Anesthesia for the High Risk Parturient

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Anesthesia for the High Risk Parturient

David J. Birnbach, MD

Parturients are considered to be high risk to theanesthesiologist if they have a preexisting medicalcondition, obstetric complication, a problem that canpotentially necessitate an emergent Cesarean delivery,or a potential uncertainty regarding anestheticmanagement.

Preeclampsia/Eclampsia/HELLP Syndrome

Problems Associated With Preeclampsia

Every organ system can be involved by the vasoconstric-tion of this disease. Systems which may be impactedinclude the following: cardiovascular (reduced cardiacoutput, intravascular depletion, hypertension), renal (ol-iguria), gastrointestinal (hepatic involvement), Centralnervous (seizures), and hematologic (platelet abnormal-ities, disseminated intravascular coagulation).

Anesthetic Considerations in PreeclampsiaDrug Interactions

Magnesium sulfateinteracts with both depolarizingand nondepolarizing neuromuscular blocking drugs.

Analgesia for Vaginal Delivery

Although several obstetricians have suggested thatepidural analgesia should not be performed in thepreeclamptic patient, there is growing opinion amonganesthesiologists and obstetricians that epidural anal-gesia, if there is no coagulation abnormality, is thepreferred method of providing analgesia to the pre-

eclamptic. Epidural analgesia offers several advan-tages including the following:

Helps with blood pressure management. Increases uteroplacental perfusion by decreasing

endogenous catecholamines. Allows a fast route for Cesarean delivery, if nec-

essary, without the use of general anesthesia.

Anesthesia for Cesarean Delivery

General Anesthesia. If general anesthesia is neces-sary, one should consider the following:

Laryngeal edema may make endotracheal intuba-tion difficult.

Hypertension may be worsened by laryngoscopyand should be treated prior to induction of anesthe-sia. Drugs that have been suggested include labe-talol, hydralazine, nitroglycerin, trimethaphan, andnitroprusside.

Magnesium sulfate interacts with neuromuscularblockade.

Regional Anesthesia. Although spinal anesthesiamay be indicated in selected cases (preeclamptic withdifficult airway for an emergency Cesarean delivery?)many authors suggest that epidural anesthesia causesless changes in blood pressure and should be usedwhen regional anesthesia is chosen for preeclampticsundergoing Cesarean delivery.

Points to consider when choosing neuraxial block-ade in the severely preeclamptic include the following:

Avoid epinephrine containing local anesthetics. Consider central line before initiation of epidural,

if volume status is in question (especially if oligu-ria is present).

Ephedrine should be used in small incrementaldoses to treat hypotension.

Assessment of Platelet Function in thePreeclamptic Patient

It is generally accepted that if the platelet count is100,000 then it is likely that the other indices ofcoagulation will be normal. However, some pre-

eclamptics may have a normal platelet count withabnormal platelet function. Although in the past thebleeding time had been suggested as the best test todetermine platelet function, it is no longer performedby most obstetric anesthesiologists because it has notbeen shown to predict the risk of hematoma forma-tion. Rogers and Levin stated that our analysis ofbleeding time data from 640 publications reveals thatthe value of the test in diagnosis remains unclear.

Thromboelastography can be used as a bedsidemeasure of viscoelastic changes but has not yet beenshown to be predictive in preeclamptic women.

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Regional anesthesia can be safely performed on thepreeclamptic patient, if:

A recent platelet count is normal The recent platelet count is not dramatically lower

than the previous value

There is no clinical evidence of coagulopathy.

Antepartum Hemorrhage

Placenta Previa

Actively bleeding/major blood lossGeneral Endo-tracheal Anesthesia

Get help, Second IV placement. IV Fluid administration (via rapid infusion device

with warmer, if available). Rapid Sequence InductionConsider Ketamine

1 mg/kg.

No active hemorrhage-hemodynamic stability If no hypovolemia, epidural or spinal anesthesia

may be used.

Placenta Accreta

Because placenta previa in a patient for a repeat Ce-sarean delivery may be associated with placenta ac-creta, these patients should be treated as though majorblood loss will occur. Two IV lines should be placed,blood should be available, and the patient should bemade aware that a Cesarean hysterectomy may be-come necessary and that general anesthesia may beused to provide appropriate operating conditions and

to protect her airway in the event of massive hemor-rhage and Cesarean hysterectomy. In an elective re-peat Cesarean delivery in a patient with a placentaprevia, regional anesthesia may be used and, if hemo-dynamic variables remain stable, may be continuedeven if a Cesarean hysterectomy is performed. In a re-cent multi-institutional study, 12 patients received epi-dural anesthesia for elective or emergency Cesarean hys-terectomy and none required intraoperative induction ofgeneral anesthesia. Should the patient become unstable,general anesthesia should be considered.

Abruptio Placenta

1. Actively bleeding/major blood lossGeneralEndotracheal Anesthesia (as in placenta previa).

2. No active hemorrhage. Regional anesthesia canbe initiated if:

There is no evidence of maternal hypovolemia. Clotting studies are within normal limits.

Substance AbuseThe use of illicit drugs has become endemic in oursociety and as a result, anesthesiologists working on

Labor and Delivery are now seeing a dramatic in-crease in the number of patients abusing illicit drugs.These drug-abusing parturients present many chal-lenges to the anesthesiologist. Of the drugs abused,cocaine has the most profound implications to theanesthesiologist.

The use of illicit drugs has become endemic in oursociety and, as a result, anesthesiologists are now see-ing a dramatic increase in the number of patients whoare using these illicit drugs. Although drug abuse is amajor problem in large inner-city hospitals, it is beingseen in all classes of patients and hospitals. Drugabuse in pregnancy involves a wide range of sub-stances and clinical presentations. Although there is astrong association between lack of prenatal care anddrug abuse, identification of the drug-abusing patientis a difficult problem. Patients in whom the anesthe-siologists should suspect drug abuse include thosewomen who are unregistered at the time of delivery,those with intrauterine growth retardation, abruptioplacenta, or delivery of a depressed neonate.

Most pregnant drug abusers deny drug abuse evenwhen confronted with positive toxicology results.Multiple drug abuse is common, with many adulter-ants being added to most street drugs. At St. Lukes-Roosevelt Hospital Center in New York City,50% ofour unregistered patients have positive toxicologyscreens and 75% of these patients deny illicit druguse. The use of these drugs in pregnancy may precip-itate life-threatening problems. These problems andthe anesthetic and obstetric implications of maternaldrug abuse and the use of spinal anesthesia in thesepatients will be reviewed in this lecture.

Cocaine

Cocaine use has now reached epidemic proportions,with 30 million Americans having tried cocaine atleast once. The prevalence of cocaine use in the obstet-ric population is also increasing, and anesthesiolo-gists, like obstetricians and pediatricians, are now be-ing affected by the abuse of this potentially lethaldrug. Positive cocaine toxicology testing has been re-ported from around the US, crossing geographic, so-

cioeconomic, and cultural boundaries. Because a ma-jority of cocaine-abusing pregnant patients deny drugabuse, the exact extent of perinatal cocaine use isunknown. It has been estimated, however, that50%of high-risk women who are cared for at urban teach-ing hospitals may be using cocaine during their preg-nancies. Although patients who do not receive prena-tal care tend to have the highest rates of cocaine use,registered private patients at suburban hospitals havealso been found to be cocaine positive.

Perinatal cocaine abuse has been linked to manymaternal and neonatal complications that may have a

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profound effect on the patients response to the ad-ministration of anesthesia. The use of cocaine is asso-ciated with high morbidity and mortality, especiallywhen the patient is to undergo an anesthetic. There isnow adequate data to demonstrate that cocaine use inpregnancy is dangerous to both the mother and fetus.This danger is exaggerated by the misconception onthe part of some patients that cocaine does not crossthe placenta and is therefore a safe way to achieve afaster and easier childbirth. It has been shown thatcocaine causes profound vasoconstriction that may, inturn, cause profound alterations to uteroplacentalblood flow and eventually cause uteroplacental insuf-ficiency and fetal distress.

Cocaine abusers may have a higher incidence of Ce-sarean delivery for fetal jeopardy than that seen in non-abusing patients. Anesthesiologists often meet these pa-tients in an emergency setting while waiting for an

emergency Cesarean delivery to begin. The choice ofanesthetic is occasionally dictated by the hemodynamicssequelae of cocaine abuse, such as the commonly seenscenario of abruptio placenta with massive hemorrhageafter cocaine use. Even the strongest supporters of re-gional anesthesia will select a general endotracheal an-esthetic for the hypotensive and hypovolemic patient foremergency Cesarean delivery. However, in the morecontrolled situation, the anesthesiologist will have tochoose regional versus general anesthesia based on acomparison of risks and benefits for that individual pa-tient. Epidural or spinal anesthesia, unless contraindi-cated, is always my first choice when anesthetizing the

cocaine-positive patient. Data has been presented re-cently on life-threatening events that occurred underanesthesia in the cocaine abusing parturient. It showedthat life-threatening events were more common duringgeneral anesthesia than during regional anesthesia in thecocaine-abusing patient undergoing Cesarean delivery.The most frequently encountered problems in the pa-tients under general anesthesia were severe hyperten-sion and arrhythmias. Because severe hypertension afterlaryngoscopy may be expected in these patients, I treatcocaine-induced hypertension before initiation of a gen-eral anesthetic to avoid the exaggerated response to la-ryngoscopy. Propranolol is relatively contraindicated inthe cocaine-abusing patient because blockade maycause unopposed adrenergic stimulation and thereforeworsen the hypertension. Labetalol has been found to beeffective in treating the hypertension associated withacute cocaine intoxication but may also trigger a para-doxical exacerbation of hypertension resulting from rel-ative stimulation.

Neuraxial anesthesia may be safely administeredto the stable cocaine abusing parturient, but mayalso be associated with certain risks. These risksinclude:

1. Thrombocytopenia has been associated with co-caine abuse and therefore these patients may beat risk of developing an epidural hematoma.

2. Profound hypotension may occur because of asympathectomy in an intravascularly depleted pa-tient with abnormal compensatory mechanisms.

3. The response to pressor agents in these patientsis unpredictable. Ephedrine may not be an effec-tive treatment in the cocaine abuser.

4. These patients may be uncooperative.

Difficult AirwayFailed intubation remains a major problem facing theobstetric anesthesiologist. Studies have shown thatfailed intubation occurs more commonly in obstetricthan in nonpregnant patients. Difficult intubation inthe obstetric patient may be caused by increased

weight, increased breast size, easy bleeding of oralcavity, and pharyngeal/laryngeal edema. In addition,the use of cricoid pressure to minimize aspiration riskmay make visualization more difficult.

To minimize difficult intubations in the obstetricpatient:

Always perform a preoperative airwayexamination.

Position the patient in the sniffing position. Placea wedge to achieve left uterine displacement.

Preoxygenate to insure appropriatedenitrogenation.

Have a trained assistant administer cricoid

pressure. Use a small endotracheal tube with a stylet, even

if you dont think it is necessary. Your first at-tempt is your best chance!

Do not initiate laryngoscopy until the patient isrelaxed.

Confirm endotracheal tube position with ETco2

monitoring and auscultation before allowing thesurgeon to begin.

Have algorithm and equipment for failed intuba-tion ready.

Management of the failed intubation in the preg-nant patient:

Call for help. Maintain cricoid pressure. Communicate with obstetrician. Determine if sur-

gery can be delayed (e.g., fetal distress or no fetaldistress).

Ventilate with 100% oxygen.

If surgery can be delayed:

Ventilate with 100% oxygen until patient awakens. Perform a regional anesthetic or an awake fiber-

optic intubation.

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If surgery cannot be delayed:

Maintain cricoid pressure throughout. Ventilate with oxygen and a volatile agent. If any difficulty with ventilation, consider LMA. In the event of a lost airway and inability to use

LMA or Combitube, consider placement of an IVcanula through the cricothyroid membrane to ad-minister transtracheal oxygenation and ventilation.

PrematurityPrematurity is defined as birth occurring between2037 wk of gestation. The incidence in the US isapproximately 7% but it accounts for the majority ofperinatal deaths.

Anesthetic Implications

Patients are often placed on tocolytic therapy,which may have profound maternal effects andinteract with anesthetics.

Beta adrenergic agents (Terbutaline/Ritodrine). Tachycar-dia, hypotension, chest pain, myocardial ischemia,arrhythmias, pulmonary edema, anxiety, nausea/vomiting, hyperglycemia, hypokalemia.

Magnesium Sulfate. Pulmonary edema, chest pain,nausea/vomiting, drowsiness, increased sensitivity tomuscle relaxants.

Anesthetic Management

Regional anesthesia may be used for labor analgesia

the patient who is delivering a premature infant. It hasthe advantage of obviating the need for parenteralnarcotics. This is advantageous because the prematurefetus may be more susceptible to the effects of thesedrugs. It also decreases catecholamine levels, may im-prove uteroplacental blood flow and gives a route forfast administration of a regional anesthetic shouldfetal distress occur and require a Cesarean delivery.By allowing the patient (and the obstetrician) morecontrol, a labor epidural can prevent a precipitousdelivery that can have devastating effects on a prema-ture infant. Previous administration of a sympatho-mimetic tocolytic agent is not a contraindication to a

regional anesthetic.Subarachnoid or epidural anesthesia may be usedfor Cesarean delivery. Administration of general an-esthesia is the same as for the term parturient, exceptthat the general anesthetics may depress the preterminfant more than the term infant. Techniques, dosages,and choices or agents are the same as for the full-termparturient. If general anesthesia is to be initiatedshortly after discontinuation of a sympathomimetictocolytic, drugs that caused maternal tachycardia (at-ropine, glycopyrrolate, pancuronium) should beavoided.

Fetal DistressThe American College of Obstetricians and Gynecol-ogists (ACOG) has issued a committee opinion enti-tled Anesthesia for Emergency Deliveries. Theysuggest:

Failed intubation and pulmonary aspiration remainprominent causes of maternal morbidity andmortality from anesthesia.

The obstetric care team should be alert to the pres-ence of risk factors that place the parturient atincreased risk for complications from emergencygeneral or regional anesthesia.

When risk factors are identified, the obstetrician shouldobtain an antepartum anesthesia consultation.

Strategies should be developed to help minimize theneed for emergency induction of general anesthe-sia. Such strategies might include early placementof an epidural or spinal catheter.

Although there are some situations in which gen-eral anesthesia is preferable to regional anesthe-sia, the risk of general anesthesia must beweighed against the benefit for those patientswho have a greater potential for complications.

Cesarean deliveries that are performed for a non-reassuring fetal heart rate pattern do not neces-sarily preclude the use of regional anesthesia.

Regional Anesthesia For Fetal Distress

Place epidural catheters inpatients who are at in-creased risk for operative delivery (poor fetal trac-ing, IUGR, preeclampsia, preterm labor, VBAC,multiple gestations, breech position, diabetes).

If epidural is functioning at the time of Cesareandelivery, administer 1520 mL of 3% chloropro-caine in 5-mL increments. Onset of block is within35 min. Chloroprocaine is rapidly metabolized inthe mother and fetus and placental transfer is notincreased in the presence of fetal acidosis.

The use of spinal anesthesia for stat Cesareandelivery remains controversial. Several authorshave reported good results with spinal anesthesiain the presence of fetal distress. If the patient is

not hypovolemic or acutely bleeding and if anesthe-sia can be achieved quickly (i.e., the patient is notmorbidly obese) spinal anesthesia is an attractivealternative to general anesthesia for emergency Ce-sarean delivery. If early attempts at dural punctureare unsuccessful, the anesthesiologists must havethe discipline to abandon further attempts and pro-ceed with an alternative plan (such as generalanesthesia).

IV fluid should be administered before initiationof a spinal anesthetic, but there is evidence thatthe anesthetic need not be delayed until the total

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1500 mL is administered. Consider having pres-sure infusion bags available so that fluid can beadministered quickly in the scenario where a pa-tient without an IV needs an emergent Cesareandelivery.

If possible, continue to monitor the FHR in theoperating room, while placing the regionalanesthetic.

In the absence of an ongoing epidural or contin-uous spinal anesthetic in a case of severe fetaldistress (e.g., profound fetal bradycardia, not re-solving) in a patient with a normal airway, gen-eral anesthesia (with a rapid sequence induction)should be considered.

In the event of a history of a failed/difficult intu-bation, the anesthesiologist should consider anawake intubation or regional anesthetic.

A large-bore atraumatic needle (such as a 22-gauge Sprotte needle) may speed the initiation of

a spinal while still minimizing the risk of post-dural puncture headache.

ReferencesPREECLAMPSIA1. Benedetti TJ, Kates R, Williams V. Hemodynamic observations in

severe preeclampsia complicated by pulmonary edema. Am JObstet Gynecol 1985;152:3304.

2. Clark SL. Severe preeclampsia with persistent oliguria. Am JObstet Gynecol 1986;154:490.

3. Clark SL, Cotton DB. Clinical indications for pulmonary arterycatheterization in the patient with severe preeclampsia. Am JObstet Gynecol 1988;158:4538.

4. Hadzic A, Vloka J, Patel N, Birnbach DJ. Hypertensive crisis aftersuccessful placement of an epidural anesthetic in a hypertensiveparturient. Reg Anesth 1995;20:1568.

5. Lind SE. The bleeding time does not predict surgical bleeding.Blood 1991;77:254752.

6. Newsome LR, Bramwell RS, Curling PE. Sever preeclampsia:hemodynamic effects of lumbar epidural anesthesia. AnesthAnalg 1986;65:316.

7. Robson SC, Redfern N, Walkinshaw SA. A protocol for theintrapartum management of severe preeclampsia. Int J ObstetAnesth 1992;1:222.

8. Rogers RPC, Levin J. A critical reappraisal of the bleeding time.Semin Thromb Hemost 1990;16:119.

HEMORRHAGE1. Chestnut DH, Dewan DM, Redick LF, et al. Anesthetic manage-

ment for obstetric hysterectomy: a multi-institutional study. An-esthesiology 1989;70:60710.

2. Clark SL, Koonings PPP, Phelan JP. Placenta previa/accreta andprior cesarean section. Obstet Gynecol 1985;66:8992.

3. Gatt SP. Anaesthetic management of the obstetric patient withantepartum or intrapartum haemorrhage. Clin Anaesthesol1986;4:37386.

THE DIFFICULT AIRWAY1. Benumof JL. Management of the difficult airway. Anesthesiology

1991;75:1087110.2. Benumof JL, Scheller MS. The importance of transtracheal jet

ventilation in the management of the difficult airway. Anesthe-siology 1989;71:76978.

3. Wilson ME, Spiegelhalter D, Robertson JA, Lesser P. Predictingdifficult intubation. Br J Anaesth 1988;61:2116.

PREMATURITY1. Benedetti TJ. Maternal complications of parenteral

B-sympathomimetic therapy for premature labor. Am J ObstetGynecol 1983;145:16.

2. Cotton DB, Strassner HT, Lipson LG, Goldstein DA. The effectsof terbutaline on acid base, serum electrolytes, and glucose ho-meostasis during the management of preterm labor. Am J ObstetGynecol 1981;141:61724.

3. Pedersen H, Santos AC, Morishima HO, et al. Does gestationalage affect the pharmacokinetics and pharmacodynamics of lido-caine in mother and fetus? Anesthesiol 1988;68:36772.

FETAL DISTRESS1. Committee of Obstetrics, Maternal and Fetal Medicine. Anesthe-

sia for emergency deliveries. American College of Obstetriciansand Gynecologists, Committee Opinion No. 1992:104.

2. Marx GF, Luykk WM, Cohen S. Fetal-neonatal status followingcesarean section for fetal distress. Br J Anaesth 1984;56:100913.

3. Philipson EH, Kuhnert BR, Syracuse CD. Fetal acidosis,2-chloroprocaine, and epidural anesthesia for cesarean section.Am J Obstet Gynecol 1985;151:3224.

4. Rout CC, Rocke DA, Levin J, et al. A reevaluation of the role ofcrystalloid preload in the prevention of hypotension associatedwith spinal anesthesia for elective Cesarean section. Anesthesi-ology 1993;79:2629.

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Anesthesia for the High Risk Parturient

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