KEEPING CURRENT ON OBSTETRIC ANESTHESIA
| PREECLAMPSIA: UPDATE ON AN OLD SUBJECT —Robert R. Gaiser, MD, Associate Professor of Anesthesiology
and Critical Care, University of Pennsylvania School of Medicine, and Director, Obstetrical Anesthesiology and Critical
Care, Hospital of the University of Pennsylvania, Philadelphia
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| Classic triad: proteinuria; elevated blood pressure (BP); edema
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| Characteristics: infrequent before 24th wk of gestation; can occur earlier with hydatidiform mole; complicates 5% to
8% of pregnancies; more likely to occur at extremes of reproductive ages; first pregnancy greatest risk factor
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| Subsequent preeclampsia: study of ≈600 parturients with recurrent preeclampsia vs 2900 nulliparous participants
with preeclampsia; recurrent preeclampsia carries greater risk for severe preeclampsia, preterm delivery, and abruptio
placentae
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| American College of Obstetricians and Gynecologists’ (ACOG) definition: systolic BP ≥140 mm Hg, diastolic
BP ≥90 mm Hg, and >300 mg protein in 24 hr (urine dipstick measure >0.1 g/L; measured twice)
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| Severe preeclampsia: end organ damage; systolic BP ≥160 mm Hg; diastolic BP ≥ 110 mm Hg; proteinuria ≥5 g in 24
hr; oliguria ≤400 mL in 24 hr; cerebrovisual disturbances (eg, blurry vision, headache); HELLP syndrome (hemolysis,
elevated liver enzymes, low platelet count); epigastric pain (edema of liver); pulmonary edema; “the minute the woman
gets the diagnosis of severe, the only treatment is delivery of the placenta and delivery of the fetus”
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| Laboratory manifestations: proteinuria; elevated creatinine; elevated uric acid (highly associated with preeclampsia);
elevated hemoglobin; thrombocytopenia (most common hematologic abnormality in preeclampsia); elevated prothrombin
time and partial thromboplastin time
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| Maternal mortality: hypertensive disorders of pregnancy third most common reason for death during pregnancy or in
postpartum period
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| Life-threatening manifestations: include seizures, cerebral hemorrhage (most common cause of maternal mortality),
renal failure, hepatic failure, disseminated intravascular coagulation, pulmonary edema, and placental abruption
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| Etiology (leading theory): requires input from fetus via placenta, and from mother via underlying susceptibility (eg,
genetic predisposition); then exposed to paternal antigen (seen early in pregnancy in young woman because she has not
been exposed to antigens, and has not developed antibodies); causes abnormal placenta (does not implant sufficiently);
remodeling of spiral arteries deficient (spiral arteries not as dilated), placenta becomes ischemic, generates O2 free radicals,
and causes attack on endothelium (endothelial cellular dysfunction); recent publication indicates heavier women
(body mass index >30) have greater risk for preeclampsia; antiretroviral therapy also appears to increase risk
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| Therapy: delivery of fetus and placenta only known treatment for preeclampsia; anticonvulsants used in all women with
preeclampsia as prophylaxis against seizures associated with eclampsia (eclampsia incidence, 1%-2%); magnesium
drug of choice; superior to phenytoin (Dilantin) and nimodipine
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 | Magnesium sulfate for prevention of eclampsia (MAGPIE) trial (2002): 10,000 parturients randomized to magnesium
or placebo; higher incidence of side effects in magnesium group, but markedly decreased risk for seizures; no difference
in maternal mortality, but lower incidence of placental abruption; no difference in progression to severe preeclampsia,
total length of labor, or oxytocin use (but slightly greater amounts in magnesium group); greater incidence of
postpartum hemorrhage
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| Low-dose aspirin: once thought it would restore imbalance of prostacyclin and thromboxane; study of ≈2500 women
found no benefit
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| Spinal anesthesia and severe preeclampsia: fear of profound hypotension and fluid overload leading to pulmonary
edema; studies show no excessive hypotension, fluid administration, or pulmonary edema; also no difference in lowest mean
BP; another study reported less frequent incidence of hypotension in severely preeclamptic than in parturient without preeclampsia
(less ephedrine and less fluids in preeclamptic group); spinal anesthesia not contraindicated in parturient with severe
preeclampsia
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| Physiology: anucleate cell bodies; normal platelet count 150,000 to 400,000 per µL; formed in bone marrow from megakaryocytes;
adhere to foreign surface during disruption in endothelium, release contents, and form aggregates; platelet contents
include α granules (contain various clotting factors, eg, platelet factor 4, fibrinogen), dense granules (calcium, adenosine
diphosphate [ADP], and serotonin; cause more platelets to aggregate), and lysosomal granules (solidify clot)
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| Function: adhesion; release; aggregation; fusion; pregnancy—causes slight decrease in platelets (from 300,000/µL to
270,000/µL); due to increased destruction; leads to gestational thrombocytopenia; preeclampsia—accompanied by
endothelial injury; leads to increased platelet activation, with platelet consumption in microvasculature
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| Thrombocytopenia: most common hematologic abnormality seen in preeclampsia; implications of low platelets—
>100,000/µL (no abnormal bleeding), 50,000 to 100,000/µL (bleed longer with severe trauma), 20,000 to 50,000/µL
(bleed with minor trauma), and <20,000/µL (spontaneous bleeding); bleeding in preeclampsia—retrospective study
showed no difference in antepartum or intrapartum bleeding when platelet counts <50,000; increased postpartum
bleeding (none life-threatening; unlikely if >40,000/µL)
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| Risk for epidural hematoma (and progression to back pain and paraplegia): from 1906 to 1994, 61 cases
of spinal hematoma involving neuraxial anesthesia; majority used heparin; 30% involved multiple difficult traumatic
placement; 46 cases (66%) occurred not with epidural placement, but with catheter removal; literature review of 42
cases of epidural placement in patients with low platelets (<100,000/µL); one case report of epidural hematoma
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| Case: 20-yr-old woman, gravida 1, para 0, at 35 wk gestation; severe preeclampsia; platelet count on admission 49,000/µL;
steroids given to help induce lung maturity; platelet count on day of surgery (cesarean delivery) 71,000/µL; transfused 6
U of platelets; no excessive bleeding, and epidural (bupivacaine, 0.5%) pulled at end of surgery; on arrival in room, seizure
occurred with sparing of lower limbs; computed tomography (CT) showed multiple air bubbles at basal cistern,
sulci, parietal frontal region, and ventricles; hematoma (2 x 1 cm) compressing spinal cord; laminectomy results in removal
of 4-mL clot (insufficient to compress spinal cord); learning points—not an easy placement (wet tap); pulled
catheter at end of surgery (may be better to wait); “jumped the gun” in removing clot
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| Platelet dysfunction and preeclampsia: studies appear to show platelet dysfunction laboratory phenomenon
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| Role of steroids: steroids shown to improve platelet number
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| IMPLICATIONS OF THE AMERICAN SOCIETY OF ANESTHESIOLOGISTS’ (ASA) AND AMERICAN COLLEGE
OF OBSTETRICIANS AND GYNECOLOGISTS’ (ACOG) GUIDELINES— Joy L. Hawkins, MD, Professor of Anesthesiology,
Associate Chair for Academic Affairs, Director of Residency Training, and Director of Obstetric Anesthesia, University
of Colorado School of Medicine, Denver
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| Definitions: guideline—recommendation for patient management; individual practice may differ, “as long as you
explain why you think this is a better way to go”; standard—incredibly rare (eg, intraoperative monitoring standards);
rules clinicians are expected to follow “no matter what”
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| American College of Obstetricians and Gynecologists
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| Guidelines for Perinatal Care: deals with all aspects of peripartum care; substantial input from ASA
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| Compendium of Selected Publications: contains all Committee Opinions, and Educational and Practice Bulletins
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| Neonatal Encephalopathy and Cerebral Palsy: invaluable for medicolegal purposes; published in conjunction with
American Academy of Pediatrics (AAP); documents that these events occur before labor and delivery “virtually all of
the time”; outlines how to proceed with documentation and defense in event of “bad baby” case; eg, criteria that define
intrapartum event severe enough to cause cerebral palsy include uterine rupture, cord prolapse, massive hemorrhage,
sudden sustained fetal bradycardia with no fetal heart rate variability, Apgar score 0 to 3 beyond usual 5-min recording
time, onset of multisystem involvement within 72 hr after birth, and early imaging study showing acute, nonfocal cerebral
abnormality
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| Pain Relief During Labor and Delivery: published in conjunction with ASA; patient education brochure outlining different
forms of pain relief
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| Vaginal Birth After Previous Cesarean Delivery (VBAC): recommends obstetrician, anesthesia personnel, and nursing
be immediately available during trial-of-labor for VBAC; operational definition of “immediately available” determined
by local institution; most recent update in 2004 points out women with ≥2 previous cesarean deliveries should
not attempt vaginal delivery (risk for uterine rupture increases acutely), women with previous vaginal delivery followed
by cesarean delivery have low incidence of uterine rupture and should be encouraged to have trial-of-labor, and
multiple cesarean deliveries will ultimately lead to greater risk for placenta previa and placenta accreta; Joint Commission
on Accreditation of Healthcare Organizations (JCAHO) has incorporated VBAC guidelines into their standards;
practitioners continue to struggle with staffing issues
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| American Society of Anesthesiologists
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| Guidelines for Regional Anesthesia in Obstetrics: early document available since mid 1980s
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| Optimal Goals for Anesthesia Care in Obstetrics: joint statement with ACOG; “in our ideal world how would we like
to see obstetric patients covered”
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| Pain Relief During Labor: written for insurance companies; joint statement with ACOG
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| Statement on Role of Registered Nurses in the Management of Continuous Regional Analgesia: response letter to
Association of Women’s Health Obstetric and Neonatal Nurses (AWHONN)
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| Guidelines for Regional Anesthesia in Obstetrics: determine expectations about anesthesiology coverage of labor and
delivery; physician with appropriate privileges should remain readily available to manage complications until postanesthesia
condition satisfactory and stable; 30-min rule—in order for any hospital to sponsor obstetric service, there should
be capability to initiate cesarean delivery within 30 min of decision to perform; not all indications for cesarean delivery
require 30-min response time; however, some situations require response time <30 min if baby expected to survive; many
anesthesia providers have chosen patient-controlled epidural analgesia (PCEA)
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| Practice Guidelines for Obstetrical Anesthesia
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| Perianesthetic evaluation: preanesthetic evaluation should include airway, heart, and lung examination; consistent with
ASA Practice Advisory on Preanesthesia Evaluation; difficult to provide legal defense if examination not performed
(even though low yield in, eg, healthy 25-yr-old)
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| Communication: system must be in place to reinforce communication between anesthesia and obstetric services
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| Routine platelet count: in healthy obstetric patient does not have any yield and does not reduce maternal anesthetic complications;
not recommended
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| Blood bank resources: no consensus about whether to routinely obtain type and screen or crossmatch; should be ordered
on individual basis based on risk factors
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| Fetal heart rate monitoring: should be performed before and after block by some qualified individual; not always possible
to monitor baby during block (positioning issues)
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| Prevention of aspiration: modest amount of clear liquids acceptable for uncomplicated laboring patient; patient in high-
risk category (eg, obesity, difficult airway, diabetes, peripheral neuropathy) should remain npo; no solid foods should
be ingested during labor; 6- to 8-hr fasting time before elective procedure; consider aspiration prophylaxis before starting
procedure
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| Labor analgesia: no evidence that early epidural adversely affects progress of labor or leads to cesarean delivery; consider
placing catheter early if worried about ultimate outcome; when neuraxial catheter techniques used, have patient
comfortable but moving; various techniques include continuous infusion, single-shot spinal, and combined spinal-epidural;
PCEA may be preferable to continuous infusion; reduces doses of local anesthetics; no data indicating background
infusion beneficial
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| Performance and outcomes measurement: task force members asked by ASA to consider whether pay-for-performance
measure could be recommended from literature review and member surveys; Centers for Medicare and Medicaid Services
mandated transition toward reimbursement based on predetermined performance standards; first item adopted by
ASA use of pencil-point spinal needles instead of cutting-bevel spinal needles to reduce frequency of postdural puncture
headache in obstetrics
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| Removal of retained placenta: no preferred anesthetic technique; heavy sedation (eg, fentanyl, midazolam, propofol, ketamine)
may not be best because patient still at risk for aspiration; major hemorrhage requires return to operating room
(OR); consider aspiration prophylaxis; give nitroglycerin (vs terbutaline or proceeding to general anesthesia with volatile
agents) for uterine relaxation
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| Cesarean delivery: equipment, facilities, and support personnel available in labor and delivery OR should be comparable to
those available in main OR; neuraxial technique preferred for most cesarean deliveries, but general anesthesia may be appropriate
in certain situations (eg, profound fetal bradycardia, uterine rupture, hemorrhage, abruption); use pencil-point
spinal needle; with uterine displacement, keep bed tilted until delivery complete; no evidence that fluid preload prevents
hypotension; both ephedrine and phenylephrine are acceptable vasopressors; preference for neuraxial opioid administration
for postoperative analgesia when possible; new recommendations for postpartum tubal ligation emphasize compliance
with oral intake guidelines and consideration of aspiration prophylaxis; preference for neuraxial technique; be aware
that opioids given during labor delay gastric emptying, and epidural catheter used for labor has higher failure rate; timing
of tubal ligation should not compromise other aspects of patient care in labor and delivery
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| Emergencies: both type-specific and O Rh-negative blood appropriate; consider cell salvage in cases of intractable hemorrhage
or if type and cross-matched blood unavailable; Ambu bag, O2 source, laryngoscope, and endotracheal tube
should be readily available (also difficult-airway equipment); laryngeal mask airway or other supraglottic airway device
appropriate in emergency; surgical airway may be needed; cardiopulmonary resuscitation issues
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Suggested Reading
ACOG Practice Bulletin #54: Vaginal birth after previous cesarean. Obstet Gynecol 104:203, 2004; Altman D et al
(Magpie Trial Collaboration Group): Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate?.
The Magpie Trial: a randomised placebo-controlled trial. Lancet 359:1877, 2002; Aya AG et al: Patients with severe
preeclampsia experience less hypotension during spinal anesthesia for elective cesarean delivery than healthy parturients: a prospective
cohort comparison. Anesth Analg 97:867, 2003; Belfort MA et al (Nimodipine Study Group): A comparison
of magnesium sulfate and nimodipine for the prevention of eclampsia. N Engl J Med 348:304, 2003; Caritis S et al:
Low-dose aspirin to prevent preeclampsia in women at high risk. N Engl J Med 338:701, 1998; Coomarasamy A et al:
Aspirin for prevention of preeclampsia in women with historical risk factors: a systematic review. Obstet Gynecol 101:1319,
2003; Hnat MD et al: Perinatal outcome in women with recurrent preeclampsia compared with women who develop preeclampsia
as nulliparas. Am J Obstet Gynecol 186:422, 2002; Erratum in: Am J Obstet Gynecol 189:244, 2003; Hood DD
et al: Spinal versus epidural anesthesia for cesarean section in severely preeclamptic patients: a retrospective survey. Anesthesiology
90:1276, 1999; Livingston JC et al: Magnesium sulfate in women with mild preeclampsia: a randomized controlled
trial. Obstet Gynecol 101:217, 2003; Lucas MJ et al: A comparison of magnesium sulfate with phenytoin for the
prevention of eclampsia. N Engl J Med 333:201, 1995; Neiger R et al: Preeclampsia effect on platelet count. Am J Perinatol
9:378, 1992; Practice guidelines for obstetrical anesthesia: A report by the American Society of Anesthesiologists
Task Force on Obstetrical Anesthesia. Anesthesiology 90:600, 1999; Ramanathan J et al: Correlation between
bleeding times and platelet counts in women with preeclampsia undergoing cesarean section. Anesthesiology 71:188, 1989;
Roberts WE et al: The intrapartum platelet count in patients with HELLP (hemolysis, elevated liver enzymes, and low
platelets) syndrome: is it predictive of later hemorrhagic complications?. Am J Obstet Gynecol 171:799, 1994; Vandermeulen
EP et al: Anticoagulants and spinal-epidural anesthesia. Anesth Analg 79:1165, 1994; Wallace DH et al: Randomized
comparison of general and regional anesthesia for cesarean delivery in pregnancies complicated by severe
preeclampsia. Obstet Gynecol 86:193, 1995; Wilson ML et al: Molecular epidemiology of preeclampsia. Obstet Gynecol
Surv 58:39, 2003; Yuen TS et al: Spinal haematoma following epidural anaesthesia in a patient with eclampsia. Anaesthesia
54:350, 1999.
Educational Objectives
| The goals of this program are to improve the diagnosis and management of preeclampsia and to ensure that American Society
of Anesthesiologists’ (ASA) and American College of Obstetricians and Gynecologists’ (ACOG) practice guidelines
are integrated into obstetric anesthesia practices. After hearing and assimilating this program, the participant will be better
able to:
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| 1. Identify the laboratory and life-threatening manifestations of preeclampsia.
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| 2. Outline the etiology of preeclampsia.
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| 3. Determine the appropriateness of using spinal anesthesia in the patient with severe preeclampsia.
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| 4. Examine the recent updates to ACOG guidelines, and consider their effect on anesthesia practice.
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| 5. Describe recent updates to ASA guidelines, focusing on the Guidelines for Regional Anesthesia in Obstetrics
and Practice Guidelines for Obstetrical Anesthesia.
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Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty members to disclose relevant
financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts
were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial
interest. For this program, the faculty reported nothing to disclose.
Acknowledgements
Dr. Gaiser spoke at Challenges for Clinicians, held December 1-3, 2006, in Chicago, IL, and sponsored by the University
of Chicago Pritzker School of Medicine, Department of Anesthesia and Critical Care; Dr. Hawkins, at Advances
in Anesthetic Practice, held February 17-21, 2007, in Rancho Mirage, CA, and sponsored by Loma Linda
University School of Medicine, Department of Anesthesiology. The Audio-Digest Foundation thanks the speakers
and the sponsors for their cooperation in the production of this program.
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