| Background. Pre-incision hypotension (PIH) is a very common consequence of general anesthesia in children. The cerebral blood flow (CBF) is maintained through cerebral auto-regulation. This study investigated the changes in internal carotid and vertebral artery blood flow during PIH in school-age children.Methods. Forty-four ASA Ⅰ-Ⅱchildren (aged 7-13 years old) scheduled for elective or emergency surgery were enrolled in this study. Patients with baseline hypotension, cardiovascular diseases and cerebrovascular diseases were excluded. HR, SBP, MAP, SpO2 were continuously monitored during the procedure. General anesthesia was induced with propofol 2.5mg kg-1, fentanyl 2ug kg-1; intubation was facilitated with rocuronium 0.6mg kg-1. Then the patients received 1MAC sevoflurane, the end tidal C02was adjusted to 35-40mmHg. Internal carotid and vertebral artery blood flow was measured using diameter and the time-averaged velocity of the spectral Doppler waveform. Measurement was made before induction and at the time of PIH.Results. When PIH occurred, the diameter of internal carotid artery reduced (0.465±0.037 to 0.447±0.033cm, P<0.001), the time-averaged velocity decreased (20.36±3.86 to 12.48±2.35cm/s, P<0.001), the blood flow decreased (300.5±61.8 to 177.2±34.3ml/min, P<0.001); the diameter of vertebral artery restored (0.315±0.023 to 0.313±0.025cm, p>=0.156), the time-averaged velocity decreased (11.64±2.13 to 7.02 ±1.29 cm/s, P<0.001), the blood flow decreased (79.5±18.3ml/min to 49.4±9.4ml/min, P<0.001). The cerebral flow of right side decreased (380.0±77.6 to 226.3±41.5ml/min, P<0.001), the internal carotid artery percentage contribution reduced (79±1.8% to 78±2.6%, P<0.01).Conclusions. When PIH occurred in school-age children, even the MAP was above the lower limit of auto-regulation, the blood flow of internal carotid and vertebral artery significantly decreased, and the CBF also decreased. |
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