with Marshall score grading on initial CT head is a strong predictor of elevated ICP. These criteria can be used in future studies to develop more objective criteria to guide ICP monitor placement.

Utilization of Ocular Ultrasound in the Evaluation of Posterior Reversible Encephalopathy Syndrome: A Case Report

Posterior reversible encephalopathy syndrome (PRES) is an infrequently encountered cause of altered mental status and seizure activity in the emergency setting. Diagnosis is often delayed by extensive testing and failure to consider PRES in the differential. Though MRI remains the gold standard for diagnosis, ultrasound-guided measurement of intra-ocular pressure is a safe, effective alternative that can expedite the diagnosis. The treatment of PRES involves the rapid reversal of offending agents and aggressive blood pressure management. The prognosis of PRES is favorable and neurologic sequelae are uncommon. This clinical case highlights the importance of the emergency physicians’ consideration of this pathology and the utilization of ultrasound as a non-invasive means of assessing intra-ocular pressure.

Ultrasonic Assessment of Optic Nerve Sheath to Detect Increased Intracranial Pressure

Purpose

Increased intracranial pressure (ICP) is one of the prevalent symptoms of trauma, especially traumatic headache, which requires quick action for the diagnosis and treatment. The optic nerve sheath diameter (ONSD) is a newly proposed technique for the detection of an increase in ICP. The aim of this study was to assess the efficacy of this new diagnostic method in patients with increased ICP induced by trauma.

Methods

This prospective study was conducted between December 2016 and February 2017. The patients with traumatic headache and who had been diagnosed with increased ICP using clinical signs and computed tomography scan were compared to the voluntary healthy group. In each patient, measurements were performed employing ultrasound three times on each eye in an axial region, and the mean of these sizes was obtained as the ONSD.

Results

A total of 112 participants were examined. The mean ONSD measurement of the patients and the voluntary healthy group was 6.01 ± 0.76 and 3.41 ± 0.56 mm in the right eye, 6.11 ± 0.75 and 3.39 ± 0.54 mm in the left eye, and 6.06 ± 0.75 and 4.02 ± 1.07 mm in both sides, respectively. The ONSD in the right and left sides had high and significant correlation in the patients (r = 0.929, P < 0.000) and voluntary healthy (r = 0.630, P < 0.000) group. The mean ONSD of one of the patients was 6.24 ± 0.56 mm, and in another patient with no clinical sign of increased ICP, the mean ONSD was 4.61 ± 0.09 mm.

Conclusions

Ultrasound performed on the diaphragm of the optic nerve with acceptable sensitivity can detect patients with an increase in ICP and can be efficacious in expediting the action needed to reduce ICP. Due to the sensitivity and specificity of the ultrasound and high accuracy of the diameter of optic nerve sheath in detecting increase in ICP, as well as considering the fact that ultrasound is a noninvasive and available technique; it can be performed at the patient's bedside.

Ocular Ultrasonography: A Useful Instrument in Patients with Trauma Brain Injury in Emergency Service

The measurement of the optic nerve sheath by ocular ultrasonography might be an indirect method to assess the quickly increase of the intracranial pressure in patients with moderate trauma brain injury, taking into account that an important proportion of these could develop the increase of the intracranial pressure in a hospital-acquired way. Therefore noninvasive, reliable, and convenient techniques are needed making the ocular ultrasonography a useful tool, due to the invasive monitoring elements' problems and the poor access to measure the intracranial pressure in emergency services. In spite of the limitations and few studies that exist to consider it as a possible early detection, this technique could work as a noninvasive one in the case that could not be possible to do invasive monitoring or when it is not recommended.

Effects of pneumoperitoneum and Trendelenburg position on intracranial pressure assessed using different non-invasive methods

BACKGROUND

The laparoscopic approach is becoming increasingly frequent for many different surgical procedures. However, the combination of pneumoperitoneum and Trendelenburg positioning associated with this approach may increase the patient's risk for elevated intracranial pressure (ICP). Given that the gold standard for the measurement of ICP is invasive, little is known about the effect of these common procedures on ICP.

METHODS

We prospectively studied 40 patients without any history of cerebral disease who were undergoing laparoscopic procedures. Three different methods were used for non-invasive estimation of ICP: ultrasonography of the optic nerve sheath diameter (ONSD); transcranial Doppler-based (TCD) pulsatility index (ICP_PI); and a method based on the diastolic component of the TCD cerebral blood flow velocity (ICP_FVd). The ONSD and TCD were measured immediately after induction of general anaesthesia, after pneumoperitoneum insufflation, after Trendelenburg positioning, and again at the end of the procedure.

RESULTS

The ONSD, ICP_FVd, and ICP_PI increased significantly after the combination of pneumoperitoneum insufflation and Trendelenburg positioning. The ICP_FVd showed an area under the curve of 0.80 [95% confidence interval (CI) 0.70-0.90] to distinguish the stage associated with the application of pneumoperitoneum and Trendelenburg position; ONSD and ICP_PI showed an area under the curve of 0.75 (95% CI 0.65-0.86) and 0.70 (95% CI 0.58-0.81), respectively.

CONCLUSIONS

The concomitance of pneumoperitoneum and the Trendelenburg position can increase ICP as estimated with non-invasive methods. In high-risk patients undergoing laparoscopic procedures, non-invasive ICP monitoring through a combination of ONSD ultrasonography and TCD-derived ICP_FVd could be a valid option to assess the risk of increased ICP.

ABCDE of prehospital ultrasonography: a narrative review

Prehospital point-of-care ultrasound used by nonradiologists in emergency medicine is gaining ground. It is feasible on-scene and during aeromedical transport and allows health-care professionals to detect or rule out potential harmful conditions. Consequently, it impacts decision-making in prioritizing care, selecting the best treatment, and the most suitable transport mode and destination. This increasing relevance of prehospital ultrasonography is due to advancements in ultrasound devices and related technology, and to a growing number of applications. This narrative review aims to present an overview of prehospital ultrasonography literature. The focus is on civilian emergency (trauma and non-trauma) setting. Current and potential future applications are discussed, structured according to the airway, breathing, circulation, disability, and environment/exposure (ABCDE) approach. Aside from diagnostic implementation and specific protocols, procedural guidance, therapeutic ultrasound, and challenges are reviewed.

Analysis of cerebral blood flow and intracranial hypertension in critical patients with non-hepatic hyperammonemia

Hyperammonemia in adults is generally associated with cerebral edema, decreased cerebral metabolism, and increased cerebral blood flow. The aim of this study was to evaluate the association between non-hepatic hyperammonemia and intracranial hypertension assessed by Doppler flowmetry and measurement of the optic nerve sheath. A prospective cohort study in critically ill patients hospitalized in intensive care units of a University Hospital between March 2015 and February 2016. Clinical data and severity scores were collected and the Glasgow coma scale was recorded. Serial serum ammonia dosages were performed in all study patients. Transcranial Doppler evaluation was carried out for the first 50 consecutive results of each stratum of ammonemia: normal (<35 μmol/L), mild hyperammonemia (≥35 μmol/L and < 50 μmol/L), moderate hyperammonemia (≥50 μmol/L and < 100 μmol/L), and severe hyperammonemia (≥100 μmol/L). The measurement of the optic nerve sheath was performed at the same time as the Doppler examination if the patient scored less than 8 on the Glasgow coma scale. There was no difference in flow velocity in the cerebral arteries between patients with and without hyperammonemia. Patients with hyperammonemia presented longer ICU stay. Optic nerve sheath thickness was higher in the group with severe hyperammonemia and this group presented an association with intracranial hypertension. Higher mortality was observed in the severe hyperammonemia group. There was an association between severe hyperammonemia and signs of intracranial hypertension. No correlation was found between ammonia levels and cerebral blood flow velocity through the Doppler examination.

Optic nerve sonographic examination to predict raised intracranial pressure in idiopathic intracranial hypertension: The cut-off points

Purpose Monitoring of raised intracranial pressure (ICP) in patients with idiopathic intracranial hypertension (IIH) is required to prevent secondary optic nerve damage. Sonographic measurement of the optic nerve sheath diameter (ONSD) is a noninvasive method to evaluate intracranial hypertension. Different ONSD cut-off values have been reported probably due to ethnic variations. Our aim was to determine optic nerve sonographic examination cut-off points to predict raised ICP in IIH patients. Methods This case-control study was conducted on 99 IIH post-pubertal female patients (both probable and definite) and 35 age- and sex-matched healthy volunteers. Sonographic ONSD and optic nerve diameter (OND) were obtained 3 mm behind the posterior edge of the globe in a horizontal plane via a 7-13 MHz linear probe. Lumbar puncture was then carried out on the patients. Results The opening cerebrospinal fluid pressure documented in the patient group was 279.64 ± 65.97 mm H₂O. A statistically significant difference was found between IIH patients and controls regarding ONSD. The best ONSD cut-off value indicating raised ICP was 6.05 mm with an area under the curve of 0.850 (95% confidence interval 0.805 to 0.894, 73.2% sensitivity and 91.4% specificity). Regarding OND/ONSD ratio, there was an insignificant difference between both groups. Conclusion Sonographic ONSD but not OND/ONSD ratio could offer a bedside adjunct or alternative indicator of elevated ICP in IIH patients. Ethnic differences, however, should be noted when using this parameter.

Optic nerve sheath diameter measured sonographically as non-invasive estimator of intracranial pressure: a systematic review and meta-analysis

PURPOSE

Although invasive intracranial devices (IIDs) are the gold standard for intracranial pressure (ICP) measurement, ultrasonography of the optic nerve sheath diameter (ONSD) has been suggested as a potential non-invasive ICP estimator. We performed a meta-analysis to evaluate the diagnostic accuracy of sonographic ONSD measurement for assessment of intracranial hypertension (IH) in adult patients.

METHODS

We searched on electronic databases (MEDLINE/PubMed^®, Scopus^®, Web of Science^®, ScienceDirect^®, Cochrane Library^®) until 31 May 2018 for comparative studies that evaluated the efficacy of sonographic ONSD vs. ICP measurement with IID. Data were extracted independently by two authors. We used the QUADAS-2 tool for assessing the risk of bias (RB) of each study. A diagnostic meta-analysis following the bivariate approach and random-effects model was performed.

RESULTS

Seven prospective studies (320 patients) were evaluated for IH detection (assumed with ICP > 20 mmHg or > 25 cmH₂O). The accuracy of included studies ranged from 0.811 (95% CI 0.678‒0.847) to 0.954 (95% CI 0.853‒0.983). Three studies were at high RB. No significant heterogeneity was found for the diagnostic odds ratio (DOR), positive likelihood ratio (PLR) and negative likelihood ratio (NLR), with I² < 50% for each parameter. The pooled DOR, PLR and NLR were 67.5 (95% CI 29‒135), 5.35 (95% CI 3.76‒7.53) and 0.088 (95% CI 0.046‒0.152), respectively. The area under the hierarchical summary receiver-operating characteristic curve (AUHSROC) was 0.938. In the subset of five studies (275 patients) with IH defined for ICP > 20 mmHg, the pooled DOR, PLR and NLR were 68.10 (95% CI 26.8‒144), 5.18 (95% CI 3.59‒7.37) and 0.087 (95% CI 0.041‒0.158), respectively, while the AUHSROC was 0.932.

CONCLUSIONS

Although the wide 95% CI in our pooled DOR suggests caution, ultrasonographic ONSD may be a potentially useful approach for assessing IH when IIDs are not indicated or available (CRD42018089137, PROSPERO).

Propofol attenuates the increase of sonographic optic nerve sheath diameter during robot-assisted laparoscopic prostatectomy: a randomized clinical trial

Background

Robot-assisted laparoscopic prostatectomy (RALP) requires pneumoperitoneum and the Trendelenburg position to optimize surgical exposure, which can increase intracranial pressure (ICP). Anesthetic agents also influence ICP. We compared the effects of propofol and sevoflurane on sonographic optic nerve sheath diameter (ONSD) as a surrogate for ICP in prostate cancer patients who underwent RALP.

Methods

Thirty-six patients were randomly allocated to groups receiving propofol (propofol group, n = 18) or sevoflurane (sevoflurane group, n = 18) anesthesia. The ONSD was measured 10 min after induction of anesthesia in the supine position (T1); 5 min (T2), 30 min (T3), and 60 min (T4) after establishing pneumoperitoneum and the Trendelenburg position; and at the end of surgery after desufflation in the supine position (T5). Respiratory and hemodynamic variables were also evaluated.

Results

The ONSD was significantly different between the propofol group and the sevoflurane group at T4 (5.27 ± 0.35 mm vs. 5.57 ± 0.28 mm, P = 0.007), but not at other time points. The ONSDs at T2, T3, T4, and T5 were significantly greater than at T1 in both groups (all P < 0.001). Arterial carbon dioxide partial pressure, arterial oxygen partial pressure, peak airway pressure, plateau airway pressure, systolic blood pressure, pulse pressure variation, body temperature and regional cerebral oxygen saturation, except heart rate, were not significantly different between the two groups.

Conclusions

The ONSD was significantly lower during propofol anesthesia than during sevoflurane anesthesia 60 min after pneumoperitoneum and the Trendelenburg position, suggesting that propofol anesthesia may help minimize ICP changes in robotic prostatectomy patients.

Trial registration

Clinicaltrials.gov identifier: NCT03271502. Registered August 31, 2017.

New Optic Nerve Sonography Quality Criteria in the Diagnostic Evaluation of Traumatic Brain Injury

Background

New sonographic quality criteria to optimize optic nerve sheath diameter (ONSD) measurements were suggested. The latter were correlated to elevated intracranial pressure (ICP) in traumatic brain injury (TBI).

Aim

We investigated whether ONSD measurements were correlated to simultaneous ICP measurements in severe TBI.

Methods

Forty patients with severe TBI (Marshall Scale ≥II and GCS ≤8) participated in the study. All patients had an intraparenchymal ICP catheter inserted, while ONSD was measured bilaterally, upon admission and over the next 48 hours, based on the new sonographic criteria. A total of 400 ONSD measurements were performed, while mean ONSD values of both eyes were used in the analysis.

Results

ONSD measurements were strongly correlated to ICP values (r=0.74, p < 0.0001). Receiver operator curve (ROC) analysis revealed that the ONSD cutoff value for predicting elevated ICP was 6.4 mm when using the mean of both eyes (AUC = 0.88, 95% CI = 0.80 to 0.95; sensitivity = 85.3%, specificity = 82.6%). Linear regression analysis nested models revealed that sex (p=0.006) and height (p=0.04) were significant predictors of ONSD values.

Conclusion

When applying the new sonographic quality criteria, ONSD is strongly correlated to ICP in severe TBI. Whether to use such criteria to monitor ONSD as a proxy for ICP trend in TBI remains to be further explored.

Comparison of Ocular Ultrasonography and Magnetic Resonance Imaging for Detection of Increased Intracranial Pressure

Background/aims

To evaluate and compare the performance of ocular ultrasonography (US) and magnetic resonance imaging (MRI) for detecting increased intracranial pressure (ICP) in patients with idiopathic intracranial hypertension (IIH).

Methods

Twenty-two patients with papilledema from IIH and 22 with pseudopapilledema were prospectively recruited based on funduscopic and clinical findings. Measurements of optic nerve sheath diameters (ONSDs) 3 mm behind the inner sclera were performed on B-scan US and axial T2-weighted MRI examinations. Pituitary-to-sella height ratio (pit/sella) was also calculated from sagittal T1-weighted MRI images. Lumbar puncture was performed in all patients with IIH and in five patients with pseudopapilledema.

Results

Average US and MRI ONSD were 4.4 (SD ± 0.7) and 5.2 ± 1.4 mm for the pseudopapilledema group and 5.2 ± 0.6 and 7.2 ± 1.6 mm for the papilledema group (p < 0.001). Average MRI pit/sella ratio was 0.7 ± 0.3 for the pseudopapilledema group and 0.3 ± 0.2 for the papilledema group (p < 0.001). Based on receiver-operator curve analysis, the optimal thresholds for detecting papilledema are US ONSD > 4.8 mm, MRI ONSD > 6.0 mm, and MRI pit/sella < 0.5. Combining a dilated US ONSD or MRI ONSD with a below-threshold MRI pit/sella ratio yielded a sensitivity of 73% and specificity of 96% for detecting IIH. Adding the US ONSD to the MRI ONSD and pit/sella ratio only increased the sensitivity by 5% and did not change specificity.

Conclusion

US and MRI provide measurements of ONSD that are well-correlated and sensitive markers for increased ICP. The combination of the ONSD and the pit/sella ratio can increase specificity for the diagnosis of IIH.

Effect of Positive End-Expiratory Pressure on Optic Nerve Sheath Diameter in Pediatric Patients with Traumatic Brain Injury

Background:

The peak incidence of traumatic brain injury (TBI) has been reported in children and young adults. Intracranial pressure (ICP) as an important component can be measured with invasive technique, whereas noninvasive measurement of optic nerve sheath diameter (ONSD) is increasingly becoming popular. Positive end-expiratory pressure (PEEP) has been found to affect ICP. We aimed to compare the effect of different values of PEEP on ONSD and to obtain the correlation with ICP measurement.

Setting and Design:

Neurointensive Care Unit, Trauma Center, AIIMS, New Delhi.

Materials and Methods:

Pediatric patients with TBI, of either gender, between 1 and 18 years of age in whom ICP was measured using intraparenchymal Codman catheter admitted in neurointensive care unit were enrolled. For this crossover study, the sequence of PEEP (0 or 3 or 5 cm H₂O) was randomized and ONSD was measured. The mean of three ONSD values was taken as final value.

Statistical Method:

The ONSD, ICP, peak airway pressure, and hemodynamic parameters at various stages were compared using two-way repeated measures analysis of variance with Bonferroni correction. A P value of <0.05 was considered to be significant.

Results:

Ten patients (seven males, three females) participated in the study. There was no significant increase in ONSD values when PEEP was increased from 0 to 3 cm H₂O. However, increase in PEEP values from 3 to 5 cm H₂O showed significantly increased ONSD values.

Conclusion:

PEEP up to 3 cm H₂O can be safely applied in pediatric patients following TBI. Further increment of PEEP might accentuate the ICP values.