Welcome back to the tasty morsels of critical care podcast.
There’s not a huge amount of notes on procedural stuff that I accumulated for the exams but I did collect some interesting bits on bronchoscopy, particularly because it was so novel to me as an EM trainee who really had no experience with bronchoscopy prior to starting to my critical care fellowship.
After 2 years of frequent, if not daily use of the bronch, I find it hard to see how I would manage in an ICU without it. Now, when I say bronch I want to be clear that I’m talking about the flexible, disposable pieces of gear. The respiratory people sometimes come and laugh at us when they arrive with their big stacks and multi-thousand euro pieces of kit.
Why might we pull out the bronch in the ICU?
Well I’m not sure there is a clear or authoritative list, but the following would be reasonable
- as an assistance in intubation
- as a guide in percutaneous tracheostomy
- as a therapeutic in mucous plugging
- sudden refractory hypoxia without obvious cause. I often find putting the bronch down quickly answers a lot of questions about tube position and mucous plugging and bleeding a whole lot quicker than waiting for the CXR
- BAL. We all love to know what we’re treating and especially in the hospital acquired or immunocompromised, it can be lovely to grow a bug. Though I don’t want to suggest this is particularly data driven.
- Airway bleeding. Finding the bleeding, clearing it, treating it.
In general we will almost always be passing the bronch through some kind of device. I have on occasion post tracheostomy spent some time practicsing getting the bronch through the cords in a sort of a poor man’s fibre optic intubation, and damn if it’s not tricky… Credit should be due to the respiratory guys who do this all the time. All be it with much weller patients and nicer and shiner equipment.
What do we look for then once we’ve passed a bronch into the large airways? We should have a good look at the airways themselves. Is there a lot of suction trauma? Is there bronchomalcia, (esp in the slow trache weans), are there hyphae and mushrooms growing in the airways suggestive of aspergilllus? We often forget to simply look at the walls as we chase down into the lobes to get our sample.
Once it comes to the process of BAL itself then I realise I’m often a little shy and cautious in my installations of saline. When I went and read up on this it turns out typically recommended volumes for installation of saline are more like 100mls rather than the paltry 20-40mls I was using when I first started. A lot of what I (and I suspect many of you) have been doing is perhaps better classified as bronchial washings rather than true bronch alveolar lavage. Also important, once you stick the saline in, to give it a decent amount of time (30-60 secs) before aspirating.
In terms of where we are aiming for, typically aim for the segment that looks worst on imaging. If it’s all awful or nil focal then the RML and the lingula are often recommended.
In some of the reading there was discussion on “wedging” the bronch which is not the infantile practice of pulling someone’s underwear up really high when they’re not suspecting it. Bronchoscopic wedging involves getting the tip of the bronch into a segment far enough where there is partial airway collapse (though not complete) on suction. If it doesn’t collapse at all you’re too proximal, If it collapses completely then you’ll likely not get a good aspirate.
Once you’ve got your samples then the qunadry you face next is what to test it for. This will likely depend on the situation, but you have a variety of options available to you
- routine culture
- cytology, things like eosonophils for daptomycin induced pneumonitis, inclusion bodies for things like CMV/HSV
- galactomannan on a BAL sample apparently more useful for aspergillus than serum
- PJP PCR (very sensitive, not specific) and silver staining is a useful test
- CMV reactivation is another common concern in the critically ill
Bronchs are not without their potential complications and can be summarised as follows
- barotrauma – this may be related to the sudden and extreme pressure changes from being on +ve pressure one moment and attached to wall suction the next. The vent settings itself will also change things as if you really ask the vent to deliver 400mls while the airways are largely occluded with a plastic bronch then expect airway pressures to be very high
- the UTD article was useful on this but you will need access
- LITFL covers it well as expected
- there is a nice simulator but it needs flash and it seems flash has not graduated into the pandemic era so it’s hard to run
- finally there’s a nice and brief anatomy review that is worth reviewing on a regular basis so you actually have some idea where the hell you are in the lungs at any given time.