Charging the Machine?

[Spinach Dip]

Background: I work with experimental swine. Our experiments involve anesthesia and recovery. Induction is done with isoflurane and a mask (IM agents such as versed and telezol have been used before, and are preferable, but our current protocol precludes them), but this is proving long and difficult because the pigs fight it.

We have made do until a few days ago. One of our pigs, while fighting during induction, split open her chin and needed several stitches. While our PI assures every animal rights group in the country that this was an isolated incident, I am trying to ensure that it remains an isolated incident.



I have heard that a common method used by pediatric anesthesiologists is to charge the machine with an induction dose before introducing the patient to the mask. (I would speak directly with a pediatric anesthesiologist if I had any contacts in that specialty, but I unfortunately do not.) (I also know that this is more of a veterinary question, but I figure the limitations imposed by our experiment would more accurately be answered by your expertise than that of veterinarians (no insult to DVMs meant).)

I would love to hear your opinions on the matter. Would this shorten induction times? How does one go about charging their machine?

Thanks ahead of time.

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[Noyac]

I'm not following your question but I think you are asking, how do you "over pressure" the system in order to do a single breath induction. Is this correct?

 

[Spinach Dip]

I'm not following your question but I think you are asking, how do you "over pressure" the system in order to do a single breath induction. Is this correct?

Sorry if I'm not using the correct terminology. I've heard it called "charging" before.

But yes, a single breath induction would be ideal.



Here is the key line: "...is to charge the machine with an induction dose before introducing the patient to the mask."

 

[Colba55o]

Isoflurane stinks; don't pigs have very sensitive noses? No wonder they fight I would too

 

[Noyac]

Yeah isoflurane does stink. I think the gas people "charge" with is sevoflurane. But I've heard of it being done with Desflurane as well. I've never done it with either.
The process as I remember is to turn the gas up to the highest conc and occlude the circuit for a period of time. Add some nitrous 2x the O2 flow rate and then when the pig is ready, slap the mask on his face.

Poor piggy.

 

[urge]

Background: I work with experimental swine. Our experiments involve anesthesia and recovery. Induction is done with isoflurane and a mask (IM agents such as versed and telezol have been used before, and are preferable, but our current protocol precludes them), but this is proving long and difficult because the pigs fight it.

We have made do until a few days ago. One of our pigs, while fighting during induction, split open her chin and needed several stitches. While our PI ensures every animal rights group in the country that this was an isolated incident, I am trying to ensure that it remains an isolated incident.



I have heard that a common method used by pediatric anesthesiologists is to charge the machine with an induction dose before introducing the patient to the mask. (I would speak directly with a pediatric anesthesiologist if I had any contacts in that specialty, but I unfortunately do not.) (I also know that this is more of a veterinary question, but I figure the limitations imposed by our experiment would more accurately be answered by your expertise than that of veterinarians (no insult to DVMs meant).)

I would love to hear your opinions on the matter. Would this shorten induction times? How does one go about charging their machine?

Thanks ahead of time.

Never realized you were a vet.

Crank the Iso all the way at high flows (>10Liters) for a minute or two before putting the mask on the pig. Sevo should be faster if you can use it.

Watch out, though. Full blast anesthesia is not very friendly on the cardiovascular system. Instead of stitching up the pig, you might end up coding her.

 

[Noyac]

Are you purposely avoiding other agents like benzos or even better ketamine?

 

[Spinach Dip]

Never realized you were a vet.

Research Assistant, actually. My superior is a DVM.

Are you purposely avoiding other agents like benzos or even better ketamine?

If I had my pick, I'd go telazol (which is an NMDA antagonist similar to ketamine, mixed with a benzo). We've used it before, but this protocol is different. We are limited to isoflurane. for reasons I won't go into fully here.

Crank the Iso all the way at high flows (>10Liters) for a minute or two before putting the mask on the pig. Sevo should be faster if you can use it.

Watch out, though. Full blast anesthesia is not very friendly on the cardiovascular system. Instead of stitching up the pig, you might end up coding her.

Thank you. And your warning is noted. I will discuss this with the decision-makers.

 

[deleted59964]

this is my preferred technique with calm cooperative primary school aged children.
70% nitrous, 8% sevo, flow at 6 l, cap the circuit and let it run for a few minutes to fill the circuit before the child enters the room.
then get the children to practice doing vital capacity breaths though a mask that is not connected to the circuit.
once they've demonstrated a few deep breaths, connect the circuit, usually 2-3 breaths are still required.

if you're stuck with iso rather than sevo it will smell worse (especially to a pig i'd think), and it will take longer to induce
nitrous if it doesn't confound your study is very beneficial in speeding induction.

 

[btbam]

Iso smells absolutely awful, why can't you guys use Sevo?

 

[urge]

Iso is not particularly unpleasant in my opinion.

 

[somedumbDO]

this is my preferred technique with calm cooperative primary school aged children.
70% nitrous, 8% sevo, flow at 6 l, cap the circuit and let it run for a few minutes to fill the circuit before the child enters the room.
then get the children to practice doing vital capacity breaths though a mask that is not connected to the circuit.
once they've demonstrated a few deep breaths, connect the circuit, usually 2-3 breaths are still required.

if you're stuck with iso rather than sevo it will smell worse (especially to a pig i'd think), and it will take longer to induce
nitrous if it doesn't confound your study is very beneficial in speeding induction.

This is what I do and works well.

 

[pgg]

this is my preferred technique with calm cooperative primary school aged children.
70% nitrous, 8% sevo, flow at 6 l, cap the circuit and let it run for a few minutes to fill the circuit before the child enters the room.
then get the children to practice doing vital capacity breaths though a mask that is not connected to the circuit.
once they've demonstrated a few deep breaths, connect the circuit, usually 2-3 breaths are still required.

if you're stuck with iso rather than sevo it will smell worse (especially to a pig i'd think), and it will take longer to induce
nitrous if it doesn't confound your study is very beneficial in speeding induction.

With calm cooperative kids I start with just 2:1 nitrous : oxygen because it doesn't stink. When they've got a good buzz going, I turn the sevo up to 8, and the nitrous off so I can use a higher FiO2.

With uncooperative little kids I start with 8% sevo in oxygen, no nitrous. Nitrous does speed induction (concentration effect and 2nd gas effect) but I find 8% sevo in O2 is fast enough. And I like the higher FiO2.

Isoflurane is the wrong gas for inhalation inductions, but I guess you use what you've got in pig-lab-land. The rest of the world that can't afford sevoflurane uses halothane for inhalation inductions. Try to get some of that. Actually, you should talk the vet into using xenon. 🙂

 

[Spinach Dip]

Iso smells absolutely awful, why can't you guys use Sevo?

Here's how that conversation went with the budget-masters:

Me: "Hey, we'd like to use sevo because it will speed along induction and recovery of our pigs, along with reducing the amount they struggle and likely preventing any injuries to pig and human experimenter."
Them: "Okay, how much does a bottle of that cost?"
Me: "Around $150"
Them: "And what's the cost of the stuff you're using now?"
Me: "About $10"
Them: "No." *click*

 

[Spinach Dip]

Poor piggy.

On the up side, she has had more cosmetic surgery than I'll ever have.

I'm a little jealous, actually.

 

[Noyac]

On the up side, she has had more cosmetic surgery than I'll ever have.

I'm a little jealous, actually.

That's disturbing.
Well, not as disturbing as some of the lips I've seen on women these days but damn close.