Maternal mortality is rising in the United States. Anesthesia-related mortality accounted for 0.2% of pregnancy-related deaths from 2011.
Maternal mortality from anesthesia complications has decreased with advancements in monitoring and establishing standards of care.
The primary goals of the obstetric anesthesiologist are the safety and comfort of the pregnant woman and her fetus and are achieved through a variety of anesthetic techniques that are individualized to the patient’s medical condition and preferences.
Analgesia refers to a lack of pain perception and is typically sought during labor; anesthesia denotes the absence of all sensation and is the goal during surgical intervention.
Epidural injections or catheters are placed in the epidural space deep to the ligamentum flavum but outside the dura mater, whereas spinal injections or catheters are placed in the intrathecal (or subarachnoid) space between the arachnoid mater and the pia mater, where the cerebrospinal fluid is found.
Neuraxial procedures allow access to either the epidural or intrathecal space for drug administration. A single injection allows for a onetime dose of medication, whereas a catheter allows for variable onset speed, dosing, and duration of analgesia or anesthesia.
Neuraxial procedures can facilitate a safe and comfortable delivery for the majority of patients. Table 3.9.1 compares the advantages and disadvantages of neuraxial analgesia and anesthesia.
Preanesthetic evaluation should include assessment of contraindications to neuraxial placement. Table 3.9.2 lists contraindications for neuraxial anesthesia.
For placement, experienced personnel, peripheral intravenous access, resuscitative equipment, and monitors should be available.
Commonly used neuraxial techniques include epidural catheters, single-shot spinal injections, combined spinal-epidurals (CSE), and dural puncture epidurals (DPE) (Figure 3.9.1A-D). Continuous spinal catheters are occasionally used as well. Table 3.9.3 compares the advantages and disadvantages of the various techniques.
Table 3.9.1 Advantages and Disadvantages of Neuraxial Anesthesia
Advantages
Disadvantages
Most complete analgesia available
Rapid onset of analgesia
Analgesia can be continuous
No maternal sedation
Minimal or no neonatal sedation
Minimizes opioid requirements
Mother able to participate in birth
Mitigates physiologic response to pain
Continuous analgesia may be converted to surgical anesthesia electively, urgently, or emergently.
Neuraxial anesthesia for cesarean delivery avoids the need for general anesthesia or airway instrumentation.
Requires skilled anesthesia provider
Risk of failed block or other complications
Sympathectomy-induced hypotension leading to decreased uteroplacental perfusion
With higher concentration labor epidural solutions, prolonged second stage of labor and increased risk of instrumental vaginal delivery possible
Contraindicated in patients with coagulopathy or on current anticoagulant therapy due to risk of spinal or epidural hematoma
From Wong CA. Advances in labor analgesia. Int J Womens Health. 2009;1:139-154. Wong used with permission of original publisher Dove Medical Press.
Table 3.9.2 Contraindications for Neuraxial Anesthetic
Patient refusal or inability to cooperate
Increased intracranial pressure secondary to a mass lesion
Skin or soft tissue infection at the site of injection
Significant coagulopathy
Recent pharmacologic anticoagulation (safety depends on drug, dose, and time of last administration)
Uncorrected maternal hypovolemia
Lack of experienced anesthesia provider
Inadequate resources for monitoring and resuscitation
From Chestnut DH, Wong CA, eds. Chestnut’s Obstetric Anesthesia : Principles and Practice. 6th ed. Elsevier; 2020.
Medication dosing differs significantly depending on the location of administration. Spinal administration of a dose intended for the epidural space can lead to total spinal anesthesia, profound hypotension, bradycardia, or respiratory arrest.
Epidural
Generally placed in the lumbar region for labor or cesarean delivery (CD), below the termination of the spinal cord at L1 to L2.
Often considered the “gold standard” for labor analgesia; less commonly placed de novo for CD. Their use in CD typically follows conversion of a functioning labor epidural to a surgical anesthetic at the time of decision for CD.
Technique: The epidural space is identified by a loss of resistance to saline or air as the needle traverses the vertebral ligaments. Once the epidural space is identified, a catheter is threaded blindly and secured.
Early labor epidural placement has not been shown to increase the rate of CD or prolong the duration of the first stage of labor (1).
Spinal
Technique: A small gauge needle is passed into the intrathecal space, and medications are administered into the cerebrospinal fluid and the needle is removed.
Pencil-point needles are the standard of care owing to the much lower rate of postdural puncture headache (PDPH) associated with their use.
Spinal blockade is most commonly performed as a single-shot technique and has a limited duration.
Compared to epidural anesthesia, spinal blockade is rapid and predictable, provides a denser block, and carries a lower risk of local anesthetic systemic toxicity (LAST) (2).
Combined Spinal-Epidural
Allows for medication administration into both the intrathecal and epidural spaces, offering the advantages of a spinal’s rapid, reliable block and an epidural catheter’s ability to extend block height and duration.
Technique: A “needle through needle” technique in which the epidural space is accessed first, followed by a spinal needle through the epidural needle into the subarachnoid space, where the intrathecal injection is administered. The spinal needle is removed, and a catheter is threaded through the remaining epidural needle into the epidural space and secured.
Table 3.9.3 Neuraxial Technique Advantages and Disadvantages
Neuraxial Technique
Advantages
Disadvantages
Epidural
Ability to titrate extent and duration of analgesia
Slowest onset
No dural puncture required
Larger drug doses required
May be converted from labor analgesia to surgical anesthesia
Greater risk for maternal local anesthetic systemic toxicity
Higher likelihood of poor block quality (unilateral or patchy block, delayed sacral coverage) compared with other techniques
Subjectively less “dense” block for surgery compared with spinal
Single-shot spinal
Technically simple
Limited duration of effect without the ability to extend the duration
Rapid onset
Limited ability to titrate the level of anesthesia
Dense neural blockade
Immediate sacral analgesia
Low drug doses
Combined spinal-epidural (CSE)
Rapid-onset analgesia/anesthesia from intrathecal injection
Possible increased risk for transient fetal bradycardia (although this does not appear to impact CD rate)
Ability to titrate extent and duration of anesthesia
May be converted from labor analgesia to surgical anesthesia
Decreased incidence of failed epidural catheter
Faster onset of analgesia compared with epidural
Slower onset compared with CSE
Ability to titrate extent and duration of anesthesia
Larger drug doses required compared to spinal
Fewer side effects (pruritis, hypotension, fetal bradycardia) compared to CSE
Greater risk for maternal local anesthetic systemic toxicity
May be converted from labor analgesia to surgical anesthesia
Continuous spinal
Ability to titrate extent and duration of anesthesia
Results in large dural puncture with a high incidence of postdural puncture headache
Rapid onset
Safety concern: Can be mistaken for epidural catheter and result in high spinal from a medication administration error
Low doses of local anesthetic and opioid
May be used for surgical anesthesia
Dural Puncture Epidural
A variation on the combined spinal-epidural technique without the administration of intrathecal medications often used for labor analgesia owing to the more rapid onset and improved blockade quality compared with a traditional epidural technique.
Technique: Similar to the “needle through needle” approach described for CSE is performed, but no intrathecal medication is administered.
The presence of free-flowing cerebrospinal fluid (CSF) through the spinal needle can act as a “confirmatory” end point, indicating a higher likelihood of correct epidural positioning.
Continuous Spinal Anesthesia
Involves the placement of a catheter into the intrathecal space, either intentionally or after unintentional dural puncture during attempted epidural placement.
Technique: Similar to that of a single-shot spinal, but the needle must be large enough to accommodate a catheter.
The presence of a catheter allows for repeated drug administration to extend the height or duration of the spinal blockade.
Owing to the larger gauge needle required for catheter insertion, continuous spinal anesthetics have the major disadvantage of a high risk for PDPH.
Neuraxial Procedures in the Setting of Coagulopathy or Anticoagulation
Neuraxial anesthesia should not be performed in patients with severe coagulopathy because of the increased risk of spinal or epidural hematoma. A minimum acceptable platelet count has not been standardized, but the risk of hematoma is low in patients with a platelet count of >70,000 ug/dL, provided there is no evidence of functional coagulopathy, platelet dysfunction, or downward trend (4).
There is a growing number of pregnant women in whom therapeutic or preventative thromboprophylaxis is indicated. The Society of Obstetric Anesthesiology and Perinatology issued a consensus statement for anesthetic management of pregnant women receiving thromboprophylaxis or higher dose anticoagulants. The recommendations are summarized in Table 3.9.4 (5).
Table 3.9.4 The SOAP Consensus Statement on the Anesthetic Management of Pregnant and Postpartum Women Receiving Thromboprophylaxis or Higher Dose Anticoagulants | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Regional anesthesia may be used as part of a multimodal postoperative analgesia strategy. Currently available evidence suggests that these blocks are most beneficial in settings where neuraxial opioids are not administered (e.g., CD performed with general anesthesia) or in patients with breakthrough pain despite neuraxial opioid administration (6).
Transversus Abdominis Plane (TAP) Block
Technique: Using ultrasound guidance, a needle is advanced into the plane between the internal oblique and transversus abdominis plane, and medication is administered into the fascial plane. A catheter may be threaded into the plane and left in place.
TAP block should be considered after CD especially for patients who do not receive neuraxial morphine (7).
Quadratus Lumborum (QL) Block
Technique: Using ultrasound guidance, a needle is advanced into the plane lateral, posterior, or anterior to the QL muscle, and medication is administered into the fascial plane. A catheter may be threaded into the plane and left in place.
QL blocks are closer to the vertebral column than TAP blocks, possibly contributing to paravertebral spread and thus visceral analgesia. Depending upon which QL block is used and the extent of paravertebral spread, hemodynamic changes and quadriceps weakness may be seen (7).
CWI
Technique: A multiorifice catheter is placed by the surgeon at the surgical site before closure, preferably deep to the rectus fascia.
Medications (most commonly local anesthetics) are delivered continuously by a pump.
All patients in the labor and delivery suite have the potential to need an anesthetic emergently and should be evaluated by an anesthesia care provider for a focused history and physical examination. Significant anesthetic or obstetric concerns should be discussed with the obstetric team in a regularly scheduled multidisciplinary team “huddle” at every shift change.
For patients with high-risk conditions, early referral for antepartum evaluation by an obstetric anesthesiologist allows for timely investigation, specialist referrals, and medical optimization. Management often requires multidisciplinary input and potentially transfer to a facility with a higher level of resources. This approach has been shown to reduce maternal morbidity and mortality (8).
Appropriate indications for antepartum and peripartum anesthesiology consultation are included in Table 3.9.5.
Preoperative Laboratory Evaluation
Obtaining preoperative or intrapartum patient labs beyond routine prenatal labs should be considered based on maternal history and physical examination.
Assessment of routine intrapartum platelet count is not necessary before neuraxial procedures in the healthy parturient and should be individualized and based on a patient’s history (e.g., preeclampsia), physical examination, and clinical signs (9).
Although blood typing is recommended for all parturients, routine crossmatching is not generally necessary for healthy patients with a history of uncomplicated pregnancy. An example of an algorithm for transfusion laboratory evaluation (e.g., blood type, screen, and crossmatch) for patients admitted to labor and delivery can optimize resource utilization (Table 3.9.6).
Neuraxial anesthesia confers a superior safety profile, postoperative analgesia, and patient experience and is considered
the preferred mode of anesthesia for CD. However, the safety of general anesthesia for CD has improved substantially, and there is no longer a significant difference in mortality rate between the techniques. General anesthesia for CD should not be avoided when indicated (10).
Table 3.9.5 Indications for Anesthesiology Consultation
Cardiovascular Disease
Congenital heart disease
Valvular heart disease
Cardiomyopathy or decreased cardiac function
Cardiac dysrhythmias
Presence of cardiac implantable electronic device
Pulmonary hypertension
Hematologic Conditions
Coagulopathy of any etiology
Current anticoagulant therapy
Sickle cell anemia
Neurologic and Neuromuscular Diseases
Cerebrovascular disease (e.g., aneurysm, AVM)
Presence of ventricular shunt (e.g., ventriculoperitoneal)
Prior spinal cord injury
Major neurologic, neuromuscular, or musculoskeletal disorders
Structural vertebral abnormalities or prior back surgery
Other Significant or Poorly Controlled Comorbidity
Autoimmune disorders
Chronic pain (especially with opioid use), substance use disorder, addiction disorder
Endocrine disorders
Hepatic or renal disorders
Metabolic or genetic disorders
Obstructive sleep apnea
Prepregnancy BMI > 50
Pulmonary disease
Solid organ transplantation (prior or awaiting)
High-Risk Anesthesia Considerations
Anticipated difficult airway or prior difficult intubation
Prior anesthesia complications including difficult or failed neuraxial block
Malignant hyperthermia
Local anesthetic allergy
Refusal of blood products
Obstetric Complications or Conditions
Placenta accreta spectrum
Nonobstetric surgery during pregnancy
Planned cesarean delivery with concurrent major abdominal procedure
Adapted from ACOG Practice Bulletin No. 209.
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