The absence of standardized definitions for events and outcomes during and after anesthesia for surgery has major implications for anesthesiology research and practice, as well as for public perceptions of anesthesia care, according to an editorial by two leading anesthesiology researchers.

Writing in the August issue of the journal Anesthesiology, Drs. Mark A. Warner of the Mayo Clinic and Terri G. Monk of Duke University Medical Center, highlight the importance of continued efforts to develop standard definitions and terminology for anesthesia. Dr. Warner comments, "Improvements in outcomes based upon scientific studies will be hindered unless and until standard definitions are developed for patient outcomes and a broad variety of other perioperative factors."

The editorial accompanies a new study showing wide variations in the definition of reductions in blood pressure during surgery, or intraoperative hypotension (IOH). In that study, a Dutch research group analyzed 140 definitions of IOH from recently published reports. "We found that there is a wide variety in definitions and that depending on the definition used, the occurrence frequency of IOH can vary between five and 99 percent," said Dr. Cor J. Kalkman of University Medical Center Utrecht.

That's just one example of the need for anesthesiology to adopt a standard terminology, Drs. Warner and Monk believe. The lack of standard definitions makes it difficult to compare the results of different studies and raises doubts about the data used to inform clinical practice.

It may also have a major impact on public perceptions of anesthesia and surgical care. "Any person speaking on perioperative care really can influence the audience based on how the outcomes are defined," says Dr. Warner. "If you're going to present outcomes and make broad statements about patient safety or any number of other issues, you have to give some context about how you define those outcomes."

The lack of standard definitions can impact areas ranging from individual medical liability cases to the debate over national health policy, says Dr. Warner. "For example, without standard definitions of IOH, you could say that anesthesia is either very dangerous or that it's extraordinarily safe. Just on this one study alone I could make a reasonable argument to influence an audience one way or the other—including policy makers, insurance companies, anybody—if I make statements without someone asking, 'Well, what data really went into that? How is that defined?'"

Despite the urgent need, it will likely take some time to reach the ultimate goal of developing standard definitions for anesthesia outcomes. "The recent effort by the International Organization for Terminologies in Anesthesia is probably the one that's gone the furthest and that is the most promising," says Dr. Warner. "So there's hope, but there will be a huge amount of work between the time that group reaches its conclusions and the development of a standard terminology that will be useful and widely accepted."

For additional information on this study, go to: http://www.anesthesiology.org

Founded in 1905, the American Society of Anesthesiologists is an educational, research and scientific association with 41,000 members organized to raise and maintain the standards of the medical practice of anesthesiology and improve the care of the patient.

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