Do you use ketamine as a sedative as premedication? So watch this video because we have a great chance to discuss. .
. Release the vignette! Hello NAVE crew, how are you?
I'm Adriano Carregaro, from nave. vet. br and in this video, from the NAVE TRETAS playlist, we're going to talk a little about the use of ketamine as a sedative premedication.
But before that, I suggest you subscribe to the channel and turn on notifications to always be alerted when there's a new video on the channel, ok? Wow Adriano? Don't you use ketamine as premedication?
No. . .
Oh Adriano, but do I use it and is it so good? Okay. .
. fine. .
. I don't use it and I'll explain why. Well guys, this discussion is frequent for me because I am extremely resistant to using ketamine as a sedative on premedication.
To start this discussion, we need to understand what premedication is. What do we expect with premedication. The first thing is to help the patient contain everything.
okay, ketamine helps. another is to promote analgesia and muscle relaxation. Okay, analgesia yes but muscle relaxation no.
And most importantly, it would be generalized depression of the central nervous system promoting tranquilization or sedation. This is the point where I completely disagree with us using ketamine as a sedative on premedication. So, if we think about the main effect of premedication, which is to promote sedation, that is, generalized depression of the central nervous system, we don't have it with ketamine.
We have to remember, including this video here, in the basic anesthesia video lesson we talk about the mechanism of action of ketamine. It actually inhibits some parts of the brain, basically the cerebral cortex, and thus inhibits the sensation of smell, vision and so on. But it stimulates other areas, especially the limbic system.
So, we don't achieve sedation, in the case of ketamine, that can promote generalized depression of the central nervous system. So, what we have with the use of ketamine is stimulation of some areas of the brain and depression of other areas. very different from when we take a benzodiazepine, a phenothiazine, an alpha2 agonist or opioid, which are generally the medications used as premedication in dogs and cats and which promote central nervous system depression.
Furthermore, ketamine does not promote muscle relaxation, on the contrary, it even promotes muscle stiffness. Okay, Adriano, but I don’t use an anesthetic dose, I use a low dose! Alright buddy, so let me show you something here.
In this study carried out with dogs that received 3 microg/kg dexmedetomidine + 0. 3 mg/kg methadone and 1 or 2 mg/kg ketamine, the authors found that sedation was worse in the groups that used ketamine compared to other animals that did not received. Even some animals in the groups that received ketamine showed sialorrhea and dysphoria, which are very marked effects, psychomimetic effects when we use ketamine.
Well, in short, we can clearly see that when these people added ketamine, whether 1 or 2 mg/kg, their sedation worsened, so they were well sedated, in the group that did not receive ketamine, and when they did, the animals got worse. and they also had these characteristics that remind us, not sedation, but chemical restraint, immobilization. And look, these people used a low dose, 1 or 2 mg/kg.
Every now and then I hear people say they do 4 to 5 mg/kg IM to get this sedative effect of ketamine. This is crazy. What is happening is immobilization, it is chemical containment.
These animals will be salivating, their eyes will be wide open, a situation of catalepsy, and, when not, vocalizing and with muscular rigidity depending on what we are associating it with. So, to summarize, This is a chemical restraint and not sedation, okay? Adriano, but I only use ketamine as premedication on evil cats!
Okay, so let me show you something else here. . .
In another recent study, cats received 7 MICROG/kg dexmedetomidine + 0. 3 mg/kg methadone + 1 mg/kg ketamine, in this case, the addition of Ketamine was beneficial, promoting intense sedation in the animals to a much greater extent than the animals that did not receive ketamine. In fact, the authors did not report any other psychomimetic effects related to ketamine.
Nice, but one important thing, the authors studied cats that were tame, that were easy to handle, they were not evil cats. So, we have to highlight this. But, the result is obviously interesting, I was thinking a little whether this increase of 1 mg/kg ketamine in cats could really help us with containment.
but it could also be a variation of the species, there could be several things at play there, which could have shown that this addition of ketamine favored intense sedation in these animals. But the result is interesting. I also agree that it is difficult for us to manipulate cats, to perform a well-done sedation on a demonic cat, sometimes it is complicated.
We do a combination, even with dexmedetomidine and an opioid and the cat won't let us move properly. But in this case, if we do dissociative, what we are doing is dissociative anesthesia, chemical containment. we are not doing sedation.
We have to remember that the animal under sedation is very oblivious to the things that are happening around it, but it is still able to react, even lifting its head or giving some signal with its eyes or something like that. these animals, when we use ketamine and in a devilish animal we are not going to use 1 or 2 mg/kg, we are going to use a slightly higher dose, we are already moving towards direct chemical containment, which is generally a protocol that we use it on wild animals. So, understand that my discussion is not about using ketamine as premedication, that's not it.
We are saying that we are using ketamine to promote sedation. That doesn’t fit in my head. Another important thing, too, when we are working at premedication is that the person wants to give pre-anesthetic medication and wants the animal to be quiet within 2 or 3 minutes.
this is not appropriate, he has to leave it there for a while so that the medications have an adequate effect and another thing, he has to avoid noise, people shouting. . .
So that whole environment there, it has to be conducive for the animal to enter a state of sedation, becoming calmer, more relaxed, And then we have all the sedative effect of the medications that we are taking. Recently we were dealing with a cat, at the clinic, and then we did dexmedetomidine and practically the cat was normal, nothing happened. But there were 10 students in the room.
What did we do? We took everyone out of the room, left the cat alone with its owner, and after 5 minutes this cat was completely sedated. So we have to understand this process, we need the environment to be collaborative so that our patient can enter a situation of tranquility or sedation and then we can achieve the ideal effects of the medications, ok?
I really believe that the drugs that we generally use as premedication, which are phenothiazines, alpha2 adrenergic agonists, associated with opioids, can promote very interesting sedation with adequate analgesia in any species. What we need to know is what is the best medicine for that species or for that patient and, as I said, leave the environment conducive to that. So, I really think that ketamine doesn't need to be part of the premedication protocol, especially because I'm a little concerned about these psychomimetic effects that we see even at low doses.
But obviously, the patient is yours. So, if you want to do ketamine, you do it. Just don't do it on my side, we're going to argue a little and if I can I won't let you, ok?
And there? Do you use it or not use it? If you don't use it, post your comments here.
But if you use it, put it in too, because what we want is movement, discussion. We don't want a monotonous life, okay? And keep watching NAVE’s videos!
A big hug and see you soon!
