Error Number 27. Failing to look up an unfamiliar drug before administering it

A 35-year-old man underwent an appendectomy. About 4 hours after the operation, he told his nurse he was unable to urinate. The nurse examined him and found that his bladder was distended. Although the doctor had left an order for straight catheterization, the patient refused to be catheterized.

The nurse notified the doctor, who then ordered an intramuscular injection of neostigmine (Prostigmin), a cholinergic that stimulates bladder contraction while relaxing the bladder sphincter. Unfortunately, the doctor made two mistakes in writing that order. First, he overlooked the patient's history of asthma. Cholinergics can cause bronchoconstriction in asthmatic patients, precipitating an acute asthmatic attack.

Second, the doctor ordered a dose of 25 mg instead of the correct dose of 0.25 mg. The nurse, unfamiliar with neostigmine, transcribed the order exactly as written. Then she went to the unit supply room to prepare the dose. There, she obtained a 10-ml vial containing a 1:2,000 solution of neostigmine.

The nurse calculated (incorrectly) that she'd need 5 ml of the solution to equal 25 mg of neostigmine. (The correct calculation would have been 50 ml.) But she prepared the injection of 5 ml and administered it to the patient. Since she didn't know how quickly the drug acts, she didn't leave a bedpan or the call bell within his reach. Then she continued on her medication rounds.

Some 15 minutes later, the nurse checked on the patient. She found a trail of urine and blood leading to his bathroom.

In his urgency to get there, the patient had climbed over the side rails and dislodged his intravenous catheter. He was barely able to stand; his face was flushed; he was wheezing and short of breath; he was incontinent; and he complained of incisional pain and severe abdominal cramps. The nurse called for help and another nurse quickly called the doctor. He ordered atropine, an anticholinergic, to reverse the effects of neostigmine. After a miserable night, the patient fully recovered from the overdose.

This series of errors drastically compounded the patient's misery. The doctor broke a cardinal rule for prescribing a cholinergic: Check first for asthma. If the doctor had been aware of the patient's asthma, he probably wouldn't have ordered the drug but rather would have emphasized to the patient the necessity of catheterization. Instead, he ordered a 100-fold overdose.

The nurse also erred by miscalculating the dose. This error reduced the overdose, of course. But if she had calculated the correct amount of 50 ml, she probably would have questioned such a large volume-and so discovered the doctor's error. To prevent such an error from happening to you, always look up an unfamiliar drug before administering it.