Dosis requeridas y efectos cardio-pulmonares del propofol diluido y sin diluir en la inducción de la anestesia en perros

Hello everyone, today we have with us Fernando Martínez Tavoada, who is our man of the SEAB in the Antipodes and he is going to talk to us about a studio that they have published very recently, in which they proved that diluting the Propofol could reduce the necessary dosage for anesthetic induction. So, whenever you want Fernando, tell us. Hello, very good. My name is Fernando Martínez Tavoada and I am going to talk about one of the works that we have recently published in veterinary anesthesia and analgesia. This small studio we published about three months ago and it has the name of two requirements in cardiopulmonary effects of diluted and undiluted Propofol for induction of anesthetic dogs. In it, what we try to evaluate is the required dosage, the cardiopulmonary effects of Propofol to a normal concentration, that is, 10 mg/mL and once it has been diluted with saline to a concentration of 5 mg/mL in both cases for anesthetic induction in the dog. On the one hand, the base for which we started working in this studio was because it has been observed that other inductive agents, when they dilute with saline or with only physiological or with injection water, water sterile, allow to reduce the dosage of induction. On the other hand, it has also been published recently, in the last two years or so, that Propofol, if it is administered in a very slow way, also requires a lower dosage than if it is administered as recommended by the manufacturer. With these premises, our goal was to evaluate the dosage and the cardiopulmonary effects of the dilution of Propofol when compared to the normal Propofol in the dog. Our work hypothesis is that it will require less Propofol if it is diluted and consequently it will have less cardiopulmonary depression. The study was approved by the Ethical Committee of the University of Sydney and obviously the management of the owners to incorporate dogs into the studio. A calculation of the size was carried out that determined that 30 dogs would be needed to detect a difference of 1mg/kg in the inductor agent dosage, assuming a loss of data of 20% due to lack of some data, etc. The recruited dogs were clinical dogs that were subjected to surgery or diagnostic procedures that required general anesthesia and they were all considered ASA-1 or ASA-2 according to the physical test and an evaluation of the clinical history. All dogs were given a dosage of 0.02mg/kg of zepromacine mixed with methadone, and both were mixed in the form of intramuscular in the spaxial muscles. Once the animals had been sedated, after about 30-40 minutes, the sedation degree was evaluated with a scale of 4 points, where 0 is the non-sedation and 3 is a deep sedation, and immediately after that one of the cephalic veins was catalyzed. Once the vein had been catalyzed, the basal values ​​of the cardiopulmonary parameters were taken. These parameters were the cardiac frequency or the respiratory frequency and the non-invasive arterial pressure and we took both the systolic and diastolic as the average. Immediately after, the dogs were connected to a herring pump or an infusion pump that allowed us to induce anesthesia to a constant speed, whether it was in the Propofol group or the diluted Propofol group. The speed was the same and it was calculated according to the milliliters by the weight of the dog. The inductions were all carried out by the anesthetist himself, but this anesthetist did not know the distribution of groups. Once the patient reached the appropriate anesthetist , the infusion pump was separated and the intubation of the tracheal was carried out. After this maneuver, the dog was connected to the circular circuit with no oxygen, but not with fluorine iso, and the cardiopulmonary parameters of the new one were monitored for five minutes, with the patient without an anesthetist. In this period, this period was used to note the total dosage required by the inductor agent in volume, the apnea time, post induction, or the time between the induction and the first respiration that the spontaneous patient performed and the cardiopulmonary parameters were measured at 0, 3 and 5 minutes, which I will explain later, but it was calculated in the middle, which was what was used for the subsequent calculations. If a dog did not breathe for 60 seconds or if a dog had an oxygen saturation of under 92% during the period of five minutes, he would have to breathe manually at a rate of 4 per minute. Once the data collection period is over, the study was completed and the dogs could follow the anesthesia in a normal way, what is considered or what is considered the anesthetist as a normal and adequate management. From the statistical point of view, once the normalcy of the data was evaluated, or the lack of normalcy, the student tests and the man-witney tests were used to compare the medias and qualitative parameters were compared through a grid. The value of significance was granted to a value of P less than 0.05. Once we have reached the results, 15 dogs were included in each of the groups. In the Propofol group, a dog had to be excluded because the dog did not reach a plan anesthetic sufficient for intubation, with the Propofol that had been loaded in the herring, because it was really a dog between the size of the herring, therefore it had to be excluded and in the Propofol diluted group, a dog was excluded and began to reurgitate during the induction, therefore for a matter of security, the study was aborted in this dog and a quick intubation was had to be carried out to prevent an aspiration. There were no differences, therefore there were basically 14 dogs in each of the two groups. Among the dogs that were really included, there were no differences between the groups in what is referred to the distribution of sex, age, weight, distribution of the ASA group or distribution of sedation. The required dose for the induction of anesthesia was in the Propofol diluted group, it was 2.62 mg/kg, while in the Propofol group it was 3.48. Almost 30% bigger. There were no differences in the cardiac frequency, there were no differences in the blood pressure, despite the fact that there was a certain tendency for the dogs of the Propofol diluted group to have a time until the first respiration relatively lower, there was no significant difference in this parameter. The quality of the intubation was in general marginally better in the normal Propofol group when compared to the diluted Propofol, but the quality of the induction was similar among the two groups. In conclusion, we can say that after reading this study we can say that the diluted Propofol allows an intubation of similar characteristics to the normal Propofol, with a dose approximately 25% lower. I hope you liked it and see you in the next one. Thank you very much Fernando, I think it is a simple and very interesting study with immediate clinical applications, so I hope you liked it all and see you in the next chapter.