I had an interesting case the other day, here at hospital 56. It was an op cab – and it ended up being more than the original grafts that were advertised. This was a fairly routine patient presentation in terms of degree of difficulty, with a particular surgeon for whatever reason always works solo, and started doing an endovascular harvest vein graft procedure that involves a process by which a long perioperative scope is inserted into the leg or legs of the patient having the open-heart procedure – and once the scope was actually in- CO2 is insufflated to allow for tissue expansion as the saphenous vein is identified and subsequently harvested.
This is as routine as routine gets in terms of heart surgery.
Then things went from normal to very edgy- in a heart beat (no pun).
We observed a sudden loss of pressure via radial arterial line that had started to drift but the dropped to a 60/40 level that obviously got my attention as well as the entire heart team. PA systolic pressures were close to systemic and CVP bumped up to 20. No ST elevation and rhythm remained steady at 90 BPM.
Non invasive blood pressure confirmed that it wasn’t a radial art line issue- and the event lasted about 20 minutes or so- but we managed to get ahead of the hypotensive episode. The chest was immediately opened to evaluate the heart.
In our world, things like that don’t happen without any sort of explanation. We weren’t manipulating the heart- as the sternum was yet unopened. Anesthesia had given no meds- and known allergies were not an issue. So that part of the “human error” equation was a “NO” for the check box.
A key observation was made by one of our circulating nurses in terms of suggesting the possibility of a gas embolism delivered to the right side of the heart- something I hadn’t considered- but it did make sense. The timing of the hypotensive episode aligned very neatly to the timing of CO2 insufflation into the patient’s leg. So there could be an argument for a CO2 mediated pulmonary embolism.
I used her hypothesis as the teeth to initiate a literature search on “the incidence of CO2 gas resulting in pulmonary embolism” and got some serious results. This isn’t an uncommon phenomena.
Depending on what study you want to look at- it presents in some form or fashion at least 17% of the time. What dilutes the inferred negative end result is that CO2 is readily absorbed into the blood stream quite faster than O2. It can be identified via TEE of the IVC and RA as the process of insufflating the leg is initiated.
What separates hazard from harm is the absence of a PFO or an ASD. If those are present, then a right heart issue becomes a left heart issue very quicky- with all things associated when you get air into the coronaries or the LV and forward that to the head. That is when you end up crashing on bypass and patient’s forget their home addresses and/or phone numbers.
Clearly- we don’t see this sort of clinical drama expressed very often, we probably experience it more often than we think- but anesthesia compensates for what they are seeing- and it remains a blip on the radar.
Typically? Blips are what they are and what we are trained to overcome. That’s why they retain their namesake “BLIPS”.
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