Effects of dobutamine on cardiovascular function and oxygen delivery in standing horses

Abstract

Dobutamine is routinely used to improve cardiovascular function in anaesthetized horses. However, dobutamine in conscious horses is insufficiently investigated. Ten research horses that were already instrumented for a preceding trial were included into the study. Cardiovascular variables were recorded and blood samples taken after instrumentation (Baseline), before starting dobutamine and after 10 min of dobutamine infusion (2 µg kg−1 min−1). A significant increase in systemic blood pressure, mean pulmonary artery pressure and right atrial pressure, and a decrease in heart rate were observed with dobutamine compared with baseline measurements. Arterial and mixed venous haemoglobin and oxygen content, as well as mixed venous partial pressure of oxygen increased. No significant changes in cardiac output, stroke volume, systemic vascular resistance, arterial partial pressure of oxygen, or oxygen consumption, delivery and extraction ratio were detected. Concluding, dobutamine increased systemic blood pressure without detectable changes in stroke volume, cardiac output or systemic vascular resistance in conscious horses.

Agreement of Bioreactance Cardiac Output Monitoring With Thermodilution in Healthy Standing Horses

“…To induce high cardiac output states dobutamine was administered at dosages of 1.5 and 3 mcg/kg/min. In anesthetized and in standing horses dobutamine infusion rates of 0.5 to 4 mcg/kg/min resulted in an increase of cardiac output up to 35% (31)(32)(33) which was also seen in our horses. These drug protocols resulted in CO values ranging from 22 to 75 L/min measured by TD and these trends and changes were detected by NICOM with great correlation (r 2 = 0.978).…”

Effect of physiological and pharmacological stress on heart rate, blood pressure, and echocardiographic measurements in healthy Warmblood horses

“…Administration of detomidine hydrochloride resulted in decreases in HR and cardiac output (CO) with a tendency to increases in left atrial and ventricular dimensions 11‐15 . Cardiac dimensions and function were also altered during physiological (treadmill exercise, lunging exercise) or pharmacological stress testing with atropine (parasympatholytic drug), or dobutamine (sympathomimetic drug), with high HR above 80 bpm and important increases in BP 16‐23 . Postexercise evaluation of cardiac variables and pharmacological stress testing demonstrated decreases in left ventricular dimensions with increases in interventricular septum and left ventricular free wall thicknesses as well as an increased left ventricular fractional shortening (FS) 18‐20,23‐27 .…”

“… 11 , 12 , 13 , 14 , 15 Cardiac dimensions and function were also altered during physiological (treadmill exercise, lunging exercise) or pharmacological stress testing with atropine (parasympatholytic drug), or dobutamine (sympathomimetic drug), with high HR above 80 bpm and important increases in BP. 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 Postexercise evaluation of cardiac variables and pharmacological stress testing demonstrated decreases in left ventricular dimensions with increases in interventricular septum and left ventricular free wall thicknesses as well as an increased left ventricular fractional shortening (FS). 18 , 19 , 20 , 23 , 24 , 25 , 26 , 27 However, the influence of slight changes within the normal physiological range of HR on echocardiographic variables of cardiac function has not been investigated yet.…”