Ultrasonographic Optic Nerve Sheath Diameter Is Correlated With Arterial Carbon Dioxide Concentration During Reperfusion in Liver Transplant Recipients

Relation between partial arterial carbon dioxide pressure and pH value and optic nerve sheath diameter: a prospective self-controlled non-randomized trial study

OBJECTIVE

This study aims to determine if there is a correlation between differences in optic nerve sheath diameter (ONSD) and changes in PaCO2 and pH values that were measured in the arterial blood gas (ABG) before and after treatment in COPD patients with acute hypercarbic respiratory failure (AHRF).

MATERIALS AND METHODS

This study serves as a prospective self-controlled non-randomized trial study conducted in the emergency clinic of a tertiary hospital. Forty-four patients with COPD, who were found to have acidosis and hypercarbia in ABG and had an indication for non-invasive mechanic ventilation (NIMV), were analyzed prospectively. Demographic information, vital findings, initial ABG values, the ONSD measurement (before the NIMV treatment), consciousness state, and the ABG results obtained in the second hour of the monitoring and the ONSD measurement (after the NIMV treatment) were recorded.

RESULTS

In this study, 13 (29.5%) of the patients were female and 31 (70.5%) were male. The age distribution was evaluated as 68.3 ± 9.2 years; the minimum age was 54 and the maximum was 91. A high level of positively significant correlation was found between the mean ONSD and PaCO2 (p < 0.0001). There is a high fit (0.72) between the mean ONSD and PaCO2. A moderate level of negatively significant correlation was found between the mean ONSD and the pH (p < 0.0001). However, there is an insignificant low fit (0.32) between the mean ONSD and the pH.

CONCLUSION

The ONSD changed significantly and in a highly correlated manner to acute changes in PaCO2 levels.

Intraoperative Optic Nerve Sheath Diameter as a Predictor of Early Tacrolimus Neurotoxicity after Living Donor Liver Transplantation

BACKGROUND

During liver transplantation, graft reperfusion triggers cerebral hyperemia, increases intracranial pressure, and disrupts the blood-brain barrier, thereby increasing the risk for immunosuppression neurotoxicity. Therefore, we tested the intraoperative optic nerve sheath diameter (ONSD) for predicting tacrolimus neurotoxicity after liver transplantation.

BASIC PROCEDURES

We prospectively included 100 adult patients who underwent living donor liver transplantation. The ultrasonographic ONSD 5 min after reperfusion was used as the index test, whereas the occurrence of early tacrolimus neurotoxicity was used as the reference. The area under the receiver operating characteristic curve (AUROC) was used to estimate the ONSD prediction accuracy. We reported the specificity and sensitivity of ONSD 5 and 30 min after reperfusion. Cutoffs were derived from the ROC curves. In addition, we used regression to control for confounders while testing the association between the ONSD and tacrolimus neurotoxicity.

MAIN FINDINGS

The AUROC at T3 was 0.74 (95% confidence interval (CI), 0.63-0.85, P < 0.001). An ONSD of ≥6.4 mm at T3 had an 86% sensitivity (95% CI, 68%-96%) and 53% specificity (95% CI, 41%-65%). An ONSD of ≥6.4 mm at T3 had an adjusted odds ratio for tacrolimus neurotoxicity of 6.3 (95% CI, 1.9-21, P = 0.003).

CONCLUSIONS

This data indicates that intraoperative ultrasonic ONSD after reperfusion can predict tacrolimus neurotoxicity after liver transplantation.

TRIAL REGISTRATION

NCT03799770; registered on January 1st, 2019.

Akut solunum yetmezliğinde optik sinir kılıf çapının prognostik önemi

Purpose: The primary aim of this study was to determine the role of the optic nerve sheath diameter (ONSD) measured using ultrasonography in the differentiation of hypoxemic respiratory failure and hypercarbic respiratory failure. The secondary aim was to determine the value of ONSD in predicting the clinical outcome in hypercarbic patients. Materials and Methods: Non-traumatic adult patients presenting with dyspnea were included in this study. Arterial blood gas and concurrent ONSD measurements were obtained from all patients included in the study during presentation and at the second hour of treatment. The patients were divided into two groups - hypoxic and hypercarbic respiratory failure. An equivalent number of healthy volunteers were enrolled as the control group. Result: Mean ONSD values were 3.8±0.2 mm in the 24 patients with type 1 respiratory failure, 5.2 ± 0.5 mm in the 25 patients with type 2 respiratory failure, and 3.9±0.3 mm in the healthy controls. The ONSD of the hypercarbic patients was statistically significantly greater than that of the hypoxic patients and healthy volunteers. The ONSD of the hypercarbic patients was 5.2±0.5mm at baseline and 4.4±0.6 mm after treatment, the difference being statistically significant. However, the difference in ONSD was not statistically significant in predicting hospitalization and mortality. Conclusion: Sonographically measured ONSD may be an effective parameter in the differential diagnosis of type 1 and 2 respiratory failure. ONSD values changed significantly with treatment in patients with type 2 respiratory failure.

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.

Ultrasonographic optic nerve sheath diameter correlation with ICP and accuracy as a tool for noninvasive surrogate ICP measurement in patients with decompressive craniotomy

OBJECTIVE

Increased intracranial pressure (ICP) results in enlarged optic nerve sheath diameter (ONSD). In this study the authors aimed to assess the association of ONSD and ICP in severe traumatic brain injury (TBI) after decompressive craniotomy (DC).

METHODS

ONSDs were measured by ocular ultrasonography in 40 healthy control adults. ICPs were monitored invasively with a microsensor at 6 hours and 24 hours after DC operation in 35 TBI patients. ONSDs were measured at the same time in these patients. Patients were assigned to 3 groups according to ICP levels, including normal (ICP ≤ 13 mm Hg), mildly elevated (ICP = 14-22 mm Hg), and severely elevated (ICP > 22 mm Hg) groups. ONSDs were compared between healthy control adults and TBI cases with DC. Then, the association of ONSD with ICP was analyzed using Pearson's correlation coefficient, linear regression analysis, and receiver operator characteristic curves.

RESULTS

Seventy ICP measurements were obtained among 35 TBI patients after DC, including 25, 27, and 18 measurements in the normal, mildly elevated, and severely elevated ICP groups, respectively. Mean ONSDs were 4.09 ± 0.38 mm in the control group and 4.92 ± 0.37, 5.77 ± 0.41, and 6.52 ± 0.44 mm in the normal, mildly elevated, and severely elevated ICP groups, respectively (p < 0.001). A significant linear correlation was found between ONSD and ICP (r = 0.771, p < 0.0001). Enlarged ONSD was a robust predictor of elevated ICP. With an ONSD cutoff of 5.48 mm (ICP > 13 mm Hg), sensitivity and specificity were 91.1% and 88.0%, respectively; a cutoff of 5.83 mm (ICP > 22 mm Hg) yielded sensitivity and specificity of 94.4% and 81.0%, respectively.

CONCLUSIONS

Ultrasonographic ONSD is strongly correlated with invasive ICP measurements and may serve as a sensitive and noninvasive method for detecting elevated ICP in TBI patients after DC.

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.

Dexmedetomidine attenuates the increase of ultrasonographic optic nerve sheath diameter as a surrogate for intracranial pressure in patients undergoing robot-assisted laparoscopic prostatectomy: A randomized double-blind controlled trial

BACKGROUND

Pneumoperitoneum and steep Trendelenburg position during robot-assisted laparoscopic prostatectomy (RALP) can increase intracranial pressure (ICP). Dexmedetomidine, a highly selective alpha-2 adrenergic receptor agonist, can cause cerebral vasoconstriction and decrease cerebral blood flow by stimulating the postsynaptic alpha-2 adrenergic receptors on cerebral blood vessels. However, the effects of dexmedetomidine on ICP are controversial and have not been evaluated during RALP under the establishment of pneumoperitoneum in the steep Trendelenburg position. Therefore, we evaluated the effect of dexmedetomidine on optic nerve sheath diameter (ONSD) as a surrogate for assessing ICP during RALP.

METHODS

Patients were randomly allocated to receive dexmedetomidine (n = 63) (loading dose, 1 μg/kg for 10 minutes and continuous infusion, 0.4 μg/kg/hr) or normal saline (n = 63). The ONSD was measured at 10 minutes after induction of anesthesia in the supine position (T1), 30 minutes (T2) and 60 minutes (T3) after establishment of pneumoperitoneum in the steep Trendelenburg position, and at closing the skin in the supine position (T4). Hemodynamic and respiratory variables were measured at every time point.

RESULTS

ONSDs at T2, T3, and T4 were significantly smaller in the dexmedetomidine group than in the control group (5.26 ± 0.25 mm vs 5.71 ± 0.26 mm, 5.29 ± 0.24 mm vs 5.81 ± 0.23 mm, and 4.97 ± 0.24 mm vs 5.15 ± 0.28 mm, all P <.001). ONSDs at T2, T3, and T4 were significantly increased compared to T1 in both groups. Hemodynamic and respiratory variables, except heart rate, did not significantly differ between the 2 groups. The bradycardia and atropine administration were not significantly different between the 2 groups.

CONCLUSION

Dexmedetomidine attenuates the increase of ONSD during RALP, suggesting that intraoperative dexmedetomidine administration may effectively attenuate the ICP increase during pneumoperitoneum in the Trendelenburg position.

A study to evaluate effect of PEEP and end-tidal carbon dioxide on optic nerve sheath diameter

Background and Aims:

PEEP is commonly used to improve postoperative respiratory outcomes in surgical and ICU patients. It is thought to increase ICP by impending CSF outflow and cerebral venous drainage. Hyperventilation is used to decrease ICP in patients having intracranial hypertension. We investigated the effect of various levels of PEEP and EtCO₂ on ONSD as an indirect predictor of ICP in patients undergoing surgery under GA.

Methods:

After induction, different levels of PEEP and EtCO₂ were applied to 50 patients. Sonographic ONSD was measured 5 minutes after stabilization of each new setting. Haemodynamic parameters like pulse, SpO₂, BP were also recorded. Quantitative variables were expressed as Mean ± SD and compared across between follow-ups using paired t-test. Qualitative variables were expressed in number and percentage.

Results:

Baseline ONSD was 0.44 ± 0.06 cm. It increased significantly to 0.45 ± 0.07 cm, 0.47 ± 0.07 cm and 0.49 ± 0.07 cm after applying PEEP of 8, 12 and 15 cm H₂O PEEP, respectively. It significantly decreased to 0.42 ± 0.06 cm, 0.41 ± 0.06 cm and 0.40 ± 0.06 cm after hyperventilation, EtCO₂ range 35–37, 32–34 and 29–31 mm Hg. Results were statistically significant but clinically not significant.

Conclusion:

We conclude that there are acute and dynamic alterations in ONSD in response to hyperventilation and presence of PEEP in anaesthetised patients. Ocular sonography may be used as a reliable indicator of acute variations in ICP.

The Importance of Optic Nerve Sheath Diameter in Post-dural Puncture Headache Diagnosis and Follow-up

Introduction

Intracranial hypotension-induced headache is caused by reduction in the volume or pressure of the cerebrospinal fluid. Headache might develop secondary to lumbar puncture. In the detection of intracranial hypotension, when compared with invasive methods, there is a good correlation between ultrasound-guided optic nerve sheath diameter (ONSD) and invasive methods. The aim of the study is to investigate the effectiveness of alteration in ultrasound-guided ONSD in diagnosis and treatment of post-dural puncture headache (PDPH) induced by intracranial hypotension.

Methods

Our study involved 40 adult patients aged 18-65 scheduled to have surgery under spinal anesthesia. Patients were randomized into two groups consisting of PDPH (Group H, n=20), and control (Group C, n=20) during their post-operative period. The ONSDs of patients were measured via ultrasound, pain severity with Numeric Rating Scale (NRS) pre-operatively, at 24^th, 26^th and 48^th hours post-operatively. Conservative treatment was started on the 24^th hour in PDPH group.

Results

There was no significant difference between the groups in terms of demographic data. In Group H, the reduction in ONSD from 3.8±0.2 to 3.2±0.3 mm in postoperative 24^th hours (p=0.001) and an increase to 4.4±0.3 mm in postoperative 48^th hours (p=0.03) were significant. When compared to postoperative 24^th hours, ONSD in postoperative 26^th (3.9±0.3 mm) and 48^th hours (4.4±0.3 mm) were significantly higher (p=0.007 and p=0.01; respectively) in Group H. NRS values in Group H at postoperative 26^th and 48^th hours were significantly lower compared to postoperative 24^th hours (p=0.001).

Conclusion

We believe that serial measurement of ultrasound-guided ONSD, which is considered a simple and non-invasive procedure in the determination of intracranial pressure changes, is a more objective method in the follow-up of intracranial hypotension-induced headache compared to NRS evaluation.

Effects of acute controlled changes in end-tidal carbon dioxide on the diameter of the optic nerve sheath: a transorbital ultrasonographic study in healthy volunteers

Transorbital ultrasonographic measurement of the diameter of the optic nerve sheath is a non-invasive, bed-side examination for detecting raised intracranial pressure. However, the ability of the optic nerve sheath diameter to predict acute changes in intracranial pressures remains unknown. The aim of this study was to examine the dynamic changes of the optic nerve sheath diameter in response to mild fluctuations in cerebral blood volume induced by changes in end-tidal carbon dioxide. We studied 11 healthy volunteers. End-tidal carbon dioxide was controlled by a model-based prospective end-tidal targeting system (RespirAct™). The volunteers' end-tidal carbon dioxide was targeted and maintained for 10 min each at normocapnia (baseline); hypercapnia (6.5 kPa); normocapnia (baseline 1); hypocapnia (3.9 kPa) and on return to normocapnia (baseline 2). A single investigator repeatedly measured the optic nerve sheath diameter for 10 min at each level of carbon dioxide. With hypercapnia, there was a significant increase in optic nerve sheath diameter, with a mean (SD) increase from baseline 4.2 (0.7) mm to 4.8 (0.8) mm; p < 0.001. On return to normocapnia, the optic nerve sheath diameter rapidly reverted back to baseline values. This study confirms dynamic changes in the optic nerve sheath diameter with corresponding changes in carbon dioxide, and their reversibly with normocapnia.

A unique method for estimating the reliability learning curve of optic nerve sheath diameter ultrasound measurement

Background

Optic nerve sheath diameter (ONSD) measurement using ultrasound has been proposed as a rapid, non-invasive, point of care technique to estimate intra-cranial pressure (ICP). Ultrasonic measurement of the optic nerve sheath can be quite challenging and there is limited literature surrounding learning curves for this technique. We attempted to develop a method to estimate the reliability learning curve for ONSD measurement utilizing a unique definition of reliability: a plateau in within-subject variability with unchanged between-subject variability.

Methods

As part of a previously published study, a single operator measured the ONSD in 120 healthy volunteers over a 6-month period. Utilizing the assumption that the four measurements made on each subject during this study should be equal, the relationship of within-subject variance was described using a quadratic-plateau model as assessed by segmental polynomial (knot) regression.

Results

Segmental polynomial (knot) regression revealed a plateau in within-subject variance after the 21st subject. However, there was no difference in overall mean values [3.69 vs 3.68 mm (p = 0.884)] or between-subject variance [14.49 vs 11.92 (p = 0.54)] above or below this cutoff.

Conclusions

This study suggests a significant finite learning curve associated with ONSD measurements. It also offers a unique method of calculating the learning curve associated with ONSD measurement.

Sonographic Optic Nerve Sheath Diameter: A Simple and Rapid Tool to Assess the Neurologic Prognosis After Cardiac Arrest

BACKGROUND AND PURPOSE

The early prediction of hypoxic encephalopathy after cardiac arrest is challenging. Measurement of the optic nerve sheath diameter (ONSD) by using sonography is a straightforward, noninvasive technique to detect an increased intracranial pressure, which can even be conducted at the bedside. However, it remains unknown whether or not sonographic ONSD measurement is valuable as a prognostic indicator of hypoxic encephalopathy.

METHODS

Seventeen patients after cardiac arrest were retrospectively enrolled in this study. ONSD measurements 3 mm behind the papilla were recorded. A Glasgow Outcome Scale score of 4 or above was considered to indicate a favorable prognosis.

RESULTS

The mean ONSD associated with a favorable prognosis was 5.0 mm (4.4-6.1 mm). The ONSD associated with a poor prognosis was 6.1 mm (5.4-7.2 mm). ONSD less than or equal to 5.4 mm was an indicator of a favorable prognosis, with a sensitivity of 83%, specificity of 73%, positive likelihood ratio of 3.1, and negative likelihood ratio of .23.

CONCLUSIONS

Sonographic ONSD measurement is a simple, rapid technique to assess the neurological prognosis after cardiac arrest.

Sonographic optic nerve sheath diameter as a surrogate measure for intracranial pressure in anesthetized patients in the Trendelenburg position

BACKGROUND

It remains to be elucidated whether the Trendelenburg position increases intracranial pressure (ICP). ICP can be evaluated by measuring the sonographic optic nerve sheath diameter (ONSD). We investigated the effect of the isolated Trendelenburg position on ONSD in patients undergoing robot-assisted laparoscopic radical prostatectomy. Additionally, we evaluated the effect of the Trendelenburg position combined with pneumoperitoneum on ONSD.

METHODS

Twenty-one patients scheduled for robot-assisted laparoscopic radical prostatectomy were enrolled. Sonographic ONSDs and hemodynamic parameters were measured at specific time points: in the supine position after induction of anesthesia, 3 min after the steep Trendelenburg position (35° incline), 3 min after the steep Trendelenburg position combined with pneumoperitoneum, and in the supine position after desufflation of the pneumoperitoneum.

RESULTS

The ONSD 3 min after the steep Trendelenburg position was significantly higher than that of the supine position after induction of anesthesia (5.1 ± 0.3 mm vs. 4.5 ± 0.4 mm). In addition, the ONSD 3 min after the steep Trendelenburg position combined with pneumoperitoneum was higher than that of the supine position after induction of anesthesia (4.9 ± 0.4 mm vs. 4.5 ± 0.4 mm). The ONSD in the supine position after desufflation of the pneumoperitoneum was similar to that in the supine position after induction of anesthesia.

CONCLUSIONS

Use of the isolated steep Trendelenburg position, for even a short duration, increased the sonographic ONSD, providing a better understanding of the effect of only a transient steep Trendelenburg position on ONSD as a surrogate measure for ICP.

Dynamic optic nerve sheath diameter responses to short-term hyperventilation measured with sonography in patients under general anesthesia

BACKGROUND

Rapid evaluation and management of intracranial pressure (ICP) can help to early detection of increased ICP and improve postoperative outcomes in neurocritically-ill patients. Sonographic measurement of optic nerve sheath diameter (ONSD) is a non-invasive method of evaluating increased intracranial pressure at the bedside. In the present study, we hypothesized that sonographic ONSD, as a surrogate of ICP change, can be dynamically changed in response to carbon dioxide change using short-term hyperventilation.

METHODS

Fourteen patients were enrolled. During general anesthesia, end-tidal carbon dioxide concentration (ETCO2) was decreased from 40 mmHg to 30 mmHg within 10 minutes. ONSD, which was monitored continuously in the single sonographic plane, was repeatedly measured at 1 and 5 minutes with ETCO2 40 mmHg (time-point 1 and 2) and measured again at 1 and 5 minutes with ETCO2 30 mmHg (time-point 3 and 4).

RESULTS

The mean ± standard deviation of ONSD sequentially measured at four time-points were 5.0 ± 0.5, 5.0 ± 0.4, 3.8 ± 0.6, and 4.0 ± 0.4 mm, respectively. ONSD was significantly decreased at time-point 3 and 4, compared with 1 and 2 (P < 0.001).

CONCLUSIONS

The ONSD was rapidly changed in response to ETCO2. This finding may support that ONSD may be beneficial to close ICP monitoring in response to CO2 change.