NPO status
During
induction of general anesthesia, the gag reflex is necessarily abol-ished.
Should the patient “choose” that most inopportune time to suffer
gastro-esophageal reflux (or worse yet, emesis), there is a high likelihood the
stomach contents could end up in the lung, causing a chemical pneumonitis or
even acute suffocation from the lodging of solid particles in the bronchial
tree. In addition to pharmacologic means (see Pharmacology), we minimize this
risk by having the patient report for surgery with an empty stomach. Patients
are asked to refrain from eating solid foods for 6–8 hours prior to elective
surgery. While there is evi-dence that clear liquid ingestion is cleared
rapidly and not dangerous in those patients with normal digestion (it may even raise the pH of the stomach con-tents
above the pH 2.5 danger zone), it remains customary to tell patients who are
scheduled for an elective operation in the morning not to eat or drink
any-thing for at least 6 hours (for infants about 2 to 3 hours) before the
operation. If the patient is already in the hospital, we write the order “NPO
after midnight”3 to achieve the
same results. Here, we can also order “maintenance i.v. fluids” overnight to
keep the patient hydrated. Therefore, on the day of surgery we ask every
patient about their most recent intake of food and liquids. Avoid asking: “When
did you have your last meal?” If the patient’s history identifies risk factors
for aspiration, e.g., gastroesophageal reflex disease (GERD), diabetes,
increased intra-abdominal pressure, hiatal hernia, and requires general
anesthesia, we use a rapid sequence induction (see General anesthesia). Pre-operatively,
we also con-sider pharmacologic means to reduce stomach volume and strengthen
the lower esophageal sphincter with a prokinetic agent and/or raise gastric pH
with H2 blockers or a proton pump inhibitor.
Many
patients have not been fasting for several hours, or their stomach did not have
time to empty. Labor pains, narcotics, or trauma can stop gastric peristalsis
for hours on end. Of course, in the presence of an ileus, we assume the stomach
not to be empty even if the patient had nothing by mouth for many hours or even
days.
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