News Release

Treating low blood pressure during surgery may decrease risk of developing postoperative delirium

Reports and Proceedings

American Society of Anesthesiologists

SAN DIEGO – Patients who experience low blood pressure during surgery are at increased risk for postoperative delirium, according to a large study being presented at the ANESTHESIOLOGY® 2021 annual meeting.

Postoperative delirium, a change in mental function that can cause confusion after surgery and the most common surgical complication for older adults, can be caused by a wide variety of factors, including pain, stress, insomnia and anxiety. While previous small studies have been inconclusive, the new study of 316,000 patients found low blood pressure during surgery to be a factor in the development of postoperative delirium. The researchers note low blood pressure decreases the supply of oxygen and glucose to the brain.

“Postoperative delirium is a major obstacle to a quick recovery from surgery, because patients are more dependent on others for activities of daily living and it can lead to an accelerated cognitive decline,” said Matthias Eikermann, M.D., Ph.D., senior author of the study and chair and Francis F. Foldes Professor of the Department of Anesthesiology at Montefiore Medical Center and Albert Einstein College of Medicine, New York. “Our research suggests rapidly addressing low blood pressure during surgery may prevent delirium and help with recovery.”

In the study of 316,717 patients who had non-cardiac surgery at one of two hospitals between 2005 and 2017, 2,183 (0.7%) were diagnosed with delirium within 30 days after surgery. Of those patients, 41.7% a had mean arterial pressure (an average of systolic and diastolic blood pressure) below 55 mmHg during surgery for fewer than 15 minutes and 2.6% had it for longer than 15 minutes. The researchers, including lead authors Luca J. Wachtendorf, B.S., and Omid Azimaraghi, M.D., found that patients who experienced low blood pressure were up to 60% more likely to experience postoperative delirium, and the effect was magnified in patients who had longer surgeries.

While postoperative delirium can affect anyone, elderly patients are at highest risk. Postoperative delirium typically lasts one to three days after surgery, although some patients experience long-term memory loss and difficulty learning, concentrating and thinking.

“Physician anesthesiologists measure patients’ blood pressure at least every three minutes during surgery,” said Dr. Eikermann. “The study shows they can help decrease the risk of postoperative delirium by immediately providing medication to increase blood pressure when it falls.”   



Founded in 1905, the American Society of Anesthesiologists (ASA) is an educational, research and scientific society with more than 54,000 members organized to raise and maintain the standards of the medical practice of anesthesiology. ASA is committed to ensuring physician anesthesiologists evaluate and supervise the medical care of patients before, during and after surgery to provide the highest quality and safest care every patient deserves.

For more information on the field of anesthesiology, visit the American Society of Anesthesiologists online at To learn more about the role physician anesthesiologists play in ensuring patient safety, visit Join the ANESTHESIOLOGY® 2021 social conversation today. Like ASA on Facebook, follow ASALifeline on Twitter and use the hashtag #ANES21.






LaSandra Cooper

Associate Director of Public Relations

American Society of Anesthesiologists
C: (708) 650-2886

Davis Renzelmann
Public Communications Inc.

C: (920) 627-0702

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