Do you really need to fast the night before surgery?
Recently, a friend of mine was having major surgery in another healthcare system and told me she could drink fluids by mouth for up to two hours prior to her surgery the next morning.
I questioned that because in my experience patients were always “nil per os (NPO)” or nothing by mouth after midnight before surgery. I wasn’t aware those recommendations had changed, as I have friends and patients who have had surgery in the past few years who were told not to eat or drink after midnight.
While the American Anesthesiologists Society (ASA) guidelines state that patients can drink up to two hours prior to surgery and eat a light meal up to 6 hours prior to surgery, there are practical aspects that anesthesiologists, surgeons, and hospitals take into consideration concerning the best outcomes for patients, said Cape Cod Hospital Anesthesiologist Eileen Micaroni, MD.
“The NPO after midnight order is a blanket order that can be given to inpatients or outpatients without having to worry about what time the surgery is actually scheduled,” she said. “Often, surgery times get changed and delays in the process can occur if that patient is not NPO long enough according to the guidelines. Also, patients may experience confusion regarding what food or drink can be ingested and how long before a scheduled surgical time they can do it. If the patient makes a mistake following the guidelines, their surgery may be postponed or canceled. For these reasons, it is reasonably practical for providers and institutions to tell patients to simply fast beginning midnight before surgery.”
Physicians who directly manage inpatients or outpatients may make the effort to give more specific guidelines to patients in accordance with updated guidelines of drinking and eating prior to surgery. But they assume the risk of canceled or delayed surgeries if the order is not followed or misunderstood by other hospital staff or patients, said Dr. Micaroni.
“Within Cape Cod Healthcare, surgeons provide the NPO guidelines to patients as part of their own preoperative instructions,” she said. “At some facilities, generally, within the preoperative clinic, anesthesiologists provide NPO guidelines directly to patients.”
The History Behind NPO
“Historically, physicians recognized that people with stomachs full of food were at risk for aspiration of food particles, which causes significant mortality,” said Dr. Micaroni. “Without data to know exactly how long it took for different foods to pass through the stomach, it was agreed that patients having procedures should not eat on the day of surgery, hence ‘NPO after midnight.’ This is a vestige from decades of previous practice.”
The Journal of Hospital Medicine noted in June 2021, that in 1883, Sir Joseph Lister (father of modern surgery) detailed 19th-century NPO practices allowing patients tea or beef tea until two to three hours before surgery. But in 1946, Curtis Lester Mendelson described chemical pneumonitis in young, healthy obstetrical patients after aspirating gastric acid while under anesthesia. The syndrome was named Mendelson Syndrome after him.
By the 1960s, anesthesia guidelines recommended nothing by mouth for both liquids and solids for all patients, regardless of pregnancy status.
In the late 1990s, new data became available that prompted the American Anesthesiologists Society (ASA) to change the guidelines, said Dr. Micaroni. They allowed patients to drink clear fluids such as water, Gatorade, or juice without pulp, up to two hours before surgery. Patients could also eat a light meal up to six hours before surgery if it didn’t have a lot of fat or protein. The guidelines were again updated about five years ago.
Further studies have led to a better understanding of gastric emptying, which shows that clear liquids transition out of the stomach within two hours of drinking.
What About Emergency Surgeries?
“In an emergency situation, it doesn’t matter what the patient’s NPO status is,” said Dr. Micaroni. “If the surgery can’t wait, we do what we can to minimize the risk of anything bad happening though the risk is increased at that time.”
“Anything we do in the operating room is co-managed with anesthesia,” said Matthew Kalliath, DO, a surgeon with Cape Cod Healthcare General and Specialty Surgery. “Nothing goes without them being ok with it. If we have emergency surgery, we must do what we need to do. We can’t wait if the patient has eaten a cheeseburger and then developed something like a perforated colon. There are ways to try and help prevent aspiration. It doesn’t decrease the risk, but we do what we can in an emergency setting.”
