A 29-year-old woman, gravida 2 para 1, undergoes a repeat cesarean delivery at 37 weeks gestation after developing preeclampsia with severe features. The patient receives a magnesium sulfate bolus for seizure prophylaxis and an epidural for neuraxial anesthesia. The procedure is uncomplicated, and she has an estimated blood loss of 750 mL. In the recovery unit, the patient suddenly develops shortness of breath and severe anxiety. Blood pressure is 90/60 mm Hg, pulse is 50/min, and respirations are 10/min. Oxygen saturation is 92% on room air. On cardiac examination, there are no rubs or murmurs. The lungs are clear to auscultation bilaterally. The abdomen is soft and nontender, with a firm uterine fundus palpable at the umbilicus. Bilateral lower extremity strength is 0/5, and bilateral upper extremity strength is 3/5. There is 1+ symmetric pedal edema and patellar reflexes are 2+ bilaterally. Magnesium level is 5.2 mg/dL (therapeutic range: 4.8-8.4 mg/dL). Which of the following is the most likely diagnosis in this patient?

Question

A 29-year-old woman, gravida 2 para 1, undergoes a repeat cesarean delivery at 37 weeks gestation after developing preeclampsia with severe features.  The patient receives a magnesium sulfate bolus for seizure prophylaxis and an epidural for neuraxial anesthesia.  The procedure is uncomplicated, and she has an estimated blood loss of 750 mL.  In the recovery unit, the patient suddenly develops shortness of breath and severe anxiety.  Blood pressure is 90/60 mm Hg, pulse is 50/min, and respirations are 10/min.  Oxygen saturation is 92% on room air.  On cardiac examination, there are no rubs or murmurs.  The lungs are clear to auscultation bilaterally.  The abdomen is soft and nontender, with a firm uterine fundus palpable at the umbilicus.  Bilateral lower extremity strength is 0/5, and bilateral upper extremity strength is 3/5.  There is 1+ symmetric pedal edema and patellar reflexes are 2+ bilaterally.  Magnesium level is 5.2 mg/dL (therapeutic range: 4.8-8.4 mg/dL).  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_da11_5b22_bc81_19062a883bd3_MD0003_00 Neuraxial anesthesia is the preferred analgesia for labor and delivery due to minimal maternal and fetal sedation. An epidural catheter is normally inserted into the epidural space to deliver a low-concentration, controlled release of local anesthetic (eg, bupivacaine) for sensory block (up to the T4 level for cesarean delivery). However, life-threatening high spinal anesthesia can occur if the catheter accidentally punctures the dura and anesthetic enters the subarachnoid (ie, intrathecal) space. This patient has high spinal anesthesia, which can have a delayed presentation as the anesthetic diffuses upward to block upper sensory, motor, and sympathetic nerves: Complete motor blockade below the low thoracic and lumbar spinal levels is typical. Patients can develop ascending paralysis as the anesthetic diffuses to the upper thoracic (then lower cervical) spinal levels. Patients initially develop bilateral upper extremity weakness (eg, C5-C7 blockade) with progression to respiratory paralysis as the intercostal muscles (eg, T1-T6) and diaphragm (eg, C3-C5) become paralyzed. Therefore, patients typically have acute dyspnea with decreased respirations (ie, apnea) and hypoxemia. Additional signs may include difficulty swallowing or speaking. Sympathetic blockade can cause bradycardia, hypotension, hypothermia (due to peripheral vasodilation), and cardiopulmonary arrest. Management is with immediate cessation of the epidural infusion, reverse Trendelenburg positioning (head up to decrease the rate of ascending anesthetic), and emergency supportive care (eg, intubation, vasopressors). (Choice A) Pulmonary edema may occur intrapartum, particularly in patients with preeclampsia, and cause acute dyspnea and hypoxemia. However, it would not explain ascending paralysis; in addition, patients typically have tachypnea and crackles (vs clear lungs in this patient). (Choice B) Guillain-Barré syndrome presents with progressive, ascending paralysis that can lead to respiratory paralysis. However, patients classically have depressed deep tendon reflexes (DTRs) and slower onset of symptoms (eg, days to weeks) in the setting of recent illness (eg, Campylobacter jejuni infection). (Choice D) Magnesium toxicity can cause decreased respirations due to neurologic depression; however, it does not cause ascending paralysis and is typically associated with depressed DTRs. In addition, this patient's magnesium level is therapeutic, making toxicity unlikely. (Choice E) Pulmonary embolism can occur intrapartum due to venous stasis and hypercoagulability associated with pregnancy. Although pulmonary embolus can cause anxiety, dyspnea, hypoxemia, and hypotension, it typically also causes tachypnea and tachycardia. In addition, it is not associated with ascending paralysis. Educational objective: A life-threatening complication of epidural anesthesia is high spinal anesthesia, or accidental injection of local anesthetic into the subarachnoid space that causes ascending motor, sensory, and sympathetic blockade. Patients are at risk for respiratory paralysis (eg, dyspnea, hypoxemia). References: Serious complications related to obstetric anesthesia: the serious complication repository project of the Society for Obstetric Anesthesia and Perinatology. (http://www.ncbi.nlm.nih.gov/pubmed/24845921)

A 29-Year-Old Woman, Gravida 2 Para 1, Undergoes a Repeat