Begin with induction dose of propofol, 1 mg/kg (patient typically apneic for few seconds only; able to breathe spontaneously reasonably quickly); then, infuse with propofol, 100 µg/kg and titrate up or down as necessary; monitor capnography so patient breathing spontaneously but generally unresponsive to voice.
sleep 1—surgeon performs local anesthetic infiltration, applies pins, and places urinary catheter.
patient awakened and allowed to remain awake during placement of drapes (knows what to expect during next awake period; gets used to manipulation); repeat propofol induction and infusion procedure (pin head holder then locked down).
sleep 2—surgeon performs craniotomy and dural reflection.
stop propofol infusion and allow patient to awaken (perform surface mapping or EEG recording).
sleep 3—once areas to be resected are identified, anesthetize patient
once resection complete, patient reawakened (if EEG monitoring necessary, electrodes reapplied to verify elimination of seizure focus; if speech mapping occurs, no second phase); sometimes when resection completed, patient not reawakened (but with EEG, verify no residual focus).
sleep 4—anesthetize for closure.
nasal airway not recommended (may induce coughing); propofol leaves high-amplitude, β frequency EEG footprint for 10 to 15 min after discontinuation.
A nice recap Ahmad. Everybody should keep in mind that the key to success is titration as every patient might respond differently. Start titrating as soon as you reach the OR, and look at the patients reaction during the second IV insertion and the Foley insertion, that will give you an idea of the level of requirements for subsequent stages ie local infiltration, pinning, incision etc.. (C.Z.)
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