- Joined
- May 13, 2011
- Messages
- 199
- Reaction score
- 27
- Points
- 4,621
- Attending Physician
So is the ischemia/pain in the area right beneath the tourniquet? Or is it more generalized limb pain?
If I feel like the pt has enough narcs/anesthesia on board and BP's are still getting outta control I like to bolus Nicardipine 100-200mcg at a time. Works great and is short acting enough that you don't have to worry about the pt's BP crashing once the tourniquet somes down.
How about regional anesthesia???
Tourniquet pain is not thought to be soley a result of neural pathways but also the release of vaso-active mediators in the setting of limb ischemia. Thus regional anesthesia is not always effective just like pgg mentioned.
I agree nicardipine is pricey but we have a few surgeons that push 2-2.5hrs of tourniquet time regularly and you gotta do something. Using cheaper longer acting agents (labetalol, hydralazine) often results in marked hypotension after tourniquet release, and I'm too much of a whimp to use nipride sans a-line
😕
Not everybody is a candidate for regional. By the time the tourniquet pain manifests, it's a bit too late to change plans.
Also, you've never seen tourniquet pain bleed through a spinal?
Tourniquet pain is not thought to be soley a result of neural pathways but also the release of vaso-active mediators in the setting of limb ischemia. Thus regional anesthesia is not always effective just like pgg mentioned.
I agree nicardipine is pricey but we have a few surgeons that push 2-2.5hrs of tourniquet time regularly and you gotta do something. Using cheaper longer acting agents (labetalol, hydralazine) often results in marked hypotension after tourniquet release, and I'm too much of a whimp to use nipride sans a-line
It seems there is a specific issue with Tetracaine where the C fibers do return to activity before other thicker fibers and that seems to explain why a Tetracaine spinal could continue to appear OK while the patient is experiencing Tourniquet pain.
I am pretty sure there was an article about that a few years back comparing Tetracaine to Bupivacaine and showed less Tourniquet pain with Bupivacaine.
I'll try to find it for you.
I wonder if you could get any relief of the hypertension with a bit of nitro paste? Put it on at around an hour when the pressure starts to climb and wipe it off when they are closing? We don't have ready access to it, so I can't give it a try. I wouldn't think it lasts very long after you wipe it off and it's got to be dirt cheap.
would lowering the BP actually decrease perfusion to the affected extremity making ischemia worse?
While that may work nice, isn't that a pretty expensive fix to a pretty simple problem?
OR time is pretty expensive.
Actually I think with a CSE a receding level is the explanation: While your spinal recedes you are replacing it with a less dense epidural block that could conceivably allow the severe pain of the tourniquet (more severe than bone pain) to pass through.Interesting, thanks.
I'm not wholly convinced though. I've done painfully long TKAs with bupivacaine too, sometimes with CSEs where the level is kept at an adequate level with epidural boluses ... and a receding level just doesn't explain why these patients will get tourniquet pain but have solid coverage of the knee itself.
These knee patients are having tourniquet pain at 90-120 min but they're not having knee pain. (As evidenced by the fact that the pain goes away when the tourniquet goes down, even though Bob The Builder is still hammering away at the knee.)
Dermatomes aren't horizontal in the leg the way they are in the trunk; it's the same spinal nerves that get anterior thigh and anterior knee. Except for the most superior portion of the anterior thigh which is L1. I would expect that a spinal that doesn't cover the anterior thigh also wouldn't cover the anterior knee.
👍I wouldn't think so.
If the tourniquet's at 300, the tissue isn't getting perfused by a BP of 140/90 any better than it is at 110/60. There's zero flow in both cases.
I wouldn't think so.
If the tourniquet's at 300, the tissue isn't getting perfused by a BP of 140/90 any better than it is at 110/60. There's zero flow in both cases.
I did a LOT of 4-5 hour total knees in residency with CSEs - tetracaine + epi spinals. We'd have dense blocks for hours, and 90 minutes into the tourniquet HR & BP predictably go up, and patients would get squirmy.
Actually I think with a CSE a receding level is the explanation: While your spinal recedes you are replacing it with a less dense epidural block that could conceivably allow the severe pain of the tourniquet (more severe than bone pain) to pass through.
Is it really more painful than bone pain?
We can find out:
Why don't you to try to inflate a blood pressure cuff around you arm to 300 mm Hg and see how long you can tolerate it?

Actually I think with a CSE a receding level is the explanation: While your spinal recedes you are replacing it with a less dense epidural block that could conceivably allow the severe pain of the tourniquet (more severe than bone pain) to pass through.
Interesting discussion.
I personally don't believe the statement "With the tourniquet inflated all circulating mediators are mechanically trapped within the ischemic area after the tourniquet and they don't circulate until the tourniquet is deflated" Just can't accept that without proof.
Do you know of any study showing "mediators" passing through an inflated cuff to 250-300 mmHg and causing hypertension and tachycardia?
What mediators are you referring to by the way?
I'm guessing he's referring to evil humors released from the proximal side of the cuff. Maybe you can bleed them off with leeches?
My money is on pain receptors and nerve transmission.
How high do you think you need to raise the cuff to stop nerve transmission?
🙂
I'm guessing he's referring to evil humors released from the proximal side of the cuff. Maybe you can bleed them off with leeches?
My money is on pain receptors and nerve transmission.
How high do you think you need to raise the cuff to stop nerve transmission?
🙂
In the good old days when we did Bier blocks we used a double tourniquet and we inflated the distal one then inflated the proximal one then deflated the distal one and kept only the proximal inflated.
Then if the case took too long and tourniquet pain started to appear we inflated the distal tourniquet and deflated the proximal one and this effectively relieved the tourniquet pain.
This indicates that there is no chemical mediators involved and that it is simply pain cause by the compression of nerves or other things under the tourniquet itself.
In the good old days when we did Bier blocks we used a double tourniquet and we inflated the distal one then inflated the proximal one then deflated the distal one and kept only the proximal inflated.
Then if the case took too long and tourniquet pain started to appear we inflated the distal tourniquet and deflated the proximal one and this effectively relieved the tourniquet pain.
This indicates that there is no chemical mediators involved and that it is simply pain cause by the compression of nerves or other things under the tourniquet itself.
Personally I think the "experiment" sheds light, but doesn't imply your conclusion (which of course could be true nevertheless).

In the good old days when we did Bier blocks we used a double tourniquet and we inflated the distal one then inflated the proximal one then deflated the distal one and kept only the proximal inflated.
Then if the case took too long and tourniquet pain started to appear we inflated the distal tourniquet and deflated the proximal one and this effectively relieved the tourniquet pain.
This indicates that there is no chemical mediators involved and that it is simply pain cause by the compression of nerves or other things under the tourniquet itself.
It seems there is a specific issue with Tetracaine where the C fibers do return to activity before other thicker fibers and that seems to explain why a Tetracaine spinal could continue to appear OK while the patient is experiencing Tourniquet pain.
I am pretty sure there was an article about that a few years back comparing Tetracaine to Bupivacaine and showed less Tourniquet pain with Bupivacaine.
I'll try to find it for you.
I had an attending that did her entire regional fellowship without a single opioid or benzo...guess what she used....esmolol...some theorize it has some activity at the substantia nigra in addition to its peripheral anti-adrenergics.
I had an attending that did her entire regional fellowship without a single opioid or benzo...guess what she used....esmolol....