Sunday, May 19, 2013


One of our staff emailed the whole group about a problem he encountered recently.  Our hospital does a lot of ureteroscopies for stones.  This is because we have the only lithotripter so we get the failures from there.  Despite having one room a week free during the day for urgent stones, we do a fair number after hours.  This is highly urologist dependent; 3 individuals account for about 90% of our after hours work.

Anyway one of these urgent stones presented to the OR in the evening having just eaten a full meal.  I didn't find out why this happened but I suspect the patient thought he was coming to the hospital to consult with the surgeon about his stone, NOT to have surgery.  It could have been that he got faulty instructions from the surgeon's office or that he is just stupid but he admitted to having eaten supper.  "That is too bad," said my colleague, "I guess you will have to have your surgery tomorrow."  "But" replied the surgeon, "he needs to have the stone done or else he might get septic!"  "Fine," says my colleague, "After a solid meal he will need to fast for 6 hours."  "That is way too late," said the surgeon, "he is going to get septic, can we do him under local with IV sedation."  "You can do what you want," replied my colleague, "But you are on your own" and went off to cool his heels.  The surgeon according to seemed shocked.

Kidney stones do get septic, I have seen one case in my medical career but as even the urologist who is chief of surgery at our hospital acknowledged, this is rare.  I suspect the urologist in this case was more concerned about getting home to tuck in his kids and have sex with his wife than any impending sepsis.

It does bring up the interesting topic of NPO.

When I started my residency a 6-8 hour fast usually written as NPO after midnight was the rule which meant patients frequently fasted for 16 hours or more.   The 6-8 hour fast was not based on any real evidence.  Up until the late 1950s fasting guidelines were much more liberal including things like tea and beef broth right up until surgery.  The introduction of longer fasting intervals coincided with other things like better anaesthetics (like halothane instead of ether), more use of endotracheal intubation, better trained anaesthesiologists and intensive care units, so any attribution of decreased morbidity with aspiration is more multifactorial rather than just due to longer fasts.  There also emerged a dogma of a gold standard of a gastric volume of less than 0.4 cc per kg and a pH of greater than 4 based on research on Rhesus monkeys extrapolated to humans.

Further we were told that narcotics delayed gastric emptying as did a myriad of other medical conditions including pregnancy so that those patients all had to have their airways protected with a rapid sequence induction and an endotracheal tube.  We asked every patient about reflux.

Many patients of course needed their surgery immediately and we managed them with rapid sequence inductions.  It was also apparent that one could use the NPO interval to manipulate emergency cases.  If you thought you could get the case put off to the next day, you quoted a longer fasting time, if you knew you were going to have the do the case anyway, you accepted  a shorter fasting time.  I played that game fairly recently.  Surgeons also clued in. When I was a resident, I was on call and one of the older surgeons booked an appendectomy.  "He ate lunch," said the surgeon smirking, "So how about we do him at 7 pm?".  What this really meant was he wanted to go home and have supper and then come back to do his case.  I on the other hand was more interested in following the list with the case. As I told the staff anaes firstly the patient had to be treated as a full stomach anyway and secondly if he was actually able to eat lunch, they didn't have appendicitis.  It didn't work, staff surgeon and anesthesiologist ate supper at home, I ate supper in the hospital cafeteria after which the patient was relieved of his appendix.

Already as I started my residency, brave anaesthesiologists were actually doing research to challenge the dogma of NPO after midnight.  One of them who gave a talk at rounds described how some of his fellow anaesthesiologists were horrified and refused to even be in the room while he did the studies.  It became clear however that patients could actually have clear fluids right up to the time of surgery and now the Canadian Anesthesiologists Society recommends allowing clear fluids up to 2 hours pre-op.  Administration asked about 3 years ago if we would relax our NPO standards at our hospital, I looked at the guidelines, asked my colleagues and we agreed that people could have water up until 4 hours pre-op just in case the case before them was cancelled.  We chose water because of the confusion over what exactly is a clear fluid.  The hospital ignored us and rolled out a 4 hour clear fluids policy with huge fanfare this January, however most patients seem to be fasting after midnight.

Exactly what a clear fluid is, has never been clarified.  If you look at the variety of fluids that are considered to be clear fluids, you see a variety of fluids with different pH and often pharmacological properties on their own (tea or coffee).  Many patients think that a large milkshake is a clear fluid.  I suggested just telling patients to drink Gatorade (any colour except red)  which is what my surgeon told me I could drink before my colonoscopy.  I am not endorsing Gatorade, it could be Poweraid, Kool Aid or Tang.  Coffee was verboten until they found it actually raised gastric pH and lowered gastric volume so black coffee is now back in.  I still am not sure what adding a few mls of milk or cream does to make coffee any less safe.

A few years ago, one of colleagues at the C of E announced that she had just cancelled a patient for chewing gum.  "Whats wrong with gum?'"  I asked (as long as they spit it out).  She looked at me like I was an idiot.  "Gum increases gastric volume," she said the voice one uses when trying to explain something to a child.  A few months later a study showed this wasn't the case.  I should have copied it and put it in her box but I didn't.

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