sux dosages

[refreshingred]

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An attending informed that sux is dosed on weight and not on ideal body weight. It seems that a drug that acts on skeletal muscle Ach receptors should be based on IBW. Can someone tell me if what my attending told me is correct -- can't seem to find anything on this in "Parmacology & Physiology in Anesthesia Practice" by Stoelting. And plus if it is correct, why it is that way.

 

[jetproppilot]

An attending informed that sux is dosed on weight and not on ideal body weight. It seems that a drug that acts on skeletal muscle Ach receptors should be based on IBW. Can someone tell me if what my attending told me is correct -- can't seem to find anything on this in "Parmacology & Physiology in Anesthesia Practice" by Stoelting. And plus if it is correct, why it is that way.

I humbly disagree with your attending. I'm not gonna give the 200kg gastric bypasses we do two-sticks of sux.

Additionally, its not needed. In residency one is meticulous with dosage figuring, and rightly so. But in reality, 100mg for a little person, 150mg for a normal size person, and 200mg for a big person works just as well.

 

[jwk]

I humbly disagree with your attending. I'm not gonna give the 200kg gastric bypasses we do two-sticks of sux.

Additionally, its not needed. In residency one is meticulous with dosage figuring, and rightly so. But in reality, 100mg for a little person, 150mg for a normal size person, and 200mg for a big person works just as well.

It's interesting how different things are done in different areas. Your "sticks" are obviously bigger than ours. ( stick envy ??? 😉 ) We have a satellite pharmacy in our OR, and they pre-draw several of our meds for us, including Sux, which comes in a 120mg pre-fill. So two sticks of sux for us is 240mg, not much different than the 200mg you say you would give to a big person. What really surprises me is the number of people at my hospital that think that that single 120mg pre-filled dose is the max to use. They'll give that to the 200kg guy for the lap bypass and wonder why he's still moving. Duh. Kinda like that old joke about all anesthesia is is giving all of the big syringe and half of the small one.

Your doses are a good bit higher than what I give. I'm normally giving 100-120mg for a "normal size person", up to a max of probably 180-200 for a big person. And I still like to save just a little in the syringe just in case of laryngospasm at extubation, which freaks out at least a couple of my newer anesthesiologists that think a second dose of sux will cause evil things to happen. Old tricks and old habits die hard.

 

[jetproppilot]

It's interesting how different things are done in different areas. Your "sticks" are obviously bigger than ours. ( stick envy ??? 😉 ) We have a satellite pharmacy in our OR, and they pre-draw several of our meds for us, including Sux, which comes in a 120mg pre-fill. So two sticks of sux for us is 240mg, not much different than the 200mg you say you would give to a big person. What really surprises me is the number of people at my hospital that think that that single 120mg pre-filled dose is the max to use. They'll give that to the 200kg guy for the lap bypass and wonder why he's still moving. Duh. Kinda like that old joke about all anesthesia is is giving all of the big syringe and half of the small one.

Your doses are a good bit higher than what I give. I'm normally giving 100-120mg for a "normal size person", up to a max of probably 180-200 for a big person. And I still like to save just a little in the syringe just in case of laryngospasm at extubation, which freaks out at least a couple of my newer anesthesiologists that think a second dose of sux will cause evil things to happen. Old tricks and old habits die hard.

Sorry for the ambiguity, JWK...didnt realize sux came in anything but 20mg/mL, 10mL vial (total=200mg, so two "sticks"=400mg). The only other way I've seen it is the powdered stuff for sux drips.

 

[powermd]

I'm sorry Jet... a sux drip? When would you have to use that? In the ICU I've seen Nimbex used routinely for tubed patients who are agitated, fighting the vent, and won't stay down with propofol.

 

[jetproppilot]

I'm sorry Jet... a sux drip? When would you have to use that? In the ICU I've seen Nimbex used routinely for tubed patients who are agitated, fighting the vent, and won't stay down with propofol.

Way back when, even before my time, sux drips were common in the OR. They used to mix 2 grams of powdered succinylcholine in 500mL crystalloid, push their thiopental or whatever, open the drip, and titrate to twitch attenuation. VERY common in the 60s and I think even the 70s for everything from orthopedics to ELAPs.
I used it a few times when I was a resident for lithotripsies where we put the patient in this swing thing, put'em to sleep, then this crane thing lifted the patient into a tub full of water, lowered them into it, and commenced lithotripsy.
The cool thing about a sux drip is as long as you keep twitches (remember with sux the twitches are attenuated evenly, not in a stepdown fashion like non-depolarizers), when you turn it off, its like, well, sux. It wears off quick.

The lack of popularity of sux drips is probably why we dont see phase 2 blocks...think about it...what are the chances of getting a phase two block from an induction sux dose, and maybe a cuppla blips of sux at the end of the case, verses running a sux drip for a cuppla hours?

Hey JWK, I'm sure you are more familar with sux drips than me. Did you see more phase 2 blocks back then?

I think a sux drip is one of those things, at least for short cases, that fell out of vogue to "better drugs" (read:more expensive, more heavily marketed drugs). BECAUSE, as far as I remember, for short cases like 30 minutes or so, the chance of a phase 2 block is low, and when you turn off the drip it is GONE. Superior neuromuscular control that costs pennies. Now for longer (hours) cases I don't know.
Whatcha think JWK?

 

[jwk]

Way back when, even before my time, sux drips were common in the OR. They used to mix 2 grams of powdered succinylcholine in 500mL crystalloid, push their thiopental or whatever, open the drip, and titrate to twitch attenuation. VERY common in the 60s and I think even the 70s for everything from orthopedics to ELAPs.
I used it a few times when I was a resident for lithotripsies where we put the patient in this swing thing, put'em to sleep, then this crane thing lifted the patient into a tub full of water, lowered them into it, and commenced lithotripsy.
The cool thing about a sux drip is as long as you keep twitches (remember with sux the twitches are attenuated evenly, not in a stepdown fashion like non-depolarizers), when you turn it off, its like, well, sux. It wears off quick.

The lack of popularity of sux drips is probably why we dont see phase 2 blocks...think about it...what are the chances of getting a phase two block from an induction sux dose, and maybe a cuppla blips of sux at the end of the case, verses running a sux drip for a cuppla hours?

Hey JWK, I'm sure you are more familar with sux drips than me. Did you see more phase 2 blocks back then?

I think a sux drip is one of those things, at least for short cases, that fell out of vogue to "better drugs" (read:more expensive, more heavily marketed drugs). BECAUSE, as far as I remember, for short cases like 30 minutes or so, the chance of a phase 2 block is low, and when you turn off the drip it is GONE. Superior neuromuscular control that costs pennies. Now for longer (hours) cases I don't know.
Whatcha think JWK?

You want the art of anesthesia? Sux drips were it - do it right and you were hot stuff - get into a phase 2 block and you sucked, especially in a quick-turnover practice. And of course you would use the same bag all day long for all your patients.

We used them into the early 80's for cases less than an hour long. You could easily do long cases with them, but as I recall, the longer you went, the more prone you were to problems. We didn't get into too many phase 2 blocks - you learned pretty quickly how to avoid them so you didn't look like an incompetent idiot. Cases that went 1.5 hours or more usually got pavulon (or curare if we didn't mind the red face). Once vecuronium and atracurium came along, sux drips dropped out of sight pretty quickly. I think one of our OB docs gradually used up our supply of sux powder for his bowhunting trips (seriously).

Hey, what do you mean "back then" ? Am I getting that friggin' old?

 

[jetproppilot]

You want the art of anesthesia? Sux drips were it - do it right and you were hot stuff - get into a phase 2 block and you sucked, especially in a quick-turnover practice. And of course you would use the same bag all day long for all your patients.

We used them into the early 80's for cases less than an hour long. You could easily do long cases with them, but as I recall, the longer you went, the more prone you were to problems. We didn't get into too many phase 2 blocks - you learned pretty quickly how to avoid them so you didn't look like an incompetent idiot. Cases that went 1.5 hours or more usually got pavulon (or curare if we didn't mind the red face). Once vecuronium and atracurium came along, sux drips dropped out of sight pretty quickly. I think one of our OB docs gradually used up our supply of sux powder for his bowhunting trips (seriously).

Hey, what do you mean "back then" ? Am I getting that friggin' old?

Geez I know...cant believe I've been out of residency since 1996...geez....

I used to supply my barber with powdered sux for his arrows too...havent been able to find it for him lately...do they even make it anymore?

 

[apma77]

to actually answer the question posted........

sux is a water soluble drug and the volume of distribution is greater in fat folks since their plasma volume is greater. that is why sux is based on actual not ideal body weight.

now back to the endless chanting by the priv practice gurus... 🙄

 

[militarymd]

Geez I know...cant believe I've been out of residency since 1996...geez....

I used to supply my barber with powdered sux for his arrows too...havent been able to find it for him lately...do they even make it anymore?

The stopped making it. In the military, it was a sought after drug because of its long shelf life....sitting in the desert, on ships, etc.



On the other part of the thread, I give 100mg to every one...no matter the size....except for kids....

 

[jetproppilot]

to actually answer the question posted........

sux is a water soluble drug and the volume of distribution is greater in fat folks since their plasma volume is greater. that is why sux is based on actual not ideal body weight.

now back to the endless chanting by the priv practice gurus... 🙄

Geez, rough crowd. Endless chanting, huh? 😱

 

[refreshingred]

So, Apma, what you're saying is that since sux is water soluble it happens to have a high Vd in fat folks B/C of their greater plasma volume.

So the secondary reasoning for why you dose it on actual body weight is b/c the plasma is where sux is metabolized AND since only a fraction of what you give actually gets to the nicotinic receptors (b/c of its rapid plasma metabolism) then you need to give it according to the pt's actually weight, not IBW. Correct?

The reason this was conufusing to me is b/c several of my attending are just not clear on this subject and i think it's b/c so many drugs that we give ARE based on IBW; and since sux's active site is the muscle, and it's a highly ionized molecule w/ a low fat solubility, it doesn't make sense (at first) to dose it on anything but IBW. But it makes sense now, i think.

 

[VentdependenT]

Geez, rough crowd. Endless chanting, huh? 😱

Its just ampa.

 

[Noyac]

On the other part of the thread, I give 100mg to every one...no matter the size....except for kids....[/QUOTE]

Thats funny, I do the same. 5cc for everyone (rare exceptions) that I need to use it on. One vial lasts me all day, mostly cause I don't use it all that often.

 

[pasgasser]

great article in Anesthesiology this month on sux. interesting that studies have found myalgias to be reduced when 1.5mg/kg given when compared to 1.0mg/kg