LOR technique with epidurals

[narcusprince]

Im currently a CA-1 on an OB rotation with my first experience's with epidurals. My problem is I engage the Tuoy get good LOR with saline. However 50% of the time I cannot tread the catheter past the needle tip. I have not gotten a wet tap, but am frustrated with being unable to pass the catheter. What would you all recommend.

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[periopdoc]

How much saline are you injecting after you get LOR? I usually inject ~5mL (or whatever is left in the LOR syringe) after I get LOR and it seems to help with getting the catheter started.

Are you certain that you are getting completely into the epidural space with the eye of the Tuohy? The catheter usually threads pretty easily if you are in the right space. If you are going slowly and stopping immediately upon LOR (like you should) it is possible that you need to add an extra millimeter of depth to get enough of the eye into the space to thread the catheter.

What you might try is obtain LOR, inject 5 mL, advance 1 mm-ish, thread catheter.

Also you might try taking a kit into the call room and threading a catheter through needle to get a feel for the inherent resistance of your system. There is typically an increase in resistance just before the catheter tip threads out of they eye of the needle. After that it should feed like you are floating the catheter through water.

- pod

 

[narcusprince]

I probably inject roughly 3cc through glass syringe. A lot of times I confirm LOR with air. I have probably done ~30 epidurals. I have had an attending tell me to advance a MM and been able to tread the catheter. I think I apply a large amount of force that when I get my LOR and the eye of the Tuoy is not completely in the epidural space and the tissue flaps over when pressure is not applied to the syringe.

 

[pgg]

My first guess is that many of the times you can't thread the catheter it's because you're getting a false LOR. Not much to be done for that except do a bunch and get a better feel for the low-resistance ease of injecting saline into the epidural space vs a pocket of soft tissue.

It may help to push a few cc of saline into the space before threading the catheter. If you're really in the epidural space there's NO resistance to injection and you may create a bit more room for the catheter tip to turn the corner ... if you're in soft tissue you may 'reacquire' some resistance as you inject, and that'll tell you that you need to keep going.

The other thing you might do is use a CSE kit and if you get a questionable LOR or can't thread the catheter, stick the 25g spinal needle through the Tuohy. If you don't get CSF back you know you're off center or not deep enough, and can safely advance the Tuohy without fear of a wet tap. If you do get CSF you don't have to inject an intrathecal dose; but now you do know the Tuohy is in the space or VERY close to it. (This was described in A&A a year or two ago as a 'dural puncture epidural' and in that study resulted in fewer one-sided blocks, better sacral spread, and surprisingly not a higher PDPH rate.)

 

[bullard]

I use LOR to air, always 3 cc. It's LOR so I usually end up injecting 2 cc at most. You should not be pushing so hard that you inject the whole syringe uncontrollably.

The 1/50 times that I can't thread the catheter, I inject saline through the Tuohy and then usually no problem. If there's a problem still, it's usually because I'm not really in space, and I put my syringe on and keep doing LOR (usually another 1 mm like you said).

I also usually do CSE as that's institutional preference...so Mom's usually very happy with her spinal dose as I'm dicking around with the catheter. One advantage of CSE, I guess.

 

[bullard]

The other thing you might do is use a CSE kit and if you get a questionable LOR or can't thread the catheter, stick the 25g spinal needle through the Tuohy. If you don't get CSF back you know you're off center or not deep enough, and can safely advance the Tuohy without fear of a wet tap. If you do get CSF you don't have to inject an intrathecal dose; but now you do know the Tuohy is in the space or VERY close to it. (This was described in A&A a year or two ago as a 'dural puncture epidural' and in that study resulted in fewer one-sided blocks, better sacral spread, and surprisingly not a higher PDPH rate.)

True, though PDPH was not primary outcome of the study, so can't really draw firm conclusion about that. We use 27g for our CSEs - no issues with PDPH, but may not get the benefits found in that article. Interesting that you say to advance if you don't get CSF back -- ever have problems with one-sided blocks or failed catheters with those epidurals?

 

[bostonblaz]

I agree that if it is not threading it is most likely not in, however I have had a few that i knew for a fact that I was in the right space and could not thread. Some times i have them mom take a deep breath in and i find it works, no scientific basis on this but I have found that it works.

 

[Planktonmd]

One advice:
Stop using saline and learn how to use air!
Saline in the glass syringes makes appreciating the LOR more difficult for beginners.
Once you master using air then you can switch to saline if you like down the road but I don't see why you should.

Im currently a CA-1 on an OB rotation with my first experience's with epidurals. My problem is I engage the Tuoy get good LOR with saline. However 50% of the time I cannot tread the catheter past the needle tip. I have not gotten a wet tap, but am frustrated with being unable to pass the catheter. What would you all recommend.

 

[pgg]

Interesting that you say to advance if you don't get CSF back -- ever have problems with one-sided blocks or failed catheters with those epidurals?

I do regular CSEs for almost everybody, which isn't exactly like their technique but is pretty close. I haven't had a one-sided or outright failed catheter in 4 or 5 months, but I do a lot less OB now that I'm out of residency.

I did a month of OB anesthesia as a visiting resident at B&W, not long after they did that study, and the 'advance if you don't get CSF back' bit was one bit of advice the author and two of the fellows were giving CA1s doing their first epidurals. There, the dural puncture without intrathecal dosing was pretty frequently used as a way for beginners to gauge whether or not their LOR was false or not. I'm not sure if the technique has a lot to offer people who've done a lot of epidurals though.

I just toss it out there as one more thing for narcus to try if his attendings are game.

 

[rsgillmd]

I'm with pgg on this one, particularly what he mentioned in post #5.

It's not entirely uncommon to get a false LOR with saline, but I like it better than air. What I tend to do is a slight combination: approx 0.5 ml of air + 2.5-3 ml of saline. The little bit of air adds springiness (for lack of a better word), but when you inject, you'll notice it is usually mainly the saline that gets injected. It's just something else to consider. Doing the combination reduced my rate of false LORs. I don't inject the entire volume of air/saline.

In the obese people, particularly when you are beginning, you are probably more likely to get false LOR with saline because you are still in fat and haven't engaged ligament yet (although you may think you have). Air is probably a little less likely to give you false LOR in these patients.

I agree with pgg about using your spinal needle as an additional test. I find it to be helpful when I am in doubt. Advancing an additonal "mm" when I think I'm in the right spot makes me too nervous, although I know many that do it without a problem. I would rather just use the spinal needle test.

If I'm confident my needle is in the epidural space but having trouble threading the catheter, and the deep breath technqiue mentioned by someone else does not help, I look at how deep my catheter is in the needle. If the tip is out of the needle, which it usually is, you are committed to either inserting it or removing it as a whole and starting over. Slow clockwise rotation of the needle with pressure on the epidural catheter sometimes helps in these situations.

If the catheter has not gone out of the needle, you got 2 obvious possibilities: a) your needle is not in the epidural space, or b) the end of your catheter is clotted/covered with blood/tissue. Usually it's (a).

However, I have seen (b) once. The CRNA struggled to get into the epidural space for a C/S block. When he got good LOR, he couldn't CSF or a pop with the spinal needle, and couldn't thread the catheter. He tried at a different space, and same problem. In order to speed things along I stepped in. As soon as I removed the needle tip, I saw the problem. Although the CRNA had inserted the stylet in the epidural needle before redirecting, it didn't clear the clot of blood at the tip. There was enough opening to give the LOR, but not enough to pass the catheter. Redid with new needle at the same level this past LOR --> smooth CSE.

Hope this helped somewhat.

 

[Jeff05]

Im currently a CA-1 on an OB rotation with my first experience's with epidurals. My problem is I engage the Tuoy get good LOR with saline. However 50% of the time I cannot tread the catheter past the needle tip. I have not gotten a wet tap, but am frustrated with being unable to pass the catheter. What would you all recommend.

you are getting FALSE LOSS and are not in the epidural space. this happens all the time with saline and beginners (you're really careful and start doing LOR way shallow) if you're really in the space the catheter goes like butter 99% of the time. i agree with using LOR to air as a beginner.

you may dilate with saline before you thread, however, i haven't found that to be necessary for smooth catheter placement. same with deep breath technique.

once you start advancing the needle after a questionable loss and twirling it around - i think you're asking for a wet tap. just my opinion.

if in doubt about patency of needle tip, just reinsert the introducer all the way, remove, then proceed.

in time you will sense of a true positive LOR will improve. do not get discouraged (you'll get the hang of it) and do NOT get frustrated and wet tap some poor preggo.

 

[dhb]

I think I apply a large amount of force that when I get my LOR and the eye of the Tuoy is not completely in the epidural space and the tissue flaps over when pressure is not applied to the syringe.

Yes, dilate the space with saline/local which will give you space to advance 1 or 2mm with the tuohy if the cath still doesn't thread then it's a false LOR.

 

[dhb]

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[ssmallz]

you're pushing way too hard on the syringe and injecting the saline creating a false LOR. I use a continuous pressure technique and you don't need very much pressure on the plunger to inject saline into the true epidural space. Try using just enough pressure to condense the saline but not enough to inject, then using your other hand guide the needle toward the epidural space slowly. Once the need enters the epidural space, that slight amount of pressure on the plunger will be enough to push the saline into the space and you'll know you've got it