Why The Most Common Anesthetic Uses Egg Yolk

We connect an Easter-season question to a real anesthesia fact: propofol is formulated with egg lecithin from egg yolk, and that doesn’t automatically mean people with egg allergies can’t receive it. We also break down why propofol safety depends on monitoring and dosing, then pivot to a listener question on CRPS and a practical look at multimodal pain control and long-term opioid risks. 

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Transcript

Handheld Ultrasound Sponsor Message

SPEAKER_00 0:18

This is going under Anesthesia Answer with Dr. Brian Schmutzler. I'm Vahid Sadarzade. We are brought to you as always by our good friends at Butterfly Network.

Easter Theme Meets Anesthesia

SPEAKER_01 0:26

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SPEAKER_00 1:30

Well, we just got a host of new listeners over the course of the last two weeks. So welcome in to yeah, Anesthesia Answered Going Under. Great. With uh Dr. Brian Schmutzler. And this week on the podcast, we're talking about the incredible not edible in this circumstance. I guess you could eat it, but Incredible Edible Egg.

Why Propofol Uses Egg Lecithin

SPEAKER_01 1:49

So egg in anesthesia is a big topic. Yes. And so, you know, it's kind of a play on the time of year. So we're we're filming this on Easter, Easter day. You can see I'm in my my coat, you know, my sport jacket here. Uh so coming straight from church. Um, and so, you know, obviously um Easter is about the resurrection of Jesus. I thought about doing the podcast on like the Lazarus effect, which you may have heard of before, but that was going to be a little bit too intense. So I thought I'd lighten it up a bit. Um, so you know, Easter is also about the Easter bunny, and the Easter bunny brings eggs. So let's talk about how to eggs uh interact with anesthesia or play into anesthesia. So did you know that the most commonly used anesthetic agent, which is called propofol, is made with eggs? I I did not know that. Well, you do now. Well, yeah, I do now. I'm smarter now that I have listened to this podcast. So it's a drug we use every single day. Yep. Help patients uh on induction, so help them get to sleep. It contains egg lecithin. Um so the lecithin is kind of a different, different portion of the egg than it's not just the white, just the oak, but we'll talk about that in a minute. And so, like I said, so today, since it's Easter, let's talk about eggs.

SPEAKER_00 3:00

So, okay, how how is it made in the drug, I guess? Like what why do they put that in there? Give us a background of why that ingredient was put in.

SPEAKER_01 3:11

So, propofol is very what we call lipophilic. So it likes to be in fats, and you can't just take a substance that likes to be in fat and inject it in the body, otherwise it's not going to get where you want it to go. So the lecithin is lipophilic on one side and then hydrophilic on the other, meaning that basically can glom onto those propofol molecules, but then also travel through the blood. And when it gets broken down, the propofol gets released where it needs to go. So it's formulated as a lipid emulsion, meaning it needs to be, it needs fat to be delivered safely into the body. Um, and so the egg lecithin is actually, even though propofol is white, if anybody's ever seen it before, it's bright white, it's actually derived from the egg yolk itself. So people who come in and say that they're um that they're allergic to egg whites and think they can't have propofol, it's actually not true. The lecithin comes from the egg yolks. But we'll talk more about that later anyway, that you know, the egg allergy thing's kind of a misnomer. Okay.

SPEAKER_00 4:09

So um the pharmacology of it, the chemistry of it, how does that come together with this?

SPEAKER_01 4:18

Yeah, so so propofol, we'll just start describe the drug a little bit basically. So propofol is the most common induction agent. Um I can't remember when it came on the scene, probably the the late 80s, early 90s. Yeah. Um, and basically what happens, it's a very fast-acting drug that that goes away very quickly as well. Pretty safe. It's got a pretty good um like lethality window, right? So you can give a lot of it without it actually causing a huge issue. Um, and so we use it on almost all inductions. And um, it's pretty smooth, it's actually anti-emetic as well, so it means it's prevents you from vomiting, which is why we use it so often in our in our sedations for things like colonoscopies, endoscopies, even for when we do a spinal for, let's say, a total joint.

Monitoring Matters With Propofol

SPEAKER_00 4:58

So but propofol has been in the news recently. Not recently. Well, years ago, yeah. Years ago. I mean, but not only with Michael Jackson, Prince, but also Yeah, Prince was fentanyl, but fentanyl, but but uh but also who's uh the the Matthew um oh yeah from Friends. Yeah, um Matthew Perry. Matthew Perry was ketamine and opioids. So so propophole though, are they like is that something that you can get prescribed like a normal person?

SPEAKER_01 5:29

No, this it's it's not it should not be a drug of abuse. It's only IV. That's the only way you can take it. How are these people getting a hold of it then? Well, allegedly, um Michael Jackson got it from his physician, who was a cardiologist who just took it from a hospital. And so what happened, and this is a very convoluted story, but basically what happened is after Conrad Murray took the propofol and gave it to Michael Jackson, he walked away and wasn't monitoring him. So propofol is incredibly safe if you're monitoring, but it does slow down your breathing, it does slow down your heart rate. So you gotta watch the patients. Um so after that, though, the laws changed where you actually have to have a certified anesthesia provider to give propofol now. So it used to be nurses could do sedation with propofol. And because of the how you know wildly, you know, um uh popular Michael Jackson was and how the story broke so widely, um now you have to you have to have an anesthesia provider to do propofol. Okay, so anytime you use propofol, you're supposed to have an anesthesia provider there. Yeah, and and there's some exceptions to that, like low doses um in the ICU, you don't have to have an anesthesiologist typically ICU doc. They use it sometimes for sedation in the ER, but like procedural sedation in general, it has to be done by an anesthesia provider.

SPEAKER_00 6:47

So take me through the process then. You mean and this is this is the part where I don't think a lot of people understand or know is that when you're back there and you're monitoring the anesthesia, there's there's dosages, right? I mean, you're like constantly adjusting levels of this.

SPEAKER_01 7:02

Yeah, so so propofol is what we call an induction agent. So we just give a slug of it, a lot of it on the front end to get a patient fully to sleep. Now, if we're doing a sedation, yeah, we do we do titrate it. So we'll give 100 mics per kilo per minute or 200 mics per kilo per minute or 50 mics per kilo per minute to keep a patient asleep at the level we want them to be asleep. But yeah, and and it's not as patients get older and larger, we're not quite as precise on the exact dose, right? So a lot of times we give what's called a unit dose. So propofol comes either in a 20cc vial, a f so 20 milliliter vial, 50 milliliter vial, 100 milliliter vial. So a lot of times to go to sleep, for most patients who are relatively healthy, you just give the whole 20 milliliters. It's got such a wide safety range that the difference between, you know, 12 milliliters and 20 probably doesn't matter. So a lot of times we just give full doses of it.

SPEAKER_00 7:54

So let's go back to the question about uh being allergic to dairy. Yeah. If you're if you're allergic dairy, eggs. Eggs. Yeah, yeah, yeah. Is the safety use property? Yes.

SPEAKER_01 8:05

Yeah. So the the cross-reactivity of people who claim to be allergic to eggs and propofol is almost zero. Now we can be a little bit overly cautious with it if somebody says, uh, yeah, every time I eat an egg yolk, I my throat swells up. I have to go to the hospital, you know, I have to get a shot. Then usually there's some other drugs we can use. Um ketamine is a good choice, dexmedatomidine and precedes is a good choice, automated is a good choice. There's a lot of other things that we could do, but nothing has quite the rapid onset, predictability, and quick recovery as propofol. So that's why it's so great for, let's say, a colonoscopy because quick on, he, you know, the the GI doc can go in, do their thing real quick, be done. And as soon as they're done, you turn it off and it goes away really quickly. Some of these other drugs, there's there's much more lingering to it. But yeah. Um, so there are some side effects. It's pretty rare if you dose it well, but low blood pressure, hypotension is a pretty common side effect. Now, in URI, if our blood pressure drops 20 points, it's not going to hurt us. If somebody who has massive heart failure and is already 100 over 60 and drops 20 points, it's a problem. Um, again, so we monitor these patients. Typically, depending on the dose, you know, a low dose of it won't cause respiratory depression, it won't make you stop breathing. A high it will cause depression, but it won't stop you breathing. A high dose of it, though, almost in everybody stops the breathing. Now, if we control the breathing on our own, like in the operating room, then it's fine. But if you inject propofol into somebody who, let's say, isn't monitored and is laying in a bed in a house in California and then just walk away and go drink a beer, you're gonna have a problem. So many questions for that.

SPEAKER_00 9:43

Yeah, keep asking. Well, why why you know, obviously there was if you know it's dangerous, why are you just letting the patient handle it?

SPEAKER_01 9:53

Because he's gotten away with it before, I'm sure. Conrad Murray would would do this. Uh it sounds like anyway, again, allegedly, I I don't know the whole story, right? I don't know if the transcripts, but um allegedly he had done this for a long time. Just give Michael Jackson the propofol, inject it, walk away. So eventually, though, either gave too much or he was also mixing with alcohol, whatever the case may be. Yeah. Ended up dying from it.

SPEAKER_00 10:14

So uh we had a question that's a good one. Oh wow, bring it up. Um I'm trying to find it now, so that's sorry for the Noah's okay.

SPEAKER_01 10:30

I can keep yeah, I keep riffing on propofol a little bit. So uh as I said, you know, giving an exact dose is not always um, you know, perfect, right? We have dose ranges, but if you give everybody the same dose, some people are gonna get overly sleepy, some people aren't gonna get sleepy enough. And so we're constantly adjusting, not only like kind of in an in a bolus or when we're giving them a patient propofol to go to sleep, but we're adjusting if we're giving them a s a um an infusion as well. Always looking at things like blood pressure ventilation, the depth of anesthesia, are they moving around, how how stimulating is the surgery, like a total knee when they're totally numb from a spinal block is not actually as stimulating to a patient as let's say an endoscopy, where you're putting um where you're putting a uh a scope down somebody's throat.

SPEAKER_00 11:16

So awesome.

SPEAKER_01 11:18

Did you get the question?

SPEAKER_00 11:19

I did, but it has nothing to do with this. That's all right. We can answer it if it's if you are we are we done with our anesthesia and egg question uh conversation.

SPEAKER_01 11:26

Let me see if there was anything else we wanted to talk about in terms of eggs.

SPEAKER_00 11:30

Uh other than you can color them and put them in an Easter basket. Yes. Which you can also not real ones. Yeah, I mean real ones you can, yeah.

SPEAKER_01 11:40

But I think that's kind of all we have about the eggs. I just thought it was kind of interesting. You know, I'm thinking about what do we talk about in terms of anesthesia for Easter? And like I said, maybe maybe next Easter we'll do the Lazarus effect, but uh which is interesting. Yeah, it is interesting. But I think the egg thing was a kind of a soft, soft one. Yeah.

SPEAKER_00 11:56

Well, if you have any questions too, I mean th this is really what we love about the podcast, is that it opens it up to some questions that uh Dr. Schmutzler receives online. And one of the questions that somebody sent in uh from Michelle, Michelle Brian says that I am a C um I'm a CRPS2 patient. Okay, yeah, uh condition um oh, regional pain syndrome, chronic regional pain syndrome due to a crushing injury to my sciatic nerve in 2012. She said, My entire right leg is involved from hip to toe. I've had two sympathetic nerve blocks. Yeah, it's a pretty common thing they do, yeah. One radio ablation, radio frequent frequency ablation, yeah. And a failed spinal cord stimulator. Okay. She said, What can I do now? I am unwilling to do another spinal cord stimulator, as the first one nearly killed me. So please don't suggest another one. And this is coming in from Michelle. Michelle, thanks for the question.

SPEAKER_01 13:04

Yeah, so CRPS is tough, um, especially when it comes from an injury and not something that, you know, the the insidious onset CRPS is sometimes easier to treat than um than something that comes from a crust injury. So I mean the process is, and I'm not a chronic pain physician, so I don't know this as well as some chronic pain physicians will, but the process is the first thing you do is medications. So sometimes medications like gabapentin, for instance, um, you know, even opioids sometimes will help. Sounds like she probably went down that path already. You do that in conjunction with physical therapy. Again, she probably went down that path already. Radio frequency ablations are trying to kind of burn the nerve. Sometimes that helps. The the uh sympathetic blocks actually are usually pretty effective. Um, and so I don't know how many she had, but I think T Pipo people typically do a series of three or four of them. So that's another possibility. Sounds like the spinal cord stimulator didn't work that well. Um, you know, there are some new kind of experimental things that are coming out, but that's way outside of the purview of what I do. Um, I would say just stay in contact with a really good chronic pain doc. Um and then I I think some of the conven or the uh the alternative therapies, you know, acupuncture and massage and all that sort of stuff, you know, is there great data they help? No, but they probably do a little bit. Um so, you know, continuing physical therapy and then chiropractic, uh uh acupuncture, massage, that sort of stuff.

SPEAKER_00 14:22

It's great that people when they send questions in, because they're they're genuinely just interested in how how you can yeah, do you have the knowledge? Can you answer the questions and help them?

SPEAKER_01 14:32

Sometimes I can answer part of it, sometimes I can answer all of it, sometimes I can't answer any of it. So pain management. Yeah.

SPEAKER_00 14:39

While we're on the topic, let's just talk a little bit about pain management. Yeah. Dr. Brian Schmutzler. Sure. And um maybe some of the uter chronic. Yeah, yeah. Maybe both. And and some of the misconceptions out there.

SPEAKER_01 14:50

Yeah. Yeah. So so I mean, I think chronic pain, or I mean acute pain-wise in the operating room, which is what I do. I don't do chronic pain. Um, we, and I know apparently this is a big buzzword for people who don't like it nowadays, but multimodal analgesia, which means using every possible technique to treat the pain, including opioids when needed. Um, but other things like anti-inflammatories, things like, as we talked about, Tylenol. IV Tylenol is incredibly effective, um, even more so than than oral Tylenol. Things like regional anesthesia, where we numb up nerves, I think is a very good thing. There's some other, you know, nerve type medications that we use, um, and then again, similar things like acupuncture and you know, physical therapy and all those sort of things. They all work together to treat acute pain. So when you say multimodal analgesia, you don't mean no opioids. You mean using multi-modes to treat pain. Uh anyway. Um, chronic pain, I can't speak a whole lot to. I mean, I know kind of the process is, you know, you initially treat with an anti-inflammatory. I mean, I just had a back issue recently, and right, so I treated they treated me with an anti-inflammatory. If that doesn't work, then kind of the next step is physical therapy, do some imaging, figure out what's going on. If it's something fairly amenable to injections, then sometimes you get the pain injections from a chronic pain doc. And if that doesn't work, you know, next step might be surgery or minimally invasive surgery, or, you know, there's all kinds of things you can do for chronic pain. So in general, it's not great for people to be on long-term opioids. And, you know, I've got a little bit of cachet in this because this is what I studied in the lab. But if you take opioids long term, they are number one, you you create a tolerance to them. So you've got to take more and more and more of them to get the same pain-relieving effect. Now, that tolerance does not mean addiction, but tolerance does mean higher and higher doses. And the side effects of opioids, which are really not good things, right? Like respiratory depression, so you slow down your breathing, constipation, there's some changes in your hormonal levels. So there's a lot of things that go on when you take opioids chronically. Now, you take them for a few days after surgery, the likelihood of those things happening pretty small. You take them long term, six months, a year, 10 years, those those are are those side effects are much more likely to occur. Again, because of escalating doses. There is an addiction potential to opioids, which there is not to a lot of these other medications like steroids, like numbing medications that we use in the operating room. You're not going to get addicted to that. So, you know, that there's that potential as well long term.

How To Send Your Questions

SPEAKER_00 17:25

All right. Well, if you have a question for Dr. Brian Schmutzer, as always, send him a message, at him at Twitter, Facebook, Instagram, whatever it is. If it's a question related to medicine, yeah, you will answer it. I will do my best. Yeah.

SPEAKER_01 17:40

Certain areas of medicine I don't know as well as others, but if we want to talk about, you know, um the operating room, anesthesia, some pain management, acute acute and subacute pain stuff, happy to answer the question.

SPEAKER_00 17:52

We are brought to you by the Butterfly Network. This has been going under anesthesia answered with Dr. Brian Schmutzler. I'm Bahit Sadarazade. See you next time.