TEVAR c carotid-subclavian graft

[nap$ter]

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thought i'd post this case both because it was a cool surgery, and because the wake-up was complicated....

70yo Cambodian physician scheduled for L carotid to subclavian graft to be followed by TEVAR.

HPI: Pt has been followed for type B thoracoabdominal aneurysm with chronic dissection for the last 10yrs by his PCP. The aneurysm extends from 1.6cm distal to the left subclavian all the way down to to the celiac takeoff, while the dissection spans just a large chunk of the descending aorta. The pt is asymptomatic, but the aneurysm has expanded to >6cm on last CT, so elective repair is scheduled.

PMH: well controlled HTN, HLD, nl ekg, nl echo, BMI 28, chemistry/CBC/coags nl

PSH: zygoma repair 1969, lithotripsy 1985

anesthetic course - 14g PIV in preop, smooth induction with propofol 120mg, fentanyl 250ug, cisatracurium 20mg. R radial aline and R IJ triple lumen placed post induction, lumbar drain placed and kept capped during entire procedure.

the case was almost unremarkable. 2.5hrs to place L carotid to subclavian graft followed by B femoral access and TEVAR. heparin 8000u for grafting, 4000u for stenting, ACT's monitored. when they deployed their stent the pt became acutely hypotensive to 60 systolic, and I notified the surgeon while giving phenylephrine, and within 60sec BP was back to MAP of 70. surgeon tells me sternly "we really don't want any hypotension during this sort of case" - I nod, bow my head, "uh-huh, you betcha, BP's back up".. had to give protamine 40 to get ACT back to normal for d/c of femoral sheaths at the end. 5hrs after induction procedure is complete....

pt received 250 of fentanyl c induction and 100 of fentanyl for entire case. had 3 twitches, i reversed with 3 of neostig/0.5 glyco, 4 twitches c tetany. turn off the iso, pt breathes, extubated when eyes open...

pt closes eyes, and doesn't wake up... hemodynamically stable, TV's 500, rr 12, SpO2 100%... still doesn't wake up after 10min.. PERRL, finally starts to withdraw on the right to sternal rub. 40ug naloxone x2 with small improvement.. begins to follow commands on the right only, appears to be trying to talk but is dysarthric, tongue midline... there's a soft swelling around the carotid/subclavian incision but surgeon thinks it's ok..

surgeon and my attg decide to go for CT angio head, surgeon calls neuro consult, describes case, mentions "everything about the case went very smoothly, but we had a hypotensive episode with BP down to 60 systolic..."

thoughts at this point?

 

[Planktonmd]

Wait a couple of hours then re-evaluate the patient.
He is most likely going to wake up and what you think is a neurological deficit right now will disappear.
There is no point of doing a CT scan at this point.
Patients sometimes don't emerge from anesthesia as soon as you turn off the vapor.

 

[seinfeld]

Subclavian steal from the bypass, Carotid dissection, iatrogenic Proximal extension of dissection, Embolic and Hemorrhagic CVA also on DDx. In this case i would think pathologic before i would assume pharmacologic (ie anesthetics).

Why did you not use the lumbar drain during the case. Given your MAP will tend to be lower under GA than awake, the time for the lowest Spinal perfusion pressure is under GA. Plus its easier to clamp post op and if the patient looses leg function restart drainage, but harder to explain when the patient wakes up paralyzed and the drain was closed.

 

[bullard]

Agreed ... no f'ing way this is an ischemic stroke.

 

[pushthesux]

Where exactly did they clamp for the first part of the procedure...and for how long?

 

[nap$ter]

Where exactly did they clamp for the first part of the procedure...and for how long?

2 places for each end of the graft: proximal and distal subclavian, then proximal and distal common carotid. the surgeon did not record clamp times in his operative record, but it could not have been longer than 10min for either anastamosis; most of the surgical time for the graft was spent in exposure..

remember guys, the patient was dysarthric, but had left-sided motor weakness, and the grafting was being done in the left carotid...

interesting; when the patient stuck out his tongue on command, we noticed a large sublingual hematoma - likely secondary to a combination of me stuffing a bite block in and heparinization...

i was curious whether the LUE weakness could have been from a brachial plexopathy from that big lump of swelling in his lower neck around their incision... but he had L leg weakness as well..

long story short - the surgeon wanted full court press (despite his comment about hypotension) and the patient went for CT angio. if there had been an embolus, i'm pretty sure the surgeon would have pushed for TPA despite his just-finished surgery.

CT angio was completely negative.

also - at our institution the surgeon (for some reason unbeknownst to me) directs capping/uncapping of the lumbar drain. this is what my attending told me. also, cord perfusion pressure = map - csf pressure (ICP essentially), and during the vast majority of the case the MAP was a straight line at 75-80. regardless, one sided deficits in upper and lower extremities is not a cord issue - paraplegia is.

what do folks do with lumbar drains in your practice for aneurysm repairs? i don't have much experience with em..

 

[nap$ter]

Subclavian steal from the bypass, Carotid dissection, iatrogenic Proximal extension of dissection, Embolic and Hemorrhagic CVA also on DDx. In this case i would think pathologic before i would assume pharmacologic (ie anesthetics).

Why did you not use the lumbar drain during the case. Given your MAP will tend to be lower under GA than awake, the time for the lowest Spinal perfusion pressure is under GA. Plus its easier to clamp post op and if the patient looses leg function restart drainage, but harder to explain when the patient wakes up paralyzed and the drain was closed.

nice ddx

with phenylephrine and an aline, you can make the MAP pretty much whatever you want..

 

[Licoricestick]

post deleted - dumb question

 

[Planktonmd]

To (theoretically) improve the perfusion to the spinal cord by decreasing the intrathecal pressure when you anticipate spinal ischemia like in the case of a thoracic aortic aneurysm repair.

Never having seen a case like this before, I'm curious as to why a lumbar drain was placed. I've heard of them being placed for neurosurg cases as well as treatment of CSF leaks and obviously their purpose is ICP reduction...but why do you need that in the setting of presumably normal ICP in this man?

 

[sevoflurane]

Interesting. Still dysarthric today? LUE/LLE weakness? How weak? Confused?I don't think the picture fits any particular single answer if you have excluded embolic/hemorrhagic stroke. Ischemic is very unlikely with systolics in the 60's for a minute unless there were some serious underlying funkyness.

I like subclavian steal because it can explain the dysarthria and LUE weakness, but does not explain LLE weakness. and... ct angio was negative.

I'd get a repeat CT scan today just to make sure.

Good post. I'm curious about the final diagnosis.

 

[sevoflurane]

Highly doubt this zebra explains things.... but it's in the ddx.

http://www.advances-in-medicine.com...miplegia-due-to-episodes-of-hypoglycemia.html

 

[urge]

Why did he need a graft form L carotid to subclavian? What is the idea behind it? Perfuse brain or perfuse arm?

You said the right side moves ok and the left not. His right brain seems to be the issue. Are you sure that central line is in a vein? Did you dislodge a carotid plaque while placing the line?

 

[paiute]

is this pt right or left-handed?

 

[sevoflurane]

Interesting. Still dysarthric today? LUE/LLE weakness? How weak? Confused?I don't think the picture fits any particular single answer if you have excluded embolic/hemorrhagic stroke. Ischemic is very unlikely with systolics in the 60's for a minute unless there were some serious underlying funkyness.

I like subclavian steal because it can explain the dysarthria and LUE weakness, but does not explain LLE weakness. and... ct angio was negative.

I'd get a repeat CT scan today just to make sure.

Good post. I'm curious about the final diagnosis.

Actually, If money, access and time was not an issue, I'd get an MRI. You may be able to pick up on edema a bit better. You are well beyond the insult and might be able to pick up on small lacunar type strokes that may not have been seen initially or not picked up by CT. Specifically, I'd be looking at the internal capsule.

 

[nap$ter]

Why did he need a graft form L carotid to subclavian? What is the idea behind it? Perfuse brain or perfuse arm?

You said the right side moves ok and the left not. His right brain seems to be the issue. Are you sure that central line is in a vein? Did you dislodge a carotid plaque while placing the line?

remember brain blood comes from carotids, and vertebrals, which arise from - subclavians - so the reason for the graft was perfusion of both arm and brain. per the surgeon, the endovascular graft needs 2-3cm of healthy aorta to "seal" to, so despite the fact that this guy had a type B aneurysm 1.6cm below the L subclavian, they had to seal over the L subclavian, necessitating the graft.

you are correct that the right brain was the issue for the L hemiplegia. but dysarthria is left brain...

and yes, the central line was in a vein, transduced during the case, placed under ultrasound, etc...

 

[nap$ter]

is this pt right or left-handed?

R handed - why does it matter?

 

[nap$ter]

Actually, If money, access and time was not an issue, I'd get an MRI. You may be able to pick up on edema a bit better. You are well beyond the insult and might be able to pick up on small lacunar type strokes that may not have been seen initially or not picked up by CT. Specifically, I'd be looking at the internal capsule.

bingo. neurology was on the ball on this consult. they never bought the hypotension suggestion from the vascular surgeon. i was initially confused a bit, because the patient had deficits possibly arising from BOTH sides of the brain - L hemiplegia (R brain), and dysarthria (usually L brain).

as it turns out, the dysarthria has improved as the sublingual hematoma improves. not all dysarthria is cns-related. turns out a big sublingual bruise will do it, too.

neurology went chasing R brain embolus differential - pt got a TTE to rule out R-L shunt (negative) and a R TCD to rule out ongoing microemboli.

On POD#2 he got an MRI - which showed an evolving R corona radiata ischemic stroke likely secondary to emboli.

the dysarthria was a weird curveball. i would not have thought that the surgeons could have dislodged an emboli up the R brain circulation given that they were primarily working downstream from there, but i guess they must have been proximal enough at some point...

the patient has shown rapid improvement over the last two days; has some residual LUE pronator drift and some mild LLE weakness, but is expected to make a good recovery with home PT/OT.

 

[Planktonmd]

Nice case.

 

[urge]

remember brain blood comes from carotids, and vertebrals, which arise from - subclavians - so the reason for the graft was perfusion of both arm and brain. per the surgeon, the endovascular graft needs 2-3cm of healthy aorta to "seal" to, so despite the fact that this guy had a type B aneurysm 1.6cm below the L subclavian, they had to seal over the L subclavian, necessitating the graft.
.

Both?

You sure about that?

Left carotid coming off left subclavian?

Explain to me like I were a 3 yr old how the graft, left carotid and left subclavian get perfused after the stent is deployed blocking off the left subclavian.

 

[urge]

as it turns out, the dysarthria has improved as the sublingual hematoma improves. not all dysarthria is cns-related. turns out a big sublingual bruise will do it, too.

neurology went chasing R brain embolus differential - pt got a TTE to rule out R-L shunt (negative) and a R TCD to rule out ongoing microemboli.

On POD#2 he got an MRI - which showed an evolving R corona radiata ischemic stroke likely secondary to emboli.

i would not have thought that the surgeons could have dislodged an emboli up the R brain circulation given that they were primarily working downstream from there, but i guess they must have been proximal enough at some point...

How about you introduced air/gunk in the A line with one of those "power flushes" people like to do, and went retrograde all the way to innominate + up the carotid?

 

[Planktonmd]

Both?

You sure about that?

Left carotid coming off left subclavian?

Explain to me like I were a 3 yr old how the graft, left carotid and left subclavian get perfused after the stent is deployed blocking off the left subclavian.

🙂

 

[sevoflurane]

bingo. neurology was on the ball on this consult. they never bought the hypotension suggestion from the vascular surgeon. i was initially confused a bit, because the patient had deficits possibly arising from BOTH sides of the brain - L hemiplegia (R brain), and dysarthria (usually L brain).

as it turns out, the dysarthria has improved as the sublingual hematoma improves. not all dysarthria is cns-related. turns out a big sublingual bruise will do it, too.

neurology went chasing R brain embolus differential - pt got a TTE to rule out R-L shunt (negative) and a R TCD to rule out ongoing microemboli.

On POD#2 he got an MRI - which showed an evolving R corona radiata ischemic stroke likely secondary to emboli.

the dysarthria was a weird curveball. i would not have thought that the surgeons could have dislodged an emboli up the R brain circulation given that they were primarily working downstream from there, but i guess they must have been proximal enough at some point...

the patient has shown rapid improvement over the last two days; has some residual LUE pronator drift and some mild LLE weakness, but is expected to make a good recovery with home PT/OT.

Thanks for the post and follow up slavin. R. corona radiata? Arrrghhhh... 😡 I was playing my odds. Learning point= You should think of the internal capsule if you see this again though (likely). I'm going to put my dorky neurology hat on. Here is why you should pick it again:

Lacunar infarcts that are not seen on CT and affect an entire side of the body, is more likely to be an internal capsule infarct (especially with dysarthria). Hands down. The corona radiata is a lot bigger so motor axons are more dispersed in a bigger area vs. the internal capsule where they all coalesce = a lot smaller structure comparatively. It only takes a little infarct in this area to cause a sh$t load of damage (which may be picked up by MRI). The good thing is that recovery is usually 75-90% (less blood/edema/clot or whatever.) at one year vs. other strokes. Good post. 👍

 

[urge]

Left carotid off aorta. Left subclavian off aorta. Aortic cross clamp proximal to left subclavian, but distal to left carotid.

I agree with that. Not the same as the left carotid coming off the subclavian as the OP had written. However, that would be an open case.

 

[urge]

Cerebral air embolism from central lines or A lines. It happens.

http://www.springerlink.com/content/g8wm04w2w14lp7j5/

Abstract Microscopic cerebral arterial air embolism (CAAE) has been described in many patients undergoing cardiac surgery as well as other invasive diagnostic and therapeutic procedures. However, massive CAAE is rare. We report a 42-year-old woman who initially presented with thalamic and basal ganglia hemorrhages. Shortly after a radial arterial catheter was inserted, the patient suffered a generalized seizure and CT demonstrated intra-arterial air in bilateral cerebral hemispheres.

http://www.astm.org/JOURNALS/FORENSIC/PAGES/JFS2005061.htm

http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijanp/vol2n2/air.xml

http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijanp/vol2n2/air.xml

http://www.mdconsult.com/das/articl...nal&source=&sp=N&sid=0/N/433866/1.html?issn=#

 

[nap$ter]

remember brain blood comes from carotids, and vertebrals, which arise from - subclavians - so the reason for the graft was perfusion of both arm and brain. per the surgeon, the endovascular graft needs 2-3cm of healthy aorta to "seal" to, so despite the fact that this guy had a type B aneurysm 1.6cm below the L subclavian, they had to seal over the L subclavian, necessitating the graft.

you are correct that the right brain was the issue for the L hemiplegia. but dysarthria is left brain...

and yes, the central line was in a vein, transduced during the case, placed under ultrasound, etc...

guys, cmon. i didn't think i had to point out that L carotid and L subclavian come off the aorta, as that seemed to be clear. but, urge asked why the graft, to perfuse brain or arm?

and the answer is BOTH, as I answered. the left vertebral artery (remember, the posterior contribution to that circle of willis thingy?) comes off the L subclavian (R vertebral comes off - R subclavian). so, L carotid to L proximal subclavian perfuses - arm (via subclavian), and brain (via L vertebral).

 

[nap$ter]

I agree with that. Not the same as the left carotid coming off the subclavian as the OP had written. However, that would be an open case.

that's not what i wrote - reread above - though guess i was a bit unclear..

 

[nap$ter]

How about you introduced air/gunk in the A line with one of those "power flushes" people like to do, and went retrograde all the way to innominate + up the carotid?

nope

 

[urge]

that's not what i wrote - reread above - though guess i was a bit unclear..

A'right dude, I get it.

BTW, you don't like my gunk theory?

 

[nap$ter]

A'right dude, I get it.

BTW, you don't like my gunk theory?

that would have to be one powerful flush.

 

[proman]

that would have to be one powerful flush.

Not really. Flushing >1cc/sec causes retrograde flow, so it's one of Urge's more believable conspiracy theories.

 

[ProRealDoc]

how about just flushing the a-line since the heparin flush bag is pressurized to ~300mmhg?

 

[proman]

how about just flushing the a-line since the heparin flush bag is pressurized to ~300mmhg?

Looks like it's probably safe. Without opening the flush, the regulator flows around 3ml/hr. Doing a "fast flush" or "power flush" delivers much less volume than it appears. From that study:

Results: In-vitro fast flush bolus volumes ranged from 0.23 ± 0.04 ml (1-s , 100 mmHg, 24-G cannula) to 2.95 ± 0.38 ml (5-s, 300 mmHg, 22-G cannula). Volumes were larger using a 22-G cannula than a 24-G cannula (P < 0.01) and increased with longer flushing periods (P < 0.0001) and higher manometer pressures (P < 0.0001). In-vivo 1- and 2-s fast flush bolus volumes correlated well with driving pressures (infusion pressure minus mean arterial pressure) (r2 = 0.81/0.72). 1-s fast flush bolus volumes delivered (ml) were 0.0025 × mmHg driving pressure and 2-s fast flush bolus volumes delivered (ml) were 0.0043 × mmHg driving pressure. The mean volume delivered to purge blood from the arterial pressure tubing was 0.94 ± 0.18 ml (range 0.61–1.34 ml).

 

[nap$ter]

Not really. Flushing >1cc/sec causes retrograde flow, so it's one of Urge's more believable conspiracy theories.

where'd you get that stat from? seems like there are too many variables (catheter gauge, CO, BP, HR etc..) to make a global statement like that.. by definition, an aline flush IS retrograde flow - the important question is how far does it go and does it cause any harm.

found this - Arterial fast bolus flush systems used routinely in neonates and infants cause retrograde embolization of flush solution into the central arterial and cerebral circulation.
Weiss M, Balmer C, Cornelius A, Frey B, Bauersfeld U, Baenziger O.
Can J Anaesth. 2003 Apr;50(4):386-91. English, French

a. this is in tiny little squirrels with fast HR's and low MAP's/small CO's..
b. can't find anything demonstrating morbidity from routine aline flushing in adults
c. i love conspiracy theory, but i won't believe it till you show me the data (and case reports aren't data)

 

[2win]

how about just flushing the a-line since the heparin flush bag is pressurized to ~300mmhg?

How about to just forget the transitory drop in BP?
Much noise for nothing....

 

[proman]

where'd you get that stat from?

Anesthesiology. 2006 Sep;105(3):492-7.
Retrograde blood flow in the brachial and axillary arteries during routine radial arterial catheter flushing.
Murphy GS, Szokol JW, Marymont JH, Avram MJ, Vender JS, Kubasiak J.

Department of Anesthesiology, Evanston Northwestern Healthcare, IL 60201, USA. [email protected]
BACKGROUND: Flushing of radial arterial catheters may be associated with retrograde embolization of air or thrombus into the cerebral circulation. For embolization into the central circulation to occur, sufficient pressure must be generated during the flushing process to reverse antegrade blood flow in the arterial blood vessels of the upper extremity. This ultrasound study was designed to examine whether routine radial catheter flushing practices produce retrograde blood flow patterns in the brachial and proximal axillary arteries. METHODS: Duplex ultrasound examinations of the brachial and axillary arteries were conducted in 100 surgical patients to quantify direction and velocity of blood flow during catheter flushing. After obtaining Doppler spectral images of brachial and axillary arterial flow patterns, manual flushing was performed by injecting 10 ml flush solution using a syringe at a rate reflecting standard clinical practices. The flow-regulating device on the pressurized (300 mmHg) arterial flushing-sampling system was then opened for 10 s to deliver a rapid bolus of fluid (flush valve opening). RESULTS: The rate of manual flush solution injection through the radial arterial catheter was related to the probability of retrograde flow in the axillary artery (P < 0.001). Reversed arterial flow was noted in the majority of subjects (33 of 51) at a manual flush rate of less than 9 s and in no subjects (0 of 48) at a rate 9 s or greater. Retrograde flow was observed less frequently during flush valve opening (2 of 99 patients; P < 0.001 vs. manual flushing). CONCLUSIONS: Rapid manual flushing of radial arterial catheters at rates faster than 1 ml/s produces retrograde flow in the proximal axillary artery.

There's really no reason to slam in your flush, is there?

 

[nap$ter]

Anesthesiology. 2006 Sep;105(3):492-7.
Retrograde blood flow in the brachial and axillary arteries during routine radial arterial catheter flushing.
Murphy GS, Szokol JW, Marymont JH, Avram MJ, Vender JS, Kubasiak J.

Department of Anesthesiology, Evanston Northwestern Healthcare, IL 60201, USA. [email protected]
BACKGROUND: Flushing of radial arterial catheters may be associated with retrograde embolization of air or thrombus into the cerebral circulation. For embolization into the central circulation to occur, sufficient pressure must be generated during the flushing process to reverse antegrade blood flow in the arterial blood vessels of the upper extremity. This ultrasound study was designed to examine whether routine radial catheter flushing practices produce retrograde blood flow patterns in the brachial and proximal axillary arteries. METHODS: Duplex ultrasound examinations of the brachial and axillary arteries were conducted in 100 surgical patients to quantify direction and velocity of blood flow during catheter flushing. After obtaining Doppler spectral images of brachial and axillary arterial flow patterns, manual flushing was performed by injecting 10 ml flush solution using a syringe at a rate reflecting standard clinical practices. The flow-regulating device on the pressurized (300 mmHg) arterial flushing-sampling system was then opened for 10 s to deliver a rapid bolus of fluid (flush valve opening). RESULTS: The rate of manual flush solution injection through the radial arterial catheter was related to the probability of retrograde flow in the axillary artery (P < 0.001). Reversed arterial flow was noted in the majority of subjects (33 of 51) at a manual flush rate of less than 9 s and in no subjects (0 of 48) at a rate 9 s or greater. Retrograde flow was observed less frequently during flush valve opening (2 of 99 patients; P < 0.001 vs. manual flushing). CONCLUSIONS: Rapid manual flushing of radial arterial catheters at rates faster than 1 ml/s produces retrograde flow in the proximal axillary artery.

There's really no reason to slam in your flush, is there?

i don't think anyone on this forum is advocating the slammin of flush.

what study are they referring to in their first statement in red?

i have a problem with this paragraph. they seem to confuse retrograde flow in the proximal axillary artery with fluid/matter from the flush actually reaching the axillary artery.

just to play devil's advocate - say your muscle-bound med student slams flush into your aline with a ten cc syringe as hard as he can to try to impress you. sure - flow's gonna be retrograde - but it's a fluid column - right? some mixing secondary to turbulence etc but not much.. it's only ten cc's - what is the volume of blood between the radial artery and axillary artery? bet it's well over ten cc's. so even if flow does become retrograde - does any fluid/bubbles/particles from the flush actually reach the subclavian artery?

i would guess there is no study out there demonstrating this because a) hard to convince an IRB committee that it's a good idea to pump some traceable element toward a patient's carotids, and b) there's too much variability in CO, HR, MAP, pulse pressure, distal arterial flow to demonstrate anything consistent.

maybe i'm wrong - maybe they did it to med students back in the day..

 

[proman]

From the article:
Lowenstein et al.20 ad- ministered tagged saline from a syringe directly con- nected to radial catheter at a rate of 12&#8211;15 ml/s. Saline was detected at the junction of the subclavian and ver- tebral arteries when an average volume of 6.6 ml was injected.

I recommend you read the article, it's an interesting piece. The full text is available for free in the link.

 

[nap$ter]

From the article:
Lowenstein et al.20 ad- ministered tagged saline from a syringe directly con- nected to radial catheter at a rate of 12–15 ml/s. Saline was detected at the junction of the subclavian and ver- tebral arteries when an average volume of 6.6 ml was injected.

I recommend you read the article, it's an interesting piece. The full text is available for free in the link.

thanks. it is an interesting article. 12-15mL/s is pretty fast. i wonder if air bubbles or particulate matter is detected at the same distance/speed.

 

[nap$ter]

From the article:
Lowenstein et al.20 ad- ministered tagged saline from a syringe directly con- nected to radial catheter at a rate of 12–15 ml/s. Saline was detected at the junction of the subclavian and ver- tebral arteries when an average volume of 6.6 ml was injected.

I recommend you read the article, it's an interesting piece. The full text is available for free in the link.

however, that paper is from 1971, and i just tried to flush 10mL through an OPEN aline tubing setup with a ten-cc syringe in 1s - it is nearly impossible.

the following paper is a bit more clinically relevant:

Anesthesiology. 2004 Sep;101(3):614-9.
Retrograde air embolization during routine radial artery catheter flushing in adult cardiac surgical patients: an ultrasound study.
Murphy GS, Szokol JW, Marymont JH, Avram MJ, Vender JS.

i always get funny looks from junior residents when i return fresh blood to patients through their arterial lines...