For decades, anesthesiologists advised patients not to eat or drink at all after midnight the night before their surgery—a guideline referred to in the medical world as “NPO after midnight.”
But experts are now revisiting the old standard. New research suggests the “NPO after midnight” rule may be unnecessarily strict for patients scheduled to undergo surgery. In both 1999 and 2011, the American Society of Anesthesiologists recommended a minimum fast of two hours from clear liquids for all healthy patients undergoing elective procedures requiring general anesthesia, regional anesthesia or sedation/analgesia.
Still, many anesthesiologists continue adhere to “NPO past midnight” rule for all surgical patients.
“We have good evidence that drinking clear liquids until two hours before surgery is safe, but we continue to have this dogma about not eating or drinking anything after midnight, which is just a number picked out of the air,” said Anesthesiologist Joyce Wahr, MD, FAHA, the director of the new University of Minnesota Health Preoperative Assessment Center (PAC).
We spoke with Wahr to discuss the new take on the longtime approach.
Why have doctors traditionally recommended that patients fast before surgery?
In the 1950s, two research papers were written about pregnant women who received heavy anesthesia during delivery and died when they aspirated the contents of their stomachs. As a result, anesthesiologists were very concerned about patients having any food in their stomach before receiving anesthesia. When patients receive general anesthesia, they can’t protect their airways. For that reason, the care team needs to prevent the contents of the stomach from entering the lungs. Now, we use an endotracheal tube to accomplish that, but the studies from the 1950s were based on outdated techniques. Doctors at the time simply put a mask on the patient’s face and used ether, which makes many people sick.
Around 2000, there was a large review of 30 or so separate studies which showed that patients drinking fluid until two hours before surgery actually had emptier stomachs.
Unfortunately, many patients go into surgery in the afternoon and are therefore required to go 18 hours without food and drink. Clearly, the guidelines have to be individualized for each patient and the time of surgery. This idea has been the official practice of the American Society of Anesthesiologists since 1999, but there’s still some stigma attached to it.
What kind of fluids are we talking about that are OK to consume before surgery?
Clear liquids—something you can see through. Some options include apple juice, Gatorade, black coffee, or tea without any milk or cream.
Are certain foods also being considered?
Only a few studies have been published about a patient’s ability to eat food before a procedure. For that reason, we still ask patients to refrain from drinking milk or eating food for eight hours prior to the operation. Milk is a protein and still has a lot of fat in it, so the digestive system takes longer to process it than other fluids. We believe it is likely safe for patients to eat up to six hours before surgery, but we want to eliminate the confusion. If a patient wants to eat before the procedure, we recommend toast and crackers.
What differences do you see in patients based on the different approach?
A number of studies show that patients do much better if they’re allowed to drink up to two hours before surgery. They use less IV fluid, and depending on what they drink, they have better metabolism. It’s also less difficult to control a patient’s sugar levels following surgery.
How does the Preoperative Assessment Center incorporate this research—and other advancements—into its preoperative care?As anesthesiologists, we know that better preparation allows for a better recovery. We’re always incorporating that idea into our care.
We advise patients about being active and getting up and moving. We talk about “prehabilitation”—instead of rehabilitation—to be active before surgery so they’re ready. Surgery is like running a marathon. You put a lot of stress on your body, so it helps to do a little training program beforehand to prepare your body.We have these conversations before the procedure. That way, after surgery, patients are prepared and informed, and we are not trying to train a patient who is groggy or in pain.