P021: OBSTETRICS RAPID RESPONSE: POST-OPERATIVE MAGNESIUM SULFATE HEMODYNAMIC COMPROMISE
Kristina T Gemayel, MS, OMSIII, Renee Alexis, MD, MBA, MPH, FACOG; Nova Southeastern University College of Osteopathic Medicine
Background: Pre-eclampsia is a multisystem disorder, and the most common hypertensive disease of pregnancy, accounting for nearly 18% of maternal deaths in the United States. This disorder, occurring in females after 20 weeks’ gestation, is characterized by increased blood pressure in a previously normotensive patient, with proteinuria. The primary etiology of pre-eclampsia is presumed to be triggered by abnormal placentation, leading to abnormalities in the nitric oxide pathway, increased uterine artery resistance and vasoconstriction, resulting in chronic placental insufficiency and oxidative stress. Chronic placental ischemia results in fetal growth complications, as well as widespread endothelial dysfunction in the mother, requiring delivery as the only curative treatment. Management of pre-eclampsia requires a multidisciplinary approach, involving both obstetricians and anesthesiologists. Although delivery is the only effective treatment for pre-eclampsia, post-operative complications following cesarean section requires close hemodynamic, neurological, and laboratory monitoring. This case describes the anesthetic management in a pre-eclamptic female status post cesarean section developing profound hypotension after administration of magnesium sulfate for prevention of eclamptic convulsion.
Methods: We present a 33-year old G4P2011 female at 37 weeks and 4 days gestation with intrauterine growth restriction, oligohydramnios, and gestational hypertension suspicious for severe preeclampsia. Due to spontaneous decelerations and non-assuring fetal heart tones, the benefits of a cesarean section outweighed risks. Subarachnoid block with 0.4mg preservative-free morphine was placed without complications, and cesarean section was successful with estimated blood loss of 800mL. Post-operatively, the patient was started on a magnesium sulfate protocol for seizure prevention. Approximately six hours after cesarean section, the patient stated she felt dizzy, and within minutes became unresponsive, hypotensive with BP of 44/24 mmHg, saturating 92% on room air. Initial H/H was 11.0/33, with a magnesium level of 5.5. Rapid response was called and anesthesia was present at bedside, administered supplemental oxygen via simple facemask, 1gram of calcium gluconate and 50mg ephedrine, increasing BP to 66/34 mmHg. An additional gram of calcium gluconate was administered, and the patient regained consciousness shortly after.
Results: Rapid action taken by the on-call anesthesiologist with total administration of 2grams of calcium gluconate, and 50mg ephedrine, quickly reversed the actions of the magnesium sulfate, and increased the blood pressure, allowing the patient to regain consciousness. A rapid response team was called, but did not have to take further action due to the prompt management from the anesthesiologist.
Discussion: Knowledge of perioperative complications encountered in the management of pre-eclamptic patients allows for rapid identification and treatment of the adverse effects of magnesium sulfate therapy. This patient population is at an increased risk for adverse effects of magnesium sulfate due to impaired sympathetic tone following subarachnoid anesthesia, producing continued sympathetic block on ganglia controlling vasomotor tone and cardiac accelerator fibers, hemoconcentration as a result of relative intravascular volume depletion and blood loss during cesarean section, and vasodilation iatrogenically induced with administration of magnesium sulfate. Proper use of prophylactic neurological checks and vital sign monitoring can prevent progression of adverse effects in this patient population, decreasing morbidity and mortality associated with magnesium sulfate toxicity.