Low dose femoral versus saphenous block

[Monty Python]

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Caveat: I work at a military hospital. We're supposed to do as much as possible using regional to keep those skills fresh, in case we're deployed overseas to an austere area where GETA is logistically undesirable.

We do a fair amount of ankle scopes and Brostrums, using popliteal and saphenous blocks. I was considering replacing the saphenous block with a low dose femoral (10 mls, as suggested in the NYSORA book). Anyone have experience with this? At first glance I can see several benefits, and wonderered others' opinions. Thanks.

 

[sevoflurane]

If you don't care about quad dysfunction, then it's a simple effective approach. You need to give it time for it to set up.

I prefer this approach for the saphenous:

[YOUTUBE]http://www.youtube.com/watch?v=bsUlZLghnpU[/YOUTUBE]



Two of the best regional anesthesiologists I've ever worked with were from the navy. Seems like a great experience.

Does the military, navy, etc, have portable USD machines for the field? Seems like a good idea.

 

[proman]

What does a femoral block get that a below knee saphenous doesn't for an ankle case? As a field block, the saphenous is simple, low risk, easy to do and works well.

I've done the subsartorial saphenous block. It's fun but can have vague anatomy. Works well for ACLs where the surgeons don't want the quads getting affected. I think it's one of the more complicated ultrasound guided blocks and I wouldn't say it's a better block for the ankle or lower leg vs. a below knee saphenous.

 

[Idiopathic]

I understand what you are saying - a femoral is a slam dunk whereas you may see variability in a saphenous. Ive had to put more than one person to sleep for a failed saphenous block that would have been prevented with a femoral block.

But yeah the quads are out for a while.

 

[Narcotized]

As a field block, the saphenous is simple, low risk, easy to do and works well.

I find the saphenous field block to be one unreliable pain in the ass. If you have done a lot of them and have a high 90's% success rate I'm very impressed. I do a lot of regional and my success rate on most blocks is pretty much a given, but I've quit doing saphenous field blocks. Total crap shoot. I was more relieved to see it work and not simply expecting it to work.

I say do the femoral and know 99.8% probablility you're good to go, or atleast trace the saphenous vein with ultrasound and blast it high up in the leg.

 

[proman]

I find the saphenous field block to be one unreliable pain in the ass. If you have done a lot of them and have a high 90's% success rate I'm very impressed. I do a lot of regional and my success rate on most blocks is pretty much a given, but I've quit doing saphenous field blocks. Total crap shoot. I was more relieved to see it work and not simply expecting it to work.

I say do the femoral and know 99.8% probablility you're good to go, or atleast trace the saphenous vein with ultrasound and blast it high up in the leg.

Definitely not the same as a real femoral block. I got used to doing a spinal for the intraop part so it gave the saphenous time to set up (plus using 10+ cc). The subsartorial approach to the saphenous is much less reliable (but does catch the knee).

 

[epidural man]

There has been a ton of stuff recently written on using ultrasound to block the saphenous nerve reliably - all with similar approaches above the knee - each naming it a little different so they sound really important as if they discovered a brand new technique.

Anyway, if you have good ultrasound skills, these techniques approach 100% success rate. A google scholar search for saphenous and ultrasound will produce a ton of them. I like Gray's approach.

No reason to kill quad strength with a femoral nerve block - and I have seen a few patients with quad atrophy and persistent weakness that was a result of a well placed femoral nerve block - it does happen.