Anesthesia for Intracranial Aneurysm Surgery Pekka O. Talke, MD

Aneurysms 2-5 % population 2-5 % population 30K SAH/yr 30K SAH/yr 2/3 get to hospital 2/3 get to hospital 1/3 in hospital severely disabled or dead 1/3 in hospital severely disabled or dead Unruptured:1-2%/yr rupture Unruptured:1-2%/yr rupture Ruptured: 50% rerupture within 6 mo Ruptured: 50% rerupture within 6 mo Urgent, not emergent cases Urgent, not emergent cases

Surgeons Lawton Lawton

Anesthetic Goals Prevent aneurysm rupture (avoid hypertension) Prevent aneurysm rupture (avoid hypertension) Decrease ICP (surgical exposure, retraction) Decrease ICP (surgical exposure, retraction) Maintain CPP (>70 mmHg) Maintain CPP (>70 mmHg) Prevent cerebral ischemia from retraction Prevent cerebral ischemia from retraction Good operating conditions (NO movement, brain relaxation for exposure) Good operating conditions (NO movement, brain relaxation for exposure)

Patients, preop Symptomatic/asymptomatic Symptomatic/asymptomatic Ruptured (SAH grade, myocardial effects), unruptured Ruptured (SAH grade, myocardial effects), unruptured Possibly intubated Possibly intubated Location and size of aneurysm Location and size of aneurysm Intracranial mass effect from SAH (increased ICP) Intracranial mass effect from SAH (increased ICP) Neurologic deficits and symptoms Neurologic deficits and symptoms Timing, vasospasm Timing, vasospasm

Preop One IV One IV Premedicate with up to 2 mg of midazolam if normal mental status. Premedicate with up to 2 mg of midazolam if normal mental status. Remind of potential post op intubation Remind of potential post op intubation Adequate fluid loading (5 to 7 ml/kg of LR, angio) Adequate fluid loading (5 to 7 ml/kg of LR, angio)

Induction Routine monitors Propofol or thiopental Fentanyl 5 ug/kg in divided doses prior to intubation Muscle relaxant (roc). Arterial cannula before intubation Arterial cannula before intubation Avoid hypertension (propofol) and hypotension (CPP, vasospasm)

Induction cont. Ceftriaxone 1 gm, 4-10 mg decadron, 1 gm/kg mannitol. Ceftriaxone 1 gm, 4-10 mg decadron, 1 gm/kg mannitol. Tape eyes with tagaderms (prep solution) Tape eyes with tagaderms (prep solution) Temp probe, foley Temp probe, foley Additional IV (limited access, 300 cc to liters of blood loss) Additional IV (limited access, 300 cc to liters of blood loss) Compression stockings Compression stockings

Positioning Supine, bump Supine, bump Long cases, lots of padding (pink and blue foam) Long cases, lots of padding (pink and blue foam) Table turned typically 90 degrees Table turned typically 90 degrees Head down?, aeroplaning Head down?, aeroplaning After draping minimal/no access to face (secure ET well) After draping minimal/no access to face (secure ET well)

Maintenance Oxygen Oxygen Propofol infusion ( ug/kg/min) (SSEPs, EEG) Propofol infusion ( ug/kg/min) (SSEPs, EEG) Inhalation agent (<0.25 MAC Isoflurane). Muscle relaxation (vec, panc) Inhalation agent (<0.25 MAC Isoflurane). Muscle relaxation (vec, panc) Moderate hyperventilation (ET CO2 30 mmHg) Moderate hyperventilation (ET CO2 30 mmHg) Euvolemia to 500 cc more (LR) Euvolemia to 500 cc more (LR) Moderate hypothermia (34 oC) Moderate hypothermia (34 oC)

Burst supression When requested by surgeon When requested by surgeon Thiopental 125 mg (5 cc) doses Thiopental 125 mg (5 cc) doses Till 70-80% EEG burst supression Till 70-80% EEG burst supression Redose as needed Redose as needed Turn fentanyl infusion off Turn fentanyl infusion off Reduce propofol infusion rate Reduce propofol infusion rate Support CPP with phenylephrine infusion Support CPP with phenylephrine infusion

Clipping Temporary clips (golden) Temporary clips (golden) Permanent clips (silver) Permanent clips (silver) Aneurysm manipulation before clipping (bleed) Aneurysm manipulation before clipping (bleed) Record clip on/off times Record clip on/off times Maintain CPP during temporary clipping Maintain CPP during temporary clipping Start closing, warming and more fluid loading after clipping Start closing, warming and more fluid loading after clipping

Toward the end First indication of end of surgery when clip aneurysm (60 min) First indication of end of surgery when clip aneurysm (60 min) Normalize CO2 once dura closed or earlier if lots of intracranial space Normalize CO2 once dura closed or earlier if lots of intracranial space Reduce propofol if possible, and titrate in labetalol Reduce propofol if possible, and titrate in labetalol

Toward the end cont. Turn propofol infusion off about 10 min before wakeup Turn propofol infusion off about 10 min before wakeup Reverse relaxation once Mayfied pins have been removed Reverse relaxation once Mayfied pins have been removed Attempt to wakeup patient. Unlikely if more than 1 gm of thiopental given. Attempt to wakeup patient. Unlikely if more than 1 gm of thiopental given.

Recovery Wake patient up as soon as possible Wake patient up as soon as possible Extubate if possible Extubate if possible Prevent post op hypertension (bleed). Labetalol Prevent post op hypertension (bleed). Labetalol Transport to ICU with monitor and oxygen Transport to ICU with monitor and oxygen Head up position Head up position

Potential Complications Delayed awakening from anesthesia Delayed awakening from anesthesia Cerebral ischemia (retraction, temporary clips, vasospasm) Cerebral ischemia (retraction, temporary clips, vasospasm) Brain swelling Brain swelling Intraoperative hemorrhage Intraoperative hemorrhage

Aneurysm rupture Reasonably common Reasonably common Intubation, pinning, skin insicion, surgical manipulation Intubation, pinning, skin insicion, surgical manipulation Maintain intravascular volume (blood in the room, get help) Maintain intravascular volume (blood in the room, get help) Maintain CPP Maintain CPP Adequate anesthesia Adequate anesthesia Thiopental before temporary clipping Thiopental before temporary clipping

Vasospasm Only if SAH Only if SAH 5-14 days after SAH 5-14 days after SAH Leading cause of SAH morbidity (infarct) Leading cause of SAH morbidity (infarct) Maintain CPP at all times (neo infusion, volume) Maintain CPP at all times (neo infusion, volume) HHH therapy HHH therapy Consider CVP measurement Consider CVP measurement

What’s new? Retractor pressure Retractor pressure Temp control Temp control Normotension Normotension

Surgical Steps Mayfield pins (stimulation), head positioning Mayfield pins (stimulation), head positioning Shaving/prepping/local anesthesia Shaving/prepping/local anesthesia Skin incision (stimulation, blood loss) Skin incision (stimulation, blood loss) Scalp off the bone (most stimulation) Scalp off the bone (most stimulation) Burr holes, sawing Burr holes, sawing Removing bone Removing bone Open dura Open dura Surgical approach to aneurysm (microscope, minimal stimulation, retraction) Surgical approach to aneurysm (microscope, minimal stimulation, retraction)

Surgical Steps cont. Burst supression Burst supression Temporary clips, permanent clip(s) Temporary clips, permanent clip(s) Close (60 min) Close (60 min) Dura (water tight) Dura (water tight) Bone flap Bone flap Scalp and skin Scalp and skin Dressing, remove pins Dressing, remove pins