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Drug errors are common in surgery, MGH-led study says

Karen Nanji, an anesthesiologist at Mass. General Hospital (above), was the study’s lead author.Pat Greenhouse/Globe Staff/File

About half of all surgeries involve some kind of medication error or unintended drug side effects, if a study done at one of America's most prestigious academic medical centers is any indication.

The rate, calculated by researchers from the anesthesiology department at Massachusetts General Hospital who observed 277 procedures there, is startlingly high, compared with those in the few earlier studies that were done. Those studies relied mostly on self-reported data from clinicians, rather than direct observation, and found errors to be exceedingly rare.

"There is a substantial potential for medication-related harm and a number of opportunities to improve safety," according to the study, published in the journal Anesthesiology. More than one-third of the observed errors led to some kind of harm to the patient.


Attention has been focused on reducing medical errors since 1999. That's when the Institute of Medicine identified them as a leading cause of death, killing at least 44,000 Americans a year — more than car crashes or breast cancer. Since then, hospitals have tried to improve safety during surgery with simple check lists to avoid lapses like operating on the wrong side of the body. They have also switched to electronic prescribing systems that can warn doctors of potential errors.

But mistakes at the intersection of medication and surgery "have really not been studied in any systematic way," said Karen Nanji, an anesthesiologist at Mass. General and lead author of the study.

Drugs delivered during an operation don't have the same safeguards other medication orders do. In most parts of a hospital, prescriptions are double-checked by pharmacists and nurses before they reach a patient. Operating wards are riskier. "In the operating room, things happen very rapidly, and patients' conditions change quickly, so we don't have time to go through that whole process, which can take hours," Nanji said.

While all the errors observed in the study had the potential to cause harm, only three were considered life-threatening, and no patients died because of mistakes, Nanji said. In some cases, the harm lay in a change in vital signs or an elevated risk of infection.


"Patients don't need to go into surgery thinking that they're going to have lasting permanent harm every second operation," Nanji said.

The research may begin to draw attention to drug mistakes in the surgical suite.

"It's like a black box," said Helen Haskell, founder of Mothers Against Medical Error, whose son died because of a medication error after routine surgery. Patients under anesthesia may not be aware an error is made, especially if there is no lasting consequence. "The rates sound high, but it's in line with other rates of patient harm," Haskell said.

Nanji's team observed randomly selected surgeries over seven months in 2013 and 2014. Nanji said she didn't get any resistance from hospital executives about a project that could reveal patient safety lapses. The hospital has a "long history of being very open with mistakes in order for themselves and other centers to learn from them," she said.

One of the study's authors disclosed a financial interest in health technology companies. The other four authors, including Nanji, disclosed no competing interests.

Not every mistake meant the patient got the wrong drug or an incorrect dose. For example, many errors had to do with properly labeling drugs when they're drawn into syringes for delivery. Because most medications just look like clear liquids, having several prepared without labeling them poses a risk that the wrong one could be delivered. Those breaches in protocol were counted as errors. In about one-fifth of the problems, adverse drug reactions were considered unavoidable — for example, if a patient had a drug allergy that doctors didn't know about ahead of time.


The study found that some kind of error was made in about one in every 20 drug administrations.

Several medications are typically used in each operation, from anesthesia to antibiotics, so that rate translated into some kind of error or adverse reaction in every other surgery.

Operations that lasted more than six hours were more likely to involve an error than shorter procedures.

The study suggests hospitals need to do more to improve safety. Nanji said the solutions involve improving both processes and technology, like bar- code scanning systems that can alert doctors to potential mistakes.

"We're only starting to understand the scope of this problem," she said, "so a lot of these suggested solutions are not widely implemented."