Depth of epidural space - obese patients

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De68801

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I have restarted OB anesthesia after a long hiatus. I used to be good - or at least average.

Currently I have no problem with epidurals in normal size patients, but with obese patients, I have been having difficulty and not sure whether I am being too cautious in insertion of the Tuohy needle. With normal size patients, I usually find the epidural space at about 4 cms, sometimes even 3.5 cm in very thin patients. But with some obese patients, I place the Tuohy needle, go in gently and never seem to get the needle into the firmer ligamentum flavum despite being deeper, even at 7 cm. Once I am at 7 cm, I am afraid to go any deeper. These are obese, but not morbidly obese patients, ex. 5 ft 4 and 190 lbs and it seems that the epidural space should be much shallower than 7 cm. I ask the patient if the needle feels midline or off to one side, but these labor patients are in too much pain to be much help, and they also do not speak English.

I realize that extra long Tuohy needles are manufactured for a reason - but these patients are just obese, not morbidly obese. Any help is appreciated.
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If you can't find the flavum, you are probably off-center.

There are threads about tips for spinals/epidurals on the forum, so I suggest you search for them. I have walked in your shoes, and the suggestions there helped me a lot.
 
I wouldn't be afraid to hub the needle. Sometimes you need all of it.

If you're still feeling cautious, consider using a CSE kit. If you get an equivocal loss of resistance, or are hesitant to push the Tuohy in further, just put the spinal needle through the Tuohy. If you hit CSF, you know you're there. If you don't, you know you can advance the Tuohy further.

I have very, very rarely needed the extra long needles even in super morbidly obese patients.

Consider moving up a space or two. The upper lumbar or even low thoracic spaces are typically easy to get in these patients, and they get good labor analgesia from epidurals all the way up to T10 or so.
 
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pgg said:
I wouldn't be afraid to hub the needle. Sometimes you need all of it.

If you're still feeling cautious, consider using a CSE kit. If you get an equivocal loss of resistance, or are hesitant to push the Tuohy in further, just put the spinal needle through the Tuohy. If you hit CSF, you know you're there. If you don't, you know you can advance the Tuohy further.

I have very, very rarely needed the extra long needles even in super morbidly obese patients.

Consider moving up a space or two. The upper lumbar or even low thoracic spaces are typically easy to get in these patients, and they get good labor analgesia from epidurals all the way up to T10 or so.
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Furthest I've gone is 11cm on the longer needles, but I've tented the regular 9cm one a few times. One of my attendings holds the record of 15cm (verified by another attending who was present). When they gave him a hard time, saying there was no way it was legitimate, he followed up on his patient every day after to ensure adequate analgesia (this was for post-op pain). It was legitimate. I think our patient population is abnormally large.
 
OP, I’m sure you have done plenty of spinals in the obese over the years without doing OB. The epidural space is just shy of that which I know you know. But the point is, you should be fairly familiar with the distance.
 
We tend to have a larger patient population. Seems average BMI around 30-35. Seems like get LoR somewhere in the 6-7 range in most, sometime less, sometimes more. Sometimes if you feel like you're going too far it might be because you're losing some distance on trajectory, if you're aiming too cephalad.
 
In the Midwest here. I would not get 10% (or more) of my epidurals if I stopped at 7 cm. It sounds like your angulation is good if you are getting many at 3.5-4 cm. You can be reassured that you are not advancing overzealously. I would take FFP's suggestion above about looking up other tips.
 
My guess is you’re either off midline or took a bad angle. <200lbers shouldn’t be more than 7-8cm deep (with rare exceptions).
 
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De68801 said:
I have restarted OB anesthesia after a long hiatus. I used to be good - or at least average.

Currently I have no problem with epidurals in normal size patients, but with obese patients, I have been having difficulty and not sure whether I am being too cautious in insertion of the Tuohy needle. With normal size patients, I usually find the epidural space at about 4 cms, sometimes even 3.5 cm in very thin patients. But with some obese patients, I place the Tuohy needle, go in gently and never seem to get the needle into the firmer ligamentum flavum despite being deeper, even at 7 cm. Once I am at 7 cm, I am afraid to go any deeper. These are obese, but not morbidly obese patients, ex. 5 ft 4 and 190 lbs and it seems that the epidural space should be much shallower than 7 cm. I ask the patient if the needle feels midline or off to one side, but these labor patients are in too much pain to be much help, and they also do not speak English.

I realize that extra long Tuohy needles are manufactured for a reason - but these patients are just obese, not morbidly obese. Any help is appreciated.
Click to expand...

not sure why you should be afraid at 7cm. usually when i jam an epidural needle in, i feel the smooth fat layer and after that i feel one of 3 things. the ligament, bone, or the dura pop. So just keep going.
 
nimbus said:
One of our OB only guys measures every one with a curvilinear probe. Takes the guesswork out of it.
Click to expand...

I tried doing this once on a typical OB fatty and the tutorial images on the internet vs my screen were like a 4k UHD snapshot vs a Salvador Dali painting on (even more) LSD.
 
vector2 said:
I tried doing this once on a typical OB fatty and the tutorial images on the internet vs my screen were like a 4k UHD snapshot vs a Salvador Dali painting on (even more) LSD.
Click to expand...
Yeah, the books never print the usual meh quality images 90% of patients produce. I sometimes wonder how many patients the YouTube'rs film before they find the one they put on the internet.

The only exception to this rule I've ever encountered was the advanced PTEeXAM (TEE) put out by the National Board of Echocardiography. I think they deliberately used crappy images. I swear they were just screwing with us on some of those questions. Also, those useless wankers have had our passing exam scores for 11 months now and still haven't finished the paperwork to finish our board certification. I didn't log all those studies so I could be a Testamur forever.

This year's class is a few weeks away from taking the exam and the NBE hasn't even finished with last year's class.

I want my money back.

But I digress.
 
okayplayer said:
So your OB patients and nurses sit there politely waiting for their epidural while you
go get your ultrasound and marker, draw on their back like Picasso and then finally do the epidural?
Click to expand...

There’s a difference between actually using it to identify a space/depth and just throwing it on and saying “yup 4cm - thatll be an extra 2 units please”
 
I have literally never in my short career needed a non-standard touhy. I work in upstate ny also so my patients are FAT. Some of you must work on patients that are so fat they can’t even move under their own power.
 
Agree with several of the points above:
- long tuohy very rarely necessary
- if not getting ligament by 7-8cm you are prob off midline, really take your time to start and stay in midline
- if you've taken a couple shots or called a colleague and no luck, something is weird, so it's definitely reasonable to get the ultrasound to identify midline and depth
 
okayplayer said:
So your OB patients and nurses sit there politely waiting for their epidural while you
go get your ultrasound and marker, draw on their back like Picasso and then finally do the epidural?
Click to expand...

I don't think anyone is advocating for this as a routine thing.

But if you have a difficult epidural, reasonable to get ultrasound. It may save you time, save some discomfort for the pt, and could be the difference in getting it not getting the block in
 
Different population, but before you do a case that needs a thoracic epidural and you look at whatever CT they have (lung, Whipple, etc), you can see the depth from skin to the epidural space, of course taking into account that little bit of soft tissue compression on the CT done supine.
 
T-burglar said:
I have literally never in my short career needed a non-standard touhy. I work in upstate ny also so my patients are FAT. Some of you must work on patients that are so fat they can’t even move under their own power.
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Or they just don't hub their needles.
 
fakin' the funk said:
I don't think anyone is advocating for this as a routine thing.

But if you have a difficult epidural, reasonable to get ultrasound. It may save you time, save some discomfort for the pt, and could be the difference in getting it not getting the block in
Click to expand...


Or should it be routine practice to use U/S for all epidurals/spinals? One could argue that regular use (even the straight forward, thin patients) would only make it that much more helpful in the difficult/obese/scoliotic cases. Also, does it decrease complication rates in high powered studies? Fewer needle stick into the back? Less puncture site pain? Etc... not sure.

There was a time when central lines were never done with u/s guidance.

There may also come a time when it is standard of care to use a video laryngoscope for all intubations.

Will there be a time when u/s becomes standard of care to slap it on the back for epidurals (even to make some general estimations about trajectory, depth, et). I predict yes.
 
MalloryWeiss said:
Or should it be routine practice to use U/S for all epidurals/spinals? One could argue that regular use (even the straight forward, thin patients) would only make it that much more helpful in the difficult/obese/scoliotic cases. Also, does it decrease complication rates in high powered studies? Fewer needle stick into the back? Less puncture site pain? Etc... not sure.

There was a time when central lines were never done with u/s guidance.

There may also come a time when it is standard of care to use a video laryngoscope for all intubations.

Will there be a time when u/s becomes standard of care to slap it on the back for epidurals (even to make some general estimations about trajectory, depth, et). I predict yes.
Click to expand...
Lol. Gotta be kidding me.
 
MalloryWeiss said:
Or should it be routine practice to use U/S for all epidurals/spinals? One could argue that regular use (even the straight forward, thin patients) would only make it that much more helpful in the difficult/obese/scoliotic cases. Also, does it decrease complication rates in high powered studies? Fewer needle stick into the back? Less puncture site pain? Etc... not sure.

There was a time when central lines were never done with u/s guidance.

There may also come a time when it is standard of care to use a video laryngoscope for all intubations.

Will there be a time when u/s becomes standard of care to slap it on the back for epidurals (even to make some general estimations about trajectory, depth, et). I predict yes.
Click to expand...

Def agree with the video thing. Ive heard that idea being floated around multiple times at conferences. Not a fan of the idea though
 
anbuitachi said:
Def agree with the video thing. Ive heard that idea being floated around multiple times at conferences. Not a fan of the idea though
Click to expand...

This is definitely coming and I wouldn't be surprised if within the next 20 years VL became "standard of care." Many EDs and ICUs already use VL for first look because their operators are less experienced, and yet they have high success rates. My former residency program now has enough mcgraths that each OR has one. Where I did fellowship, the CA1s all started out in July using a mcgrath so the attending could see what was going on. Just like how current old timers complain about u/s being a crutch for CVLs, I can see myself in the future being one of those old fogeys droning on to the whippersnappers about how back in my day the Miller 2 was blah blah blah...
 
12cm my record on a bmi 76 lady.
It was left lateral though so that's probably 10.5cm lor seated

No way short touhy was working on her.

Ultrasound works reasonably well even on the supermorbid obese patients, shows you midline, level and a reasonable starting angle and the depth but you have to have 20 odd ultrasounds done on skinny people to build up confidence with what you're doing.

My question that I haven't answered myself yet, is why not start with the 6" touhy when you have a bmi 60 odd lady? Lor is going to be minimal 8cm hubbed. Why not go with the 12 or 13cm needle to make sure you get it first pass and not need the second needle?
 
vector2 said:
This is definitely coming and I wouldn't be surprised if within the next 20 years VL became "standard of care." Many EDs and ICUs already use VL for first look because their operators are less experienced, and yet they have high success rates. My former residency program now has enough mcgraths that each OR has one. Where I did fellowship, the CA1s all started out in July using a mcgrath so the attending could see what was going on. Just like how current old timers complain about u/s being a crutch for CVLs, I can see myself in the future being one of those old fogeys droning on to the whippersnappers about how back in my day the Miller 2 was blah blah blah...
Click to expand...

“Ultrasound is a crutch “

Being a Luddite in medicine is mind blowing to me.

You will hit the carotid frequently if you don’t use ultrasound. Whether you know it or not . If you don’t use ultrasound, all those times you thought you got into the vein but can’t seem to get flow or thread wires, it’s because youre way off lacerating the lateral limit of the vessel or you hit the carotid and the arterial extravasation is compressing the jugular making it a small target. You don’t have to see a large neck grapefruit to have made a small carotid injury.

I’m personally interested in neuraxial ultrasound for thoracic epidurals. I think mid thoracic epidurals are tough to be sure about by feel only.
 
T-burglar said:
I have literally never in my short career needed a non-standard touhy. I work in upstate ny also so my patients are FAT. Some of you must work on patients that are so fat they can’t even move under their own power.
Click to expand...

you don't have fat patients if you haven't put epidurals in 500 lbers. I mean it's not often I need the harpoon, but I've had to hub that thing once or twice for an epidural in people with BMIs > 70. The regular 3.5 inch needle works just fine most of the time, but every now and then I need the big one.
 
MalloryWeiss said:
Or should it be routine practice to use U/S for all epidurals/spinals? One could argue that regular use (even the straight forward, thin patients) would only make it that much more helpful in the difficult/obese/scoliotic cases. Also, does it decrease complication rates in high powered studies? Fewer needle stick into the back? Less puncture site pain? Etc... not sure.

There was a time when central lines were never done with u/s guidance.

There may also come a time when it is standard of care to use a video laryngoscope for all intubations.

Will there be a time when u/s becomes standard of care to slap it on the back for epidurals (even to make some general estimations about trajectory, depth, et). I predict yes.
Click to expand...
No
 
I use ultrasound all the time for central lines and nerve blocks. I cannot imagine ever using it for a labor epidural. The complication rate for a labor epidural from a technical error during placement is probably an order of magnitude lower than it is for a central line or a nerve block. And unlike a CVP or nerve block where I can real time guide my needle during the procedure to reduce needle pokes and things like arterial puncture, labor epidural U/S use is mostly people just identifying a depth to the epidural space before they even put gloves on. I identify the depth to the epidural space with my needle and some saline. It usually takes about 5 or 10 seconds to do and then I thread the catheter and finish up the procedure.
 
While U/S can be useful in select situations for epidurals, it would be ridiculous to use it in its current iteration as a matter of routine.

If a probe/technique is developed that allows for continuous live U/S guidance then maybe I could see the argument.
 
okayplayer said:
So your OB patients and nurses sit there politely waiting for their epidural while you
go get your ultrasound and marker, draw on their back like Picasso and then finally do the epidural?
Click to expand...
If you know what you’re doing this takes an extra 45 seconds to scan. I personally have done this as a courtesy to my oncology colleagues(who can be technically challenged) when we get a morbidly obese kid (usually teenager) for LP...or I just do it myself. On OB, (doc only) agree it can be logistically challenging. However, I recently had one patient BMI 50 , and I hubbed the 9cm T., had to break out the 15 cm spike and got LOR at 10cm...when placing that harpoon, I wished I had scanned the patient’s back! It was already taking a long a$$ time, what’s another minute?For huge patients or folks with altered anatomy, I think it’s a good idea, and easy to learn. In the above case, it was after hours, no tech to bring me ultrasound, nurses were useless, so I just pushed on...literally and regretfully.
 
Uss epidural/spinal is surprisingly quick and easy if you get the nurses on board. In one hospital i work at the nurses bring the USS along with the epidural kit. We have them trained. They have it positioned in a good spot according to the patient too. It literally takes 90 seconds extra max

It took us a while to get to there but it's great. Another hospital doesn't have that and getting the USS yourself is a pain
 
I agree with the US for normal patients. That way when you have a difficult one, you can actually glean something from it. Although, I am always in too much of a hurry to actually use the US. I guess I will change when the rest of you change! lol

I have had 13 cm without angulation (under fluoroscopy). I just feel like the 6" tuohy is somewhat unwieldy to use, so I never start with it even if I suspect I might need it.
 
I'm in residency in one of the most obese states in the nation. Parturients with a BMI 35-40 is the norm. BMI of 60+ is not uncommon. I usually find the epidural space between 6.5 and 7cm. I've tented the skin using a 9cm touhy many times. We use the harpoon fairly often. If your patients are fat you will often need to advance 7cm + in my limited experience. I've probably only done a handful of patients with a BMI less than 30, I'm not sure if that's good or bad from a training standpoint but it would be nice to be able to actually palpate landmarks.
 
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I'll throw out a few cents of my own since I'm on call, in house, and there is likely a pending C/S out there so here goes it:

My epidural (and spinal) tips:
1) POSITIONING is KEY!!! In my younger days, if I felt someone looked easy but they had poor position, I would forge ahead and try to get it in even though they're being uncooperative from pain (at 3 AM my patience was never there). But after a pass or two of bone and then really making them round that back out, the epidural would just slide right in. Now in my current days, I will not start until they are in about as good of position as they can get. If they're squirmy, uncooperative, etc ... I absolutely will stand there and wait a minute or two for them to calm down, sit still, slump the shoulders forward, and round that back out. An easy epidural can be very difficult if the positioning is poor.

2) They must be STRAIGHT and EVEN. They cannot be on a crack in the bed or leaning one way or the other. No matter how obese someone is, you can almost always feel their C spine. I start feeling there and work my way down. I always visualize the center of the neck and the butt crack. If they're too fat to feel the SP and they have scoliosis down low, then yea, you're probably screwed, but getting to that MIDLINE is absolutely important. I really press firmly with my 2nd and 3rd fingers of my left hand to dent the skin/fat around the SP and then use my right thumb to really feel the bone. I then use my pen to mark where I want to go by pressing it firmly against the skin so it makes a circle from the tip.

3) The average depth is around 4 cm but I've been as little as 3 and as deep as 11. I've used the 12 cm needle maybe 4 times in my career and as others have stated, you can pretty much hub the 9 cm on just about anyone especially since skin/fat can push in an extra 1-2 cm at least. If you're constantly hitting bone you're either off midline or the patient is not in good position. I was the 3rd guy to come and replace someone's epidural about 2 hours ago and at 5'3, 130 kg, I was in at 7 cm. As a side note about that patient, one of her prior attempts was a solid 2" off midline. Her back fat hid her butt crack pretty well but if you really sat her up the right way, I could barely see it and could find the midline on her just by making that imaginary straight line from her neck to butt.

4) You want to be fairly perpendicular to the skin though I usually start off with a slight upwards angle. I have witnessed people trying to angle down after they're struggling (epidurals and spinals) and I am not sure I've ever seen anyone get in that way before (maybe it can be done??).

In terms of ultrasound, if you have a machine readily available and it takes an extra 30-45 seconds to give you useful info, then more power to you. If it means walking down the hall, rolling it into the room, scanning for several minutes, then yea, waste of time. Of course finding the depth at x cm, that's a perfectly straight line and in no way means that will be exactly where your LOR is. I will add knowing the depth is useful because it also means you pretty much can go that depth without wet tapping someone. For me, sometimes the trickiest ones are the super skinny ladies who I'm afraid to go past 3-4 cm even though I'm not really feeling ligament but one thing I never want to do is to plow through the dura without even trying to test for loss.

Hopefully this was useful to someone.
 
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MalloryWeiss said:
Will there be a time when u/s becomes standard of care to slap it on the back for epidurals (even to make some general estimations about trajectory, depth, et). I predict yes.
Click to expand...

No.

Because it doesn't actually let you see the thing you want to see, and especially not in real time. U/S is not a good tool for checking out an inherently bony structure.

Compare to central lines with real-time ultrasound, or video laryngoscopy. They actually show you what you want to see.

Incidentally, VL is definitely slower than DL in a normal population. Not by much, but slower.
 
fakin' the funk said:
No.

Because it doesn't actually let you see the thing you want to see, and especially not in real time. U/S is not a good tool for checking out an inherently bony structure.

Compare to central lines with real-time ultrasound, or video laryngoscopy. They actually show you what you want to see.

Incidentally, VL is definitely slower than DL in a normal population. Not by much, but slower.
Click to expand...

I rarely find it necessary due to time constraints but helpful images do exist. A column of CSF, preceded by epidural space as well as bony landmarks are easily visible. I agree it’s not as big of a game changer as ultrasound for vascular access, but in the right hands it’s a useful tool for certain patients.

Screaming 8cm multip, probably not. Scheduled repeat CS with L4-L5 fusion, BMI of 50 that told you preop it took multiple attempts last CS, maybe helpful?
 
Newtwo said:
12cm my record on a bmi 76 lady.
It was left lateral though so that's probably 10.5cm lor seated

No way short touhy was working on her.

Ultrasound works reasonably well even on the supermorbid obese patients, shows you midline, level and a reasonable starting angle and the depth but you have to have 20 odd ultrasounds done on skinny people to build up confidence with what you're doing.

My question that I haven't answered myself yet, is why not start with the 6" touhy when you have a bmi 60 odd lady? Lor is going to be minimal 8cm hubbed. Why not go with the 12 or 13cm needle to make sure you get it first pass and not need the second needle?
Click to expand...
I am more interested in how she got pregnant. lol
 
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