What does a wet tap look like?

[signumvitalis]

CA1 resident on OB, learning the ropes of CSEs. Watched a senior advance the touhy slowly (mm by mm) get great LOR (intermittent technique). When he removed the LOR syringe, saw a few drops of clear fluids gush out. It seemed not to slow down, and I thought it was a wet tap. The resident pulled needle back just a touch and re-checked for LOR. This time he did not have any fluid come back when he removed the LOR syringe. Spinal needle went in with a 'visible' pop and clear fluid obtained.
I was told that the fluid coming back was just the saline in the LOR syringe and that he pulled back and rechecked just to be safe.
I haven't watched a lot of CSEs and am wondering if this is normal. Does saline from LOR syringe backflow like that when the loss is felt, or is this a wet tap? What do you think of pulling back the Touhy and threading the catheter, is that safe?
What does a wet tap look like - is it clear fluid gushing out with no signs of stopping? Or can it look like a few cc falling out of the touhy that usually stops in a 5-10 seconds (or is that just the saline injected for detection of LOR) ?

Our patient did fine following the CSE. Occurrence of PDPH remains to be seen.

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[powermd]

To some degree it depends on the gauge of the needle, and the position of the patient. We used 17g Touhy needles on our OB service. I only ever had one wet tap. I felt something like a 'crack' as I went through what must have been the dura and it was a freakin' waterfall of CSF. Not subtle at all! I looked at the attending and asked "spinal catheter?". He shook his head and took over, repeating the procedure a level higher, successfully this time. I recall she was an older patient with known spinal stenosis (and this is typically worst at L4-5 where I made my attempt).

I get wet taps occasionally doing epidural steroid injections (maybe a few per year). The patients are prone, and we use 20g needles. Generally I see fluid rapidly fill the needle hub, and it may be blood tinged. It may or may not trickle out from there. My next move is to aspirate, and if I can easily remove 2-3 cc of fluid, I assume DP and abort. If not, I'll inject dye to double check.

What does a wet tap look like - is it clear fluid gushing out with no signs of stopping? Or can it look like a few cc falling out of the touhy that usually stops in a 5-10 seconds (or is that just the saline injected for detection of LOR) ?

Our patient did fine following the CSE. Occurrence of PDPH remains to be seen.

 

[Notorious T.E.E.]

Based on my experience, what you described is not a wet tap. It would not be unusual to get a few drops of fluid back from the 17 gauge touhy if you used saline in your LOR syringe or to dilate the space. As another physician mentioned, with a 17 gauge touhy things are not subtle and there is constant stream of fluid coming out of the hub. Usually it would require your thumb or the stylet back in the touhy to stem the flow of CSF. I suppose it is possible to create a scenario where the needle tip barely pierces the Dura, preventing a significant flow of CSF due to partial occlusion of the tip. The fact that the resident in question pulled back a bit to get to the right spot after seeing the fluid does make me wonder about that possibility.

 

[Mman]

if you use LOR to saline through a 17 or 18 g Tuohy, you get a little bit of saline dripping back at you after removing the syringe when in the epidural space. Or at least you usually do.

Wet tap with same needle? Generally have clear fluid gushing out nonstop under pressure. It ain't subtle.

 

[signumvitalis]

Thank you for the responses!

We use a Touhy 17G needle for CSE.
Am I to understand that if it is a true wet tap, it would be a continuous gush of fluid - like an arc of fluid- from the needle as opposed to a steady drip-drip?

For those who have experienced the saline from the LOR syringe backflow from the Touhy: how much fluid usually comes back/ how long do you watch it drip before feeling safe that it isn't a dural puncture?

In the case I described, I observed steady dripping that did not cease until the resident pulled the needle back ~ took him about 10 seconds to do that.

 

[vector2]

If you have the TUOhy all the way in the subarachnoid space it is a stream of continuous fluid that you have to stylet or put your thumb on to stop. Also, the patient usually feels something unpleasant when they're being CSF depressurized this fast. I suppose if you just barely got some of the needle tip into the space it could be a slower trickle. However, a real wet tap doesn't stop until you move the needle. If you're using saline for LOR, it might be a few drops of saline but it should stop after no longer than 15-20 seconds, and obviously you shouldn't be able to aspirate a large amount of fluid from the tuohy. In any case, I use air for LOR and avoid this issue completely.

 

[kazuma]

Do you guys do lumbar drains? We're asked to place them occasionally and our kit comes with a 14ga tuohy. In younger patients it will produce an impressive waterfall even in the lateral position. I did one recently in an elderly pt undergoing an thoracic aneurysm repair and barely got a dribble, but one of my partners had already attempted placing it at other levels so a portion of the CSF was already removed.

 

[pjl]

Based on what you said, I would imagine this was just some of the saline dripping out. You dont need to pull the needle back for that. Just thread a catheter or put the spinal needle in if CSE.

I did a lot of epidurals before getting my first wet tap, and for a long time I wondered about those drops that come out after injecting saline, thinking maybe I had a partial wet tap. None of them ever developed a headache though, or had positive test doses.

When I finally got my first wet tap, I was shocked at the HUGE amount of fluid coming out. It is a stream that forcibly comes out of the needle, and makes an arc in the air. One of my 3 wet taps actually pushed the plunger back at me. When you have a true wet tap, you will know it, until then if you have any question, just be careful with a test dose. Sooner or later you will get a wet tap and be able to compare.
When you get your wet tap, make sure you dont inject air into the intrathecal space, and put your thumb over the back of the needle quickly. Otherwise the headache comes much quicker since you effectively drain their CSF.

From what I have seen, if you have done a 14G spinal drain in lateral position, it is a similar flow to a 17 G epidural needle wet tap in sitting position.


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[Arch Guillotti]

CA1 resident on OB, learning the ropes of CSEs. Watched a senior advance the touhy slowly (mm by mm) get great LOR (intermittent technique). When he removed the LOR syringe, saw a few drops of clear fluids gush out. It seemed not to slow down, and I thought it was a wet tap. The resident pulled needle back just a touch and re-checked for LOR. This time he did not have any fluid come back when he removed the LOR syringe. Spinal needle went in with a 'visible' pop and clear fluid obtained.
I was told that the fluid coming back was just the saline in the LOR syringe and that he pulled back and rechecked just to be safe.
I haven't watched a lot of CSEs and am wondering if this is normal. Does saline from LOR syringe backflow like that when the loss is felt, or is this a wet tap? What do you think of pulling back the Touhy and threading the catheter, is that safe?
What does a wet tap look like - is it clear fluid gushing out with no signs of stopping? Or can it look like a few cc falling out of the touhy that usually stops in a 5-10 seconds (or is that just the saline injected for detection of LOR) ?

Our patient did fine following the CSE. Occurrence of PDPH remains to be seen.

It was probably just the saline dripping back. I am not sure whey the resident would pull the needle back; although if you do wet tap someone pulling back a bit and threading the catheter is an option.

CSF will usually come gushing out like a geyser if you have a wet tap. I have seen a couple that just slowly drip also.

I have seen a couple of epidurals that were "normal". Except that after the catheter is threaded and dosed, it is obviously in the subarachnoid space. I don't know if this is a wet tap per se but unrecognized intrathecal placement is absolutely a possibility when doing an epidural.

 

[Mman]

I have seen a couple of epidurals that were "normal". Except that after the catheter is threaded and dosed, it is obviously in the subarachnoid space. I don't know if this is a wet tap per se but unrecognized intrathecal placement is absolutely a possibility when doing an epidural.

In those I wonder if the Tuohy has tented the dura and the catheter coming out of it breaks through a weak spot

 

[Arch Guillotti]

In those I wonder if the Tuohy has tented the dura and the catheter coming out of it breaks through a weak spot

It seems likely since if the dura is truly breached it seems like some amount of fluid should come out of the end of the needle. This is why I don't normally dose through the needle and if I do it isn't more than a dose that could cause a high block.

 

[urge]

a few drops of clear fluids gush out. It seemed not to slow down, and I thought it was a wet tap. The resident pulled needle back just a touch and re-checked for LOR.

Sounds like a wet tap to me.

What is confusing is how you mix "few drops" with "gush out", and not "slow down".

Was it a few drops because he quickly pulled out?

 

[urge]

In the case I described, I observed steady dripping that did not cease until the resident pulled the needle back ~ took him about 10 seconds to do that.

Non stop drip is a wet tap in my book.

 

[dhb]

Non stop drip is a wet tap in my book.

Not if only for a couple of seconds

 

[nimbus]

Sounds like a wet tap to me.

What is confusing is how you mix "few drops" with "gush out", and not "slow down".

Was it a few drops because he quickly pulled out?

I can think of a situation where even a few drops can cause problems. His pullout game was weak

 

[urge]

Not if only for a couple of seconds

Agree. But in 10 seconds it didn't stop.

Only reason it stopped was because the needle was pulled back.

 

[Orin]

The epidural space has some depth to it and if you're doing LOR with saline, you can for sure get some back flow in obese folks or older canals/stenosis.

A true dural puncture with a tuohy generally flows and doesn't stop for quite a bit, even prone...

 

[Infexious]

.

 

[signumvitalis]

Thank you all.

- urge: Yes, it was dripping out continuously and didn't stop till the needle was pulled back. I am confused because if it was saline backflowing, then it should have recurred when the resident redid the LOR after pulling out.

- Vector2: If I am doubtful about a wet tap, perhaps it is not the best idea to wait 20 seconds watching to see if the dripping stops in order to rule out saline backflow, am I right? I feel guilty if I am watching the saline drop back for more than 5 or 6 seconds and do nothing about it, is that an over reaction?

-pjl: Thank you for the awesome description. I am basically worrying about exactly the same events you described, so it is nice to know I'm not the only one wondering about the little dribbles :-/

If I do have wet tap, is it acceptable to pull the Tuohy out a few mm and thread the catheter? I thought my only options after a wet tap were to thread a spinal catheter or try again at a higher level.

 

[Notorious T.E.E.]

If you have the TUOhy....

Damn. I've been spelling TUOhy wrong for 15 years! Good thing my handwriting is sloppy. Thanks for the heads up.

 

[vector2]

vector2: If I am doubtful about a wet tap, perhaps it is not the best idea to wait 20 seconds watching to see if the dripping stops in order to rule out saline backflow, am I right? I feel guilty if I am watching the saline drop back for more than 5 or 6 seconds and do nothing about it, is that an over reaction?

If it's only a pretty slow drip from a dural tear, there's probably not going to be a large difference in clinical outcome between watching for 5-6 secs vs 20 secs to confirm whether the drips stops. If you have indeed violated the dura, the damage has been done and the etiology of their PDPH is going to be from a slow CSF leak over the course of hours to days (assuming leak rate > CSF production rate). And again, this entire issue can be avoided by just using air for loss.

 

[Mman]

And again, this entire issue can be avoided by just using air for loss.

and then you increase the chances of a patchy epidural block. There is literally no confusing saline from LOR vs CSF. It's obvious.

 

[Jimmy Chitwood]

I've only had one in the ~200 labor epidurals I've done as a resident, and it was quite obvious. The plunger on my syringe shot back, and when i pulled it off, it was gushing. 17ga tuohy.

 

[vector2]

and then you increase the chances of a patchy epidural block.

I still dilate with saline after LOR to air, at which point I don't care if it does drip back. But even if I didn't dilate I'm not convinced by the evidence (anecdotal or otherwise) that air leads to significantly more patchy blocks. But of course I haven't done 40,000 epidurals while simultaneously running 8 rooms like Blade so my n as a CA-3 is obviously relatively low.

There is literally no confusing saline from LOR vs CSF. It's obvious.

I think this is true 99.9% of the time, but it's not bulletproof considering people still occasionally get PDPHs from epidurals where there was no obvious (waterfall, gushing) wet tap.

 

[Mman]

I think this is true 99.9% of the time, but it's not bulletproof considering people still occasionally get PDPHs from epidurals where there was no obvious (waterfall, gushing) wet tap.

that's because you can push the catheter through the dura without the needle having totally broken through

 

[deleted162650]

that's because you can push the catheter through the dura without the needle having totally broken through

That's been formally studied. The older stiff monofilament Braun type caths can pop through "scored" dura. The researchers were unable to get a soft spring-wound Arrow type catheter (although Braun now makes these too) to pop through "scored" dura.

 

[deleted162650]

I can think of a situation where even a few drops can cause problems. His pullout game was weak

 

[Arch Guillotti]

that's because you can push the catheter through the dura without the needle having totally broken through

I think this is true 99.9% of the time, but it's not bulletproof considering people still occasionally get PDPHs from epidurals where there was no obvious (waterfall, gushing) wet tap.

Sounds like you are talking about 2 completely different things.

 

[Orin]

The "correct" answer was a bedside glucometer since any glucose would indicate CSF rather than NaCl.

Yeah, especially since we don't get thiopental anymore...oh and the fact that it didn't work.

http://www.ncbi.nlm.nih.gov/pubmed/9161743

 

[urge]

There is literally no confusing saline from LOR vs CSF. It's obvious.

The person doing the epidural that started the whole thread claimed he pulled back "just to be sure".

I guess he literally does not agree with you.

If it is so clear cut, why do we have tests like mentioned above?

 

[Mman]

The person doing the epidural that started the whole thread claimed he pulled back "just to be sure".

I guess he literally does not agree with you.

If it is so clear cut, why do we have tests like mentioned above?

The person doing the epidural in the start of the thread was a resident. If it isn't so clear cut, how come I've never had to do one of the made up tests that nobody does in real life?

 

[urge]

The person doing the epidural in the start of the thread was a resident. If it isn't so clear cut, how come I've never had to do one of the made up tests that nobody does in real life?

I suspect no one in this forum has ever checked either.

Then you wonder why some epidural catheters end up intrathecal.

In those I wonder if the Tuohy has tented the dura and the catheter coming out of it breaks through a weak spot

Ring a bell? How about it was a wet tap that was not recognized?

 

[Mman]

I suspect no one in this forum has ever checked either.

Then you wonder why some epidural catheters end up intrathecal.



Ring a bell? How about it was a wet tap that was not recognized?

Nope. Hard to have a wet tap with an 18 g needle with no fluid coming out the needle.

 

[urge]

Nope. Hard to have a wet tap with an 18 g needle with no fluid coming out the needle.

Who said there was no fluid coming out?

The whole point of this thread is that there is a non stop drip. You claim it is just the saline from the LOR syringe.

That is my point. You keep telling yourself it is saline, when it is csf, and then wonder dumbfounded why your catheters end intrathecal.

In those I wonder if the Tuohy has tented the dura and the catheter coming out of it breaks through a weak spot

 

[Mman]

Who said there was no fluid coming out?

The whole point of this thread is that there is a non stop drip. You claim it is just the saline from the LOR syringe.

That is my point. You keep telling yourself it is saline, when it is csf, and then wonder dumbfounded why your catheters end intrathecal.

You seem to be meshing together lots of different posts to try to come up with something that just isn't there. I don't have "catheters end intrathecal", I've seen it once or twice out of thousands and both times there was no fluid coming out the needle. The other 99.9% of the time the fluid that I see is saline from the syringe and the catheter is in the epidural space. Wet taps with a big needle are obvious. If you don't think they are, you simply haven't done enough.

 

[urge]

You seem to be meshing together lots of different posts to try to come up with something that just isn't there. I don't have "catheters end intrathecal", I've seen it once or twice out of thousands and both times there was no fluid coming out the needle. The other 99.9% of the time the fluid that I see is saline from the syringe and the catheter is in the epidural space. Wet taps with a big needle are obvious. If you don't think they are, you simply haven't done enough.

My concern is that not all wet taps are the same. Some might be by the needle through the dura, some might just a little scratch on the dura. One will flow loke a geyser, the other will be a slow drip.

 

[Planktonmd]

This whole dilemma would have been avoided had he used air for LOR, and before someone pops and tells me about pneumocephalus and all the badness that a little bubble of air can cause, let me say it's all BS and I have always used air with ZERO problems!

 

[nimbus]

My concern is that not all wet taps are the same. Some might be by the needle through the dura, some might just a little scratch on the dura. One will flow loke a geyser, the other will be a slow drip.

Needle tip and catheter can also be subdural between the dura and arachnoid. Supposedly the arachnoid is very delicate so it may be susceptible to puncture and leak of csf.

 

[urge]

CA1 resident on OB, learning the ropes of CSEs. Watched a senior advance the touhy slowly (mm by mm) get great LOR (intermittent technique). When he removed the LOR syringe, saw a few drops of clear fluids gush out. It seemed not to slow down, and I thought it was a wet tap. The resident pulled needle back just a touch and re-checked for LOR. This time he did not have any fluid come back when he removed the LOR syringe. Spinal needle went in with a 'visible' pop and clear fluid obtained.
I was told that the fluid coming back was just the saline in the LOR syringe and that he pulled back and rechecked just to be safe.
I haven't watched a lot of CSEs and am wondering if this is normal. Does saline from LOR syringe backflow like that when the loss is felt, or is this a wet tap? What do you think of pulling back the Touhy and threading the catheter, is that safe?
What does a wet tap look like - is it clear fluid gushing out with no signs of stopping? Or can it look like a few cc falling out of the touhy that usually stops in a 5-10 seconds (or is that just the saline injected for detection of LOR) ?

Our patient did fine following the CSE. Occurrence of PDPH remains to be seen.

Did the woman get a headache?

Needle tip and catheter can also be subdural between the dura and arachnoid. Supposedly the arachnoid is very delicate so it may be susceptible to puncture and leak of csf.

Agree.

 

[caligas]

 

[partydoc]

I've had maybe 4 or 5 drops come out of the needle after LOR to saline. Any more than that or a continuous drip I would be concerned for a wet tap- which is what it sounds like OP was talking about.

I've had one wet tap, and that was a constant fast drip that didn't slow down.

 

[Urzuz]

I really don't understand what all the fuss is over.

If there's any question as to whether or not the drops you get back are CSF -- either remove the needle and do it again, or thread the catheter and give your test dose. That's what a test dose is for...so you can sleep easier knowing your catheter isn't in the wrong spot. You can base your decision whether to repeat it off the bat or thread the catheter and test it on your own personal judgment as to how much fluid is coming back, how quickly the fluid is dripping, how much fluid you injected during LOR, etc. Don't understand all the debate and mental masturbation.

 

[ZzzPlz]

Put your finger under the dripping fluid. Is it warm? Then it's csf. Is it cool like the fluid in your LOR syringe? Thread that beyatch.

 

[ZzzPlz]

Put your finger under the dripping fluid. Is it warm? Then it's csf. Is it cool like the fluid in your LOR syringe? Thread that beyatch.

Disclaimer: don't use this test if your patient is profoundly hypothermic

 

[wickedskillz]

The one wet tap I saw had more forceful fluid ejection than this

 

[wickedskillz]

looked more like this

 

[sigrhoillusion]

It was probably just the saline dripping back. I am not sure whey the resident would pull the needle back; although if you do wet tap someone pulling back a bit and threading the catheter is an option.

CSF will usually come gushing out like a geyser if you have a wet tap. I have seen a couple that just slowly drip also.

I have seen a couple of epidurals that were "normal". Except that after the catheter is threaded and dosed, it is obviously in the subarachnoid space. I don't know if this is a wet tap per se but unrecognized intrathecal placement is absolutely a possibility when doing an epidural.

Just bumping this topic, cause tonight I was doing an epidural and had good LOR to saline. Took the syringe off and had a drip or two of fluid which stopped as usual when getting LOR with saline. Tried to thread the epidural catheter and couldn't get it to go in. So I put the syringe back on and push and have some resistance but what feels like loss but again can't thread catheter. So I put syringe back on and go in another 1mm and get really good LOR. Take the syringe off and have fluid coming back in steady drops but not the usual geyser but doesn't stop after 5-6 drops which isn't usual wven with saline. So I thread the catheter, and this time it goes in easily. End of catheter has drops of fluid coming out so I cap it and put a syringe on it and aspirate 1/4cc of fluid before I stop and inject fluid back and cap it. Put test dose syringe on and aspirate can clearly see different density fluids mixing so give 1cc of test dose. Patient gets a decent block but can still wiggle toes.

Run 0.125% bupi with fentanyl at 1cc/hr with 1cc PCEA bolus q1hr.

Some studies show that intrathecal catheters reduce PDPH if left in for 24-36 hours. What are you guys doing with the catheters after the delivery? Are you capping them? Running saline?

 

[deleted162650]

Just bumping this topic, cause tonight I was doing an epidural and had good LOR to saline. Took the syringe off and had a drip or two of fluid which stopped as usual when getting LOR with saline. Tried to thread the epidural catheter and couldn't get it to go in. So I put the syringe back on and push and have some resistance but what feels like loss but again can't thread catheter. So I put syringe back on and go in another 1mm and get really good LOR. Take the syringe off and have fluid coming back in steady drops but not the usual geyser but doesn't stop after 5-6 drops which isn't usual wven with saline. So I thread the catheter, and this time it goes in easily. End of catheter has drops of fluid coming out so I cap it and put a syringe on it and aspirate 1/4cc of fluid before I stop and inject fluid back and cap it. Put test dose syringe on and aspirate can clearly see different density fluids mixing so give 1cc of test dose. Patient gets a decent block but can still wiggle toes.

Run 0.125% bupi with fentanyl at 1cc/hr with 1cc PCEA bolus q1hr.

Some studies show that intrathecal catheters reduce PDPH if left in for 24-36 hours. What are you guys doing with the catheters after the delivery? Are you capping them? Running saline?

The studies are pretty damn equivocal on this. I really don't think leaving it in does much good at all. Leaving an IT catheter in someone who is not under your direct care/supervision for 24-48h is also asking for potential badness if you ask me. If you do decide to leave it then at least knot it a handful of times or crush the Luer lock or something so some dingbat RN doesn't think it's an IV and accidentally pushes something through there that really shouldn't go there. Entertain yourself sometime by looking up all the case reports of drugs that have been accidentally given IT.

 

[sigrhoillusion]

The studies are pretty damn equivocal on this. I really don't think leaving it in does much good at all. Leaving an IT catheter in someone who is not under your direct care/supervision for 24-48h is also asking for potential badness if you ask me. If you do decide to leave it then at least knot it a handful of times or crush the Luer lock or something so some dingbat RN doesn't think it's an IV and accidentally pushes something through there that really shouldn't go there. Entertain yourself sometime by looking up all the case reports of drugs that have been accidentally given IT.

Yea the only other time I did an intrathecal catheter, I ended up pulling it out shortly after delivery. But then some attending ssaid that for "maximal benefit" it should stay in as do some fo the studies. But none really say what the catheter is doing. Is it just hanging out there or are they infusing something through it.

 

[sigrhoillusion]

Yea the only other time I did an intrathecal catheter, I ended up pulling it out shortly after delivery. But then some attending ssaid that for "maximal benefit" it should stay in as do some fo the studies. But none really say what the catheter is doing. Is it just hanging out there or are they infusing something through it.

Unless someone gave me a strong reason to keep it, I was planning on pulling it assuming the patient delivers before 7am. That way my colleague coming on will only have to deal with the possible PDPH and nothing else...

I'm jsut upset that I tapped her. She was only slightly above average in size and had good anatomy. Like I said, got good LOR but catheter didn't thread twice. Probably should have rotated the bevel a little more. Wondering if maybe I was just up against the dura. Oh well... she's comfy. Hopefully she avoids the HA.