Accidental intravenous infusion of a large dose of magnesium sulphate during labor: A case report
A 28-year-old primigravida was admitted to the antenatal ward for close fetal and maternal observation with dichorionic diamniotic twin pregnancy complicated by severe preeclampsia as well as abnormal doppler studies. The 24-h urine protein was elevated to 6 g, requiring labetalol 400 mg t.i.d., to control her blood pressure. Induction of labor was planned as there was persistence in the abnormality of doppler studies of twin babies.\nPhysical examination revealed an easy looking airway and unremarkable cardiovascular and respiratory exam. Induction was carried out with amniotomy, oxytocin infusion and labor epidural used for pain control. She was started on magnesium sulfate for preeclampsia management. Her initial magnesium sulfate levels were 1.4 on the first day evening and 1.97 on the next day morning. Her reflexes were intact. The following day, the patient delivered both the babies vaginally. Post-delivery, she had significant immediate postpartum hemorrhage. There was a small second-degree perineal tear, which was repaired, but bleeding per vagina persisted. The nurse was instructed to open up oxytocin. The uterus was manually massaged. However, this failed to contract down the fundus. Therefore, 400 μg of misoprostol was placed rectally. B y that time, she had already lost approximately 1 l of blood, but she was adequately resuscitated and her vitals were stable.\nThe uterus contracted post misoprostol, but shortly afterwards was filled with clots and blood. Therefore, one dose of hemabate (Carboprost Tromethamine) was given intramuscularly. At this stage, she complained of increased shortness of breath. Her saturation had dropped to 92%, and she was increasingly somnolent. A second intravascular (IV) line was started, as there was persistent excessive vaginal bleed. Bimanual massage was continued. The bleeding settled with administration of hemabate, but her level of consciousness continued to decrease. Anesthesiologist was called in for help and assessment. The patient was found to be having difficulty in responding verbally, but did continue to breathe unsupported. Her blood pressure was 107/46 mmHg and heart rate was 96/min. The bleeding had stopped, but her respiratory efforts continued to decrease to such an extent that she required intubation. A rapid sequence induction and intubation was performed with 40 mg of propofol and 100 mg succinylcholine and her oxygen saturation was maintained at 100%. Blood samples were sent for blood gas analysis, serum electrolytes including calcium and magnesium levels, coagulation profile, and hemoglobin level. The working diagnosis at the time was magnesium toxicity versus possibility of pulmonary, amniotic fluid embolus, and brain edema secondary to preeclampsia maternal stroke or seizure. A trial of 1 g of calcium gluconate was given because the last magnesium level had been within the normal therapeutic range. During the physical examination, her pupils were non-dilated, but they were asymmetrical and reacting to light. She was promptly taken for a head computed tomography (CT) scan, which was negative. Chest CT conducted to rule out Pulmonary embolism was inconclusive. In the meantime, magnesium levels had returned to be within the toxic range at 8.6 mmol/l. Magnesium toxicity was perceived to be the etiology behind her respiratory arrest and neurologic suppression. She was admitted to the intensive care unit (ICU) for respiratory support and correction of magnesium levels. An additional 2 g of calcium was given and planned for forced diuresis with lasix. A cardiologist was consulted for a bedside echocardiogram to rule out any pulmonary embolus. There was no evidence suggesting PE. A minimal pericardial effusion was also noted.\nThe team visited the labor and delivery room, as the increase in magnesium level had occurred within a short period of time, a drug error was suspected. The duration and dose of the magnesium infusion that was started the night before matched with the amount of magnesium remaining in the bag. The garbage from the delivery room was checked for discarded bags and an empty bag labeled with magnesium sulfate was found in the garbage. Presumably this had been mistakenly hung by the nurse considering it to be oxytocin. Oxytocin-labeled IV bag was not found in the garbage. The working diagnosis was inadvertent magnesium sulfate toxicity secondary to misplacement of magnesium sulfate IV bag for oxytocin. Therefore, the patient had received 40 g of magnesium sulfate as an IV push.\nBy early evening of the day of delivery, her magnesium levels had returned to within therapeutic range. After extubation, she was alert, oriented, and asymptomatic and required no supplemental oxygen. She was observed in the ICU overnight and transferred to the postpartum floor in a stable condition.