Cerebral Hyperemia During Recovery from General Anesthesia in Neurosurgical Patients

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Changes in the cerebral circulation during recovery from neurosurgical anesthesia are poorly understood. We used transcranial Doppler to compare cerebral blood flow velocity changes (Vmca) during recovery after anesthesia. In the first part of the study, 30 patients were randomized to propofol- or isoflurane-based anesthesia. Vmca, mean arterial pressure (MAP), and CO2 partial pressure (Paco2) were measured before anesthesia, at tracheal extubation, at 5 to 60 min after extubation, and at 24 h after anesthesia. There was a 60% increase in Vmca above the awake value at extubation. The increase in Vmca was significant at least for 30 min after extubation. There was no difference between the Propofol and Isoflurane anesthesia groups. There was no correlation between Vmca and MAP or Paco2 at any time. In the second part of the study, Vmca, MAP, and jugular venous bulb saturation in oxygen (Sjvo2) were measured after isoflurane anesthesia. Sjvo2 increased significantly at extubation, consistent with cerebral hyperemia. In conclusion, cerebral hyperemia occurs during recovery from general anesthesia independently of the anesthetic technique or hemodynamic or ventilatory changes. It is speculated that cerebral hyperemia is a nonspecific response to stress during emergence from anesthesia.

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