Pregnant Patient with Eclampsia for Emergency Cesarean Section Case File
Lydia Conlay, MD, PhD, MBA, Julia Pollock, MD, Mary Ann Vann, MD, Sheela Pai, MD, Eugene C. Toy, MD
Case 35
A 40-year-old G3P2002 woman, at 383/7 weeks’ gestation, was admitted in early labor. During her prenatal course, she had been diagnosed with pregnancy-induced hypertension (PIH). On admission, her BP was 155/96 mm Hg, HR 110 beats/minute (bpm), and she had +2 pedal edema. Her hemoglobin was 9.8 g/dL, platelet count was 117, 000/mm3, and urinalysis showed 2+ proteinuria. Her laboratory tests were otherwise normal. She was started on infusions of oxytocin and magnesium.
Shortly after admission, the patient complained of a headache. Her blood pressure was noted to be 166/101 mm Hg, signs of fetal distress were noted on the monitor, and the anesthesiologist was notified of the urgent cesarean section. As the operating room team was being mobilized, the obstetrician noticed an acute change in the patient’s mental status, followed shortly thereafter by a tonic-clonic seizure.
➤ What are the pathophysiological alterations in preeclampsia and their implications on the anesthesia for cesarean section?
➤ What anesthetic modalities are utilized for emergency cesarean section in PIH?
➤ What are the effects of the anesthetic management on PIH?
ANSWERS TO CASE 35:
Pregnant Patient with Eclampsia for Emergency Cesarean Section
Summary: A 40-year-old G3P2002 woman at 383/7 weeks’ gestation with severe PIH and seizure requires emergency cesarean section.
➤ Pathophysiological alterations with preeclampsia: Preeclampsia can present with elevated blood pressure, proteinuria, pulmonary edema, elevated liver function tests, thrombocytopenia, and neurologic dysfunction, including seizures. These alterations may have significant impact on the anesthetic plan.
➤ Anesthetic modalities in cesarean: General and neuraxial regional anesthesia may be used for cesarean section in PIH. The choice of anesthetic technique depends on the specific patient presentation and the severity of the organ system dysfunction.
➤ Effects of anesthesia: Use of general anesthesia may be associated with rapid swings in blood pressure during airway manipulation. Additionally, the incidence of difficult airway is increased in the presence of both pregnancy and exacerbated by PIH. Use of neuraxial blockade in the presence of thrombocytopenia may be associated with epidural hematoma and neurological complications of the hematoma.
ANALYSIS
Objectives
1. Understand the pathophysiology and the clinical presentation of PIH.
2. Understand the implications of eclampsia and preeclampsia for the anesthesia management.
3. Identify the benefits and risks of general and regional anesthesia for emergency cesarean section and develop a plan for anesthesia and intraoperative monitoring.
4. Manage the perioperative complications during cesarean section of a patient with eclampsia.
Considerations
This patient’s BP is well controlled with a signal agent (magnesium). Her laboratory results do not show evidence of end-organ damage which could result from her chronically elevated blood pressure. But the onset of seizures with loss of consciousness on day of presentation makes this an emergent situation requiring immediate c-section.
Given, the emergent nature of the procedure, general anesthesia with rapid-sequence intubation is the anesthetic of choice. Nevertheless, an exaggerated hypertensive response to laryngoscopy, and/or to the administration of exogenous vasopressors should be anticipated. The airway changes in pregnancy are further compounded by PIH and edema, and may result in difficulty at intubation. The patient’s intravascular volume could be normal, or even markedly reduced from chronic vasoconstriction, further contributing to the considerable hemodynamic lability. Intravenous (i.v.) fluids should be administered judiciously to avoid the risks of fluid overload, congestive heart failure, and even pulmonary edema. Magnesium and beta-blockers, treatments for PIH, add to the risk of heart failure. She is receiving the definitive treatment for PIH, which is delivery of the fetus.
APPROACH TO
Pregnant Patient with Eclampsia
DEFINITIONS
PIH: It includes a spectrum of disorders from isolated hypertension to hypertension associated with multiorgan dysfunction (preeclampsia) and seizures (eclampsia).
HELLP SYNDROME: It is a severe form of preeclampsia that includes hemolysis, elevated liver enzymes and low platelet count.
CLINICAL APPROACH
The management of PIH is individualized, and depends on the severity of the disease. Treatments range from medical treatment until the delivery for mild disease, to cesarean section for patients with major maternal complications and fetal distress. Thrombocytopenia is the most notable hematologic abnormality in PIH, increasing the risk of bleeding and thus hematoma with a neuraxial block. Thrombocytopenia in the range of 80,000 to 100,000/mm3 does not appear to significantly increase the bleeding risk with regional anesthesia. The hypercoagulable state associated with PIH is usually less clinically significant.
Hepatic dysfunction marked by abnormal liver function can alter the clearance of anesthetic drugs. Renal dysfunction correlates with the severity of PIH. It is marked by proteinuria and oliguria and can progress to renal failure. Neurologic complications can range from visual disturbances and headache to seizures, coma, and cerebral hemorrhage. The first-line treatment is magnesium, usually administered by infusion to raise the seizure threshold. Benzodiazepines and barbiturates, particularly sodium thiopental, are used to treat seizures if they occur.
Neuraxial anesthesia is preferred in the absence of significant thrombocytopenia or coagulopathy. Neuraxial anesthesia produces a sympathectomy, with resultant drop in blood pressure. Of the neuraxial techniques, epidural anesthesia produces a more gradual sympathectomy in contrast with a subarachnoid block, useful for the judicious titration of fluids. Early epidural placement in high-risk patients provides labor analgesia thus attenuating the BP increases that occur with painful contractions, and may be used in case of an emergency cesarean section as well. However, if coagulopathies exist or are likely to develop, an epidural may not be the best choice because of the size of the needle used in the setting of engorged epidural veins. The benefits of spinal anesthesia at delivery include faster placement, more reliable blockade, and less epidural vascular trauma. Fluid administration is individualized according to the patient’s needs. It can be tempting to administer fluids excessively to sympathectomized patients, since the sympathectomy increases the circulating blood volume. But excessive fluid administration can easily result in pulmonary edema.
Indications for general anesthesia include coagulopathy, hemorrhage, sepsis, or the presence of cardiovascular disorders, in which an acute reduction in the blood pressure (from sympathectomy) is detrimental. In the setting of eclampsia, general anesthesia provides control of the airway, ventilation, and seizure activity. The airway management in a patient with PIH requires careful planning and a backup intubation plan. The airway difficulties associated with pregnancy are exaggerated due to upper airway and laryngeal edema, while the coexisting coagulopathy makes the airway more friable. An awake fiberoptic intubation may provide a safer option in certain cases. Pregnancy also renders the patient at higher risk for aspiration of gastric contents during induction of general anesthesia. The need for aspiration prophylaxis should be evaluated.
The anesthetic plan must address the issue of the wide swings in BP that occur at intubation, delivery of the infant, and at emergence from general anesthesia. Magnesium, used to treat PIH, also affects anesthetic management. It causes skeletal muscle weakness, as well as potentiating the effects of the depolarizing and nondepolarizing muscle relaxants and prolonging their duration. Therefore, use of lower doses and close monitoring of muscle relaxants is indicated.
The anesthesiologist may be called for an emergency intubation to control the airway if the patient has a seizure. In this setting, sodium thiopental is the treatment of choice. It is important to remember that the goal of any treatment is to terminate the seizure. The administration of nondepolarizing muscle relaxants should be avoided, since they are longer acting, and they prevent the evaluation of reflexes, and the diagnosis of seizures should they occur.
The maintenance of anesthesia is typically achieved with a low dose of volatile anesthetic and nitrous oxide, to avoid fetal respiratory depression. Higher doses of anesthetics and supplemental opiates may be used after the fetus is delivered. Oxytocin, needed to achieve adequate uterine contraction, may also result in elevation in the blood pressure. In severe cases, invasive arterial blood pressure and central venous pressure monitoring may be indicated to guide hemodynamic control and fluid management. Prior to extubation, consideration must be given to the possibilities of persistent airway edema, blood pressure control, and the potential prolongation of the patient’s neuromuscular blockade.
Comprehension Questions
35.1. A 19-year-old G1P0 at 39⅐ estimated gestational age (EGA) is transferred from the obstetric clinic to labor and delivery with PIH for labor induction. She has no contraindication to regional anesthesia. Which of the following statements regarding the anesthesia management is accurate?
A. Platelet count should be obtained before neuraxial anesthesia is considered.
B. General anesthesia for cesarean delivery has fewer risks and is the safest option for her.
C. Her condition is likely to effect the medications used for anesthesia.
D. A vagal response to direct laryngoscopy and intubation may be encountered.
35.2. A 38-year-old G3P2002 at 38 EGA is admitted in early labor. Her weight is 78 kg. BP is noted to be 151/94 and 160/96 mm Hg on two separate occasions, 6 hours apart. Mild proteinuria is noted. Which of the following is correct?
A. The seizures associated with eclampsia should be treated with magnesium only.
B. Airway difficulty is unlikely since she is not very obese.
C. Large fluid bolus should be given prior to performing regional anesthesia.
D. Platelet count of 100,000/mm3 is not a contraindication to regional anesthesia.
35.3. A 35-year-old G4P2 woman at 37⅐ EGA was diagnosed with severe PIH. She is treated with magnesium infusion and labor induction is started. She is noted to have acute mental status changes, followed by
a seizure, and an abrupt decrease in her O2 saturation to 85%. Which of the following is the most likely reason for her hypoxia?
A. Pulmonary edema
B. Upper airway obstruction
C. Pneumothorax
D. Pulmonary aspiration
ANSWERS
35.1. A. A platelet count should be obtained prior to the administration of a neuraxial block. In the absence of coagulopathy or other contraindications, regional anesthesia such as an epidural or subarachnoid block is a safer option. General anesthesia carries risks related to difficult airway management, aspiration, hemodynamic instability, prolonged drug action, and fetal depression. While the patient’s condition per se does not affect the anesthetic drugs used for a general anesthetic, magnesium, which she may receive for PIH, does effect the duration of action of muscle relaxants.
35.2. D. A platelet count of 50,000/mm3 (not 100,000/mm3) represents significant thrombocytopenia, and is a contraindication to regional anesthesia. However, mild thrombocytopenia does not significantly increase the risk of bleeding with regional anesthesia. While magnesium is the drug of choice for prevention and treatment of eclampsia, other antiepileptic medications such as benzodiazepines and barbiturates may be needed to control an eclamptic seizure. Airway difficulty in pregnant women is related to multiple factors and can be exaggerated in PIH due to increased laryngeal edema. Fluid bolus prior to regional anesthesia in PIH should be determined by a patient’s specific hemodynamics and given cautiously to avoid pulmonary edema.
35.3. B. Given the abrupt reduction in her SaO2 , the most likely diagnosis in this postictal patient is upper airway obstruction, which should be treated with an elevation of the mandible while oxygen is administered. Airway edema, pulmonary edema, and aspiration are all also possible causes of hypoxemia associated with eclampsia. However, the sudden desaturation makes them less likely. Spontaneous pneumothorax is much less likely in this patient.
Clinical Pearls
➤ In the setting of PIH, hemodynamic instability can occur with general or regional anesthesia.
➤ Patients typically have a significantly reduced circulating blood volume, despite the presence of pedal edema.
➤ Pulmonary and laryngeal edema can lead to difficult airway management and respiratory failure.
➤ In the absence of a coagulopathy, a regional technique is the anesthetic of choice.
➤ Magnesium causes muscle weakness, and prolongs the action of nondepolarizing neuromuscular blockers.
➤ A seizure, if it occurs, is treated with benzodiazepines and barbiturates, particularly sodium thiopental.
References
Karumanchi SA, Lindheimer MD. Advances in the understanding of eclampsia. Curr Hypertens Rep. 2008;10(4):305-312.
Mandal NG, Surapaneni S. Regional anaesthesia in pre-eclampsia: advantages and disadvantages. Drugs. 2004;64(3):223-236.
Ramanathan J, Bennett K. Pre-eclampsia: fluids, drugs, and anesthetic management. Anesthesiol Clin North Am. 2003;21(1):145-163.
Tihtonen K, Kööbi T, Yli-Hankala A, Huhtala H, Uotila J. Maternal haemodynamics in pre-eclampsia compared with normal pregnancy during caesarean delivery. BJOG. 2006;113(6):657-663
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