When a patient arrives in the operating room (O.R.) for surgery, one of the first things a physician will do is take his or her blood pressure, a "baseline" measurement used throughout the procedure. However, a new study presented at the ANESTHESIOLOGY® 2015 annual meeting found blood pressure taken before the patient enters the O.R. may produce more accurate measurements and should be used to determine baseline blood pressure.
"We found that blood pressure measured in the O.R. was significantly higher than readings taken during pre-surgical testing before the day of surgery or in the holding area on the day of surgery," said John L. Ard Jr., M.D., clinical associate professor, Department of Anesthesiology, Perioperative Care, and Pain Medicine at NYU School of Medicine, NYC Langone Medical Center, New York. "The O.R. environment seems to provoke anxiety in some patients that may not be present in other areas prior to surgery. This research could help physicians make better decisions regarding blood pressure management in the O.R., which could lead to fewer perioperative complications such as stroke or heart attack."
A common approach to blood pressure management in the O.R. is to keep patients' intraoperative blood pressure within 20 percent of the baseline blood pressure. According to the authors, a precise definition of baseline blood pressure is urgently needed; recent articles continue to define it as blood pressure obtained in the operating room prior to induction of anesthesia.
In the study, researchers analyzed 2,087 patients undergoing non-cardiac surgery with general anesthesia. Patients had their blood pressure taken at three points: at a pre-surgical testing clinic one to 30 days before surgery; in a preoperative holding area the day of surgery; and immediately upon entering the O.R. Comparisons were made between blood pressures taken at each phase of care.
On average, blood pressure taken in the O.R. was significantly higher than blood pressure taken during pre-surgical testing or while in a preoperative holding area. The increase in blood pressure remained, even when researchers accounted for gender, age and whether the patient had been prescribed antihypertensive medication - drugs used to prevent complications from high blood pressure. Blood pressure was not found to be significantly different when taken in either the pre-surgical clinic or the preoperative holding area.
"The one caveat to our findings is the variability of blood pressure readings in general," said Dr. Ard. "Because of this, more research is needed to determine whether averaging multiple blood pressure readings prior to entering the O.R. may give an even more realistic picture of a patient's baseline blood pressure and further improve outcomes."
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