Noninvasive estimation of raised intracranial pressure using ocular ultrasonography in liver transplant recipients with acute liver failure -A report of two cases-

Mannitol Is Comparable to Hypertonic Saline for Raised Intracranial Pressure in Acute Liver Failure (MAHAL Study): A Randomized Controlled Trial

BACKGROUND

Raised intracranial pressure (ICP) due to cerebral edema (CE) is central to development of hepatic encephalopathy in acute liver failure (ALF). Mannitol (MT) and hypertonic saline (HS) have been shown to improve CE. We compared the efficacy and safety of the 2 modalities.

METHODS

ALF with CE was prospectively randomized in an open study to receive either 5 mL/kg of either 3% HS, as continuous infusion; titrated every 6 hourly to achieve serum sodium of <160 (Group A; n = 26) or 1 g/kg of 20% MN as a IV bolus, repeated every 6 hourly (Group B; n = 25) in addition to standard ALF care. Primary end-point was reduction of ICP defined as optic nerve sheath diameter <5 mm and middle cerebral arterial pulsatility index <1.2 at 12 h.

RESULTS

Fifty-one patients with ALF, hepatitis E being commonest (33.3%), median jaundice to HE interval of 8 (1-16) days, were randomized to HS (n = 26) or MN (n = 25). Baseline characteristics were comparable including King's college criteria (>2: 38.4% vs.40%). Overall, 61.5% patients in the HS and 56% in the MN group showed reduction in ICP at 12 h (p = 0.25). Rebound increase in ICP indices was noted in 5 (20%) patients in MT and none in HS (p < 0.05) group. New onset acute kidney injury was common in the MT group than in the HS group. The ICU stay and 28-day transplant-free survival were not different between the groups.

CONCLUSIONS

While both agents had comparable efficacy in reducing ICP and mortality in ALF patients was comparable, HS was significantly better in preventing reducing rebound CE with lower renal dysfunction.

Dynamic Optic Nerve Sheath Diameter (ONSD) guided management of raised intracranial pressure in pediatric acute liver failure

BACKGROUND AND AIMS

The objectives were to evaluate the role of optic nerve sheath diameter (ONSD) to detect raised intracranial pressure (ICP) in pediatric acute liver failure (PALF), study the variations in ONSD with ICP-lowering measures and to evaluate its prognostic role.

METHODS

PALF with clinical evidence of raised ICP were enrolled as cases, while those without raised ICP were control group A. ONSD was measured at admission and repeated regularly. It was also measured at time of each new episode of raised ICP and 2 h after the management of such episode.

RESULTS

31 PALF with raised ICP were included as cases and 15 without as control group A. ONSD was significantly higher in cases: 5 mm (IQR: 4.7-5.4) as compared to control group A: 3.8 mm (IQR: 3.3-4). ONSD greater than 4.55 mm at baseline diagnosed clinically raised ICP with 87.5% sensitivity and 100% specificity. The mean ONSD was 5.44 ± 0.49 mm during a total of 90 events of acute raised ICP. Clinical responders had a decrease in ONSD by 0.59 ± 0.24 mm by 2 h, whereas non-responders showed a decrease of 0.18 ± 0.23 mm, p < 0.0005. ONSD persisting more than 4.6 mm by 24 h of management predicted poor outcome with sensitivity and specificity of 83.3% and 72.7%.

CONCLUSION

ONSD is a simple, bedside, inexpensive, reproducible and repeatable modality to assess ongoing change in ICP in PALF. ONSD more than 4.55 mm suggests raised ICP. The goal should be to bring ONSD down to less than 4.6 mm within 24 h by aggressive anti-ICP therapy to achieve favourable outcome.

Optic nerve sheath diameter in children with acute liver failure: A prospective observational pilot study

BACKGROUND & AIMS

Early detection of raised intracranial pressure (ICP) improves outcome in acute liver failure (ALF). We evaluated the feasibility of bedside, ultrasound-guided measurement of optic nerve sheath diameter (ONSD) in normal and ALF children and correlation of ONSD with grade of hepatic encephalopathy (HE), international normalized ratio (INR) and blood ammonia (BA).

METHODS

Forty-one ALF and 47 healthy children (5-18 years) were prospectively enrolled and 12 hourly clinical evaluation was done. Laboratory parameters including INR and BA were recorded. ONSD was measured at admission, change in HE grade and at recovery in ALF, and once in controls.

RESULTS

One hundred and twenty-one ONSD measurements (ALF-74, controls-47) were taken without complications. ONSD was 4.2 (3.9-4.3), 4.4 (4.0-4.6), 5.2 (4.8-5.8) and 3.9 (3.3-4.1) mm in controls, ALF without HE, with HE and at recovery respectively. ONSD was significantly higher in ALF with HE than those without HE. ALF without HE and at recovery had ONSD similar to controls. ONSD was higher in ALF with the clinical signs of raised ICP than those without (5.4 [4.9-5.7] vs 4.6 [4.1-5.3] mm; P = .01). ONSD of 4.6 mm differentiated ALF with HE vs without HE and 5.1 mm between poor vs good non-transplant outcome with ≥80% sensitivity and specificity. ONSD positively correlated with INR (r = .53, P < .001) and BA (r = .42, P = .002).

CONCLUSIONS

ONSD can be safely and easily measured in ALF children and correlates with HE grade, INR and BA. Normal ONSD in children (>4 years) is <4.5 mm and value of >5.1 mm in ALF requires urgent attention.

The Role of Transocular Ultrasound in the Assessment of Neurotoxicity-Related Encephalopathy in Mushroom Poisoning

Objective

Mushroom poisonings can lead to life-threatening organ dysfunctions and neurotoxicity-related encephalopathy. This study aimed to detect increased intracranial pressure by measuring optic nerve sheath diameter (ONSD) ultrasonographically and to determine its association with clinical and laboratory parameters.

Methods

In this prospective case-control study, we evaluated the patients aged above 18 years who presented to the emergency department with mushroom poisoning. Vital signs, clinical and laboratory parameters and ONSD of both eyes measured with transocular ultrasound were noted at initial admission and the 24th hour.

Results

We measured ONSD in 26 cases with mushroom poisoning and 26 healthy volunteers. Baseline ONSD measurements of the poisoning group were significantly higher than those of the control group (5.94±0.73 vs. 4.11±0.64, p<0.0001). ONSD values significantly regressed at 24th hour compared with the baseline measurements in the poisoning group (5.94±0.73 vs. 5.06±0.56, p<0.001).The ONSD values were significantly higher in patients who had a clinical picture of encephalopathy compared with patients who didn’t have (6.05±0.72 vs. 4.36±1.03, p<0.001). No significant deterioration was observed in ammonium levels, hepatic and renal functions of the patients.

Conclusion

We detected increased ONSDs in patients with mushroom poisoning compared with those in the control healthy volunteers. Our findings suggest that ONSD, measured by ultrasonography, may be safely and effectively used to diagnose transient encephalopathy associated with neurotoxicity.

Neurological Monitoring in Acute Liver Failure

Cerebral oedema and Intracranial Hypertension (ICH) are serious complications of acute liver failure affecting approximately 30% of patients, resulting in neurological injury or death. Multiple pathogenetic mechanisms contribute to the pathogenesis of HE including circulating neurotoxins such as ammonia, systemic and neuro-inflammation, infection and cerebral hyperaemia due to loss of cerebral vascular autoregulation. Early recognition and diagnosis is often difficult as clinical signs of elevated Intracranial Pressure (ICP) are not uniformly present and maybe masked by other organ support. ICP monitoring provides early diagnosis and monitoring of ICH, allowing targeted therapeutic interventions for prevention and treatment. ICP monitoring is the subject of much debate and there exists significant heterogeneity of clinical practice regarding its use. The procedure is associated with risks of haemorrhage but may be considered in highly selected patients such as those with highest risk for ICH awaiting transplant to allow for patient selection and optimisation. There is limited evidence that ICP monitoring confers a survival benefit which may explain why in the context of risk benefit analysis there is reduced utilisation in clinical practice. Less or non-invasive techniques of neurological monitoring such as measurement of jugular venous oxygen saturation to assess cerebral oxygen utilisation, and transcranial Doppler CNS to measure cerebral blood flow can provide important clinical information. They should be considered in combination as part of a multi-modal platform utilising specific roles of each system and incorporated within locally agreed algorithms. Other tools such as near-infrared spectrophotometry, optic nerve ultrasound and serum biomarkers of brain injury are being evaluated but are not used routinely in current practice.

Optic nerve ultrasound for fluid status assessment in patients with severe preeclampsia

Background There are no data on usefulness of optic nerve sheath diameter (ONSD) as a marker of patient's fluid status in preeclampsia. The objective was to examine potential correlation between ONSD and lung ultrasound estimates of extravascular lung water in severe preeclampsia. Patients and methods Thirty patients with severe preeclampsia were included. Optic and lung ultrasound were performed within 24 hours from delivery. ONSD was measured 3 mm behind the globe. Lung ultrasound Echo Comet Score (ECS) was obtained summing B-lines ("comet tails") in parasternal intercostal spaces bilaterally. Pearson's correlation analysis was used to assess the relationship between ONSD and ECS (p < 0.05 significant). Results Median ONSD was 5.7 mm (range 3.8-7.5 mm). Median ECS value was 19 (range 0-24). Statistically significant correlation was found between ONSD and ECS (r2 = 0.464; p < 0.001). Conclusions Significant correlation between ONSD and ECS suggests optic ultrasound could be used for assessing fluid status and guiding peripartum fluid therapy in patients with severe preeclampsia.

Ocular ultrasonography for diagnosing increased intracranial pressure in patients with severe preeclampsia

BACKGROUND

Ultrasound measurements of optic nerve sheath diameter (ONSD) and optic disc height (ODH) measured outside pregnancy correlate with intracranial hypertension. Data on the usefulness of ocular ultrasonography in preeclampsia are limited.

OBJECTIVE

To determine whether ONSD and ODH are greater in patients with features of severe preeclampsia compared to healthy controls.

METHODS

Consecutively admitted patients with severe preeclampsia (according to the ACOG Task Force on Hypertension in Pregnancy) and healthy term control pregnant women were included in this prospective observational study. Optic nerve sheath diameter measured 3 mm behind the globe and ODH were assessed using ocular ultrasonography. Patients with severe preeclampsia were compared to controls before delivery, and at one and four days post-delivery.

RESULTS

We included 30 patients with severe preeclampsia and 30 controls. Optic nerve sheath diameter was significantly higher in patients with severe preeclampsia compared to controls before delivery, and one day and four days post-delivery (P <0.001). Optic disc height was significantly greater in patients with severe preeclampsia compared to controls before delivery (P <0.001), and one day (P <0.001) but not four days, post-delivery (P=0.66). Before delivery, 43% of patients with severe preeclampsia had an ONSD >5.8 mm and 77% an ODH ≥1 mm: compatible with intracranial hypertension. None of the control patients had an ONSD of >5.8 mm or an optic disc height of ≥1 mm before or after delivery.

CONCLUSIONS

Severe preeclampsia was associated with a significantly higher ONSD and increased ODH, which could be ultrasonographic evidence of papilledema.

Ultrasonographic Optic Nerve Sheath Diameter as a Surrogate Measure of Raised Intracranial Pressure in Severe Pregnancy-induced Hypertension Patients

Context:

It is a well-known fact that severe pregnancy-induced hypertension (PIH) can be disastrous at times as it can cause a lot of complications to both pregnant women and her baby. Hence, it is always desirable to know the extent of severity by a real-time and easily accessible modality like ultrasound.

Aims:

The aim of the study was to evaluate the incidence of raised intracranial pressure (ICP) in severe preeclampsia and eclampsia patients using ocular ultrasonography with optic nerve sheath diameter (ONSD) measurement.

Settings and Design:

This study design was a prospective and clinically controlled blinded observational study.

Materials and Methods:

After taking necessary permissions from the Institution Ethical Committee, 75 patients were enrolled for the study. However, finally, 25 patients in severe preeclampsia and 24 in eclampsia group were compared with 25 normal term antenatal women. Demographic profiles, hemodynamic parameters, laboratory markers for severity of PIH, and ultrasonographic OSND were measured.

Statistical Analysis Used:

They were statistically analyzed and compared using one-way ANOVA and Tukey's test. Value of P < 0.05 was considered statistically significant.

Results:

All the three groups were comparable in terms of age, body weight, gestation age, gestity, and the number of primigravida in each group. There was a significant difference (P < 0.05) in mean levels of hepatic aminotransferase levels and platelet counts between groups. Aspartate transaminase and alanine transaminase levels were much higher in Group II and III as compared to Group I, while platelet levels were lower in study groups indicating increase in severity of PIH. There was also a significant difference for systolic blood pressure and diastolic blood pressure (P < 0.001) as both were significantly higher in study groups. Among severe PIH groups (Group II and III), the difference was comparable.

Conclusions:

OSND is a surrogate marker for raised ICP in severe PIH patients. It is a rapid, bedside, noninvasive, and readily accessible tool and could be a part of a holistic approach for managing such patients.

Acute Liver Failure

Acute liver failure (ALF) is a life-threatening condition of heterogeneous etiology. Outcomes are better with early recognition and prompt initiation of etiology-specific therapy, intensive care protocols, and liver transplantation (LT). Prognostic scoring systems include the King's College Criteria and Model for End-stage Liver Disease score. Cerebral edema and intracranial hypertension are reasons for high morbidity and mortality; hypertonic saline is suggested for patients with a high risk for developing intracranial hypertension, and when it does, mannitol is recommended as first-line therapy. Extracorporeal liver support system may serve as a bridge to LT and may increase LT-free survival in select cases.

Noninvasive monitoring intracranial pressure - A review of available modalities

Background:

Intracranial pressure (ICP) monitoring is important in many neurosurgical and neurological patients. The gold standard for monitoring ICP, however, is via an invasive procedure resulting in the placement of an intraventricular catheter, which is associated with many risks. Several noninvasive ICP monitoring techniques have been examined with the hope to replace the invasive techniques. The goal of this paper is to provide an overview of all modalities that have been used for noninvasive ICP monitoring to date.

Methods:

A thorough literature search was conducted on PubMed, selected articles were reviewed in completion, and pertinent data was included in the review.

Results:

A total of 94 publications were reviewed, and we found that over the past few decades clinicians have attempted to use a number of modalities to monitor ICP noninvasively.

Conclusion:

Although the intraventricular catheter remains the gold standard for monitoring ICP, several noninvasive modalities that can be used in settings when invasive monitoring is not possible are also available. In our opinion, measurement of optic nerve sheath diameter and pupillometry are the two modalities which may prove to be valid options for centers not performing invasive ICP monitoring.

Multimodal brain monitoring in fulminant hepatic failure

Acute liver failure, also known as fulminant hepatic failure (FHF), embraces a spectrum of clinical entities characterized by acute liver injury, severe hepatocellular dysfunction, and hepatic encephalopathy. Cerebral edema and intracranial hypertension are common causes of mortality in patients with FHF. The management of patients who present acute liver failure starts with determining the cause and an initial evaluation of prognosis. Regardless of whether or not patients are listed for liver transplantation, they should still be monitored for recovery, death, or transplantation. In the past, neuromonitoring was restricted to serial clinical neurologic examination and, in some cases, intracranial pressure monitoring. Over the years, this monitoring has proven insufficient, as brain abnormalities were detected at late and irreversible stages. The need for real-time monitoring of brain functions to favor prompt treatment and avert irreversible brain injuries led to the concepts of multimodal monitoring and neurophysiological decision support. New monitoring techniques, such as brain tissue oxygen tension, continuous electroencephalogram, transcranial Doppler, and cerebral microdialysis, have been developed. These techniques enable early diagnosis of brain hemodynamic, electrical, and biochemical changes, allow brain anatomical and physiological monitoring-guided therapy, and have improved patient survival rates. The purpose of this review is to discuss the multimodality methods available for monitoring patients with FHF in the neurocritical care setting.

Noninvasive Brain Physiology Monitoring for Extreme Environments: A Critical Review

Our ability to monitor the brain physiology is advancing; however, most of the technology is bulky, expensive, and designed for traditional clinical settings. With long-duration space exploration, there is a need for developing medical technologies that are reliable, low energy, portable, and semiautonomous. Our aim was to review the state of the art for noninvasive technologies capable of monitoring brain physiology in diverse settings. A literature review of PubMed and the Texas Medical Center library sites was performed using prespecified search criteria to identify portable technologies for monitoring physiological aspects of the brain physiology. Most brain-monitoring technologies require a moderate to high degree of operator skill. Some are low energy, but many require a constant external power supply. Most of the technologies lack the accuracy seen in gold standard measures, due to the need for calibration, but may be useful for screening or monitoring relative changes in a parameter. Most of the technologies use ultrasound or electromagnetic radiation as energy sources. There is an important need for further development of portable technologies that can be operated in a variety of extreme environments to monitor brain health.

Monitoring of Intracranial Pressure by CT-Defined Optic Nerve Sheath Diameter

BACKGROUND AND PURPOSE

Intracranial pressure (ICP) can be monitored by the optic nerve sheath diameter (ONSD) technique. We hypothesized that diameter of the optic canal (OC) can be a limiting factor for this technique.

METHODS

In the prospective cohort study, we analyzed CT scans of 600 OCs of healthy adults and 54 canals of patients with ICP monitoring. The diameters were measured through its length and the narrowest one was chosen for further analysis. ONSD was measured at 3 and 10 mm from the anterior opening of the canal. The correlation analysis was performed between invasive and ONSD methods of ICP monitoring and OC diameters in pathological cases.

RESULTS

The narrowest cross-sectional area of the normal OC was 13.85±2.89 mm² and varied from 25.5 to 6.6 mm². Apparently 9.17% OCs were narrow (˂10.9 mm²). Correlations exist between the optic nerve sheath area at the 3-mm distance from the anterior opening of the canal and the area of the anterior opening itself (P = .012), and the sheath area 10 mm from the anterior opening and the narrowest part of the canal (P = .015). Cases with narrow canals provided false-negative readings via ONSD method if compared with invasive monitoring.

CONCLUSION

In its narrowest part, the average OC is 11 to 16.75 mm² wide. We suggest measuring this area simultaneously with the ONSD during ICP monitoring. If the area of the narrowest lumen of the canal is less than 10 mm², ONSD technique for ICP monitoring should not be used.

Diagnosis and Management of Hepatic Encephalopathy in Fulminant Hepatic Failure

Hepatic encephalopathy (HE) is associated with cerebral edema (CE), increased intracranial pressure (ICP), and subsequent neurologic complications; it is the most important cause of morbidity and mortality in fulminant hepatic failure. The goal of therapy should be early diagnosis and treatment of HE with measures to reduce CE. A combination of clinical examination and diagnostic modalities can aid in prompt diagnosis. ICP monitoring and transcranial Doppler help diagnose and monitor response to treatment. Transfer to a transplant center and intensive care unit admission with airway management and reduction of CE with hypertonic saline, mannitol, hypothermia, and sedation are recommended as a bridge to liver transplantation.

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.

Neuromuscular ultrasound of cranial nerves

Ultrasound of cranial nerves is a novel subdomain of neuromuscular ultrasound (NMUS) which may provide additional value in the assessment of cranial nerves in different neuromuscular disorders. Whilst NMUS of peripheral nerves has been studied, NMUS of cranial nerves is considered in its initial stage of research, thus, there is a need to summarize the research results achieved to date. Detailed scanning protocols, which assist in mastery of the techniques, are briefly mentioned in the few reference textbooks available in the field. This review article focuses on ultrasound scanning techniques of the 4 accessible cranial nerves: optic, facial, vagus and spinal accessory nerves. The relevant literatures and potential future applications are discussed.