Hemodynamic Responses and Changes in Oxygen Extraction When Using Amrinone, Dobutamine and Isoproterenol in Cardiac Tamponade-Induced Dogs

Chung, Sung Won; Kim, Jin Mo; Cheun, Jae Kyu; Kim, Ae Ra; An, Youn Jeong

Abstract

BACKGROUND: Cardiac tamponade is most commonly treated by needle aspiration or surgical drainage. During this process, it may be necessary to temporarily improve cardiac output and to maintain peripheral perfusion by using vasoactive drugs and volume expanders. The purpose of this study is to examine the hemodynamic effect along with oxygen availability on cardiac tamponade induced dogs caused by the use of dobutamine, isoproterenol and amrinone following pentastarch infusion.
METHODS
Twenty-four dogs were divided into four groups including a control group (group I), which received only pentastarch 10 ml/kg after artifical tamponade was induced. Following the administration of pentastarch, group II (n = 6) received dobutamine by dripping 10 microgram/kg/min, and then by 20 microgram/ kg/min, group III (n = 6) received isoproterenal (0.5 microgram/kg/min, 1.0 microgram/kg/min) and group IV (n = 6) received amrinone (50 microgram/kg/min, 100 microgram/kg/min). The hemodynamic parameters were measured in seven intervals: baseline, thoracotomy, tamponade, tamponade plus pentastarch, pentastarch plus dripping (1st dose), pentastarch plus drug (2nd injection = two times the 1st dose), and pericardiostomy. Arterial and mixed venous blood gas analyses were carried out in three intervals: after thoracotomy, tamponade, pentastarch plus drug (infusion). Subsequently, oxygen extraction ratios were calculated from the oxygen delivery and oxygen consumption.
RESULTS
The heart rate increased significantly during the infusion of isoproterenol (P = 0.032) 1.0 microgram/kg/min in group III and also during the dobutamine infusion when the pericardiostomy (P = 0.028) was performed in group II. Compared to the control group, cardiac output increased significantly in group II from the infusion of the 1st dose and also in group III with the 2nd dose infusion but there were no significant changes in group IV. Although the average intrapericardial pressure was 0.93 mmHg in each group and was increased to 8.23 mmHg during the induced tamponade, no significant changes occurred in the groups with drug infusion. The oxygen extraction ratio fell significantly in the groupII, III and IV during the drug infusion.
CONCLUSIONS
As results of this study, it was concluded that the most effective hemodynamic improvements during the induced cardiac tamponade occured in group II with pentastarch-dobutamine while the least effective combination occurred in group IV with pentastarch-amrinone.