Written by Physician’s Weekly Blogger, Skeptical Scalpel

A couple of years ago, I blogged about preoperative fasting here. I had conducted a Twitter poll asking surgeons, anesthesiologists, and residents what their hospital’s policy was regarding oral clear liquid intake before surgery. Although published guidelines from various organizations including the American Society of Anesthesiologists state that patients can have clear liquids up to 2 hours before surgery, 47% of the 3800 people who responded to the poll said their hospitals required patients to be NPO (nothing by mouth, from the Latin nil per os) after midnight before surgery.

This problem is not unique to the United States. A recent paper from the Netherlands looked at prospectively collected data from two hospitals during two time periods—period 1 [2009 to 2011] and period 2 [2018 to 2019].

In period 1, 127 patients agreed to participate in the study, and 184 took part in period 2. The guidelines recommend allowing solid food in the form of a light meal for up to 6 hours before an operation. Of the combined cohort of 311 patients, 280 (90.3%) had a prolonged fast lasting a median of 15:19 hours for solid food.

No improvement in the duration of solid food abstinence occurred between periods 1 and 2. The median duration of fasting from solid food was 16 hours in period 1 compared to 14:51 hours in period 2, not a statistically significant difference.

The duration of fasting from clear liquids was somewhat better with 99 (32.2%) of the 311 total patients taking clear liquids up to 2 hours before their surgery. In period 1, 45 patients (36.3%) fasted according to the guidelines compared to 55 (30.1%) in period 2, not a significant difference. The median fasting time for clear liquids was 5:00 hours in period 1 and 5:23 hours in period 2.

International guidelines for preoperative fasting of 6 hours for solid food and 2 hours for clear liquids have existed since 1999, but as this and other studies have shown, they have not been universally adopted.

Why is this important? In addition to the obvious negative effects of fasting such as increased thirst and hunger, fasting leads to decreased insulin sensitivity, which has been found to increase the risk of major postoperative complications such as infection, cardiac stress, hypothermia, and mortality.

In the discussion section of the paper, the authors state, “There is a growing body of evidence suggesting that preoperative consumption of carbohydrate beverages is safe, reduces postoperative insulin resistance, positively influences well-being, and shortens duration of hospital stay up to 1 day.” They recommend instead of telling patients what not to do, we should tell them what to do by encouraging them to drink and eat according to the guidelines.

I agree with that recommendation. However, I also agree with what the authors said in their conclusion, “Old habits die hard,” and they will continue to do so as long as anesthesiologists, surgeons, and hospitals stick with “NPO after midnight.”

Little-known fact—a legendary American surgeon once tweeted:


Skeptical Scalpel is a retired surgeon and was a surgical department chair and residency program director for many years. He is board-certified in general surgery and a surgical sub-specialty and has re-certified in both several times. For the last 9 years, he has been blogging at SkepticalScalpel.blogspot.com and tweeting as @SkepticScalpel. His blog has had more than 3,700,000 page views, and he has over 21,000 followers on Twitter.