Monday, July 22, 2019

The Bermuda Triangle of Guidewires: Do They Just Fly Away Never to Be Seen Again?

In last week's NEJM, author Matt Bivens reports an extraordinary experience: while inserting a venous catheter, he let go of the guidewire and moments later looked and saw it migrating into the patient's jugular vein, on its own.  He grabbed it as it was running away, just before it escaped from him.  While I can imagine, as he did, how it may have happened, it is an exceptional claim.  Some aspect of the venous circulation or respiratory motion must have been pulling the wire downstream into the patient, if this story is true.  I say "if" because it is truly extraordinary.  Not only must the venous circulatory flow have been "grabbing" the wire, carrying it downstream, it had to do so with enough force to overcome the friction of the wire as it traversed the tissues of the neck.  (Not mentioned is the size of the patient's neck or whether this happened pre- or post-dilation, or whether the patient was in Trendelenberg - if so the catheter had to be pulled up hill!)

I have never seen or felt a guidewire move in such a way, over 20 years and thousands of lines.  However, I did turn my back on an intern circa 2000 and that intern pushed and/or flushed the guidewire into the patient.  So I was interested in the 4 references in the article purporting to show that guidewires have wings or feet or that the venous circulation can pull them and overcome the tissue resistance and mass of the wire.  Here is a summary:

  • Schummer, 2002:  This is a series of 4 cases.  In case 1 an intern put a catheter in, but it was dislodged and the wire left in the patient.  Because the catheter was inserted, the guidewire clearly was pushed or flushed.  A second catheter was inserted with the first wire still in the patient.  In case 2, an intern flushed the wire through the catheter.  In case 3, a PGY5 trainee inserted a catheter successfully but the wire was left in the patient - again a case of pushing it in with the catheter or flushing it in.  In case 4, a first-timer successfully inserted the catheter but pushed or flushed the wire in so that it was dangling from the distal end of the catheter and was retrieved.  In none of these cases did the guidewire migrate on its own or propelled by respiratory mechanics or the venous circulation.
  • Auweiler, 2005: A series of 3 cases, similar to above.  In all three cases, the wire was discovered days or weeks after successful cannulation.  Thus, the operators pushed or flushed the wire into the circulation during the insertion of the catheter.
  • Guo, 2006:  Another case of a successful cannulation where the wire was discovered much later protruding from the patient's neck - a case of "wire necessitans".  It was pushed or flushed in, it did not migrate prior to catheter insertion.
  • Khatami, 2010:  Another case of successful catheter insertion where the guidewire was later incidentally discovered.
In every single case, the catheter was successfully inserted.  In no instance was it reported that, before insertion of the catheter, an operator looked and said "Oh, Shit, where did that guidewire fly off to?"  If Bivens' report is true, it appears to be the very first time a wire was (almost) lost in the way he reported.

A trusted and famed mentor used to tell me not to believe everything I read, and I'm going to apply that advice to this case.  I simply do not believe it happened as reported.  I wager (>9:1 odds) that it is an embellishment used for dramatic storytelling and editorializing about the horrors of nuclear war.  Which is probably fine.  But I don't think it should mislead trainees about what a wire can do, or what you ought to do to prevent mishaps.  That wire doesn't have wings, but when you don't pay attention, you give it the push it needs to get into the patient, during catheter feeding and flushing afterwards.

Carl Sagan said "Extraordinary claims require extraordinary evidence" (he must have been a Bayesian).  So if you ever see a catheter migrate on its own, please shoot a video of it.  Else I'm going to call your bluff.

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