WITHDRAWN: Determination of Minimum Infusion Rate and Cardiorespiratory Effects of Total Intravenous Anesthesia of Ketofol With or Without Lidocaine, Fentanyl or Dexmedetomidine in Dogs

Abstract

Background: Ketofol is a 1:1 mixture of ketamine and propofol that has been proposed for induction and maintenance of anesthesia aiming to provide more cardiovascular stability and less undesirable impacts compared to the use of propofol and ketamine alone. However, it has been associated with exacerbated respiratory depression in dogs. Diminishing the dose of ketofol may improve cardiovascular effects and attenuate respiratory depression. The present study was designed to evaluate the effect of adding lidocaine, fentanyl or dexmedetomidine at the required dose and cardiorespiratory variables in dogs undergoing total intravenous anesthesia (TIVA) with ketofol. In phase I, twelve dogs were induced and maintained with two out of four anesthetic regimens of KET: ketofol (4 mg/kg and 0.3 mg/kg/min, respectively), KLD; ketofol and lidocaine (1.5 mg/kg and 0.25 mg/kg/min, respectively), KFN: ketofol and fentanyl (LD: 5 µg/kg and 0.1 µg/kg/min, respectively) and KDX: ketofol and dexmedetomidine (2 µg/kg and 2 mg/kg/h, respectively). Minimum infusion rate (MIR) of ketofol was determined in this phase. Subsequently, in phase II, other twelve dogs were given the same anesthetic regimens for 60 min similar to the previous phase, except the infusion rate of ketofol. Cardiorespiratory variables were recorded in predetermined interval. Results: In phase I, mean MIR of ketofol for KET, KLD, KFN and KDX were determined to have decreasing manner as 0.35, 0.23, 0.15, and 0.08 mg/kg/min, respectively. In phase II, the times of recovery events were shorter in KFN and KDX than KET and KLD. Notably, HR was significantly higher than baseline during anesthesia in KET and KLD, which also was significantly lower than baseline in KFN and KDX at several time points. Significant higher values of MAP were observed over time in KDX. In all treatments, there was a decrease in respiratory rate and pH as well as an increase in PCO2 during the anesthesia session. Conclusions: It was concluded that despite decreasing the dose of ketofol, none of the added drugs attenuated respiratory depression caused by ketofol.

Effects of total intravenous anesthesia using ketamine and propofol combinations on physiological and anesthetic parameters in xylazine-premedicated mixed-breed dogs

“…The vomiting observed in some animals in this study could be associated with the use of the alpha-2-adrenoceptor agonist xylazine, as it is reported to stimulate the chemoreceptor trigger zone of the brain in cats, resulting in nausea and thus vomiting (Colby et al 1981). The respiratory depressant effect observed in this study and reported in other studies (Kennedy and Smith 2015;Rastabi et al 2021) could be due to the ability of ketamine and propofol to decrease the response to carbon dioxide and arterial hypoxemia (Rastabi et al 2021) but could also be a classical complication of xylazine (Clarke and Trim 2013). Combining the three drugs xylazine, propofol, and ketamine may also exacerbate respiratory depression.…”

“…Other parameters assessed included the quality and period of induction, anesthetic depth and recovery in addition to side effects, if any. Assessment of the quality of induction, anesthetic depth and recovery was adopted from Mair et al (2009), Kennedy and Smith (2015) and Rastabi et al (2021) with minor changes.…”

“…The ketofol induction dose was selected following previous studies by Kennedy and Smith (2015) and Rastabi et al (2021). The maintenance dose also followed the results of Kennedy and Smith (2015).…”

“…Constant rate infusion delivers a constant amount of short-acting anesthetic drug per unit time, thus producing a more stable plane of anesthesia over extended periods to cover the amount of time required for the animal to be under general anesthesia. The common delivery method for CRIs is calibrated syringe pumps; however, intravenous infusion sets such as burettes may also be used (Rastabi et al 2021). Compared with intermittent bolus infusion, this technique has also been reported to result in less cardiopulmonary depression and other negative effects and is thus relatively safer for animals (Njoku 2015).…”

“…A 1:1 ketamine:propofol combination ratio has been used but is associated with aggravated respiratory depression in dogs (Mair et al 2009;Kennedy and Smith 2015;Rastabi et al 2021). Few studies have also been undertaken in mixed breed dogs to determine their physiological responses to anesthetic agents.…”