Neuroanesthesia for the Pregnant Woman Review Article Anesth Analg 2008107:193200

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Neuroanesthesia for the Pregnant Woman(Review
Article) Anesth Analg 2008107193200

• Journal Meeting 2008.07.08
• R4??? Albert Wai Cheung, LAU

????????????? China Medical University Hospital,
Anesthesia Department
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Introduction

• Neuroanesthesia for the pregnant patient is
  required infrequently.
• It is to present a framework for a practical
  approach to anesthesia of the pregnant patient
  with subarachnoid or intracerebral hemorrhage,
  intracranial or spinal tumor, spinal tumor,
  traumatic brain injury, spinal injury.

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• Trauma during pregnancy, including head injury,
  is a leading cause of incidental maternal death
  and morbidity, and complicates 67 of all
  pregnancies.
• Trauma in pregnancy. Emerg Med Clin N Am
  20032161529
• The pregnant trauma patient. Anaesth Intensive
  Care 20053316780

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• General principles of neurosurgical and obstetric
  anesthesia
• Case reports and small studies or case series

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THE REQUIREMENT FOR NEUROSURGERYDURING PREGNANCY

• Brain tumor. Meningioma, contain estrogen and
  progesterone receptors. Suprasellar and
  cerebellopontine angle tumors.
• ICH
• Traumatic Brain injury
• Spinal procedures

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• ICH is due to
• SAH from ruptured aneurysms (65),
• bleeding from AVMs (35),
• The incidence of ICH is approximately 10 50 in
  100,000 deliveries
• ICH accounts for 7 of pregnancy-related maternal
  mortality.

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• During pregnancy, SAH carries a sinister
  prognosis, with a 35 maternal mortality and a
  25 fetal mortality.
• Intracranial hemorrhage from aneurysms and
  arteriovenous malformations during pregnancy and
  the puerperium. Neurosurgery 19902785566
• Subarachnoid hemorrhage due to cerebral
  aneurysmal rupture during pregnancy. Acta Obstet
  Gynecol Scand 200483330

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• Traumatic brain injury may associate other trauma
  
• Effective Maternal resuscitation is the main
  priority because, also provides fetal
  resuscitation.
• If tracheal intubation, a rapid sequence
  induction with thiopental or propofol and
  succinylcholine should be used.
• To avoid caval venous compression, after 20 wk
  gestation, left lateral tilt of the whole body
  should be applied through log-rolling, because
  a wedge under the right hip may result in
  undesirable vertebral column rotation.

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• Difficult intubation can be expected in 1 in 300
  pregnant patients.
• Difficult intubation in the parturient. Can J
  Anaesth 19893666874
• Fiberoptic techniques may be preferable in a
  pregnant patient with cervical-spine injury
  because of the additional difficulty that may
  come from pregnancy and an unstable neck.
• Lack of time, equipment, or expertise may
  necessitate direct laryngoscopy with manual
  in-line stabilization for intubation.

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• In a small series, 3 pregnant patients positioned
  themselves prone for lumbar spinal surgery under
  epidural anesthesia.
• Surgery for lumbar disc herniation during
  pregnancy. Spine 2001264403
• The prone position for spinal surgery in
  pregnancy may cause difficulties with respect to
  fetal monitoring, emergent cesarean delivery, and
  increased epidural venous bleeding.
• However, in this position, the placental
  perfusion may increase as shown in 23 pregnant
  women.

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FETAL CONCERNS IN THE PERIPARTUM PERIOD

• The fetus may be compromised indirectly by
  maternal hypotension,
• uterine artery vasoconstriction,
• maternal hypoxemia, and
• acidbase changes, indeed
• any change in maternal physiology that reduces
  uteroplacental perfusion or compromises fetal gas
  exchange.
• Severe fetal bradycardia intraoperatively try to
  improve uteroplacental flow and fetal oxygenation
  by increasing maternal arterial blood pressure
  (BP) and ensuring left lateral tilt and
  normoventilation.

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TIMING AND METHOD OF DELIVERY

• Neurosurgery performed with a view to maintaining
  the fetus in utero in early pregnancy. General
  principles of neurosurgical and obstetric
  anesthesia apply. Previous neurosurgical
  procedures and current neuropathology may have
  implications for anesthetic management for later
  cesarean delivery.
• Cesarean delivery before the neurosurgical
  procedure. Obstetric and neurosurgical anesthesia
  principles may need to be modified.
• Cesarean delivery followed by later neurosurgery.

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Basic Anesthetic Considerations During Pregnancy

• Multidisciplinary and Cooperative approach
  involving neurosurgeon, neuroradiologist,
  anesthesiologist, obstetrician, midwife, and
  neonatologist is recommended.
• Anticonvulsant therapy may need to be implemented
  or continued in the preoperative phase.
• Aspiration prophylaxis is considered to be
  important
• Oxygen thoroughly administrated.
• Careful airway assessment and management planning
  is necessary

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Basic Anesthetic Considerations During Pregnancy

• LMA for unanticipated difficult intubation.
• Rapid sequence induction is advisable to reduce
  the risk of aspiration.

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INTRAOPERATIVE MANAGEMENT OF THE PREGNANTPATIENT
DURING NEUROSURGERY

• Hemodynamic Considerations
• Ventilatory Management
• Depth of Anesthesia Monitoring
• Temperature Regulation
• Mannitol and IV Fluid Therapy
• Steroid Treatment
• Antiemetic Treatment

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Hemodynamic considerations

• Arterial BP, CVC, BIS.
• Ephedrine is no longer considered the vasopressor
  of choice for obstetric anesthesia, because good
  levels of evidence support advantages such as
  better maternal cardiovascular stability and
  improved neonatal acidbase status when an
  alpha-receptor agonist, such phenylephrine, is
  administered.
• Fetal and maternal effects of phenylephrine and
  ephedrine during spinal anesthesia for caesarean
  delivery. Anesthesiology 200297158290

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• BP should be within narrow limits, close to
  baseline values.
• If the BP is within the range of 140/90 (mild
  preeclampsia) to 160/110 (severe preeclampsia),
  it should be reduced or controlled, aiming for a
  level of approximately 140/90 mm Hg.
• For an emergency neurosurgical procedure where
  the intracranial pressure (ICP) is increased,
  decreasing the BP is less advisable.
• The ideal BP in the case of an unsecured cerebral
  aneurysm remains controversial, although a
  systolic BP of less 150 mm Hg has been
  recommended for the normotensive patient.42,43

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• Controlled hyperventilation to reduce the ICP
  remains an option in the case of acutely
  increased ICP.
• Although the clinical effects on placenta blood
  flow are arguable, severe hyperventilation (PACO2
  25 mm Hg) may cause uterine artery
  vasoconstriction.
• maternal Paco2 be kept in the range of 2530 mm
  Hg.

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• Mannitol given to the pregnant woman slowly
  accumulates in the fetus, and fetal
  hyperosmolality leads to physiological changes
  such as reduced fetal lung fluid production,
  reduced urinary blood flow, and increased plasma
  sodium concentration.
• However, in individual case reports, mannitol in
  doses of 0.25 0.5 mg/kg has been used and
  appears safe.
• Furosemide should be used with cautious.
• IV fluid should be isonatremic, isotonic and
  glucose-free.

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• The administration of steroids to reduce
  peritumor edema (e.g., dexamethasone 4 mg IM or
  IV injection four times a day) also acts to
  accelerate fetal lung maturity by increasing
  surfactant production, although betamethasone is
  the preferred steroid for this purpose based on
  better neonatal outcome.

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ANESTHESIA FOR COMBINED CESAREAN DELIVERYAND
EMERGENCY NEUROSURGERY

• Surgery indicated urgently during pregnancy, but
  a ruptured intracranial aneurysm or a patient
  with cauda equina syndrome.
• For 3rd trimester gestations, the patient may be
  suitable for initial cesarean delivery, followed
  by the neurosurgical procedure.

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• Despite infusion of an oxytocic drug, some
  authors suggest a change from a volatile-based
  anesthetic for cesarean delivery to an IV
  technique for the intracranial procedure to
  further reduce uterine blood loss. Others have
  uneventfully used a volatile anesthetic for both
  procedures.

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GENERAL ANESTHESIA

• When adequate doses of thiopental (45 mg/kg) or
  propofol (22.5 mg/kg) are followed by
  succinylcholine (11.5 mg/kg), there may be a
  transient, but clinically unimportant, increase
  in ICP.

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• moderate dose of fentanyl (25 g/kg) and an
  intermediate-acting neuromuscular blocking drug
  to achieve stable hemodynamic variables.
• remifentanil 1 g/kg over 60 s immediately before
  induction.
• aware that neonatal naloxone may be required.
• IV magnesium sulfate 3060 mg/kg given as a bolus
  immediately after induction is effective and a
  good choice for patients with eclampsia or SAH.

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• Esmolol 0.51 mg/kg may cause fetal bradycardia.
• Nitrous oxide should be avoided in
  neuroanesthesia, because it increases ICP,
  increases cerebral blood flow and cerebral oxygen
  metabolic rate, impairs auto-regulation, expands
  air bubbles, and may contribute nausea and
  vomiting.

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ANESTHESIA FOR CESAREAN DELIVERY AFTER RECENT
NEUROSURGERY

• In the late second and third trimesters, if
  neurosurgery is undertaken and the fetus remains
  well, the pregnancy can be allowed to continue.
  There are several considerations if subsequent
  cesarean delivery is planned.

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ICP AND REGIONAL ANESTHESIA

• Regional anesthesia may be appropriate to use
  when cesarean delivery is performed subsequent to
  recent successful and uncomplicated neurosurgery.
• The woman should be alert, cooperative, and
  preferably have normal ICP.

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• Intracranial SDH formation after epidural
  anesthesia and SAH after spinal anesthesia have
  been reported several times in the literature.
• Epidural injection can cause an increase in ICP
  by compression of the dural sac.79
• The clinical significance of this increase has
  been questioned, but slow injection of
  incremental volumes of local anesthetic has been
  recommended.80

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POSTOPERATIVE MANAGEMENT

• Pain Management
• Deep Vein Thrombosis Prophylaxis
• nonpharmacological prophylaxis (antithromboembolic
  stockings, calf stimulation, calf compressors,
  or pedal pumps)

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• Good postoperative analgesia should be provided
  for maternal comfort and mobility and to reduce
  undesirable hemodynamic disturbances.
• Analgesia is best obtained using a multimodal
  approach combining local anesthetic infiltration
  or scalp blocks, opioids, and paracetamol.

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• Patient-controlled IV opioid (fentanyl or
  morphine) can be considered if the maternal
  mental state is satisfactory and is most
  appropriate after extracranial surgery.
• Neuraxial opioids and epidural analgesia are both
  very effective after spinal surgery, although
  regional techniques with local anesthetic may
  delay initial neurological assessment.

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SUMMARY

• Neurosurgery is infrequently required during
  pregnancy, but mandates a multidisciplinary
  approach and careful consideration of the timing
  of both surgery and delivery. Modification of
  neuroanesthetic and obstetric practices to
  accommodate the safety requirements of the mother
  and fetus may be required.

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Thank you