A 32-year-old nulliparous woman starts to experience more painful contractions as she transitions into active labor. On admission, her blood pressure is 120/80 mm Hg. Fetal heart rate tracing shows a baseline of 130/min, moderate variability, positive accelerations, and no decelerations. Uterine contractions occur every 2-3 minutes. Cervical examination shows 6 cm dilation, 75% effacement, and 0 station. She requests epidural anesthesia for pain control. After induction of anesthesia, she begins to feel light-headed and her blood pressure is 90/55 mm Hg, heart rate is 120/min, and respirations are 12/min. The patient has normal strength and sensation of the upper extremities. What is the most probable cause of her hypotension?

Question

A 32-year-old nulliparous woman starts to experience more painful contractions as she transitions into active labor.  On admission, her blood pressure is 120/80 mm Hg.  Fetal heart rate tracing shows a baseline of 130/min, moderate variability, positive accelerations, and no decelerations.  Uterine contractions occur every 2-3 minutes.  Cervical examination shows 6 cm dilation, 75% effacement, and 0 station.  She requests epidural anesthesia for pain control.  After induction of anesthesia, she begins to feel light-headed and her blood pressure is 90/55 mm Hg, heart rate is 120/min, and respirations are 12/min.  The patient has normal strength and sensation of the upper extremities.  What is the most probable cause of her hypotension?

Quizplus · Accepted Answer

This patient is experiencing hypotension as a side effect of epidural anesthesia. Hypotension occurs in up to 10% of epidurals given during labor and can be easily prevented and treated. Continuous epidural analgesia involves infusion of a low concentration of a local anesthetic into the epidural space at the L2-L5 level, blocking nerves responsible for labor pain. It is a highly effective modality for pain relief in labor. Hypotension occurs when the sympathetic nerve fibers responsible for vascular tone are blocked, resulting in vasodilation (venous pooling), decreased venous return to the right side of the heart, and decreased cardiac output. Persistent, untreated hypotension can result in decreased placental perfusion and can lead to fetal acidosis. It can be prevented by aggressive intravenous fluid volume expansion prior to epidural placement. Treatment includes left uterine displacement (positioning patient on the left side) to improve venous return, additional intravenous fluid bolus, or vasopressor administration. epidural space (Choice A) Acute depression of myocardial contractility develops during myocardial infarction and is usually accompanied by chest pain and dyspnea. Hypotension occurs secondary to cardiogenic shock. This patient has no symptoms of myocardial infarction and it is rare in a healthy 32-year-old. (Choice B) Depression of cervical spinal cord and brainstem activity occurs when local anesthesia ascends toward the head, also known as a "high spinal" or "total spinal," a dangerous complication of epidural anesthesia. It may happen with intrathecal injection or overdose of the anesthetic. First signs include hypotension, bradycardia, and respiratory difficulty, and later, diaphragmatic paralysis and possibly cardiopulmonary arrest. (Choice C) Leakage of cerebral spinal fluid may occur if the dura is inadvertently punctured during epidural placement. This results in leakage of spinal fluid and is known as a "wet tap." Patients may experience postural headaches that are worse with sitting up and improved with lying down after delivery. Hypotension is not characteristic. (Choice D) Progressive hypovolemia may be secondary to ongoing fluid and blood loss or electrolyte abnormalities. In an otherwise healthy obstetric patient, volume depletion or electrolyte abnormalities are uncommon. Hemorrhage may accompany obstetric complications such as uterine rupture, abruptio placenta, or placenta previa but is uncommon and is typically accompanied by vaginal bleeding with or without abdominal pain. Educational objective: Hypotension is a common side effect of epidural anesthesia. The cause of hypotension is blood redistribution to the lower extremities and venous pooling from sympathetic blockade. References: Recent advances in obstetric anesthesia. (http://www.ncbi.nlm.nih.gov/pubmed/12908685)

A 32-Year-Old Nulliparous Woman Starts to Experience More Painful Contractions