Comparing the Hemodynamic Effects of Epinephrine Versus Dexmedetomidine as an Adjuvant to Bupivacaine in Caudal Anaesthesia Assessed by Cardiometry

Electrical cardiometry (EC) is a non-invasive method of estimating cardiac parameters by measuring changes in thoracic bioimpedance during the cardiac cycle. The ICON (Cardiotronic Osypka Medical, San Diego, California) monitor uses four electrocardiogram electrodes and estimates the maximum rate of impedance change to peak aortic blood acceleration. An impedance change occurs between diastole and systole as red blood cell orientation is altered from random during diastole to align during systole. This device is validated against Fick cardiac output and transthoracic echocardiography in infants and children, as well as thermodilution in adults with R values of 0.9. This device is approved by the Food and Drug Administration (FDA) for use in pediatrics. Hypotension is expected to occur after epidural anesthesia (EA) due to the dilatation of venous vessels by sympathetic blockade with a subsequent decrease in venous return and cardiac output (CO). Also, the association of general anesthesia (GA) to EA can lead to more decrease in CO. The addition of epinephrine to local anesthetics (LA) could worsen hypotension through the systemic absorption of epinephrine that leads to a vasodilator β effect. Yet, CO may be enhanced by this β-adrenergic stimulation. However, it is well known that caudal epidural anesthesia has few or no hemodynamic changes in children less than 8 yr old. This could be attributed to the immaturity of their sympathetic system and smaller lower-limbs blood volume compared to adults. Caudal anesthesia is highly effective in abdominal, urinary tract, and lower extremity surgeries in children for intra- and postoperative analgesia. The addition of dexmedetomidine to local anesthetics in caudal anesthesia is a frequent practice. Dexmedetomidine, a highly selective alpha-2 adrenoreceptor agonist, is used as an intravenous sedative and analgesic drug. It has an a2/a1 selectivity ratio of 1600: 1 and is eight times more potent than clonidine. Intrathecal and