Etomidate Succs: Preventing Dogma from Becoming Practice in RSI

The editorial about the PreVent trial in the NEJM a few months back is entitled "Preventing Dogma from Driving Practice".  If we are not careful, we will let the newest dogma replace the old dogma and become practice.

The PreVent trial compared bagging versus no bagging after induction of anesthesia for rapid sequence intubation (RSI).  Careful readers of this and another recent trial testing the dogma of videolaryngoscopy will notice several things that may significantly limit the external validity of the results.

• The median time from induction to intubation was 130 seconds in the no bag ventilation group, and 158 seconds in the bag ventilation group (NS).  That's 2 to 2.5 minutes.  In the Lascarrou 2017 JAMA trial of direct versus video laryngoscopy, it was three minutes.  Speed matters.  The time that a patient is paralyzed and non-intubated is a very dangerous time and it ought to be as short as possible
• The induction agent was Etomidate (Amidate) in 80% of the patients in the PreVent trial and 90% of patients in the Larascarrou trial (see supplementary appendix of PreVent trial)
• The intubations were performed by trainees in approximately 80% of intubations in both trials (see supplementary appendix of PreVent trial)

I don't think these trials are directly relevant to my practice.  Like surgeon Robert Liston who operated in the pre-anesthesia era and learned that speed matters (he could amputate a leg in 2.5 minutes), I have learned that the shorter the time from induction to intubation, the better - it is a vulnerable time and badness occurs during it:  atelectasis, hypoxemia, aspiration, hypotension, secretion accumulation, etc.

The Respiratory Rosenhan Experiment on Obese Patients

Normally this post would be on Status Iatrogenicus, but the implications for "evidence" and the EBM movement are too important, so it goes here.

For those not inclined to read about the Rosenhan Experiment, a brief history.  In the early 1970s, Dr. Rosenhan a Stanford psychologist, was concerned about the validity of psychiatric diagnoses.  So he and a half dozen confederates faked mental illness and presented themselves to several prominent psychiatric facilities.  Their feigned symptoms were sufficient to have them admitted with psychiatric diagnoses, usually paranoid schizophrenia.  After admission, they behaved normally.  Nonetheless, they had been diagnosed, put on psychotropic medications, and not allowed to leave until they signed documents swearing to continue the medications upon their release.  The damning report of this experiment was published in Science Magazine in 1973 with the title "On Being Sane in Insane Places."

Psychiatric hospitals were blindsided, having been caught unawares and humiliated.  They challenged Rosenhan to "do it again", but the second time they would be vigilant about these disimulations.  Send us some more fakes, they said.  On the second experiment, they determined that 40 some patients were confederates.  But Rosenhan had the upper RosenHand - he had send no confederates.  Sensitivity, if it can be called that, suffered to specificity on round two.

Previously I have complained about patients who are intubated but needn't have been (see here, and here.)  Oftentimes, after the fact, it is difficult to determine whether the intubation was necessary, especially with alleged upper airway compromise, and with obese patients.  With the latter, roentgenograms of the chest are difficult to interpret because of "fatelectasis" or atelectasis in obese persons,  "flatelectasis" due to recumbency, fluid loading after paralysis and intubation, all which may require high PEEP to counteract.  If you were not present prior to intubation, it is very difficult to determine if respiratory distress preceded the intubation, or if "won't breathe" was mistaken for "can't breathe".  The differentiation between those two entities is "critical".

A man in his late 40s was sent to us recently for "acute respiratory failure" on the ventilator receiving 100% FiO2 and PEEP of 16.  EMS responded to a call to his 18-wheeler that he could not breathe.  His SpO2 was in the 50% range and he was admitted to a local hospital.  There were basilar opacities, and oxygen was administered.   He weighed near 500#.  The opacities were said to represent pneumonia and he was given antibiotics.  Not long after admission, in the middle of the night, he could not be aroused, an ABG was obtained, and his PaCO2 was 90-something with a pH of 7.10 or thereabouts.  This was interpreted to represent acute hypercapneic respiratory failure, on top of his "acute hypoxemic respiratory failure" and an hour-long intubation ensued.  Afterwards he was sent to us on the aforementioned high ventilator settings.

Bite the Bullet and Pull It: The NIKE approach to extubation.

I was very pleased to see McConville and Kress' Review article in the NEJM this week (December 6, 2012 issue) regarding weaning patients from the ventilator. I have long been a fan of the University of Chicago crew as well as their textbook and their pioneering study of sedation interruption a decade ago.

In their article, they provide a useful review of the evidence relating to the discontinuation of mechanical ventilation (aka weaning , liberation, and various other buzz words used to describe this process.) Yet at the end of the article, in describing their approach to discontinuation of mechanical ventilation, they provide a look into the crystal ball that I think and hope shows what the future may hold in this area. In a nutshell, they push the envelope and try to extubate patients as quickly as they can, ignoring inconvenient conventional parameters that may impede this approach in select instances.

Much of the research in this field has been dedicated to trying to predict the result of extubating a patient. (In the case of the most widely cited study, by Yang and Tobin, the research involves predicting the result of a predictor of the ultimate result of interest. This reminds me of Cervantes' Quijote - a story within a story within a story....but I digress.) And this is a curious state of affairs. What other endeavor do we undertake in critical care medicine where we wring our hands and so helplessly and wantonly try to predict what is going to happen? Don't we usually just do something and see what happens, making corrections along the way, in silent acknowledgment that predicting the future is often a fool's errand? What makes extubation so different? Why the preoccupation with prediction when it comes to extubation? Why not "Just Do It" and see what happens?