A healthy 21-year-old pregnant woman delivered a healthy baby via Caesarean section after an uncomplicated pregnancy. Two hours after delivery, the post-anesthesia care unit (PACU) nurse removed the patient's epidural catheter (placed prior to Caesarean section) and implemented an order for a morphine patient-controlled analgesia (PCA) with a 2-mg bolus, 6-minute lockout, and a 4-hour limit of 30 mg. Two concentrations of morphine are normally available for PCA use, 1 mg/mL and 5 mg/mL. The nurse used a 5 mg/mL morphine cassette because a 1 mg/mL cassette was not available. Upon admission to the ward 3 hours after delivery, the ward nurse reviewed the history settings on the PCA pump and confirmed the pump settings were consistent with the order. However, she did not read the label on the cassette, open the pump, or assess the volume being infused.
Four hours after delivery, the patient complained of itching after breastfeeding her infant. The nurse administered 25 mg Benadryl intravenously followed by a second 25-mg dose of Benadryl 45 minutes later. Six hours after delivery the patient was alert, oriented, and awake. Later in the evening the patient was found asleep and snoring. Her vitals were within normal range and the nurse noted that 20 mg of morphine had been infused. Thirty minutes later the patient had no detectable pulse or respirations. Despite resuscitation efforts, she was pronounced dead 7.5 hours after initiation of the PCA.
Autopsy revealed a toxic concentration of morphine. The available evidence is consistent with a concentration programming error where morphine 1 mg/mL was entered in the infusion pump instead of 5 mg/mL.
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