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The patient is a 32-year-old black woman G1P0 at 31-weeks gestation. Her medical history is notable for mild obesity (102 kg; BMI 39), a suggestion of sleep apnea (a report of significant snoring and periods of apnea while she sleeps), and treatment for chronic hypertension for the past 6 years.
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Five days prior to admission, the patient's hypertension and peripheral edema worsened, and she developed new-onset proteinuria. A 3.0 kg weight gain during the 7 days prior to admission was also noted. At the time of admission, the patient had a blood pressure of 168/102 mm Hg, a heart rate of 85 beats per minute (bpm), a short neck, large breasts, an airway classified as Mallampati Class IV, a 3 cm mouth opening with prominent incisor teeth, a thyromental distance of 2.0 cm, and a limited range of motion of her neck. She was placed on strict bed rest and treated aggressively with atenolol and furosemide.
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Twenty-four hours prior to delivery, a non-stress test demonstrated little or no reactivity and late decelerations with the few contractions she was having. The decision was made to induce labor and deliver the fetus. In the 8 hours preceding her induction, her hematocrit rose from 32% to 41% and her platelet count fell from 178K to 75K × 109 /L. The patient was placed on a magnesium sulfate intravenous infusion. She was noted to become increasingly edematous and somnolent.
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With induction of labor, the patient has developed regular contractions of appropriate strength for some 12 hours. She has progressed to 10 cm cervical dilation and has been pushing for 3 hours. The baby has remained at −1 station and does not appear to be descending. Because of the risk of inadequate coagulation, the patient has been managed throughout labor with a systemic opioid. A decision has been made to perform a cesarean section. The fetus is stable at the present time.
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50.2.1 What Are the Physiological Changes of Pregnancy that Impact on the Airway Management of This Patient?
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This patient is at considerable risk of rapid oxygen desaturation because of her pregnancy-associated increase in oxygen consumption, decrease in FRC, increase in closing volume, and increase in alveolar-arterial oxygen gradient. She is also at risk for aspiration because of pregnancy-related decreased gastroesophageal sphincter tone, increased gastric acid production, and decreased gastrointestinal motility. Therefore, this patient must be pretreated with a nonparticulate antacid and perhaps an H2 receptor blocker. If the patient is rendered unconscious before her airway is secured, a rapid-sequence induction with cricoid pressure must be employed to minimize the risk of gastric content reflux and aspiration.
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50.2.2 What Is the Most Likely Diagnosis for This Patient?
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This patient has chronic hypertension, with superimposed severe preeclampsia, that is, severe hypertension, edema, and proteinuria. She has been given magnesium sulfate for both seizure prophylaxis and blood pressure ...