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A patient recovering from a total laryngectomy was scheduled to receive 20 mg of liquid morphine through her nasogastric (NG) tube every 3 hours p.r.n. A bottle of morphine containing a concentration of 20 mg/5 ml was kept in the medication room on the nursing unit.
During the evening shift, the patient told her nurse she was in severe pain. Almost 3 hours had passed since the last dose had been given, so the nurse obtained the bottle and measured the dose in a calibrated medication cup. Because the patient was so distressed, the nurse quickly administered the drug without checking the measurement.
As soon as she'd emptied the cup into the patient's NG tube, the nurse realized she'd made a mistake. Instead of pouring 20 mg (5 ml) of morphine into the cup, she had poured and administered 20 mI. She'd just given the patient 80 mg of morphine-four times the ordered dose.
The nurse called the patient's doctor, who ordered a naloxone (Narcan) injection to counteract the narcotic's effect. He also ordered charcoal slurries to be given through the NG tube. The nurse closely monitored the patient's respirations, blood pressure, and level of consciousness. Her respirations decreased, but she didn't lose consciousness.
These measures averted a serious reaction to the high dose of morphine. But the patient and her family were extremely upset by the error. The next day, to reassure the patient and provide a safeguard against future overdoses, the patient's nurse poured the correct dose of morphine into a medication cup and showed the dose to the patient. She told the patient to refuse any dose of morphine that appeared to be more than the dose in the cup.
This teaching turned out to be effective; a few days later, another nurse again mistakenly poured too much morphine from the bottle. When she showed the dose to the patient, the patient refused it.
The fact that this error was almost repeated illustrates why you must think carefully when calculating the dose of a liquid medication. Don't get so rushed or distracted that you confuse milligrams. with milliliters. When you know you're distracted, have another nurse double-check the dose.
This incident also offers a second lesson: When possible, enlist the patient's aid in preventing errors. By teaching this patient how to check all of her doses, her nurses prevented a second overdose of morphine.