Hi folks Thomas Green Morton inhalation anesthesia winning one of the techniques anesthetics most used in both medicine and veterinary medicine another one is questioned but it resists mainly due to the evolution of anesthetics so very good things in this technique others not so much and that's it that we're going to see in this video lesson, drop the vignette there o Hello crew members donate everything well in this video lesson of the course Anesthesia the basics we’re going to talk a little bit about General inhalation anesthetics General inhaled anesthetics are unlike anything we've seen so far
in the course they are administered exclusively via pulmonary and are eliminated basically by the same route all right they already tried make isoflurane chloroform ether several times intravenously But let's leave aside a very important feature of inhalation anesthesia is that it allows the rapid change of anesthetic plans this makes anesthesia more predictable and adaptable for each This situation is compounded by the ease of quantifying and changing the concentration of anesthetic quickly and dynamically This is the great advantage in comparison Total intravenous anesthesia is important to use the specific equipment that ensure safety in this procedure
this can all be checked in the video lesson of anesthetic circuits Ok as we've seen video classes inhalation anesthesia itself began in the 19th century and we can say that for about 100 years it was basically based on use of chloroform ether and cyclopropane all of this is just fine with the over the years, people realized that these anesthetics were discharged toxicity and also they were flammable is have that patient side on fire in the middle of the surgical procedure Especially when started using electricity and also the electric scalpel was a god help us in
1956 halothane appeared and it is in practice considered the first non-flammable anesthetic then for a long time it was the basis of inhalation anesthesia However, this anesthetic has a high rate of biotransformation about 25 percent that has multiple effects undesirable and he also ran the anesthesia machine people find fighting in the market somewhere in the world he has already been in Toledo it’s practically not used anymore fighting right I won't even say anything I used it even in so-and-so is to have it never left after the a little struggling inhaled anesthetics were synthesized and basically
today we use isoflurane or sevoflurane or desflurane it has restricted use in the veterinary basically used in research good in this video lesson we’re going to put more emphasis on isoflurane and it’s so and so we will also compare them to halothane when going down Uranus even for us understand how and why this evolution of anesthetics happened so that the better understand how these drugs work in the body need to talk a little about their physical and chemical characteristics Ok Let's go and when we are doing inhalation anesthesia it is very important know how much
we are giving anesthetic to the patient each At the time of the procedure, the vapor pressure is important because it will tell which anesthetic is easier to vaporize the higher the pressure of vapor easier to vaporize the agent in that case the maximum vaporization of the isoflurane can reach 32 percent and that of the servant 21 percent but has two factors that are also important in this vaporization and can change these values that are the temperature EA barometric pressure the higher the temperature easier to vaporize the anesthetic to barometric pressure when otherwise the lower the
barometric pressure the easier to vaporize the anesthetic why it is important we used pollinators calibrated because they compensate for these variations another characteristic important is the solubility of the anesthetic in each medium that is fundamental for us to understand and it will balance between different means such as the lungs and the blood or brain to try to explain it better we will do a theoretical exercise here ok we imagine that we have two dogs like Clones that have not received MPA and will be induced with inhalation anesthesia one with at and the other with isoflurane
these anesthetics will migrate from the alveoli to the blood and then to the brain which is the site of action In this case the solubility will determine whether this anesthetic will reach the brain quickly or slowly for that we use a coefficient that is called blood-gas partition coefficient the coefficient of blood-gas partition of the ether is more or less 12 so at the beginning of anesthesia with ether to be in high concentration in the alveoli and will quickly migrate to good blood would be if it migrated quickly to the brain too but it doesn't happen
as it is very water-soluble it to bill the blood well to start effectively reaching the brain this in theory will only happen when we had the ratio of 12 molecules diet and blood for one in the alveoli now let's go to the dog that is receiving isoflurane the blood gas partitioning coefficient of laughter is more or at least one email in the same way after billing the alveoli Enzo wins bloodstream The difference is that the balance between the ISO concentration in the blood and in the alveoli occurs much faster than it is not to have
isoflurane reaches the brain at a speed eight times greater than the Eder that's why ISO and servo promote anesthetic inductions much faster than old anesthetics like chloroform ether and even halothane obviously the reverse is true so the ISO and the servo promote recoveries anesthetics faster than the others I cited this article here shows this well here dogs and heavy with equipotent doses of ISO servo and desflurane and the animals that received ISO take a little longer to to present in reflexes and to be this base in comparison to the servant and the desflurane so guys
when we see in the film One person anesthesia in the other there with anesthetic on the cloth in a matter of seconds the person is anesthetized the correct would she return from anesthesia at the same speed and not as we see in the movies there that after two or three hours the person wakes up and it’s groundless I don’t know if you noticed but when I was talking of that article I talked to the authors used equipotent doses of anesthetics But how can we know this in the case just for the understand if we provide
the patient with two percent isoflurane we're not going to have the same depressing effects as two percent of servo sticks we have to compare medications according to minimum alveolar concentration everything akan definition is alveolar concentration minimal level capable of inhibiting the motor response of a supramaximal painful stimulus in fifty percent of individuals theoretically after all isoflurane has stabilized in the patient in all organs we need to send a stitch 3 percent volume of isoflurane to maintain that patient's anesthesia for as long that we want but obviously we don't want in this desert only 50 per
percent of patients so in theory we need to make a point 3 cam to be able to anesthetize 100 percent of patients So in this case the concentration required to maintain anesthesia in this patient is approximately 1.7 percent volume if we keep conserving Puran O value is about three volume is percent o let me clarify a deal akan it is not obtained with what appears in the vaporizer the concentration actually it comes from the inspired fraction of anesthetic obtained with an but in practice here we will understand that these concentrations are well alright Ok but
it has to be clear that they are not the same Ok well all this Khan’s explanation It’s for you to understand that it’s more or less equal to the dose of injectable anesthetics only here the anesthetic is given and in continuous form then basically we just have to put the vaporizer there, telling us what we want and let anesthesia roll but not my old man in mind that animals are not experimental and mathematical models so this value will never be accurate it can be higher or lower something else very important is that when we are
determining dogs experimentally mind the animals do not receive any medication and in practice we do not we usually associate several drugs that are used in MPA and in induction So this Khan value is just for us to have a base but no one will leave that right amount there and will think it's okay so vaporization required for the patient it is always based on the anesthetic plans to several physiological factors that influence the amount of anesthetic that we offer the patient the main are association of drugs hypotension hypothermia severe epoxy Severe hypercapnia gestation of changes
in acid-base balance Here we have some important data about each of the inhalation anesthetics girl we must not forget that it still has a lot of important characteristics of these anesthetics such as the equilibrium constant between the device anesthesia and what we are delivering to the patient the constant of balance between the inspired and inspired fraction and more I suggest that anyone interested in learning a little more about inhalation anesthesia gives one checked here in the description references that are very interesting ok and even though inhaled anesthetics have been used for over 150 years there
is still no certainty as to how they act on the brain basically what what we know is that they inhibit excitatory neurons, for example glutamatergic nmda ampa and stimuli and inhibitors such as gaba a cardiovascular depression certainly the great disadvantage of anesthesia inhalation as we can see in these figures the blood pressure drops considerably according to the increment of inhaled anesthetic that happens in all species and is dose-dependent the same happens with the stroke volume and consequently with cardiac output depression cardiovascular is considerable with halothane that is greater than the same that is greater than
the servant which in turn is greater than desflurane the mechanism physiological compensatory effect that increases the heart rate only happens in almost all species an example of how it doesn't happen but this mechanism it doesn't work very well and cardiac output remains low It's not my old man has nothing to do if you don't want to Do what's with you but only for us to understand if we want a total intravenous anesthesia only with propofol we have to use high infusion rates and blood pressure will fall the same then regardless of the anesthetic modality what
we have what to do is always a balanced anesthesia to use more medicines with lower doses And with that impact less on the physiology of patient an important thing that yes Active is better and patients who cannot have increased intracranial pressure inhaled anesthetics further increase the pique than injectables like propofol so in those cases Active is the best option but we have to understand which one will be anesthetic protocol adopted to make this happen in the best possible way Another important feature, at least historically, is that older anesthetics such as ether and halothane sensitize myocardium
to catecholamines then turn and move people to electrocardiographic operations patients this does not happen with ISO I conserve basically every inhalational anesthetics promote dose-dependent respiratory depression a power scale, desflurane is what most depresses the respiratory system after the servant and isoflurane the patient will certainly have a decrease in volume current and minute this may reflect hypercapnia but it is easy to resolve ventilatory support and it is not a problem a characteristic interesting thing that differentiates the iso from the servant is that the iso has an odor unpleasant then it is not very advisable to be
used by mask induction in this case serves the best option I particularly don't I really like doing it because of a mask first because Pollo and the operating room And the animal also tends to be particularly stressed I don't think that's cool but I know several people who make São Pô mask look good and Okay I only use induction for the most in peace India first and the biotransformation and hepatotoxicity of the struggling that perhaps have been the responsible for its abandonment, halothane has an average of 25 percent of biotransformation The problem is that the
main metabolite generated is acid trifluoroacetic which is hepatotoxic halothane still decreases blood flow liver and can promote for immune mediated Titis this usually happens in patients who received the fighting or even from the surgical team all effects undesirable effects of halothane are rarely seen with servo ISO and disfiguring only for us to have an idea the isoflurane biotransformation is 02 Percent and the disk per year 0.02 percent the so-and-so servant is yes percent I transformed but it generates inorganic fluorides that are inert to the organism the possibility of kidney damage with inhaled anesthetics is rare
this can happen in long procedures and with care but then in the case the root cause is going to be hypotension and doesn't use inhaled anesthetics and it's also easily reversed most of the time with vasoactive fluid therapy but heard in the context my old important thing student doesn't memorize but thing that doesn't have importance he knows everything is impressive hello compound a is formed by the degradation of the so-and-so servant in soda lime it is nephrotoxic but it has only been verified in rats in very good situations in practice this does not happen but
for safety the lime formulations currently used does not have monovalent bases in its composition that are the ones that make this reaction to malignant hyperthermia is a syndrome pharmacogenetics caused by inhaled anesthetics and blockers neuromuscular races some races of some species are predisposed to develop malignant hyperthermia in inhalation anesthesia the main clinical signs of malignant hyperthermia are hyperthermia muscle stiffness tachycardia and sweating this is even relatively frequent when we do anesthesia for some breeds of pigs with the hedgehog but this is very rare with that or I conserve it in case it happens very high
But we can try do supportive therapy with patient cooling and administration dantrolene one and environmental pollution is really the nerve point of inhalation anesthesia not only in the surgical environment but also in the atmosphere until the 1970s there is practically no anesthetic removal system from the operating room in medicine today this is mandatory in both medicine and veterinary we can do this with very simple systems in the passive system for example connecting an exhaust valve hose to an external outlet but there are other anesthetic escape possibilities other than the pop off valve like for example
when we have São by mask potting through the tube tracheal leakage by the equipment in filling the vaporizer And also the anesthetic return mainly in large animals the contamination of the room surgery with inhaled anesthetic can cause several changes in the team surgery such as cognitive motor deficit Oi Cleia nausea and irritation among two other concepts very questioned come out since the 1980s are the teratogenic and mutagenic power of inhalational anesthetics what is agreed is that there is no consensus that inhalational anesthetics promote mutagenic teratogenic effect how do we we will have a consensus that
there is no consensus identify a slight increase in the number of abortion among women on the team surgical but not teratogenic effect until abortion is somewhat questioned by safety I advise that pregnant women do not stay in a surgical environment in anesthesia inhalation Another very questioned point was mutagenicity but several studies Recent studies have already demonstrated that there is no relationship between inhalation anesthesia with cancer both in the patient and in the good surgical team even purging the anesthetic in the operating room they have the ability to gain the Beast and they contribute to global
warming both by destroying the ozone layer or by increasing the greenhouse effect halothane contains promo and Chlorine in its molecule this causes it to detonate the ozone layer isoflurane in turn only has chlorine and also damages the ozone layer but at a much lower intensity it doesn’t happen anymore and with desflurane in greenhouse effect all anesthetics contribute in this aspect we we can see in this table that the life span of the servant is very small about a year and a half the iso is a little more reaching up to those sticking with more 10
years old take a look at nitrous oxide over 100 years old should nitrous talks of the atmosphere until the time of Horácio Wells good in short we have that ISO and servo are less polluting than other anesthetics and the servo is still a little better than the ISO but obviously everyone contributes to this what we have This is the rational use of anesthesia inhalation using the balanced anesthesia protocol making low flow of fresh gas use suitable equipment that reduces leakage remove the anesthetic from the operating room and obviously use techniques that are better to reduce
this pollution but obviously the solution is not Bunny inhalation anesthesia on the planet as a conclusion of this video lesson we have to inhalation anesthesia has the advantages of providing rapid changes in plans autonomy in anesthetic time and low transformation inhaled anesthetics promote hemodynamic depression and should not be unique in the anesthetic protocol balanced anesthesia helps to decrease this impact and thus promote best anesthesia currently isoflurane ie so-and-so are the most common anesthetics employed because they are safer for both the patient and the ambient music environmental pollution is an important point in anesthesia inhalation and
should be viewed responsibly using low flow to minimize anesthetic consumption and removal from the environment surgical good people who are following the video lessons following already saw that we talk about associative anesthesia of general anesthesia intravenous and now inhalation anesthesia they all have advantages and disadvantages that must be considered according to the patient the procedure surgery continue to follow the video lessons Ok big hug and see you soon What's up
