Isobaric VS hyperbaric

[Mman]

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What do you mean by so many? I think I've had one spinal fail.

I'd guesstimate somewhere in the neighborhood of 1-2% of spinals for ortho procedures fail. Spinals for csections almost never fail. Why??? I have no idea.

 

[coffeebythelake]

I'd guesstimate somewhere in the neighborhood of 1-2% of spinals for ortho procedures fail. Spinals for csections almost never fail. Why??? I have no idea.

I imagine getting CSF back initially, then needle inadvertently moved out of thecal space while hooking up the syringe and injecting

 

[Mman]

I imagine getting CSF back initially, then needle inadvertently moved out of thecal space while hooking up the syringe and injecting

no, I'm referring to situations with perfect CSF flow including aspiration after injection. Obviously the occasionally iffy flow is bound to fail more likely. Ortho spinals just fail more often.

 

[coffeebythelake]

no, I'm referring to situations with perfect CSF flow including aspiration after injection. Obviously the occasionally iffy flow is bound to fail more likely. Ortho spinals just fail more often.

I've never had that experience or noticed this. We do lots of ortho cases.

 

[Mman]

I've never had that experience or noticed this. We do lots of ortho cases.

some people suggest it is from Tarlov cysts which contain CSF but do not allow free flow of the local into the rest of the subarachnoid space. I don't pretend to know the mechanism, but just note it happens way more often in an old hip fracture patient population compared to a young OB patient population.

 

[Velefunt]

I imagine getting CSF back initially, then needle inadvertently moved out of thecal space while hooking up the syringe and injecting

Don't most people aspirate a little bit of CSF after hooking up the syringe, for confirmation?

 

[coffeebythelake]

Don't most people aspirate a little bit of CSF after hooking up the syringe, for confirmation?

nope
barbotage
this is not a standard practice
i assess CSF is dripping back freely then hook up the syringe and inject
the only time i had a spinal not set up as expected was a chip shot CSE on a prego where i aspirated back on the syringe before injecting (needle must have slipped out of the thecal space when i was aspirating, fortunately the epidural worked just fine)

 

[GassYous]

Don't most people aspirate a little bit of CSF after hooking up the syringe, for confirmation?

If you have csf dripping back what more confirmation do you need

 

[Arch Guillotti]

If you have csf dripping back what more confirmation do you need

Ones that don't aspirate well may not work well.

 

[MirrorTodd]

Every section/spinal I've performed, I have had the attending instruct me to aspirate csf for swirl. Reason being (especially when performed a cse) how do you know that fluid isn't the saline or local dripping out? I think I'm confident enough now to be sure of my technique, but I partially agree with that. After all, how do you know that firearm isn't loaded unless you observe the empty chamber?

 

[coffeebythelake]

Every section/spinal I've performed, I have had the attending instruct me to aspirate csf for swirl. Reason being (especially when performed a cse) how do you know that fluid isn't the saline or local dripping out? I think I'm confident enough now to be sure of my technique, but I partially agree with that. After all, how do you know that firearm isn't loaded unless you observe the empty chamber?

This assumes u use saline with your LOR technique

 

[GassYous]

Every section/spinal I've performed, I have had the attending instruct me to aspirate csf for swirl. Reason being (especially when performed a cse) how do you know that fluid isn't the saline or local dripping out? I think I'm confident enough now to be sure of my technique, but I partially agree with that. After all, how do you know that firearm isn't loaded unless you observe the empty chamber?

Because you can tell by the feel that you're in the right space, just like the epidural. I don't use saline and I use most of my local pretty superficially.

 

[gcc322]

Read this yesterday and found it helpful as someone who hasn’t used mepiv and only used iso when we didn’t have hyperbaric.

Mepivacaine versus Bupivacaine Spinal Anesthesia for Early... : Anesthesiology

s study was designed to test the hypothesis that patients who received mepivacaine would ambulate earlier than those who received hyperbaric or isobaric bupivacaine for primary total hip arthroplasty. Methods This randomized controlled trial included American Society of Anesthesiologists...

pubs.asahq.org

 

[Mman]

Used 0.5% isobaric bupivacaine for a csection yesterday for the hell of it (used it many times for ortho but not previously for OB) and it worked fine. Probably couldn't even tell you if I was blinded what it was. Her levels got at least T4-5 or so as she did the "I can't breathe" thing because her chest was numb (not the high spinal whisper of I can't breathe) and her pressure dropped enough to need several doses of vasopressor to smooth it out. I used about 2.4 mls (12 mg) as I figured that was roughly a standard dose of hyperbaric that most people use.

 

[GassYous]

Used 0.5% isobaric bupivacaine for a csection yesterday for the hell of it (used it many times for ortho but not previously for OB) and it worked fine. Probably couldn't even tell you if I was blinded what it was. Her levels got at least T4-5 or so as she did the "I can't breathe" thing because her chest was numb (not the high spinal whisper of I can't breathe) and her pressure dropped enough to need several doses of vasopressor to smooth it out. I used about 2.4 mls (12 mg) as I figured that was roughly a standard dose of hyperbaric that most people use.

Standard dose for ob? I think a lot of people use 7.5-10 for joints

 

[Mman]

Standard dose for ob? I think a lot of people use 7.5-10 for joints

yes for OB.

I also can't fathom only using 7.5 mg of bupivacaine for a total joint. I mean why? If I am using bupivacaine for a joint it's because I would like it to last a little while and the patient benefits from extended pain relief postop. If I want something faster to send someone home ASAP I use mepivacaine.

 

[deleted162650]

yes for OB.

I also can't fathom only using 7.5 mg of bupivacaine for a total joint. I mean why? If I am using bupivacaine for a joint it's because I would like it to last a little while and the patient benefits from extended pain relief postop. If I want something faster to send someone home ASAP I use mepivacaine.

I use 7.5mg iso and get a solid 3hrs out of it. I’m going to try mepi here soon based on feedback from the SDN brain trust, but I’m very skeptical that my surgeons are fast enough for it.

 

[Southpaw]

I use 7.5mg iso and get a solid 3hrs out of it. I’m going to try mepi here soon based on feedback from the SDN brain trust, but I’m very skeptical that my surgeons are fast enough for it.

I’ve never tried iso 7.5 for a joint but when I use 10 for knees/hips patients are moving roughly 2 hours later in the pacu. Also, unless I run them real deep on propofol at incision I see a lot of movement or groaning on skin incision. This is like 20 minutes post spinal. My 0.5 isobaric bupi sounds very different than yours and it’s why I also said it wouldn’t be ideal for CS as we typically incise within 10 minutes of the spinal on a standard CS.

 

[deleted162650]

I’ve never tried iso 7.5 for a joint but when I use 10 for knees/hips patients are moving roughly 2 hours later in the pacu. Also, unless I run them real deep on propofol at incision I see a lot of movement or groaning on skin incision. This is like 20 minutes post spinal. My 0.5 isobaric bupi sounds very different than yours and it’s why I also said it wouldn’t be ideal for CS as we typically incise within 10 minutes of the spinal on a standard CS.

Maybe I just have a lightweight patient population? 1.5mL iso bupi plain. Propofol at 75ish. They might be wiggling in PACU 2.5hrs later, but they’re pain free. No response to incision, but our prep times are admittedly a little slow.

I’ll have maybe 2 per year where the block isn’t quite dense enough and I have to LMA them.

Never a problem on OB, but that population is more sensitive to neuraxial meds as mentioned above.

 

[GassYous]

I’ve never tried iso 7.5 for a joint but when I use 10 for knees/hips patients are moving roughly 2 hours later in the pacu. Also, unless I run them real deep on propofol at incision I see a lot of movement or groaning on skin incision. This is like 20 minutes post spinal. My 0.5 isobaric bupi sounds very different than yours and it’s why I also said it wouldn’t be ideal for CS as we typically incise within 10 minutes of the spinal on a standard CS.

Eh moving toes in pacu and feeling pain in the knee or hip are different things. I think 10 should give you at least 3 hours of numbness. My prop can be anywhere from 25-150.

Also I like low dose ketamine for the spinal/incision.

 

[kmurp]

Read this yesterday and found it helpful as someone who hasn’t used mepiv and only used iso when we didn’t have hyperbaric.

Mepivacaine versus Bupivacaine Spinal Anesthesia for Early... : Anesthesiology

s study was designed to test the hypothesis that patients who received mepivacaine would ambulate earlier than those who received hyperbaric or isobaric bupivacaine for primary total hip arthroplasty. Methods This randomized controlled trial included American Society of Anesthesiologists...

pubs.asahq.org

Strange choices of dosing on the bupivacaine. They used more isobaric than hyperbaric. At equivalent doses, isobaric lasts longer so certainly no surprise that the iso bupivacaine did so poorly. Ropivacaine is nice in the isobaric form as it’s lower potency cancels out the usual longer duration of its isobaric form.