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Published on: September 27, 2024
Pulsatility Index Measurement via the Submandibular Internal Carotid Artery: An Alternative to Transcranial
Yoshihisa Fujimoto1, Kenji Numata1, Aya Sakuma1
1Department of Emergency and Critical Care Medicine, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki, Kanagawa, 216-8511, Japan.
Background/Objective:
Pulsatility index (PI) measurements using transcranial color flow imaging via the temporal bone are one of the clinical substitutes for invasive intracranial pressure (ICP) monitoring. Although the PI measurements obtained through this window are commonly used, they cannot be evaluated in up to 20% of the patients. Given that PI in the internal carotid artery (ICA) can be easily measured through the submandibular window in all cases, this study aimed to investigate whether PI measurements through the submandibular window could be used as a substitute for PI measurements in the middle cerebral artery (MCA).
Methods:
This single-center, retrospective, observational study included cases from our intensive care unit between May 2024 and September 2024, in which transcranial ultrasound was performed during treatment of neurological disorders. The PI measurements from the temporal (MCA-PI) and submandibular (ICA-PI) windows were obtained at the same situation; the correlation between ICA-PI and MCA-PI was evaluated across various brain injuries using Pearson's correlation coefficient.
Results:
Data from 46 patients, totaling 116 measurements, were analyzed. The patients included 57 (49.1%) male patients aged 67 (interquartile range [IQR], 49-74) years. The primary diagnoses were subarachnoid hemorrhage [n = 52 (44.8%)], intracerebral hemorrhage [n = 21 (18.1%)], cerebral infarction [n = 9 (7.8%)], and traumatic brain injury [n = 8 (6.9%)]. The median MCA-PI was 1.11 [IQR: 0.87-1.36] and the median ICA-PI was 1.09 [IQR: 0.86-1.37]. A significant correlation was observed between the ICA-PI and MCA-PI, with a correlation coefficient of 0.894 (MCA-PI = 0.946 × ICA-PI + 0.057).
Conclusions:
Despite the inclusion of various neurocritical disorders, the ICA-PI through the submandibular window was strongly correlated with the conventional PI (i.e., MCA-PI through the temporal window). In neurocritical care, the ICA-PI may be used in combination with other ICP surrogate markers for integrated assessment when the view through the temporal window is unavailable.
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