The Slow Motion Plane Crash
White New Balance shoes with grass stains
Dave is 65 years old. Now retired, he gets up every morning and grinds fresh coffee and brings it out to his yard with him. In Dave’s yard there is a seemingly never-ending list of self-imposed tasks that keep him busy for several hours each day. One morning, Dave noticed that there was no spring in his step. The next morning, he barely wanted to get out of bed - in fact, he felt a little short of breath. After spiking a fever later in the day and becoming rather sickly, he decides to let his wife Judy drive him to the ED (after much convincing on her part).
Diagnosis? Influenza. Unfortunately, Dave’s fever would not come down despite efforts by the ED, and his blood pressure and pulse oximetry were a little concerning. Course of action? Admission to the general floor for observation. Turns out, Dave had a little bit of pneumonia along with his influenza that didn’t show up too obviously on his chest X-ray, and went unnoticed for a while. Eventually, Dave ends up in the ICU. He’s intubated, requiring high PEEP to keep him oxygenated. He’s also on pressors and sedation to keep him calm and his blood pressure at a perfusing level. As Judy sits by his bedside, she can barely believe that less than a week ago his only complaint was that he felt a little too tired to do his morning routine. You’ve been called upon to transfer Dave from this small, outlining hospital, to a larger center for critical care. Judy greets you as you and your partner enter the room.
Don’t lose what you’ve got
You take note of a few vital signs:
The MAP is floating right around 60 - 65 mmHg.
The Heart rate is currently 92.
The SPO2 has a good pleth wave, but only reads 88-90 as it fluctuates slightly.
Dave seems to be tolerating the ventilator well. The RASS is -3 - Dave will open his eyes to a close and rather loud voice in his ear, but he doesn’t really sustain any eye contact or interact with his environment.
His infusions include:
Propofol - 35 mcg/kg/min
Fentanyl - 100 mcg/hour
Norepinephrine - 5 mcg/min
Since the SPO2 is borderline, your eyes gaze over to the ventilator next. Settings:
Mode: AC/VC
Tidal Volume: 400 (~6mL/kg of IBW)
Frequency: 20
PEEP: 18
FiO2: 1.0
I-Time: 1.0 second
I:E Ratio: 1:2
Ppeak: 35
Pplat: 28
Judy: “Will someone be in the back of the ambulance with my husband during the ride?”
Let’s pause there. So far, this patient seems…. okay. The sending facility appears to have done the right stuff - they’re keeping the patient sedated, pressors are keeping the MAP up, and the ventilator settings seem to indicate that they’re trying to oxygenate the patient. The stressful part about a call like this is all you have to do is not screw up. You must avoid a crime of commission - just don’t do anything stupid and the patient will probably maintain at their current status. This can be more stressful than the unstable patient. Why? Because unstable patients are difficult. We can always say that we were dealt a losing hand and that we did everything we could. In our current situation with Dave, we just have to continue what the sending ICU already started - there aren’t many excuses or sympathies to be found in this situation.
“Of course - we’ll be continuing all the treatments and monitoring that he’s receiving here in the ICU while we’re transporting him. Plus, we’ll be by his side the entire time. We’ll be keeping an extra close eye on your husband.”
A Bump in the Road
You and your parter go about assessing Dave and transferring him over. He’s on your cot and your monitor so far. You decide you will place Dave on your vent, while you assign your partner to transfer over the IV infusions.
Your partner notices that his PICC line will not withdraw blood, nor will it flush with ease - the IV pump also has been having high pressure alarms. Your attention shifts to the problem, since you just finished with the ventilator. “Dave has horrible veins, always has…” Judy adds. Dave has an 18G Angiocath IV in his right arm that you will have to use for access. You decide all three infusions plus a saline drive line is too much for one port, so you decide to push dose his fentanyl later and piggy back the propofol and norepinephrine together with a saline drive line. Your partner agrees, and they go to work on transferring those over. You quickly look for IV access somewhere else, but there doesn’t seem to be any. You decide you’ll be fine with the 18G.
You assess Dave one more time before you wrap him up for transport. Your mental checklist before leaving the room goes like this:
Airway: His ETT looks good… still at the same depth. Getting good ETCO2. No leaks.
Breathing: Calculated the vent settings... suggests he’s oxygenating and ventilating well. Pplat is still okay. Grabbed that BVM and it’s on the cot.
Circulation: MAP still right around 60-65… That’s okay for now. Might turn the NorEpi up a little later. Pulse is still below 100. 12 lead looked fine. Sucks about that IV - I’ll look again during transport. The IV lines are set up pretty much the same as the facility had them.
Disability: He seems pretty out. That RASS is still probably like -2… I think we’ll be alright for transport.
Exposure: We gave him the once over, checked his temp from the foley before we disconnected. Okay, I think we can wrap him up like a burrito and get outta here.
Wait!
“We’re all set to go.” You and your partner start wrapping up Dave and telling Judy he’ll be nice and warm - but not too warm - during transport. Judy asks if she can sit next to Dave during the transport. You and your partner look at each other. “Sure, that should be fine.” You’re stopped on your way out of the room by the nurse who informs you of a couple things. First, there’s a room change. Second, she’s printing out a new packet because the old one now has the wrong room, and report given to the wrong receiving nurse. A few minutes go by, and you’re all finally on your way to the elevator. Judy appears to be a very active and in-shape 65 year old woman which is a relief because it’s a long walk and an elevator ride before you get out to the ambulance bay.
You’re just about to the elevator when you start to notice Dave has his eyes open. Before, in the room, and even during transfer, Dave wouldn’t track you with his eyes. His eyes would open, but he was in a stupor - the lights were on, but no one was home. Now, he appears to have his wits about him. Judy takes this as a good sign, but it makes you a little uncomfortable.
Judy: “Oh good - Dave we’re taking you to a new hospital! These people are going to take care of you on the--”
!********************!
The ventilator alarm interrupts Judy before she’s done with her sentence. The Peak alarm just sounded and Dave has a face as red as a tomato from coughing and gagging on the endotracheal tube.
Judy: DAVE! It’s OKAY! You’re in an elevator. We’re going to a new hospital.
*Thought to self - put syringe and ETOH wipe on my new mental checklist - I wish I could bolus a little fentanyl and propofol right now*
“Well, we want to make sure he’s comfortable and calm, why don’t we turn up his sedation a little.”
You tell your partner to increase the dose by 10 mcg/kg/min. The problem is, your partner only copied and pasted in the mL/h, and didn’t put the pump in calc mode. You pull out your phone…
*Micrograms x kilograms x 60.. divided by concentration…*
“Turn the mL/H to -“
Ding, ding. You came from the fourth floor, the elevator stops at the third. Patient transport is trying to take a patient from med-surg to CT.
“Oh - sorry guys! “I’ll grab the next one!”
“No problem!”
It’s at this point your eyes glance up from the ventilator alarm you’re trying to troubleshoot and the calculator on your phone and notice that the soft restraints are on, but the shoulder straps are not tight enough. You arrive at this conclusion because what Dave is currently doing is sitting forwards (the head of the bed is elevated to ~45º) and bringing his head to his right hand. He grabbed the endotracheal tube with a surprising amount of accuracy and strength.
“Wait!”
Too late. Dave has a hold on his endotracheal tube, and while you and your partner prevent him from pulling it all the way out, the best it is now is a supraglottic airway - it’s no longer inside his trachea. Your vent is giving you low pressure alarms, and Dave can now phonate and cough. Without PEEP, he now has massive atelectasis and his SPO2 starts to plummet. The next number you draw your eyes to is the heart rate - it’s starting to decline quickly.
“Do we have a mask??”
Frantically looking through the bag the BVM came in, you realize that you don’t have one. Nor do you have suction to manage the massive amount of secretions Dave currently has in his upper airway.
It’s been a rather long elevator ride for not really going very far. You arrive on the ground floor and start rushing to the closest empty ED room that you know will have a mask for your BVM. Dave currently has an SPO2 of 45% and his pulse is lower than that.
“They just didn’t like our vent”
What’s going on with Dave? Why do self-extubations like this occur? And if not self-extubations, we hear stirring accounts that are similar:
‘We put in the same ventilator settings but the patient just didn’t like our vent.’
‘Of course *eyes roll* the patient decided crash as soon as we got them to the bay/pad’
‘All the stimulation really agitated the patient’
‘We set up the infusions the same way as the hospital and they just didn’t work.’
Sound familiar? I’ve muttered a version of every single one of those lines. The answer may come down to something I call the slow motion plane crash.
The Slow Motion Plane Crash
Have you ever taken the time to look at your IV pump tubing? I know you’ve seen it - and probably used it a thousand times. But how much do you know about it? All IV tubing is different, so you’ll have to do this experiment for yourself, but stay with me here. From the distal port to the end of the tubing, what is the priming volume? I’ve noticed volumes ranging between ~2 and ~2.5 mL. ('Half-Set' IV tubing is sometimes less). And, most IV extension sets are ~2mL if they’re the 8” tubings. Then, you have a tiny bit more if you include things like hubs and catheters.
Regardless of your volumes being above or below this, it still takes a little time for medication to flow through these areas and mix properly. Your patient has been getting well mixed medication, and now you’re putting on an un-mixed infusion set that will take some time to get the proper mixture to the patient. How much time could this potentially be?
Let’s go on the worse end of the spectrum and say that your priming volume for the area in red above is right around 2.5 mL, and then the IV extension set that’s attached to that 18G is about 2mL. Since you have 2 extensions your going through, that’s 5mL, plus 2mL before the IV catheter hub.
2.5 + 2.5 + 2 = 7mL total.
7 mL? Doesn’t really seem like a big deal. Most of the time, it won’t be. But, if you have a fragile, borderline patient like Dave, you might not have very much wiggle room on this one. This is especially true if your flow rates are kind of low - the medications can take a surprising amount of time to make it through that tubing. Let’s look at exactly what happened to Dave.
Let’s look at the first two infusions. Norepinephrine is running at 10 mL/h, and the Propofol is running at 20 mL/h. Flow (rate) is additive, which means we can add those two together and figure out how long it will take them to get to the drive line. At 30mL per hour (10+20 = 30) you clear 0.5 mL/minute. How long will it take to reach the drive line? About 5 minutes.
Next, those two medications come into contact with the drive line. Let’s add the flows together again. 10 + 20 + 30 = 60. 60 is a nice round number because it clears one (1.0) mL of tubing every minute. So how long until that mixed medication makes it to the patient? About another 4.5 - 5 minutes if you add a little bit of time for the hub/port space.
If you take into account how long it took to switch the tubing over, clean the ports, confirm one last time, just to hit ‘start’ on the infusions - and realize they are still clamped - you can figure that the patient will not receive any propofol for at least the next 10-12 minutes. Not to mention he has been off of fentanyl for about 20 minutes now, because that was discontinued in the room at the beginning of transferring infusions. How long does propofol last? Depends. In some cases patients can wake up in under 10 minutes. How long does fentanyl last? Depends. But, a lot of the sedation and analgesia is gone inside of 20 minutes. Not to mention fentanyl and propofol have synergistic effects since they bind to some of the same plasma proteins. This means that when you discontinue one, the opposite of synergy happens (negative synergy?). This also means that when you adjust a medicaton, it takes roughly this long for the patient to see the results of that adjustment.
You can also see from the graph above that Dave first received only 2mL of saline, then 2.5 mL again of just saline, then 2.5 mL of norepinephrine mixed in saline, then finally a fully mixed solution of propofol, norepinephrine, and saline.
Considering all of this, it isn’t hard to see why your patient went from adequately sedated to extubated before you ever got to the ambulance.
Outliers
Can you identify the errors made on this mission? They were all throughout the story, but each one was not very obvious, nor would you consider each one a ‘big’ mistake. They were just little things that added up. Errors that on their own would probably have gone unnoticed or forgotten. Now, these errors are bullet points on a white board as your medical director puts together a sentinel event debrief.
Failure to insist on starting another IV.
Failure to turn up the NE immediately.
Failure to understand the lag period of medications due to the priming volume of the IV tubing.
Failure to bolus fentanyl and propofol so that you could make it through that lag period.
Failure to bring a syringe, flush, and ETOH wipe with you when leaving the room.
Failure to use Calc mode on the pump.
Failure to check the BVM bag for a mask.
The list could probably go on.
8. Failure to use a manifold for the IV infusions to avoid the priming volume issues.
9. Failure to let the infusions run by themselves to mix before placing them on the patient.
I’m going to share with you some quoted and paraphrased thoughts from my favorite part of a book called "Outliers” by Malcolm Gladwell. I think you’ll see the obvious correlations to taking care of patients - especially in EMS. In speaking about rare events like plane crashes, he explains how these crashes generally occur (which is where the name of this blog came from).
'It’s not like in the movies. There isn’t some explosion, or alarms going off, or even frantic speech and yelling on the radio. Usually, the pilots don’t know something is wrong until nearly the moment they crash. There is a few things that seem to increase the risk of crashing:
The weather is poor... not terrible. It's just bad enough so that the pilot is under a little more stress than usual.
The plane is behind schedule - causing the pilots to feel rushed.
In 52% of crashes one pilot has been awake for 12 hours or more - they’re tired and not thinking straight.
In 44% of crashes the pilots have not flown together previously.'
'That’s when errors start. On average, 7 consecutive human errors. One pilot does something wrong that by itself would not have been a problem. Still, another error occurs that again even when combined with the previous error still does not amount to catastrophe. Then, another error. And so on. It’s the combination of all those errors that leads to disaster.'
'These crashes are not due to a lack of knowledge or flying skill. It’s not that the pilots have to navigate some critical maneuver and fail in doing so. The kind of errors that cause a plane to crash are errors of team work and communication. One pilot doesn’t tell the other one what’s going on. One pilot does something wrong and the other one doesn’t notice it.'
'Airplanes are very unforgiving if you don’t do things right.'
Conclusion
I won’t just leave you hanging with no fixes. There are a few things you can do to avoid at least the priming volume issues experienced on this mission.