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Dallas Researchers Find Patients Still Fasting Too Long Before Surgery

DALLAS — Nurse researchers at Texas Health Presbyterian Hospital Dallas say that patients are still being told to fast much longer than necessary before surgery. The researchers also note that clear liquids taken up to two hours before surgery may actually make procedures safer.

Jeannette Crenshaw, M.S.N., R.N. and Elizabeth H. Winslow, Ph.D., R.N., F.A.A.N.

Jeannette Crenshaw, M.S.N., R.N. (left) and Elizabeth H. Winslow, Ph.D., R.N., F.A.A.N.

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Their study, “Preoperative Fasting Duration and Medication Instruction: Are We Improving?,” appears in the AORN Journal.

“Longer is not necessarily better,” said author Jeannette Crenshaw, M.S.N., R.N., clinical education specialist for The Centers for Learning and Career Development at Texas Health Resources. Texas Health is the parent organization of Texas Health Presbyterian Hospital Dallas.

“Fasting for too long before surgery can lead to discomforts such as thirst, hunger, and caffeine withdrawal headaches for patients who depend on their morning coffee, as well as more serious side effects such as dehydration and lowered blood sugar.”

Fasting is aimed at preventing vomiting and pulmonary aspiration while under anesthesia, which can be a serious and sometimes fatal complication of anesthesia. The American Society of Anesthesiologists adopted new fasting guidelines, based on extensive research, more than 10 years ago, advocating liberalized fasting recommendations for healthy patients undergoing elective surgery.

“The guidelines note that pulmonary aspiration is now a rare complication in modern anesthesia and that clear liquids go through the stomach quickly,” Crenshaw said. “In fact, it may be safer to encourage patients to have clear liquids, since it may promote gastric emptying. Several studies found less fluid in the stomach of patients who drank clear liquids until 2 to 4 hours before their surgery compared to patients who fasted from midnight.”

But most patients are still being told not to eat or drink anything after midnight the day of surgery, whether their surgery is scheduled for early morning or afternoon, according to the researchers. The authors found that care providers continue to encourage this unnecessarily-long fasting despite educational efforts to reduce the time patients fast.

“Old habits die hard,” said co-author Elizabeth H. Winslow, Ph.D., R.N., F.A.A.N., nurse researcher at Texas Health Presbyterian Hospital Dallas. “It’s a problem throughout the country. We hope our research will spur changes in this tradition — preoperative fasting practices should be based on research that shows the best approaches, not on outmoded traditions.”

The authors did find, however, that significantly more patients were given specific instructions about whether to take their routine medications the morning of surgery.

“This was one of the bright spots in our findings,” Winslow said. “Patients might otherwise take medications they shouldn’t take, for example, medications that can increase the risk of bleeding. Or they might not take medications they should take, like their asthma medicine.”

The research included a comparison of preoperative fasting durations in patients (430 subjects in all) before and after widespread educational efforts to publicize the less stringent fasting recommendations and before and after adopting a policy on fasting from clear liquids. The average time patients were instructed to fast from clear liquids was 9.4 hours before educational initiatives and nine hours after educational initiatives.

The new guidelines recommend that most patients fast before surgery a minimum of two hours from clear liquids, such as black coffee and tea, soda, and juice without pulp; four hours from breast milk; six hours from infant formula, milk, and from a light meal, like toast and juice; and eight hours from a regular or heavy meal (this is called the 2-4-6-8 Guideline).

What to do if you’re scheduled for surgery:

  • Find out the time of your surgery and get detailed fasting instructions
  • If you are scheduled for afternoon surgery, ask if you may have a light breakfast the morning of surgery and/or clear liquids
  • If your surgery is delayed, ask if it’s OK to have something to drink
  • Tell your doctor or nurse what medicines you take regularly and find out which ones to take the morning of your surgery
  • Remember the “2-4-6-8 Guideline”

About Texas Health Resources
Texas Health Resources is one of the largest faith-based, nonprofit health care delivery systems in the United States and the largest in North Texas in terms of patients served. Texas Health’s system of 13 hospitals includes Texas Health Harris Methodist, Texas Health Arlington Memorial, Texas Health Presbyterian, and a medical research organization. Texas Health is a corporate member or partner in six additional hospitals and surgery centers. For more information about Texas Health Resources, visit

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