Slow demise for long preoperative fasts

Doctors ban food, drink for hours before surgery, though the practice has little benefit

July 23, 2006|By DAVID KOHN | DAVID KOHN,SUN REPORTER

Do not eat or drink anything after midnight the night before your surgery.

To anyone who has had planned surgery or helped care for someone who has had it, these are familiar words.

What they mean is that you are likely to spend the day of surgery not only nervous about the operation but also hungry, thirsty and perhaps light-headed.

Your torment was probably in vain. It turns out that the widespread practice of keeping patients' stomachs empty overnight has little evidence to back it up.

Critics say that doctors who follow the approach are choosing discredited tradition over up-to-date science - perhaps for their own convenience.

"Longer fasting is not safer, and it is often associated with adverse effects," says Elizabeth Winslow, a nurse and researcher at the Presbyterian Hospital of Dallas who has spent years studying preoperative fasting.

Chief among these effects are hunger and dehydration. But Winslow notes that some patients also suffer from headaches, dizziness and nausea.

For early-morning surgeries, an overnight fast is a minor annoyance. But for those who undergo later procedures, the policy can be stressful - particularly for caffeine addicts, who can suffer headaches and nausea without a cup or two of coffee or tea.

"We treat the 7 a.m. patients the same as the afternoon patients," says Winslow. "That makes no sense."

The post-midnight policy appeared 60 years ago, when a New York doctor named Curtis Mendelson reported that surgery patients who had recently ingested food and drink were more likely to regurgitate their stomach contents.

In addition to being unpleasant, such episodes are dangerous: In the worst case, patients can choke to death. Even if that doesn't happen, regurgitated matter can enter the lungs, potentially causing injury and infection.

Pulmonary aspiration, as doctors call the leakage of vomit into the lungs, occurs in about three of every 10,000 elective surgeries.

Subsequent studies on animals confirmed Mendelson's findings. Soon, anesthesiologists and surgeons around the world were giving orders for "NPO after midnight." NPO stands for nil per os, a Latin phrase that means "nothing by mouth."

For about a half-century, NPO after midnight held undisputed sway. But in the 1980s, researchers revisited the issue and discovered that long fasting did not reduce the incidence of pulmonary aspiration. The stomach, it seems, processes food more quickly than previously realized.

With fluids, scientists found that patients could imbibe water, coffee or juice - so-called "clear liquids" - up to two hours before surgery with no ill effects. (Dairy liquids such as milk tend to curdle in the stomach, so in this context, scientists generally classify them as solids.)

"In healthy patients of all ages, going without clear liquids for longer than two hours does not improve safety," says Jeanette Crenshaw, a faculty member and researcher at Texas Health Resources, a network of 13 hospitals in the state. Together, she and Winslow have published four studies looking at preoperative fasting.

In response to this evidence, the American Society of Anesthesiologists adopted new fasting guidelines in 1998. The new policy states that for most surgeries, healthy patients should not eat a large meal for eight hours before a surgery and should not drink clear liquids in the two hours before a procedure. A "light meal," such as tea and dry toast, is permitted up to four hours before the operation.

Experts say the policy is not scientifically controversial. "There's no doubt that it's safe," says Dr. Mark Warner, chief of anesthesiology at the Mayo Clinic in Rochester, Minn., and chairman of the committee that developed the guidelines. "There have been lots of studies to prove it."

In fact, longer fasts might increase risk. Studies have shown that drinking clear liquids can help the stomach empty more quickly. And some anesthesiologists say hungry, dehydrated patients tend to have less stable vital signs.

"Patients who haven't had anything at all for hours tend not to do well with blood pressure and pulse during surgery," says Dr. Douglas Martz, clinical director of anesthesiology at the University of Maryland Medical Center.

Last month, for example, Randallstown preschool teacher Cynthia Bralove, 56, underwent surgery at Greater Baltimore Medical Center to remove a benign tumor from her neck. She was told not to eat or drink after midnight.

Even though her surgery occurred at 7:30 a.m., nurses had trouble drawing her blood. She says they told her dehydration was to blame.

After perhaps 10 tries, the needle finally hit home, and the surgery went off without a hitch. Still, Bralove wishes she had known that clear liquids were OK until two hours before. "I could have easily had time to drink if they had told me that," she says.

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