Imagine you’re in the ICU and the cuff of an ETT (endotracheal tube) ruptures. You exchange it for a fresh ETT over a catheter, right? Easy peasy.
Blind airway exchange over a catheter has been the standard practice in various ICUs that I’ve rotated through. ETT exchange over a catheter is a simple and effective procedure… until it’s not. The fundamental problem with ETT exchange over a catheter is that it works beautifully most of the time, but rarely it may go horribly sideways. For better or worse, the fail rate is low enough that the evils of ETT exchange tend to run under the radar.
If we start to think critically about ETT exchange, we detect some signals that this is a dangerous procedure:
- ETT exchange is an airway procedure, which risks injury or loss of airway.
- ETT exchange is a relatively rare procedure (e.g., a critical care trainee might get experience with a handful of ETT exchanges in comparison with 100-200 endotracheal intubations).
- ETT exchange is hardly mentioned or researched in the medical literature. Available data suggests that this is a far from perfect procedure (with a failure rate on the order of 10%).1
- ETT exchange is typically overlooked in airway management curricula.
- ETT exchange is subject to enormous practice variation. Some practitioners perform this blindly, whereas others perform the exchange under vision using laryngoscopy.
Risks of ETT exchange
(1) Airway loss due to inability to replace the ETT. There’s no guarantee that a fresh ETT will pass into the trachea. Occasionally the fresh ETT may get hung up on the glottis (this usually responds to gentle 90-degree rotation of the ETT, but not always!). If you are unable to pass the ETT, this may cause a huge problem – especially if you aren't properly prepared with all your airway equipment at the bedside.
(2) Laryngeal trauma. What happens if you’re having difficulty inserting the fresh ETT? Well, the natural tendency is to push harder. Blindly shoving an ETT into the trachea increases the potential of damaging delicate airway structures.
(3) Pneumothorax. A large series of patients undergoing airway exchange detected a pneumothorax rate of 1.5%.2 There are a couple ways that this can occur:
First, if the exchange catheter is passed too deeply into the airway, it may puncture a bronchus, leading to a huge pneumothorax.3 I’ve seen this happen and it’s not pretty. In the heat of the moment there’s a natural tendency to advance the catheter too far (to avoid it’s falling out). Additionally, the airway exchange catheter may be inadvertently advanced while the fresh ETT is being inserted over it.
Second, the exchange catheter may occasionally exit the endotracheal tube through the Murphy eye, causing it to veer off at a sharp angle that impinges against the wall of the trachea. This could cause the exchange catheter to perforate through the tracheal wall.4
(4) Esophageal intubation. There are a couple of ways this can happen:
First, an extremely common cause of a “blown ETT cuff” is that the ETT has been pulled upwards out of the trachea. When the ETT is pulled out of the trachea there is a cuff leak, which is managed by insufflating more air into the ETT cuff. The leak often occurs intermittently, so the ETT cuff winds up getting overinsufflated with a ton of air over time (e.g., 50-100 ml). Eventually, what you’re left with is essentially an ETT that is functioning similarly to a laryngeal mask airway. If an exchange catheter is blindly passed through the endotracheal tube it may go into either the trachea or the esophagus. So, a blind ETT exchange may land the fresh tube straight into the esophagus.
Second, even if the ETT is in the trachea initially, it is possible for the airway exchange catheter to loop around backwards as it is advanced (figure below).1 If the airway exchange catheter loops around, it’s possible that a blindly advanced ETT could wind up in the esophagus.
How to perform an ETT exchange safely over an airway exchange catheter?
There’s little evidence on this topic, so what follows is speculative.
Components to enhance safety might include the following:
- Preoxygenation, gastric suctioning, and sedation.
- Positioning the patient to optimize laryngoscopy (sniffing position).
- Gentle advancement of a laryngoscope to achieve direct vision of the glottis.
- Paralysis, followed by gentle advancement of an airway exchange catheter to 26 cm at the upper teeth. Avoid any advancement of the exchange catheter to greater depths.
- Performing ETT exchange under direct vision, with visual confirmation that the fresh ETT is entering the trachea.
- Confirmation that the new ETT is correctly situated using continuous waveform capnography.
As a general principle, to make ETT exchange safe we want to make this procedure as similar as possible to standard intubation procedures. If we are following similar approaches compared to most intubations, when things go sideways we can apply the usual principles of airway management. (Alternatively, if we’re just running into a room and swapping out an ETT blindly, if something does wrong then we’re completely flummoxed.)
For a more detailed discussion about how to perform this procedure, including some more advanced techniques, see this post by Scott Weingart.
A simple approach for most patients: just extubate the patient and reintubate
If the patient was able to be intubated without much difficulty (as nearly all patients are), the safest and easiest approach to ETT exchange may be as follows:
- Preoxygenate to 100% oxygen and suction the stomach with an orogastric/nasogastric tube.
- Sedate and paralyze the patient.
- Remove the old ETT and then perform intubation using standard techniques. All airway adjuncts and preparations should be made, similarly to any intubation.
The advantage of performing intubation in the standard fashion is that we’ve now transformed a rare procedure into a common procedure. Endotracheal intubation is a procedure which we are comfortable with and well-trained in.
If there is concern regarding the possibility of a difficult airway, a video laryngoscope may be gently inserted following sedation to allow visualization of the glottis (prior to extubation). If a view of the vocal cords and endotracheal tube can be easily obtained (as is usually the case), then it’s arguably easier and safer to simply remove the old endotracheal tube and intubate from scratch. Specifically, for a patient whose vocal cords are easily visualized during laryngoscopy, the use of an airway exchange catheter may introduce more confusion than benefit.
OK, I’ll just see myself out now.
Airway management is subject to massive variation, depending on geography and specialty. So, it would be delusional to propose that there is a single best approach to this procedure that could be applied everywhere, by everyone.
The purpose of this post isn’t to prescribe any single technique as best. Rather, the goal is primarily to shine a bit of light on this issue.
To be honest, I’m worried that many junior clinicians may approach airway exchange with a false sense of security – assuming that the airway exchange catheter will eliminate all problems. In reality, the exchange catheter solves some problems, but it does this at the cost of creating unexpected error patterns.
So, regardless of your preferred technical approach to airway exchange, approach it with the respect and trepidation it deserves.
Peer Review by Scott Weingart!
Since this is a controversial airway piece, I thought it would benefit from some additional review. I think Scott and I see this problem through slightly different lenses: he is conceptualizing it from the perspective of a master airway manager, whereas I'm conceptualizing it more from the perspective of an average airway manager. So, take a listen and think about what approach would work best in your context.
- ETT leaks and tube exchanges by Scott Weingart
- 1.Foglia J, Guy J. An underappreciated risk of an airway exchange catheter. Can J Anaesth. 2020;67(4):491-492. doi:10.1007/s12630-019-01504-7
- 2.McLean S, Lanam C, Benedict W, Kirkpatrick N, Kheterpal S, Ramachandran S. Airway exchange failure and complications with the use of the Cook Airway Exchange Catheter®: a single center cohort study of 1177 patients. Anesth Analg. 2013;117(6):1325-1327. doi:10.1213/ANE.0b013e3182a7cd3d
- 3.de A, Hajjar L, Fukushima J, Nakamura R, Albertini R, Galas F. Bronchial injury and pneumothorax after reintubation using an airway exchange catheter. Braz J Anesthesiol. 2013;63(1):107-109. doi:10.1016/j.bjane.2012.02.001
- 4.Harris K, Chalhoub M, Maroun R, Elsayegh D. Endotracheal tube exchangers: should we look for safer alternatives? Heart Lung. 2012;41(1):67-69. doi:10.1016/j.hrtlng.2011.06.005
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