Why can't I eat or chew gum before surgery?

Unfortunately our breathing passage and eating passage cross paths
while anesthetized.  People can vomit or just passively regurgitate the
contents of their stomach. The normal gag reflexes that protect their
airways are inactive under anesthesia and these fluids or partly
digested solids can get into the trachea and lungs. The resulting
pneumonia ("Aspiration Pneumonitis") can be lethal.

The biggest single step in preventing this complication is making sure
patients have empty stomachs before beginning an anesthetic. The long-standing
standard was to have adults and older children fast for 8 full
hours before an operation. This period generally ensures an empty
stomach and does not risk dehydration.

Newer research has shown that, in people with normal stomach functions,
clear liquids readily pass through the stomach within two to three hours
and according to some studies, may lower the acid content compared to a
strict fast. Along with this has come a realization that normal patients
empty their stomachs of solids within six hours.

We have embraced the newer practice as an aid to patient comfort and a
likely improvement in patient safety. Problems remain with trying to make
these changes universal: the usual minor snafus in running an 0.R.
schedule make exact timing impossible. The liberalized guidelines don't
apply to moderate numbers of our patients who have conditions that are
known to delay stomach emptying: diabetics, those with ulcer disease, the
obese, and the traumatized, among others.

Obviously, in emergent and urgent situations we cannot wait for the
stomach to empty normally, In these cases we have precautionary measures
that are very good at preventing the Aspiration Pneumonitis syndrome.

Your individual anesthesiologist is ultimately responsible for your safety
during surgery. Her or his assessment of the situation and judgment of
how to proceed are the best and final determinates for your specific case.