Neuroanesthesia for the Pregnant Woman Presentation Transcript
Neuroanesthesia for the Pregnant Woman ( Review Article) Anesth Analg 2008;107:193–200 Journal Meeting 2008.07.08 R 4 劉煒翔 Albert Wai Cheung, LAU 中國醫藥大學附設醫院麻醉部 China Medical University Hospital, Anesthesia Department
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.
Trauma during pregnancy, including head injury, is a leading cause of incidental maternal death and morbidity, and complicates 6%–7% of all pregnancies.
Trauma in pregnancy. Emerg Med Clin N Am 2003;21:615–29
The pregnant trauma patient. Anaesth Intensive Care 2005;33:167–80
General principles of neurosurgical and obstetric anesthesia
Case reports and small studies or case series
THE REQUIREMENT FOR NEUROSURGERY DURING PREGNANCY
Brain tumor. Meningioma, contain estrogen and progesterone receptors. Suprasellar and cerebellopontine angle tumors.
Traumatic Brain injury
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.
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 1990;27:855–66
Subarachnoid hemorrhage due to cerebral aneurysmal rupture during pregnancy. Acta Obstet Gynecol Scand 2004;83:330
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.
Difficult intubation can be expected in 1 in 300 pregnant patients.
Difficult intubation in the parturient. Can J Anaesth 1989;36:668–74
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.
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 2001;26:440–3
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.
FETAL CONCERNS IN THE PERIPARTUM PERIOD
The fetus may be compromised indirectly by maternal hypotension,
uterine artery vasoconstriction,
maternal hypoxemia, and
acid–base 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.
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.
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
Basic Anesthetic Considerations During Pregnancy
LMA for unanticipated difficult intubation.
Rapid sequence induction is advisable to reduce the risk of aspiration.
INTRAOPERATIVE MANAGEMENT OF THE PREGNANT PATIENT DURING NEUROSURGERY
Depth of Anesthesia Monitoring
Mannitol and IV Fluid Therapy
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 acid–base 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 2002;97:1582–90
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
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 (PA CO2 25 mm Hg) may cause uterine artery vasoconstriction.
maternal Pa co 2 be kept in the range of 25–30 mm Hg.
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.
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.
ANESTHESIA FOR COMBINED CESAREAN DELIVERY AND 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.
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.
When adequate doses of thiopental (4–5 mg/kg) or propofol (2–2.5 mg/kg) are followed by succinylcholine (1–1.5 mg/kg), there may be a transient, but clinically unimportant, increase in ICP.
moderate dose of fentanyl (2–5 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 30–60 mg/kg given as a bolus immediately after induction is effective and a good choice for patients with eclampsia or SAH.
Esmolol 0.5–1 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.
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.
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.
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
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.
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.
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.