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Trans-Cranial Doppler as a Screening Test to Exclude Intracranial Hypertension in Brain Injured Patients: The IMPRESSIT-2 Prospective Multicenter International Study
31 Pages Posted: 1 Dec 2021
More...Abstract
Background: The reference standard method for diagnosing intracranial hypertension(IH) is invasive measurement of intracranial pressure. In situations where ICP i is not available, or contraindicated, non-invasive methods may prove useful; however, their diagnostic accuracy remains debated. This study was conducted to evaluate the accuracy of transcranial Doppler(TCD) as a screening test to exclude IH in acute brain-injured patients.
Methods: This was a prospective, international, multicenter study involving 16 ICUs. Critically ill brain-injured patients were enrolled if they required invasive ICP (ICP i ) monitoring. ICPi measurements (reference test) were compared to simultaneously recorded TCD-based, non-invasive ICP (ICP tcd) measurements (index test) at three different timepoints: before, immediately after and 2 to 3 hours following ICP i catheter insertion. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated at three different ICP i thresholds (>20, >22 and >25mmHg) to assess TCD as a bedside real-practice screening method. A receiver operating characteristic (ROC) curve analysis with the area under the curve (AUC) was used to evaluate the discriminative accuracy and predictive capability of ICP tcd.
Findings: A total of 266 patients were recruited, 262 of whom were considered for final analysis. IH(>22 mmHg) occurred in 87 patients(33.2%). The total number of paired comparisons between ICP tcd and ICP i was 687. The NPV was elevated (ICP>20mmHg=91.3%, >22mmHg=95.6%, >25mmHg=98.6%), indicating high discriminant accuracy of ICP tcd in excluding IH. Concordance correlation between ICP tcd and ICP i was 33.3%(95% CI 25.6% - 40.5%) and Bland-Altman showed a mean bias of -3.3 mmHg (limits of agreement between –26.1mmHg and +19.5mmHg). The optimal ICPi threshold for ruling out IH was 20.5 mmHg, corresponding to a sensitivity of 70%(95% CI 40.7%-92.6%) and a specificity of 72%(95% CI 51.9%-94.0%) with an AUC of 76%(95% CI 65.6%-85.5%).
Interpretation: ICP tcd has a high NPV in ruling out IH in situations where invasive methods cannot be used or not available.
Clinical Trial Registration Details: ClinicalTrials.gov NCT02322970.
Funding Information: None.
Declaration of Interests: None.
Ethics Approval Statement: For the coordinating center of Brescia, Italy, the ethics committee approval was obtained on July 17, 2017 (NP-2762). The study approval was also obtained at each site from local regulatory boards before the study started. Written informed consent was obtained by family representatives. In the Italian centers, the requirement of informed consent was waived, because relatives are not regarded as legal representatives of the patient in the absence of a formal designation. Written informed consent was requested from all surviving patients if, and as soon as, they regained their mental competency.
Keywords: intracranial pressure, non-invasive monitoring, brain injury, IH
Suggested Citation: Suggested Citation