Checklisting the Unnecessary

We shouldn’t need to make intubated patients “NPO” (“nil per os”, meaning nothing by mouth) prior to surgery.

In 1946, Mendelson described a syndrome wherein pregnant patients would develop severe pneumonitis when being placed under general anesthesia.  In order to place a breathing tube into the trachea (windpipe) for the administration of general anesthesia, chemical paralysis of the body’s muscles is produced by infusing specific paralyzing drugs into the bloodstream.  As a result, normal responses like the cough and gag reflexes are blocked.  If a patient strains or actively vomits during induction, stomach acid and food (if present) can regurgitate into the back of the mouth and be inhaled, causing severe lung damage.  However, with an empty stomach and some medication to counteract stomach acid, we can avoid this complication.  It is for this reason that patients are made NPO (nil per os, meaning “nothing by mouth”) the night prior to receiving a general anesthetic.  This checklist item is considered very important, and patients who were not made NPO after midnight prior to their operation can find their cases canceled in all except the most extreme emergencies.

Of course, the complication can also be avoided by already having a tube already in the trachea, because the endotracheal tube has a cuff near its tip that seals the tracheal channel, preventing fluid and air from going around the tube and allowing only air to go through the tube.  An interesting situation occurs when a previously intubated patient, such as an ICU patient receiving mechanical ventilation, is taken to the operating room to undergo a surgical procedure.  These patients are routinely made NPO as well, and their cases are canceled if an oversight failed to make them NPO.  Unfortunately, repeated cancellations can occasionally result in underfeeding or missed medications due to the NPO status.

Exactly why this is necessary in an already intubated patient is never made clear by those who enforce it, usually because they don’t understand why.  One of the paradigm shifts in medicine will be to understand conditional exceptions to every checklist.