Forget diffusion hypoxia…this is worse.
Close your eyes for a moment and imagine that you get called to the new endoscopy suite in your hospital to help sedate a patient for an EGD and colonoscopy. It’s nice in here…more modern decor, more spacious, and less mental institution looking than the OR. You think, “I wouldn’t mind coming out here to do anesthesia cases every now and then, just to get out of the OR.”
As you do your preop spiel with the patient, you strap an oxygen mask on him, start a propofol infusion, and watch the end-tidal CO2 of the patient rise and fall with the inhalation and exhalation of his spontaneous breathing. The patient starts to get sleepy with a moderate amount of obstruction, so the pulse ox reading decreases into the low 90’s. You decide to insert a nasal trumpet and adjust the patient’s head position until you hear the obstruction give way to minimally stertorous but spontaneous breathing. There is mist in the mask and the oxygen is flowing at 6Lpm.
Patient looks comfortable but the sats are even lower into the 80’s now. At this point you stop the propofol infusion. A second later the pulse ox breaches into the 70’s. Although the patient is spontaneously and very adequately taking breaths, you take over the airway with an Ambu bag and double check that the wall O2 is dialed to 15 liters per minute. The patient is now looking very dusky but with no other signs of distress. You think to yourself, “The patient will wake up from the propofol any second now. I’ll just keep bagging.“
By now it feels like you have taken a running jump off the cliff of the oxyhemoglobin dissociation curve and the pulse ox has plummeted well-below the usefully accurate nomogram-based scale and reads an SpO2 of <30% with continuous chiming. Even though you have been listening to its melodically descending scale so keenly all along, only now do you realize that the intervals between the pulse tones have stretched out so far that you start to wonder if you had mistaken some other alarm for the patient’s heart rate all along.
You glance up finally at the EKG and for moment you see a wide-complex bradycardia and the number “20” just before the monitor goes into a fit displaying what looks like fine V-fib vs. PEA. You call a code, successfully intubate the patient to free up your hands and continue to ventilate the patient via the Ambu bag. CPR is performed, epi is given, shocks are delivered. THIS CAN’T BE HAPPENING! ALL I GAVE WAS A WHIFF OF PROPOFOL AND THE PROCEDURE HAD NOT EVEN BEGUN.
The code team is dispersing now and the still-warm patient is now just…still.
The above scenario is a product of my very active imagination. But I don’t really have to do a whole lot of de novo imagining, because art and real life have both now shown us that this very scenario can happen, has happened already, and without better safeguards is destined to happen again and again. Those of you who have been following my Twitter feed @gopasspas probably already know what I am talking about. If not, perhaps the image at the top of this page looks familiar to you. In fact, I used this same image in one of my very first posts in the Anesthesia Flix Fix series. It is taken from the movie art for the 1978 Michael Crichton movie based on the 1977 book Coma by Robin Cook. Does that ring any bells?
SPOILER ALERT! The book/movie Coma spins the tale of a couple of scrappy yet attractive medical students who happen upon a nefarious scheme involving a preeminently evil surgeon conspiring to basically kill patients in order to harvest their organs for transplant…healthy patients basically went under anesthesia for minor surgery and somehow didn’t wake up and thus were declared brain, clearing the way for their organs to be harvested. Devious plan…but how did he do it? Did I mention that the surgeon always brought his patients to Operating Room #8??? Turns out that the nitrous oxide and oxygen pipelines to OR#8 were most conveniently crossed, and patients were being suffocated with nitrous while the anesthesiologist was happily thinking he was delivering oxygen the whole time. Bad. But that movie plot was based on anesthetic practice in the 1970’s, and today we have much better safeguards in place to prevent just such a mix up of gases.
Well then you can imagine my dismay when I found the following two REAL LIFE news reports, one from 2007 and the other from just last year, 2016:
The scenario that I presented at the beginning of this post was indeed imaginary, but the reality of these two modern incidents go beyond my wildest imagination…to think that so many people actually died secondary to the same N2O/O2 pipeline switch as envisioned in Coma is truly unfathomable. Even though no villainous plot was responsible for these real-world tragedies, the shocking simplicity and efficiency of human error reminds us that it doesn’t take any stretch of the imagination for life to imitate art.
So…what would you do?
Seems like it should be a familiar oral boards stem question. First, patient obstructs, then desaturates, doesn’t respond to airway maneuvers or increasing inspired oxygen concentrations, intubation ensures ventilation but the patient continues to desaturate. Your move.
Anesthesia delivery systems have become much more technologically advanced over just the last several years. Just think about how many different modes of ventilation are available to us on our anesthesia machines. And the alarms! Don’t even get me started about all the different alarms and limits and setpoints that are foisted upon us. As anesthesia has become increasingly complex, our thought processes have also adapted to become much more complex and detail oriented.
At the same time, look at the actual technology around us. The operating room is littered with boxes packed with technology and indeed the boxes are getting smaller and smaller. Even the anesthesia machine itself…once compared to the engine of yesterday’s cars: If there was a leak or the ventilator was doing something funny or the scavenging system was acting up, you could take it all apart and fix the problem in a fairly straightforward mechanical way because the whole thing ran off oxygen. Now with the Fisher Price models of today, it’s clear the days of building anesthesia machines like tanks are over. Moreover, at the heart of all the surrounding plastic parts is all the technology jammed into ever miniaturizing formats. Effectively, our anesthesia machines are disposable. They are black boxes. If something goes wrong with it, fixing it becomes a cost/benefit analysis. And in a moment of crisis we don’t have the time to crunch the numbers.
So the point of this exercise is that we have to recognize the complexity. And when something goes wrong or even when something just doesn’t smell right…our first response should not be to troubleshoot the complexity. We should look to shed all the dependencies of our equipment and technology…and think simple. Get back to the basics. If the ventilator fails, forget the ventilator and start bagging the patient with the Ambu bag. If you smell a leak or the vaporizer is doing something funky or you otherwise can’t deliver volatile anesthetic, forget the gas and switch to TIVA. Right? We’ve all done this a million times.
But now think back to the scenario. Nothing that you’re doing is working…not even the oxygen! And what would it have taken for anyone to suspect that the oxygen coming out of the wall wasn’t the life-sustaining gas at all? Does an index of suspicion for this situation even exist? The next time you find yourself in a situation where the oxygen coming out of the wall just doesn’t seem to be working, you should reflexively disconnect from the wall and switch to an independent source of oxygen, much like you would switch to TIVA if your anesthesia machine stopped working.
Life imitating art…it’s tragic in this case. But I’m hopeful that we can all use this as a learning experience. Have any other examples of real-world anesthesia? Let me know. Tweet your interesting finds to me @gopassgas and start following GoPassGas.com today!
Shortly after I published this post, one of my readers pointed me to the final report of the investigation into the June/July 2016 nitrous/oxygen pipeline cross in Australia that resulted in the death of one infant and permanent hypoxic brain injury to another. It turns out that the gas pipeline work was done a full year earlier before the error was discovered. The particular operating room served by the crossed pipeline simply had not been used until that time. For the original pipeline construction, though, there was an engineer assigned to test the gas outlets and his certified affirmative documentation of that particular oxygen outlet was on file. Obviously, the veracity of the entire scope of this engineer’s work and ethic has been called into question and he is undoubtedly facing various criminal and civil charges.
Interesting footnote: It was only after I read this report that I realized that this most recent gas pipeline cross happened in Operating Theatre 8…just like in the movie Coma! Strange coincidence I’m sure, but readers of the (above) original Letter to the Editor of Anesthesiology in 1979 might not think it a facetious suggestion anymore!