Anesthetic Complications of Awake Craniotomies for Epilepsy Surgery

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Anesthetic Complications of Awake Craniotomies
for Epilepsy Surgery

• Anesth Analg 2006 102882-7
• Date 2006.07.25
• ??? ???

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Introduction

• Awake craniotomies are often performed for
  resection of epileptogenic foci close to vital
  areas of the brain (including those responsible
  for speech and motor activity).
• To permit mapping of language, motor, and/or
  sensory function and electrocorticography (ECoG)
• The challenge for the anaesthetist is to provide
  adequate analgesia and sedation, hemodynamic
  stability, and a safe airway, with an awake,
  cooperative patient for neurological testing.

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• The benefits of awake craniotomy
• Providing a more favorable outcome regarding
  postoperative language impairment
• Possibly improving seizure-free postoperative
  outcomes
• Possibly reducing hospital length of stay
• Using fewer invasive monitoring devices (e.g.,
  A-line, CVP, Foley)

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• Asleep-awake-asleep (AAA) technique for
  craniotomy, concerns including
• Lack of a secured airway
• Poor patient cooperation
• Patients experience nausea or pain
• Others

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Methods

• Retrospective chart review (anesthetic records,
  recovery room nursing notes, operative
  dictations, postoperative chart notes, discharge
  summaries), from Feb 1993 to Jan 2004

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• In AAA (asleep-awake-asleep) group
• Receiving propofol infusion for the asleep
  portion
• Discontinuation of propofol for the awake
  portion
• Spontaneous ventilation no use of ETT, LMA
• Propofol initial IV bolus of 0.5 mg/kg, then
  subsequent bolus doses of 0.25 mg/kg until
  desired level of sedation, followed by continuous
  infusion at 75-250 µg/kg/min
• Oxygen 3-6 L/min via nasal prongs or facemask

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• In GA group
• Induced with one or more IV drugs (thiopental,
  propofol, lidocaine, and/or opioid)
• endotracheal tube insertion, mechanical
  ventilation
• maintained with volatile anesthetic (isoflurane
  or sevoflurane in oxygen)
• supplemented with an IV drug (fentanyl,
  sufentanil, or remifentanil)

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Definition (I)

• Airway/ventilation complications
• In AAA cases any maneuver beyond placement of an
  oral or nasal airway
• In GA cases difficulty or inability to insert
  ETT, or difficulty with ventilation after
  tracheal intubation
• Oxyhemoglobin desaturation
• Moderate SpO2 91-95
• Severe SpO2 90

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Definition (II)

• Hemodynamic complications
• Abnormal arterial blood pressure
  and heart rate
• Hypertension SBP gt 150 mmHg
• Hypotension SBP lt 90 mmHg
• Tachycardia HR gt110 bpm
• Bradycardia HR lt 45 bpm
• Other complications seizure, new intraoperative
  neurologic deficits, nausea without vomiting,
  nausea with vomiting, patient movement, brain
  swelling, bleeding, LA toxicity, pulmonary
  aspiration, air embolism, death

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Results

• Awake craniotomies 332 cases
• GA craniotomies 129 cases
• No significant differences in underlying
  comorbidities except that a larger portion of GA
  group had mental retardation/ development delay
  or psychiatric issues precluding cooperation with
  awake testing
• A large portion of GA cases were re-do
  craniotomies

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• Airway /ventilation complications 6 in AAA cases
  (1.8)
• Oral endotracheal intubation (via fiberoptic
  bronchoscope) after induction of GA for SpO2 lt93
• LMA for SpO2 88
• Apnea after a remifentanil bolus? poor mask
  ventilation? LMA, nasal 2 lidocaine and tracheal
  4 lidocaine, nasal ETT (via fiberoptic
  bronchoscope)
• Nasal airway and attached to anesthetic circuit
  for SpO2 93 (spontaneous ventilation)
• ETT blindly placed through nares to a position
  above the glottis (spontaneous ventilation)
• Intraoperative laryngospasm but the specific
  management was not noted (not require tracheal
  intubation)

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• Airway /ventilation complications 6 in AAA cases
  (1.8)
• All six of these incidents occurred before awake
  testing
• Obesity
• no underlying diagnosis of asthma, tobacco use,
  obstructive sleep apnea, or other pulmonary
  disease
• Airway /ventilation complications 1 in GA cases
  (0.8)
• Endotracheal tube cuff leak (not require
  reintubation)
• None of GA cases had difficulty with ventilation
  or inability to intubate

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• AAA cases more frequent incidences of
  oxyhemoglobin desaturation, hypertension,
  hypotension, tachycardia and significant higher
  levels of PaCO2.
• GA cases more frequent incidence of bradycardia
• A-line use 54.3 in GA group versus 13.6 in AAA
  group
• No reported instances of LA toxicity, pulmonary
  aspiration, air embolism, or death

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Discussion

• Protocol for AAA craniotomies using propofol
  infusion began in 1991 premedicated with
  fentanyl and droperidol to minimize respiratory
  complications and interference with ECoG
• By 1993, all premedications was discontinued
  opioids only administered at the end of a case

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• Properties of propofol useful for AAA
• ease of titration
• rapid and smooth recovery
• antiemetic properties
• sedative effect
• reduced incidence of introperative seizures

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Respiratory complications

• Airway compromise during AAA relatively rare and
  occurred in obese pts, no association with
  asthma, tobacco use, or OSA
• Obesity (BMIgt30)? risk factor that led to oxygen
  desaturations requiring a secure airway
• No significant respiratory complications in GA
  group

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PaCO2

• Higher PaCO2 more common in AAA group
• Brain swelling noted in only 2 of 332
  (significant hemorrhage with dural opening)
• Benefited by more definitive airway control to
  allow hyperventilation before dural opening

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Hemodynamic changes

• Hypertension, hypotension, and tachycardia ? more
  frequent in AAA group
• Bradycardia was relatively rare in both groups
• Propofol infusion remifentanil infusion
  clonidine
• ? suggest smoother hemodynamic
• ? may not outweigh the risk of respiratory
• complications from opioid use

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Intraoperative seizure

• No statistically significant differences of
  intraoperative seizures between two groups
• In AAA group
• half were tonic-clonic seizures and half were
  focal seizures of one or two extremities.
• Half occurred during asleep portion, and half
  during awake testing
• 8 seizures were so brief in duration? no
  treatment
• 1 seizure ? a small propofol bolus
• 1 seizure ?a midazolam bolus

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• In AAA group, nausea with/without vomiting, and
  patient movement were relatively rare.
• No prophylactic antiemetic medications
• Infrequent nausea in AAA group
• Antiemetic properties of propofol
• Lack of opioid administration

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Comparison of Complications incidences in other
AAA studies

• Airway complications occurred in propofol group
  when opioids were added.
• The highest rates of seizures and nausea occurred
  in predominantly opioid-based protocols.

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• Limitation of this study accuracy of the
  original medical chart and an intraoperative
  complication that were not reported
• Preoperative anesthetic assessment
• Selection of GA in pts determined to not be good
  candidates for AAA technique

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In GA group

• Controlled mechanical ventilation
• Hyperventilation to relieve brain swelling
• ?the risk of tearing a cerebral vessel or sinus
  at the time of dural opening
• Arterial catheter? more frequent sampling of GAS
  for PaCO2
• Larger proportion of re-do craniotomies
• ??risks associated with dural adhesions and
  other
• scarring resulting from previous surgeries

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Summary

• In this series of 332 epilepsy patients who
  underwent a propofol-based AAA technique with an
  unsecured airway, there were relatively
  infrequent clinically significant complications.