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. 2021 Dec 5;11(12):1302.
doi: 10.3390/jpm11121302.

A Novel Noninvasive Technique for Intracranial Pressure Waveform Monitoring in Critical Care

Sérgio Brasil  1 , Davi Jorge Fontoura Solla  1 , Ricardo de Carvalho Nogueira  1 , Manoel Jacobsen Teixeira  1 , Luiz Marcelo Sá Malbouisson  2 , Wellingson da Silva Paiva  1
Affiliations

A Novel Noninvasive Technique for Intracranial Pressure Waveform Monitoring in Critical Care

Sérgio Brasil et al. J Pers Med. .

Abstract

Background: We validated a new noninvasive tool (B4C) to assess intracranial pressure waveform (ICPW) morphology in a set of neurocritical patients, correlating the data with ICPW obtained from invasive catheter monitoring.

Materials and methods: Patients undergoing invasive intracranial pressure (ICP) monitoring were consecutively evaluated using the B4C sensor. Ultrasound-guided manual internal jugular vein (IJV) compression was performed to elevate ICP from the baseline. ICP values, amplitudes, and time intervals (P2/P1 ratio and time-to-peak [TTP]) between the ICP and B4C waveform peaks were analyzed.

Results: Among 41 patients, the main causes for ICP monitoring included traumatic brain injury, subarachnoid hemorrhage, and stroke. Bland-Altman's plot indicated agreement between the ICPW parameters obtained using both techniques. The strongest Pearson's correlation for P2/P1 and TTP was observed among patients with no cranial damage (r = 0.72 and 0.85, respectively) to the detriment of those who have undergone craniotomies or craniectomies. P2/P1 values of 1 were equivalent between the two techniques (area under the receiver operator curve [AUROC], 0.9) whereas B4C cut-off 1.2 was predictive of intracranial hypertension (AUROC 0.9, p < 000.1 for ICP > 20 mmHg).

Conclusion: B4C provided biometric amplitude ratios correlated with ICPW variation morphology and is useful for noninvasive critical care monitoring.

Keywords: acute brain injury; intracranial compliance; intracranial hypertension; intracranial pressure.

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Conflict of interest statement

S.B. has recently joined brain4care’s scientific committee, although nor him or the other authors have received grants for performing this study.

Figures

Figure 1
Figure 1
The B4C device in use; real time monitoring is displayed in a common portable device. All data collected is immediately processed on the cloud resulting in the qualitative and quantitative report of intracranial pressure waveforms obtained noninvasively. Waveforms obtained depicting P2/P1 ratio and time-to-peak under normal standards (A) and altered (B).
Figure 2
Figure 2
Sample of patient 36, craniectomized after severe TBI. Compacted ICP (mmHg), B4C (µm) and ABP recordings, with the mean-pulse morphologies depicted of the period pre-compression (left), during compression (middle, green zone) and posterior to IJVs compression (right). The automated algorithm based on the ABP cycle localized P1 and P2 on ICP and B4C pulses, performing P2/P1 ratio and time-to-peak calculations. ICP: intracranial pressure, B4C: brain4care device, ABP: arterial blood pressure, IJVs: internal jugular veins, TBI: traumatic brain injury.
Figure 3
Figure 3
A B4C monitoring report sample of more than an hour length. Real time report is obtained without monitoring interruption as needed. P2/P1 ratio, time to peak, pulse amplitudes and useful pulses (pulses that were successfully recognized) are disclosed for the entire monitoring (each blue point is the mean value for a minute) and a mean waveform with confidence interval (gray zone along the slope) of each monitored minute is also displayed (bottom).
Figure 4
Figure 4
Bland-Altman plots for P2/P1 ratio (up, values from 0.6 up to 1.8) and TTP (down, values from 0.05 up to 0.45) features from ICP and B4C waveform morphologies at the baseline and IJVs compression intervals. The dashed lines represent the 95% limits of agreement (standard deviation 1.96). IJVs: internal jugular veins, TTP: time to peak.
Figure 5
Figure 5
Pearson’s correlation analysis for P2/P1 ratio (up) and TTP (down) separated between groups according to cranial status.
Figure 6
Figure 6
Dispersion plot for both techniques (ICP and B4C). P2/P1 ratio variation according to groups distribution: no cranial damage (A, n = 12), craniotomy/large cranial fractures (B, n = 20) and craniectomy (C, n = 9), regarding ICP elevation intervention. ICP: intracranial pressure, IJVs: internal jugular veins.
Figure 7
Figure 7
Entire sample ROC analysis of ICP and B4C P2/P1 ratios for an ICP value cut-off >20 mmHg (up). The power of predicting intracranial hypertension was reduced because of sample heterogeneity. The B4C P2/P1 ratio cut-off 1 (down) was equivalent to ICP P2/P1 ratio cut-off 1 (AUC 0.9).
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