Chapter 50. Airway Management of the Obstetrical Patient with an Anticipated Difficult Airway

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.

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.

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.

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.

50.2.1 What Are the Physiological Changes of Pregnancy that Impact on the Airway Management of This Patient?

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.

50.2.2 What Is the Most Likely Diagnosis for This Patient?

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 ...