What the Anesthesiologist Should Know before the Operative Procedure
Multiple gestations have become more common because they can occur in conjunction with infertility treatments. In comparison to singleton gestations, multiple gestations are more likely to be complicated by supine hypotension syndrome, anemia, preeclampsia, polyhydramnios, preterm premature rupture of membranes, preterm labor and/or delivery, dysfunctional labor, cord entanglement, umbilical cord prolapse, malpresentation, obstetric trauma, uterine atony, and peripartum hemorrhage.
Cesarean delivery is also more common in multiple gestation pregnancies. Whether a vaginal delivery is an option in twin gestations is dependent on multiple obstetric factors, including the presentation of twin A (the first presenting twin) and the estimated size of the twins. Triplets and larger order gestations are exclusively delivered by cesarean.
Obstetric complications occur in nearly all triplet gestations and greater. In such pregnancies, respiratory distress may be present because of diaphragmatic elevation or pulmonary edema, the risk of which is high in pre-eclampsia and when multi-medication tocolysis is employed.
If an anesthesiologist is working in a small hospital, it is important to ensure the ready availability of adequate neonatal personnel at the time of delivery, as a single anesthesiologist could have great difficulty caring for a mother who will be at increased risk for hemorrhage and assisting in the resuscitation of multiple infants. Most of these babies will be born prematurely, with gestational age decreasing as the number of multiples increase.
1. What is the urgency of the surgery?
What is the risk of delay in order to obtain additional preoperative information?
Delaying an emergent cesarean delivery when the obstetric provider believes that an immediate threat to the life of a fetus or mother is present can be fatal for the mother, the fetus, or both. Therefore, do not delay an emergency cesarean delivery for laboratory values.
Because of the increased risk of preeclampsia in multiple gestation pregnancies, hypertension and proteinuria may warrant checking a platelet count prior to proceeding with neuraxial anesthesia. If the obstetrician is highly suspicious of preeclampsia and there is no time to check laboratory values, some anesthesiologists may prefer to proceed with general anesthesia.
If the parturient has had no clinical signs of bleeding, others may be comfortable proceeding with a single shot spinal anesthetic. General anesthesia may also be necessary because there simply may be no time to establish neuraxial anesthesia. Because of the risk of postpartum hemorrhage and uterine atony, obtaining a type and screen for the potential administration of blood products may be prudent after surgical conditions have been safely established.
Emergent: Emergent surgery for multiple gestations would likely be a result of fetal distress or maternal hemorrhage. A unique scenario to multiple gestations can occur when twin A has been delivered vaginally and twin B either shows signs of distress or turns breech, and because of size is not a candidate for breech extraction. Generally, twin B must have an estimated fetal weight no more than 2500g and cannot be larger than twin A in order to be a candidate for vaginal breech extraction. This can result in the need for an emergent cesarean delivery of twin B after vaginal delivery of twin A.
Twin B may experience distress immediately following the delivery of twin A because of placental abruption or cord prolapse, and could also proceed to emergency cesarean delivery because of cephalopelvic disproportion or malpresentation. It may be prudent to have an epidural in place for twin deliveries so that if the need for emergency surgery arises during labor and delivery, an immediate bolus of 3% 2-chloroprocaine or 2% lidocaine could establish an adequate surgical level and general anesthesia could be avoided. Some anesthesiologists make this recommendation to their multiple gestation patients who have a concerning airway exam.
Urgent: Because 60% of women pregnant with twins deliver before 37 weeks gestation, it is not uncommon to have a parturient who is planning a term cesarean delivery present in preterm labor. Multiple gestations need not affect the anesthesiologist’s choice of neuraxial technique or the use of general anesthesia. Such decisions can be based on other criteria.
Elective: For elective cesarean delivery, many anesthesiologists prefer to have an active type and screen in the blood bank so that if peripartum hemorrhage does occur, antibodies have been ruled out and matched blood is available.
2. Preoperative evaluation
Patients with multiple gestations are at increased risk for developing pre-eclampsia. A platelet count should be obtained prior to neuraxial techniques in patients with pre-eclampsia to rule out thrombocytopenia, which can also result from HELLP syndrome.
Multiple gestation pregnancies increase a patient’s risk of developing pulmonary edema. The presence of pre-eclampsia and therapy with multiple tocolytic agents can further increase a patient’s risk.
Reactive airway disease
In multiple gestation pregnancies, it is not uncommon to need uterotonic medications after delivery because of uterine atony. The presence of asthma alerts the anesthesiologist to avoid Hemabate® (prostaglandin F2-alpha), because this agent can cause lethal bronchial constriction in asthmatic patients.
In multiple gestation pregnancies, it is not uncommon to need uterotonic medications after delivery because of uterine atony. The presence of hypertension alerts the anesthesiologist to avoid ergot uterotonic agents, such as Methergine ®.
Medically unstable conditions warranting further evaluation include: Pre-eclampsia, pulmonary edema
Delaying surgery may be indicated if: Delaying an emergent cesarean delivery when the obstetric provider believes that an immediate threat to the life of a fetus or mother may be present can be fatal for the mother, the fetus, or both. Therefore, do not delay an emergency cesarean delivery. Elective cesarean delivery could be delayed for a preeclampsia diagnosis to control hypertension and to obtain a platelet count.
3. What are the implications of co-existing disease on perioperative care?
b. Cardiovascular system
Perioperative evaluation- Evaluating for pre-eclampsia, pulmonary edema, or acute obstetric hemorrhage would involve obtaining vital signs (especially blood pressure, heart rate, and respiratory rate), performing a physical exam (especially auscultating for pulmonary crackles) and obtaining a history (asking about significant vaginal bleeding or abdominal pain). If the patient is hypertensive, then a pre-eclampsia work up should be performed assessing urine protein, obtaining repeated blood pressure evaluations, and evaluating a complete blood count, which includes a platelet count.
Perioperative risk reduction strategies- If pre-eclampsia is present, then initiating anti-hypertensive therapy can reduce the patient’s risk of cerebral hemorrhage, and initiating magnesium therapy can reduce the patient’s risk of seizure. Obtaining a platelet count can direct an anesthesiologist away from neuraxial instrumentation.
Baseline coronary artery disease or cardiac dysfunction – Goals of management
The cardiovascular changes of pregnancy are more pronounced in patients with multiple gestations. Further, multiple gestations puts parturients at greater risk for peripartum cardiomyopathy.
Perioperative evaluation- Evaluation for significant cardiac disease in pregnancy involves obtaining a history from the patient, focused on shortness of breath, significant exercise intolerance, chest pain, or fainting spells. These symptoms can be hard to interpret during pregnancy, when dyspnea and decreased exercise tolerance are common. Performing a physical exam may or may not be helpful, but the results of the H&P can direct subsequent testing, such as electrocardiogram and echocardiogram.
Perioperative risk reduction strategies- The knowledge that a patient has significant cardiac disease, such as an arrhythmia or peripartum cardiomyopathy, may change an anesthesiologist’s monitoring recommendations for vaginal or surgical delivery. The type of anesthesia, the fluid management, and even the level of postpartum care can be directed by this information.
COPD: COPD is rare in women of childbearing age.
Reactive airway disease (Asthma)
Perioperative evaluation- Simply asking a patient if she has a history of asthma is typically adequate for evaluation.
Perioperative risk reduction strategies- In multiple gestation pregnancies, it is not uncommon to need uterotonic medications after delivery because of uterine atony. The presence of asthma alerts the anesthesiologist to avoid Hemabate® (prostaglandin F2-alpha), because this agent can cause lethal bronchial constriction in asthmatic patients.
Perioperative evaluation- In multiple gestation pregnancies, no specific renal testing needs to be considered unless pre-eclampsia is present, in which case a creatinine should be obtained. If the parturient reports gastroesophageal reflux disease, then they may be at an increased risk of aspiration.
Perioperative risk reduction strategies- To prevent reflux of gastric contents into the lungs, most anesthesiologists employ aspiration prophylaxis for all parturients. Oral sodium citrate, intravenous metoclopramide and/or H2 receptor blocking medications, and rapid sequence intubation techniques during general anesthesia are examples of medications and techniques often used for aspiration prophylaxis for parturients.
Acute issues: Unless pre-eclampsia or eclampsia is present, patients with multiple gestations have no greater neurologic concerns than do women with singleton pregnancies.
Chronic disease: Unless pre-eclampsia or eclampsia is present, patients with multiple gestations have no greater neurologic concerns than do women with singleton pregnancies.
Gestational diabetes is more common in patients with multiple gestations. Obstetricians will closely follow blood glucose levels in parturients, with a goal of < 100 mg/dl in order to minimize neonatal hypoglycemia after birth.
g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)
4. What are the patient's medications and how should they be managed in the perioperative period?
Typically, parturients are on minimal medications. There are certain medications that may need management in the perioperative time. Anticoagulant medications should be noted and the performance of neuraxial anesthesia should follow the American Society of Regional Anesthesia (ASRA) guidelines as closely as possible.
Insulin to control blood glucose levels needs to be continued through labor and cesarean delivery with maternal glucose levels followed closely. If patients are on cardiac medications for chronic hypertension or a history of arrhythmia, these should be continued throughout labor or surgery.
Medications that cause sedation in the mother will likely cause a similar effect in the neonate, and informing the neonatology team can help them provide appropriate neonatal care, especially in cases of mothers on high doses of opioids or benzodiazepines. Do not acutely withdraw a parturient from such chronic medications in order to decrease fetal exposure.
h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?
Multiple tocolytic medication therapy is common in multiple gestation pregnancy and can increase a parturient’s risk of pulmonary edema. Examples of common tocolytics are intravenous magnesium, oral nifedipine, and parenteral or oral terbutaline. Administration of steroids for fetal lung maturity may also exacerbate pulmonary edema through their mineralocorticoid properties. Steroids, such betamethasone and dexamethasone, are used in premature labor to improve respiratory and potentially neurologic outcomes in preterm neonates.
Further, patients with multiple gestations are at increased risk of pre-eclampsia, and magnesium may be administered for this or other indications. Note that peripartum magnesium treatment may improve neurologic outcomes for very premature infants, so it may be used even when a parturient is not preeclamptic. The anesthesiologist should be alert to the possibility of magnesium toxicity in these mothers, especially in those with renal insufficiency due to preeclampsia.
Treatment of magnesium toxicity includes intravenous calcium gluconate or calcium chloride, intravenous fluids, and, in rare cases, renal dialysis (since magnesium is only cleared by glomerular filtration).
i. What should be recommended with regard to continuation of medications taken chronically?
Cardiac: Continue all antiarrhythmic and antihypertensive medications throughout labor or cesarean delivery.
Pulmonary: Typically asthma improves with pregnancy, but continuation of asthma inhalers or oral medications is appropriate throughout labor or prior to cesarean delivery.
Neurologic: Antiseizure medications should be continued throughout labor or surgery.
Anti-platelet: Anticoagulant medications should be noted, and the performance of neuraxial anesthesia should follow the American Society of Regional Anesthesia guidelines as closely as possible. (. ASRA guidelines: http://www.asra.com/publications-anticoagulation-3rd-edition-2010.php)
Psychiatric: Continue all chronic antipsychotic, opioid, and benzodiazepine medications throughout labor or cesarean delivery, and inform the neonatology team. Do not acutely withdraw a parturient from these medications prior to the birth.
j. How To modify care for patients with known allergies –
Local anesthetic or opioid allergies may change a neuraxial anesthesia plan. For example, if a patient reports a morphine allergy, intrathecal morphine could be avoided for cesarean delivery and postoperative pain control could be managed with patient controlled intravenous analgesia using an alternative opioid, such as fentanyl or hydromorphone.
Also, if an amide local anesthetic allergy is reported, an epidural dosed with an ester local anesthetic, such as chloroprocaine, could be used, or a general anesthetic could be performed.
k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.
l. Does the patient have any antibiotic allergies- – Common antibiotic allergies and alternative antibiotics]
For cesarean delivery, if a cephalosporin allergy is reported, alternative antibiotics include clindamycin or ampicillin and gentamycin.
m. Does the patient have a history of allergy to anesthesia?
Documented- avoid all trigger agents such as succinylcholine and inhalational agents:
Proposed general anesthetic plan: Regional anesthesia would be preferred with spinal or epidural anesthesia.
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5. What laboratory tests should be obtained and has everything been reviewed?
Common laboratory normal values will be same for all procedures, with a difference by age and gender.
Hemoglobin levels: Although red cell mass increases in pregnancy, plasma volume increases even more, creating a “relative” anemia with a parturient’s hemoglobin at sea level typically being around 11.7. The relative anemia of pregnancy may be even greater in higher order multiples.
Electrolytes: Magnesium levels for patients on magnesium therapy with renal insufficiency are important. Electrolyte abnormalities are unlikely in parturients.
Coagulation panel: Patients with preeclampsia should have a platelet count, and in some circumstances a coagulation profile. If the platelet count is abnormal, if the preeclampsia is severe, if placental abruption is suspected, or if subcutaneous unfractionated heparin has been administered, a coagulation profile including PT, INR, APTT, and fibrinogen are indicated.
Imaging: If the placenta is located anteriorly on the uterus by ultrasound, then the obstetricians may need to incise the placenta during a low transverse cesarean. Blood loss and the need for resuscitation of Twin B may be greater. Further, if the placenta is low-lying or a previa, risk for abnormal placentation, such as an accreta, is greater. The possibility of massive blood loss should be considered in these patients, especially if the patient has had prior cesarean deliveries or if the obstetricians see signs of accreta on the ultrasound.
Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?
For labor analgesia, a lumbar epidural may be placed (either alone or as part of a combined spinal-epidural technique) and bolused with 10 to 20 cc of dilute bupivacaine (e.g., 0.0625% to 0.125%) plus fentanyl (e.g., 2 mcg/mL) and run at 5 to 10 mL per hour via a continuous infusion pump with a patient controlled epidural analgesia option (e.g., 5mL of the solution upon patient demand every 5 to 15 minutes).
A traditional epinephrine-containing test dose may be administered (e.g., 3mL 1.5% lidocaine with 1:200,000 epinephrine) to check for intrathecal or intravascular placement of the epidural catheter. Use caution with epinephrine in the intravascular component of the test dose if the mother is hypertensive or if the fetus has shown signs of uteroplacental insufficiency. The benefits of an epidural catheter technique includes excellent patient comfort during labor, as well as a method to obtain rapid neuraxial anesthesia should the need arise for an instrumented vaginal delivery or cesarean delivery of one or both twins.
Regional anesthesia for cesarean delivery for multiple gestations includes the epidural option or a spinal anesthetic, which is often performed with hyperbaric bupivacaine (e.g. 1.5 ml 0.75% bupivacaine with dextrose) with fentanyl (e.g. 10-25 mcg) and morphine (e.g. 0.1 -0.3 mcg). An alternative is a combined spinal-epidural technique, which involves dosing the spinal anesthetic then threading an epidural catheter, either for labor analgesia or if it is anticipated that the surgery will proceed longer than the duration of the spinal alone.
Benefits: The mother gets to be awake for the birth of her babies. There is typically no need for airway management. The fetuses are not exposed to general anesthetic agents. The obstetricians do not feel the urgency to proceed rapidly from induction to delivery in order to reduce anesthetic exposure for the fetuses.
Drawbacks: There is a rare risk of neuraxial bleeding, infection, or nerve damage from neuraxial instrumentation. These risks may be greater in patients with HELLP syndrome, bleeding diatheses, or who are on anti-thrombotic medications, such as low molecular weight heparin, unfractionated heparin, Coumadin, or Plavix®. The latter two are rarely used in pregnancy in the U.S. Risk of infection may be increased in patients with a systemic infection, such as untreated chorioamnionitis, and treatment with antibiotics is recommended prior to instrumentation of the neuraxis. Patients with pre-existing nerve damage, spinal stenosis, or hardware about the spine may be at increased risk of neurologic complications, although all risks and benefits need to be weighed. In spite of these considerations, neuraxial anesthesia is often the chosen method. Local anesthetic toxicity is a possibility with epidural anesthesia. Mothers may feel discomfort during cesarean delivery, more commonly under epidural than spinal anesthesia. Hypotension after initiation of neuraxial anesthesia can lead to nausea, vomiting, and fetal decelerations. This is easily treated with left uterine displacement positioning, co-loading with crystalloid intravenous solution, and vasopressors, such as boluses of ephedrine and/or phenylephrine.
Peripheral Nerve Block
Not applicable for cesarean anesthesia.
Benefits: If massive hemorrhage is anticipated, the patient is already under general anesthesia.
Drawbacks: The mother is asleep for the birth of her babies. The fetus is exposed to general anesthetic agents. The obstetricians feel additional pressure to operate rapidly to minimize exposure of the fetus to the anesthetic agents. Previously it was believed that general anesthesia put a mother at greater risk of mortality than regional anesthesia because of the risk of difficult airway management at induction. However, more recent data indicates that this may not be the case.
Other issues: General anesthesia for cesarean delivery is a procedure with a high risk of intraoperative awareness.
Airway concerns: Parturients have greater airway risks than nonpregnant patients, including decreased apnea time (decreased functional residual capacity and increased oxygen consumption), increased risk for aspiration (decreased lower esophageal tone and a displaced stomach), increased airway edema, and increased risk of airway bleeding (especially nasal bleeding with manipulation). These changes may be even greater in the parturient with multiple gestations. Further, the need to obtain an airway rapidly in the event of an emergency cesarean delivery may be more likely in the parturient with multiple gestations. Rapid sequence intubation with cricoid pressure is recommended for parturients undergoing general anesthesia for cesarean delivery — this is especially important for patients in labor, or those who are not appropriately fasted.
Monitored Anesthesia Care
MAC is not performed for cesarean delivery.
6. What is the author's preferred method of anesthesia technique and why?
What prophylactic antibiotics should be administered?
Antibiotics are not administered to patients in labor unless chorioamnionitis is suspected or the patient is Group B Strep culture positive. The American College of Obstetricians and Gynecologists recommends 1-2 grams cefazolin within one hour of skin incision before cesarean delivery.
What do I need to know about the surgical technique to optimize my anesthetic care?
If vaginal delivery of twins is to be attempted, the delivery itself will occur in the operating room because of the high risk of Twin B needing a cesarean delivery. The anesthesiologist should be immediately available during and after delivery of Twin A with a plan in place for quickly initiating surgical anesthesia via epidural catheter or general anesthesia if necessary for delivery of Twin B.
What are the most common intraoperative complications and how can they be avoided/treated?
Hemorrhage is the most likely complication during delivery of multiples, with the most common cause being uterine atony. Uterotonic agents such as oxytocin, ergot alkaloids (e.g. Methergine®), prostaglandin F2 alpha (Hemabate®), and misprostol (Cytotec®) should be available in the operating room as treatment options. Fetal distress in Twin B after delivery of Twin A is a possibility, and the ability to rapidly induce surgical conditions with either general or regional anesthesia before or after the delivery of Twin A is important. Uterine inversion or severe shoulder dystocia may need to be treated with uterine relaxants such as nitroglycerin, terbutaline, or volatile anesthetic agents. Amniotic fluid embolism is a rare but deadly complication in the peripartum period. There is no method to prevent AFE, but supportive care including cardiopulmonary resuscitation, advanced cardiac life support, and ECMO or cardiopulmonary bypass are treatment options.
Cardiac complications: Cardiac arrhythmias or peripartum cardiomyopathy are rare.
Pulmonary: Pulmonary edema can be treated with supportive therapy as necessary to maintain oxygenation and ventilation (diuresis, CPAP, BIPAP, or intubation with mechanical ventilation). Intravenous furosemide, careful fluid management, and discontinuation of multiple tocolytic agents can also assist in treatment.
b. If the patient is intubated, are there any special criteria for extubation?
Recent data indicates that postoperative airway loss is a cause of anesthesia-related maternal mortality. Waiting to extubate the mother until standard extubation criteria have been met (3-second headlift, following commands, spontaneously breathing with good tidal volumes) and appropriate monitoring in transport and in the postoperative area are important for patient safety.
c. Postoperative management
What analgesic modalities can I implement?
Unless significant vaginal trauma has occurred, analgesic modalities other than ibuprofen are not necessary after vaginal delivery. After cesarean delivery, intrathecal long-acting opioid medications (e.g. 0.1-0.3mg morphine) can be administered at the time of a spinal anesthetic. Epidural long-acting opioid medications (e.g. 4 mg morphine) can also be administered. Alternatively, an epidural infusion can be run into the postoperative period for analgesia.
What level bed acuity is appropriate?
After uncomplicated vaginal or cesarean delivery, floor care is appropriate.
What are common postoperative complications, and ways to prevent and treat them?
Appropriate postoperative assessments for hypoventilation are important in patients that have been administered intrathecal long-acting opioids (e.g. morphine) as well as patients that are on intravenous opioid patient-controlled analgesia pumps. The American Society of Anesthesiologists guidelines should be followed by the postpartum nursing service.
What's the Evidence?
Pratt, SD. “Anesthesia for breech presentation and multiple gestation”. Clin Obstet Gynecol. vol. 46. 2003. pp. 711-29. (This article reviews concerns regarding the anesthetic management of patients with multiple gestations.)
“American College of Obstetricians and Gynecologists. Committee Opinion No. 455: Magnesium Sulfate Before Anticipated Preterm Birth for Neuroprotection”. Obstet Gynecol. vol. 115. 2010. pp. 669-71. (This document states the ACOG committee opinion that "magnesium sulfate given before anticipated early preterm birth reduces the risk of cerebral palsy in surviving infants.)
Simhan, HN, Caritis, SN. “Prevention of preterm delivery”. New Engl J Med. vol. 357. 2007. pp. 477-87. (This article reviews the current management for the prevention and treatment of spontaneous preterm labor and delivery.)
Horlocker, TT, Wedel, DJ, Rowlingson, JC. “Regional Anesthesia in the Patient Receiving Antithrombotic or Thrombolytic Therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines”. Regional Anesthesia and Pain Medicine. vol. 35. 2010. pp. 64-101. (These are the ASRA guidelines regarding neuraxial anesthesia and the use of prophylactic or therapeutic antithrombotic or thrombolytic therapy.)
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- What the Anesthesiologist Should Know before the Operative Procedure
- 1. What is the urgency of the surgery?
- What is the risk of delay in order to obtain additional preoperative information?
- 2. Preoperative evaluation
- 3. What are the implications of co-existing disease on perioperative care?
- b. Cardiovascular system
- c. Pulmonary
- d. Renal-GI:
- e. Neurologic:
- f. Endocrine:
- 4. What are the patient's medications and how should they be managed in the perioperative period?
- i. What should be recommended with regard to continuation of medications taken chronically?
- j. How To modify care for patients with known allergies -
- l. Does the patient have any antibiotic allergies- - Common antibiotic allergies and alternative antibiotics]
- m. Does the patient have a history of allergy to anesthesia?
- 5. What laboratory tests should be obtained and has everything been reviewed?
- 6. What is the author's preferred method of anesthesia technique and why?
- a. Neurologic:
- b. If the patient is intubated, are there any special criteria for extubation?
- c. Postoperative management