We excluded examinations performed on patients under 15 years of age, foreigners, those who had a suspected diagnosis of brain death or who had undergone a hemicraniectomy and evaluations in which one temporal window (TW) was missing. Patients with

incomplete studies in which both TWs were examined were included. An experienced sonographer (AB) used an FDA-approved power-mode TCD unit (100 M, Spencer Technologies, Seattle, WA) with a 2-MHz probe at 100% power and a 6-mm sample volume for the examination. A standard insonation protocol was used. An insonation depth of 45–65 mm was used to identify the M1 middle cerebral learn more artery (MCA), and a depth of 30–45 mm was used Inhibitors,research,lifescience,medical for the M2 MCA Inhibitors,research,lifescience,medical through the transtemporal window. The proximal anterior cerebral artery (ACA) was identified at a depth of 58–70 mm, aiming the probe inferiorly and anteriorly. The terminal internal carotid artery (TICA) was identified at a depth of 60–70 mm. The posterior cerebral artery (PCA) was identified at a depth of 58–67 mm, with the probe aimed 30 degrees posteriorly. Vertebral artery (VA) was identified by insonating through the transforaminal window at a depth of 40–79 mm, with the probe aimed at the bridge of the nose. The basilar artery (BA) was identified at

a depth of 80–100 mm. For the transorbital window, the TCD Inhibitors,research,lifescience,medical power was decreased to 10% and the ophthalmic artery was identified at a depth of 50–52 mm. The carotid siphon was identified at a depth of 60–64 mm. The insonation of the transtemporal windows was considered optimal if the flow signals Inhibitors,research,lifescience,medical could be measured for the mean,

peak, and end-diastolic velocities with the pulsatility indices at a depth of 64, 55, and 45 mm for the MCA, and if the ACA, TICA, and PCA were identified. Windows were considered suboptimal if one or more of the segments were not accessible, and windows were considered absent when no flow signals were detected. The transforaminal window was classified as optimal if both the VA and basilar segments were identified at depths of 80, 90, and 100 Inhibitors,research,lifescience,medical mm, and if flow signals could be measured for the mean, peak, and end-diastolic velocities, and pulsatility index. A window was suboptimal if one artery or artery segment was not identified, and the window was considered absent if no flow signals were detected. In the case Oxygenase of the transorbital window, the examination was classified as optimal if the ophthalmic artery and the carotid siphon were identified, as suboptimal if one of them could not be detected, and as absent if both arteries were not identified. Data on the patient age, sex, place of examination (emergency room [ER], intensive care unite [UCI], hospital ward [HW], and neurosonology laboratory [NSL]), and time of day (day time, 8:00–19:59 vs. night time, 20:00–7:59) were recorded.