Cardiovascular effects of alfaxalone on hemodynamic function in pigs

Abstract

Background:The purpose of this study was to investigate the short-term cardiovascular effects of intravenous (IV) alfaxalone bolus injections in healthy pigs. Materials and methods: Each pig was sedated with ketamine, azaperone, and atropine intramuscularly, mixed in one syringe. Anesthesia was induced and maintained intravenously with alfaxalone. Then, three defined test bolus injections of alfaxalone were given intravenously. Vascular ultrasonography and pulse-induced contour cardiac output thermodilution monitoring were used to evaluate the direct cardiovascular effects after bolus injection. The following vascular and hemodynamic variables were recorded at the right common carotid artery (CCA) for 10 minutes after each alfaxalone injection by ultrasonography, pulse oximetry, and capnometry: peak systolic, minimum diastolic, end-diastolic, and time-averaged blood flow velocities; average volumetric flow; resistance index and vessel diameter; heart rate (HR); arterial oxygen saturation; and end-tidal carbon dioxide (PETCO 2 ). In addition, pulse contour-derived cardiac output recorded cardiac output, contractility, and volumetric variables for preload and afterload, as well as extravascular lung water, blood temperature, arterial blood pressure, and central venous pressure. Results: Alfaxalone bolus injections caused an initial short-lasting (0.25 minutes) decrease in diameter at the CCA after each bolus. During this very acute reaction, peak systolic blood flow velocity, thermodilutional cardiac output, and HR increased significantly. Average volumetric flow decreased, but not significantly. Mean arterial blood pressure decreased significantly at a time point of 0.25 minutes. Stroke volume, end-diastolic blood flow velocity, and resistance index did not change significantly. No cumulative effect was seen when three bolus injections of alfaxalone were given. Conclusion: Alfaxalone bolus injections produced two-phased short-lasting vascular (vasoconstriction at the CCA, vasodilation in the peripheral vessels) and hemodynamic changes (HR, mean arterial pressure), which were easily compensated by young healthy pigs. Because of those very short changes, alfaxalone is a safe hypnotic agent in healthy pigs; however, it may be used carefully in patients with ventricular dysfunction.

Differential effects of four intramuscular sedatives on cardiorespiratory stability in juvenile guinea pigs (Cavia porcellus)

“…Diazepam and midazolam increased HR to a greater degree than alfaxalone and ketamine. Such effects have previously been ascribed to alterations in vascular tone [ 6 , 24 , 25 ], despite no differences observed in the cutaneous microvasculature nor blood pressure during the current study. Cardiovascular depression is commonly noted with most sedative agents including alfaxalone and diazepam or midazolam [ 26 ], with commonly used adjuvants potentiating their effects [ 27 ].…”

“…Ketamine acts directly and indirectly on the cardiovascular system to simultaneously depress and enhance function [ 6 ], such that its cardiovascular effects are minimal, and are only observed when an adjuvant exacerbates its efficacy (e.g., KZ [ 22 ]). Alfaxalone is increasingly used as a sedative as it also has limited cardiovascular effects [ 5 , 24 , 28 – 30 ]. However, alfaxalone does elicit dose-dependent respiratory depression [ 5 , 30 ], as observed within the current study.…”

A Comparison of the Hemodynamic Effects of Alfaxalone and Propofol in Pigs

“…The reports regarding the direct, short-term cardiovascular effects of the hypnotics propofol and alfaxalone on hemodynamic function have already been published [6,7], the objective of the current study was to determine the hemodynamic and cumulative effects of these hypnotics during anaesthesia of 2.5 h in pigs.…”

“…However, no significant differences in means between medication groups were found in the post hoc Student's t-test for paired samples. GEF exhibited a significant decrease of 0.439±0.137 over time in the propofol given that after a bolus injection, an extremely brief baroreceptor reflex response could be observed for both hypnotics directly after the bolus injections [6,7]. A primary decrease in heart rate due to propofol is typically not evident; instead, heart rate typically increases due to blood pressure depression [18].…”

“…The objective of this study in pigs was to determine the most stable and gentle hypnotic agent with respect to the cardiovascular system; ideally, this agent should also be relatively non-cumulative. This investigation was followed by using previous studies that investigated the direct short-term cardiovascular effects of alfaxalone and propofol on porcine hemodynamic function [6,7].…”