Health and Medical News and Resources

General interest items edited by Janice Flahiff

[Reblog] Healthstyles: Pre-operative Fasting–Too Long?

Fasting instructions for healthy pre surgical patients should be based on the known differences in gastric transit times of clear liquids, full liquids, and other foods.

Screen Shot 2014-01-26 at 6.44.46 AM

From the 23 January 2014 post at HealthCetera – CHMP’s Blog
     Center for Health Media & Policy at Hunter College (CHMP): advancing public conversations about health & health

This week on Healthstyles, I'm rebroadcasting an important interview that I did with Dr. Jeannette Crenshaw, RN, DNP, two years ago about what the evidence suggests is appropriate for pre-operative fasting--what should you not eat or drink and for how long before surgery.
Unfortunately, little attention is paid to this topic. Most people are told to fast for much longer periods of time than is necessary, and this can lead to dehydration and other adverse effects.
Tune in tonight on WBAI (; 99.5 FM), or click here to listen anytime: Crenshaw

[The broadcast is about 22 minutes long, but very informative]

For those interested, the broadcast is based on her article Pre-operative Fasting – Will the Evidence Ever be put into Practice? 

Highlights from the article

  • Overview: Decades of research support the safety and health benefits of consuming clear liquids, including those that are carbohydrate rich, until a few hours before elective surgery or other procedures requiring sedation or anesthesia.
    Still, U.S. clinicians routinely instruct patients to fast for excessively long preoperative periods. Evidence-based guidelines, published over the past 25 years in the United States, Canada, and throughout Europe, recommend liberalizing preoperative fasting policies.
    To improve patient safety and health care quality, it’s essential that health care professionals abandon outdated preoperative fast- ing policies and allow available evidence to guide preanesthetic practices.

Preoperative fasting practices in the United States often disregard both the guidelines of the American Society of Anesthesiologists (ASA)1, 2 and the most current available evidence on the subject.


The U.S. practice of requiring an extended fast before scheduled anesthesia or sedation is based primarily on the following three myths8-12:

• Myth: Overnight fasting from all solids and liquids is the optimal approach to reduce the risk of pul- monary aspiration during anesthesia.

• Myth: Gastric emptying time is the same for clear liquids as for full liquids (those that are not transpar- ent, such as milk, creamed soup, and nonstrained fruit juice) and solids.

• Myth: Clear liquids ingested up to two hours be- fore surgery increase the risk of vomiting and pul- monary aspiration.


The ASA (American Society of Anesthesiologists) recommends that healthy patients


  • consume clear liquids up to two hours before elective surgery or conscious sedation but cautions that their guidelines aren’t intended for women in labor and may need to be modified for patients with conditions that affect gastric emptying or fluid volume and those in whom airway management may be difficult.3-5
  • Evidence gathered throughout the world over the past 25 years not only supports the ASA guidelines, but establishes the health benefits of preoperative carbohydrate loading (through the consumption of carbohydrate-rich clear liquids) the evening before and the morning of surgery.6, 7

Clear liquids leave the stomach almost immediately, while full liquids and solids remain for significantly longer periods. It’s long been established that patients who drink clear liquids a few hours before surgery have significantly lower gastric volumes and similar or higher pH values compared with those who fast overnight, suggesting that drinking clear liquids may stimulate gastric emptying and dilute acidic gastric secretions, thereby lowering the risk of pulmo- nary aspiration and increasing patient safety.15-1 

Screen Shot 2014-01-26 at 6.36.06 AM

  • In addition to discomforts such as thirst, hunger, anxiety, drowsiness, and dizziness, excessive preoperative

    fasting may have adverse physiologic effects, including dehydration, insulin resistance, postoperative hy- perglycemia, muscle wasting, and a weakened immune response.18, 23-25 Clear liquids, taken alone, may be in-sufficient to ward off such effects. Emerging evidence suggests that, in addition to offering clear liquids up until two hours before anesthesia or sedation, the best way to avert the harmful consequences of preoperative fasting is to prescribe a carbohydraterich clear bev-erage to be consumed two to three hours before the scheduled procedure

  • The author also details reasons for resistance by the medical community and research needs (as for patients who are not healthy and/ or have stomach and breathing issues).


So, does one take the law into one’s hands, so to speak? The radio interview seems to suggest be careful if you drink clear liquids up to two hours before the surgery and/or drink a carbohydrate beverage.  Best not to tell the health care providers, perhaps on the day of surgery.




Enhanced by Zemanta

January 26, 2014 - Posted by | health care | , , ,

No comments yet.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: