Ultrasound non-invasive measurement of intracranial pressure in neurointensive care: A prospective observational study

Abstract

BackgroundThe invasive nature of the current methods for monitoring of intracranial pressure (ICP) has prevented their use in many clinical situations. Several attempts have been made to develop methods to monitor ICP non-invasively. The aim of this study is to assess the relationship between ultrasound-based non-invasive ICP (nICP) and invasive ICP measurement in neurocritical care patients.Methods and findingsThis was a prospective, single-cohort observational study of patients admitted to a tertiary neurocritical care unit. Patients with brain injury requiring invasive ICP monitoring were considered for inclusion. nICP was assessed using optic nerve sheath diameter (ONSD), venous transcranial Doppler (vTCD) of straight sinus systolic flow velocity (FVsv), and methods derived from arterial transcranial Doppler (aTCD) on the middle cerebral artery (MCA): MCA pulsatility index (PIa) and an estimator based on diastolic flow velocity (FVd). A total of 445 ultrasound examinations from 64 patients performed from 1 January to 1 November 2016 were included. The median age of the patients was 53 years (range 37–64). Median Glasgow Coma Scale at admission was 7 (range 3–14), and median Glasgow Outcome Scale was 3 (range 1–5). The mortality rate was 20%. ONSD and FVsv demonstrated the strongest correlation with ICP (R = 0.76 for ONSD versus ICP; R = 0.72 for FVsv versus ICP), whereas PIa and the estimator based on FVd did not correlate with ICP significantly. Combining the 2 strongest nICP predictors (ONSD and FVsv) resulted in an even stronger correlation with ICP (R = 0.80). The ability to detect intracranial hypertension (ICP ≥ 20 mm Hg) was highest for ONSD (area under the curve [AUC] 0.91, 95% CI 0.88–0.95). The combination of ONSD and FVsv methods showed a statistically significant improvement of AUC values compared with the ONSD method alone (0.93, 95% CI 0.90–0.97, p = 0.01). Major limitations are the heterogeneity and small number of patients included in this study, the need for specialised training to perform and interpret the ultrasound tests, and the variability in performance among different ultrasound operators.ConclusionsOf the studied ultrasound nICP methods, ONSD is the best estimator of ICP. The novel combination of ONSD ultrasonography and vTCD of the straight sinus is a promising and easily available technique for identifying critically ill patients with intracranial hypertension.

Non-Invasive Detection of Intracranial Hypertension Using Random Forests

“…The RF classifier can easily be extended to include categorical features, such as annotations about clinical interventions, the patient's medical history and lab results. Given modern multimodal brain monitoring systems, using additional measurements, such as the optic nerve sheath diameter [14], central venous pressure or near-infrared spectroscopy recordings, could uncover potential confounding factors and increase performance of the classifier further.…”

Optic nerve oedema at high altitude occurs independent of acute mountain sickness

“…Assessment of the optic nerve sheath diameter (ONSD) by ultrasonography is a well-established surrogate marker for raised ICP in the clinical setting 12. Studies have shown that intracranial hypertension and elevated brain volume are associated with an increased ONSD, as the sheath surrounding the optic nerve presents a continuum to cerebral dura and subarachnoid mater 13.…”

Avaliação da hemodinâmica cerebral através da técnica de ultrassonografia Doppler e suas correlações com as variações da pressão intracraniana em um modelo animal de hipertensão intracraniana

“…Por muitos anos tentou-se avaliar a vasculatura cerebral com transdutores que emitem frequências de som de 4 MHz a 10 MHz, porém sem sucesso, pois a barreira óssea do crânio atenuava essas ondas. Em (Bellner et al, 2004;Cardim et al, 2017). Já outros trabalhos encontraram uma fraca correlação entre PIC e IP, concluindo ser este um método limitado para tal fim (Behrens et al, 2010;Cardim et al, 2016c;Morgalla e Magunia et al, 2016;Zweifel et al, 2012;).…”

“…Por isso, nos últimos anos, há um grande número de estudos que visam a desenvolver diversas técnicas não invasivas para estimação da PIC (Bellner et al, 2004;Cardim et al, 2016c;Robba et al, 2017;Roh e Park 2016).…”

“…Dentre estas técnicas se destaca o estudo do DTC, com ênfase no IP como parâmetro de estimação não invasiva da PIC (Bellner et al, 2004;Bouzat et al, 2016;Cardim et al, 2016aCardim et al, e 2016b Outros trabalhos também obtiveram resultados positivos referentes à correlação da PIC com o IP em pacientes com lesões cerebrais (Czosnyka et al, 1998;Voulgaris et al, 2005;Melo et al, 2011;de Riva et al, 2012;Wang et al, 2014;Wakerley et al, 2014;O'Brien et al, 2015 (Hanlo et al, 1995;Zweifel et al, 2012;Cardim et al, 2016c;Morgalla e Magunia, 2016;Robba et al, 2017).…”