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Multimodal non-invasive assessment of intracranial hypertension: an observational study.

ABSTRACT: BACKGROUND:Although placement of an intra-cerebral catheter remains the gold standard method for measuring intracranial pressure (ICP), several non-invasive techniques can provide useful estimates. The aim of this study was to compare the accuracy of four non-invasive methods to assess intracranial hypertension. METHODS:We reviewed prospectively collected data on adult intensive care unit (ICU) patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), or intracerebral hemorrhage (ICH) in whom invasive ICP monitoring had been initiated and estimates had been simultaneously collected from the following non-invasive indices: optic nerve sheath diameter (ONSD), pulsatility index (PI), estimated ICP (eICP) using transcranial Doppler, and the neurological pupil index (NPI) measured using automated pupillometry. Intracranial hypertension was defined as an invasively measured ICP >?20?mmHg. RESULTS:We studied 100 patients (TBI?=?30; SAH?=?47; ICH?=?23) with a median age of 52?years. The median invasively measured ICP was 17 [12-25] mmHg and intracranial hypertension was present in 37 patients. Median values from the non-invasive techniques were ONSD 5.2 [4.8-5.8] mm, PI 1.1 [0.9-1.4], eICP 21 [14-29] mmHg, and NPI 4.2 [3.8-4.6]. There was a significant correlation between all the non-invasive techniques and invasive ICP (ONSD, r?=?0.54; PI, r?=?0.50; eICP, r?=?0.61; NPI, r?=?-?0.41-p?

SUBMITTER: Robba C

PROVIDER: S-EPMC7318399 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Multimodal non-invasive assessment of intracranial hypertension: an observational study.

Robba Chiara C Pozzebon Selene S Moro Bedrana B Vincent Jean-Louis JL Creteur Jacques J Taccone Fabio Silvio FS

Critical care (London, England) 20200626 1

<h4>Background</h4>Although placement of an intra-cerebral catheter remains the gold standard method for measuring intracranial pressure (ICP), several non-invasive techniques can provide useful estimates. The aim of this study was to compare the accuracy of four non-invasive methods to assess intracranial hypertension.<h4>Methods</h4>We reviewed prospectively collected data on adult intensive care unit (ICU) patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), or intracere ...[more]

PMID: 32591024

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Project description: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.

Project description:Although the placement of an intraventricular catheter remains the gold standard method for the diagnosis of intracranial hypertension (ICH), the technique has several limitations including but not limited to its invasiveness. Current noninvasive methods, however, still lack robust evidence to support their clinical use. We aimed to estimate, as an exploratory hypothesis generating analysis, the discriminative power of four noninvasive methods to diagnose ICH. We prospectively collected data from adult intensive care unit (ICU) patients with subarachnoid hemorrhage (SAH), intraparenchymal hemorrhage (IPH), and ischemic stroke (IS) in whom invasive intracranial pressure (ICP) monitoring had been placed. Measures were simultaneously collected from the following noninvasive methods: optic nerve sheath diameter (ONSD), pulsatility index (PI) using transcranial Doppler (TCD), a 5-point visual scale designed for brain Computed Tomography (CT), and two parameters (time-to-peak [TTP] and P2/P1 ratio) of a noninvasive ICP wave morphology monitor (Brain4Care[B4c]). ICH was defined as a sustained ICP > 20 mmHg for at least 5 min. We studied 18 patients (SAH = 14; ICH = 3; IS = 1) on 60 occasions with a mean age of 52 ± 14.3 years. All methods were recorded simultaneously, except for the CT, which was performed within 24 h of the other methods. The median ICP was 13 [9.8-16.2] mmHg, and intracranial hypertension was present on 18 occasions (30%). Median values from the noninvasive techniques were ONSD 4.9 [4.40-5.41] mm, PI 1.22 [1.04-1.43], CT scale 3 points [IQR: 3.0], P2/P1 ratio 1.16 [1.09-1.23], and TTP 0.215 [0.193-0.237]. There was a significant statistical correlation between all the noninvasive techniques and invasive ICP (ONSD, r = 0.29; PI, r = 0.62; CT, r = 0.21; P2/P1 ratio, r = 0.35; TTP, r = 0.35, p < 0.001 for all comparisons). The area under the curve (AUC) to estimate intracranial hypertension was 0.69 [CIs = 0.62-0.78] for the ONSD, 0.75 [95% CIs 0.69-0.83] for the PI, 0.64 [95%Cis 0.59-069] for CT, 0.79 [95% CIs 0.72-0.93] for P2/P1 ratio, and 0.69 [95% CIs 0.60-0.74] for TTP. When the various techniques were combined, an AUC of 0.86 [0.76-0.93]) was obtained. The best pair of methods was the TCD and B4cth an AUC of 0.80 (0.72-0.88). Noninvasive technique measurements correlate with ICP and have an acceptable discrimination ability in diagnosing ICH. The multimodal combination of PI (TCD) and wave morphology monitor may improve the ability of the noninvasive methods to diagnose ICH. The observed variability in non-invasive ICP estimations underscores the need for comprehensive investigations to elucidate the optimal method-application alignment across distinct clinical scenarios.

Project description:Hepatic venous pressure gradient (HVPG) measurement is currently the only validated technique to accurately evaluate changes in portal pressure. In this study, we evaluate the use of non-contrast quantitative magnetic resonance imaging (MRI) as a surrogate measure of portal pressure.Thirty patients undergoing HVPG measurement were prospectively recruited. MR parameters of longitudinal relaxation time (T1), perfusion of the liver and spleen (by arterial spin labelling), and blood flow in the portal, splanchnic and collateral circulation (by phase contrast MRI) were assessed. We estimated the liver stiffness measurement (LSM) and enhanced liver fibrosis (ELF) score. The correlation of all non-invasive parameters with HVPG was evaluated.The mean (range) HVPG of the patients was 9.8 (1-22) mmHg, and 14 patients (48%) had clinically significant portal hypertension (CSPH, HVPG ?10mmHg). Liver T1 relaxation time, splenic artery and superior mesenteric artery velocity correlated significantly with HVPG. Using multiple linear regression, liver T1 and splenic artery velocity remained as the two parameters in the multivariate model significantly associated with HVPG (R=0.90, p<0.001). This correlation was maintained in patients with CSPH (R=0.85, p<0.001). A validation cohort (n=10) showed this linear model provided a good prediction of HVPG. LSM and ELF score correlated significantly with HVPG in the whole population but the correlation was absent in CSPH.MR parameters related to both hepatic architecture and splanchnic haemodynamics correlate significantly with HVPG. This proposed model, confirmed in a validation cohort, could replace the invasive HVPG measurement.In patients with cirrhosis, the development and progression of portal hypertension is related to worse outcomes. However, the standard technique of assessing portal pressure is invasive and not widely used in clinical practice. Here, we have studied the use of non-invasive MRI in evaluating portal pressure. The MRI measures of liver architecture and blood flow in the splenic artery correlated well with portal pressure. Therefore, this non-invasive method can potentially be used to assess portal pressure in clinical trials and monitoring treatment in practice.

Project description:Invasive monitoring of pulsatile intracranial pressure can accurately predict shunt response in patients with idiopathic normal pressure hydrocephalus, but may potentially cause complications such as bleeding and infection. We tested how a proposed surrogate parameter for pulsatile intracranial pressure, the phase-contrast magnetic resonance imaging derived pulse pressure gradient, compared with its invasive counterpart. In 22 patients with suspected idiopathic normal pressure hydrocephalus, preceding invasive intracranial pressure monitoring, and any surgical shunt procedure, we calculated the pulse pressure gradient from phase-contrast magnetic resonance imaging derived cerebrospinal fluid flow velocities obtained at the upper cervical spinal canal using a simplified Navier-Stokes equation. Repeated measurements of the pulse pressure gradient were also undertaken in four healthy controls. Of 17 shunted patients, 16 responded, indicating high proportion of "true" normal pressure hydrocephalus in the patient cohort. However, there was no correlation between the magnetic resonance imaging derived pulse pressure gradient and pulsatile intracranial pressure (R = -.18, P = .43). Pulse pressure gradients were also similar in patients and healthy controls (P = .26), and did not differ between individuals with pulsatile intracranial pressure above or below established thresholds for shunt treatment (P = .97). Assessment of pulse pressure gradient at level C2 was therefore not found feasible to replace invasive monitoring of pulsatile intracranial pressure in selection of patients with idiopathic normal pressure hydrocephalus for surgical shunting. Unlike invasive, overnight monitoring, the pulse pressure gradient from magnetic resonance imaging comprises short-term pressure fluctuations only. Moreover, complexity of cervical cerebrospinal fluid flow and -pulsatility at the upper cervical spinal canal may render the pulse pressure gradient a poor surrogate marker for intracranial pressure pulsations.

Project description:BACKGROUND:Accurate assessment of volume status to direct dialysis remains a clinical challenge. Despite current attempts at volume-directed dialysis, inadequate dialysis and intradialytic hypotension (IDH) are common occurrences. Peripheral venous waveform analysis has recently been developed as a method to accurately determine intravascular volume status through algorithmic quantification of changes in the waveform that occur at different volume states. A noninvasive method to capture peripheral venous signals is described (Non-Invasive Venous waveform Analysis, NIVA). The objective of this proof-of-concept study was to characterize changes in NIVA signal with dialysis. We hypothesized that there would be a change in signal after dialysis and that the rate of intradialytic change in signal would be predictive of IDH. METHODS:Fifty subjects undergoing inpatient hemodialysis were enrolled. A 10-mm piezoelectric sensor was secured to the middle volar aspect of the wrist on the extremity opposite to the access site. Signals were obtained fifteen minutes before, throughout, and up to fifteen minutes after hemodialysis. Waveforms were analyzed after a fast Fourier transformation and identification of the frequencies corresponding to the cardiac rate, with a NIVA value generated based on the weighted powers of these frequencies. RESULTS:Adequate quality (signal to noise ratio?>?20) signals pre- and post- dialysis were obtained in 38 patients (76%). NIVA values were significantly lower at the end of dialysis compared to pre-dialysis levels (1.203 vs 0.868, p?<?0.05, n?=?38). Only 16 patients had adequate signals for analysis throughout dialysis, but in this small cohort the rate of change in NIVA value was predictive of IDH with a sensitivity of 80% and specificity of 100%. CONCLUSIONS:This observational, proof-of-concept study using a NIVA prototype device suggests that NIVA represents a novel and non-invasive technique that with further development and improvements in signal quality may provide static and continuous measures of volume status to assist with volume directed dialysis and prevent intradialytic hypotension.

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Multimodal non-invasive assessment of intracranial hypertension: an observational study.

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Multimodal non-invasive assessment of intracranial hypertension: an observational study.

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