Reliability of Assessing Non-severe Elevation of Intracranial Pressure Using Optic Nerve Sheath Diameter and Transcranial Doppler Parameters

Pcv-aCO2/Ca-cvO2 Combined with Optic Nerve Sheath Diameter in Predicting Elevated Intracranial Pressure of Patients with Traumatic Brain Injury in Prehospital Setting

Purpose

To investigate a correlation between the central venous minus arterial CO2 pressure to arterial minus central venous O2 content ratio (Pcv-aCO2/Ca-cvO2) combined with optic nerve sheath diameter (ONSD) in predicting prehospital elevated intracranial pressure (ICP) in traumatic brain injury (TBI) patients.

Patients and Methods

This was a prospective observational study of all adult TBI patients from the surgical intensive care unit who underwent invasive ICP monitoring between January 2023 and December 2023. Using a Delica MVU-6300 machine with 14-5 MHz linear probe to measure ONSD. We drew blood samples for arterial and central venous blood gases to measure and calculate the following indicators such as Pcv-aCO2, Ca-cvO2, and Pcv-aCO2/Ca-cvO2 ratio. ONSD and Pcv-aCO2/Ca-cvO2 were recorded during the first 3 days after admission. Simultaneous ICP values were gained from the invasive monitoring. Associations between ONSD, Pcv-aCO2/Ca-cvO2 and simultaneous ICP were explored by Spearman correlation analysis. We constructed an ROC curve to identify the ONSD and Pcv-aCO2/Ca-cvO2 cutoff for the evaluation of elevated ICP.

Results

We included 54 patients aged mean 57.13 (standard deviation 4.02) years and 24 (44%) were male. A significant correlation was observed between ONSD and ICP (r = 0.74, P < 0.01). The AUC was 0.861 (95% CI: 0.727-0.951), with a best cutoff value of 5.62 mm. Using a cutoff of 5.62mm, ONSD had a sensitivity of 92.8%, specificity of 80.4%. The Pcv-aCO2/Ca-cvO2 ratio also significantly correlated with ICP (r = 0.70, P < 0.01). The AUC was 0.791 (95% CI: 0.673-0.889). The optimal Pcv-aCO2/Ca-cvO2 value for predicting elevated ICP was 1.98 mmHg/mL. Using a cutoff of 1.98 mmHg/mL, Pcv-aCO2/Ca-cvO2 had a sensitivity of 87.3%, specificity of 77.2%. The AUC for ONSD combined with Pcv-aCO2/Ca-cvO2 was 0.952 (95% CI: 0.869-0.971), which had a sensitivity of 95.1%, specificity of 93.9%.

Conclusion

Pcv-aCO2/Ca-cvO2 combined with ONSD performed best in predicting elevated intracranial pressure of patients with TBI in a prehospital setting. Our findings provide a crucial tool to improve earlier management of these patients in prehospital care, where the availability and utilization of invasive monitoring is limited. It could lead to significant changes in how TBI patients are monitored and treated before reaching a hospital.

Assessment of childhood intracranial pressure: a comparative study of transcranial Doppler ultrasound indices and findings at ventriculoperitoneal shunt

PURPOSE

This study compares transcranial Doppler (TCD) Pulsatility Index (PI) and Resistivity Index (RI) with intra-operative CSF opening pressure measured by manometric technique during ventriculoperitoneal (V-P) shunt in children with hydrocephalus.

METHODS

It was a prospective, hospital-based study performed among patients diagnosed with hydrocephalus. Patients had TCD ultrasonography before V-P shunt. The TCD sonography was repeated within 1 week post-op, and at 1 month post-op. The PI and RI were retrieved after insonating the middle cerebral artery. Ventricular CSF opening pressure was measured. Associations between TCD indices and CSF pressure were determined using the t-test and the Wilcoxon rank /Mann-Whitney tests where the normality test failed. A p-value of < 0.05 was considered significant for associations.

RESULTS

Fifty-two patients were enrolled with a mean age of 9.9 ± 11.5 months. Of these, 41 (78.8%) were aged ≤ 12 months. The mean CSF opening pressure was 21.4 ± 9.0. When raised, ICP was defined as opening pressure > 15 cm of H2O, high PI (≥ 1.19), and high RI (> 0.8) diagnosed it with a sensitivity of 55% and 50%, respectively. The mean pre-operative PI (1.17 ± 0.56) reduced to 0.96 (Z =  - 2.032, p = 0.042), while that of RI (0.66 ± 0.17) also decreased to 0.58 (t = 2.906, p = 0.044) after V-P shunt surgery. A strong positive correlation exists between a reduction in PI and RI after V-P shunt (r = 0.743, p = 0.014).

CONCLUSION

Both PI and RI significantly decrease following V-P shunt, but a single reading has a poor sensitivity in predicting ICP.

Non-Invasive Intracranial Pressure Monitoring

(1) Background: Intracranial pressure (ICP) monitoring plays a key role in the treatment of patients in intensive care units, as well as during long-term surgeries and interventions. The gold standard is invasive measurement and monitoring via ventricular drainage or a parenchymal probe. In recent decades, numerous methods for non-invasive measurement have been evaluated but none have become established in routine clinical practice. The aim of this study was to reflect on the current state of research and shed light on relevant techniques for future clinical application. (2) Methods: We performed a PubMed search for “non-invasive AND ICP AND (measurement OR monitoring)” and identified 306 results. On the basis of these search results, we conducted an in-depth source analysis to identify additional methods. Studies were analyzed for design, patient type (e.g., infants, adults, and shunt patients), statistical evaluation (correlation, accuracy, and reliability), number of included measurements, and statistical assessment of accuracy and reliability. (3) Results: MRI-ICP and two-depth Doppler showed the most potential (and were the most complex methods). Tympanic membrane temperature, diffuse correlation spectroscopy, natural resonance frequency, and retinal vein approaches were also promising. (4) Conclusions: To date, no convincing evidence supports the use of a particular method for non-invasive intracranial pressure measurement. However, many new approaches are under development.

Prediction of intracranial lesions in patients with consciousness disturbance by ultrasonography in the intensive care unit

Objective

This study was performed to evaluate the correlation between parameters measured by bedside ultrasonography and detection of intracranial organic lesions in patients with impaired consciousness in an intensive care unit (ICU) setting.

Methods

We retrospectively reviewed the medical records of patients who were admitted to our ICU from April 2017 to July 2019. Patients who underwent computed tomography or magnetic resonance imaging examination and measurement of the flow velocity of the carotid and intracranial arteries and the optic nerve sheath diameter by ultrasonography were selected for analysis.

Results

In total, 64 patients were analyzed in this study. Of these, intracranial lesions were detected by computed tomography or magnetic resonance imaging in 17 (27%) patients. The left:right ratio of the end-diastolic velocity of the bilateral common carotid artery (CCA-ED ratio) and the pulsatility index of the middle cerebral artery (MCA-PI) were significantly higher in patients with than in those without intracranial lesions. The cut-off value of the CCA-ED ratio was 1.55 (sensitivity, 66.7%; specificity, 81.6%), and that of the MCA-PI was 1.21 (sensitivity, 57.1%; specificity, 76.7%).

Conclusion

Bedside ultrasonography is useful for predicting intracranial lesions requiring therapeutic intervention in ICU patients with impaired consciousness.

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.

Review: Optikussonografie – ein update 2020

Die Optikus-Sonografie bildet Papille, Sehnerv sowie dessen perineuralenLiquorraum ab und eröffnet damit u. a. einen diagnostischen Zugang zumintrakraniellen Liquorsystem und dessen Druck(ICP). Auf diese Weise lässt sich eine relevante ICP-Erhöhung über 20 mmHg nicht-invasiv und bettseitig belegen. Mit Einzelmessungen und Verlaufskontrollen hilft die Methode u. a. vor und nach der Etablierung eines invasiven ICP-Monitorings in der Intensiv- und Notfallmedizin sowie bei der Beurteilung chronischer Dysregulationen des ICP.