Effects of Clonidine on the Requirements of Dopamine Used as a Concomitant Drug of Amrinone in Coronary Artery Bypass Surgery (CABG) / 대한마취과학회지

BACKGROUND: Clonidine premedication has many beneficial effects in patients undergoing CABG surgery. Amrinone, having the ability to increase cardiac performance without increasing myocardial O2 consumption, is a valuable drug in postoperative management after cardiopulmonary bypass (CPB). The use of amrinone with a catecholamine is also important clinically because the cathecholamines support perfusion pressure and the combined use exerts synergistic or additive effects. We performed this study to examine whether clonidine premedication could change the amount of dopamine used concomitantly with amrinone for management after CPB. METHODS: Nineteen patients for elective CABG were allocated to two groups according to their premedication; a placebo (Group 1, n = 13) or clonidine 4 microgram/kg p.o. (Group 2, n = 6). All patients arrived in the operating room with infusion of isosorbide dinitrate (ID). Anesthesia was performed with standard techniques. Before initiation of CPB, significant lowering of BP or HR was treated with phenylephrine or atropine respectively. Amrinone was given bolus (0.75 mg/kg) and infusion (10 microgram/ kg/min) was begun instead of ID at the release of aortic cross-clamp. Dopamine infusion (3 microgram/kg/min) was started at 35degree C (rectal) and its rate was adjusted for maintaining acceptable hemodynamics. We compared the amount of infused dopamine within 90 mins after CPB between the two groups. We also compared systolic BP, HR and CVP before induction, 10 mins after induction and 60 mins after CPB. RESULTS: Systolic BP and HR before induction and HR 10 mins after induction were significantly lower in Group 2 (P < 0.05), but they were all within normal range. The proportion of patients who needed phenylephrine or atropine before CPB was not significantly different in the two groups. The amount of infused dopamine was significantly larger in Group 2 (P < 0.05). Hemodynamics were acceptable after CPB although HR 60 min after CPB was significantly lower within the normal range in Group 2 (P < 0.05). Weaning time from CPB was not significantly different in the two groups. No significant adverse effect was observed throughout this study. CONCLUSIONS: Clonidine, used as premedication, increases the need of catecholamine which is concomitantly administered with amrinone for weaning from CPB. But this method provides clinically effective result without jeopardizing hemodynamics in CABG.

Effects of Amrinone on Systemic and Pulmonary Arterial Pressure in Infants with Intracardiac Left to Right Shunt / 대한마취과학회지

BACKGROUND: Amrinone is a nonglycosidic noncatecholamine with both vasodilator and positive inotropic effects that has not been evaluated widely in pediatric patients with intracardiac left to right shunts. The present study was performed to evaluate the hemodynamic effects of amrinone in infants and children with intracardiac left to right shunts. METHODS: Twenty patients (aged 2 months to 24 months) who underwent open heart surgery to correct one or more intracardiac left to right shunts were evaluated. Before cardiopulmonary bypass, a 22 gauge angiocatheter was placed at the main pulmonary artery by surgeons to measure pulmonary arterial pressure. Patients with a mean pulmonary arterial pressure or = 25 mmHg were assigned to Group B (n = 10). Mean systemic arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), central venous pressure (CVP) and heart rate (HR) were measured before loading of amrinone (3 mg/kg), 5 minutes, and 15 minutes after continuous infusion of amrinone (10 microgram/kg). The mean pulmonary arterial pressure to mean systemic arterial pressure ratio (MPAP/MAP) and rates of changes of mean arterial pressure (delta MAP) and mean pulmonary arterial pressure (delta MPAP) were calculated. RESULTS: Amrinone reduced MAP, MPAP, CVP and increased HR. MPAP/MAP increased in Group A but decreased in Group B (P < 0.05). In Group A, delta MAP was significantly greater than that of Group B (P < 0.005). In Group B, delta MPAP was significantly greater than that of Group A (P < 0.005). CONCLUSION: In infants with intracardiac left to right shunts, amrinone reduces MAP, MPAP, CVP and increases HR. Amrinone appears to have a potent vasodilating effect on the pulmonary artery in infants with pulmonary hypertension. However, more hemodynamic measurements such as cardiac output, vascular resistance and doppler echocardiographic study are necessary to evaluate the hemodynamic effects of amrinone precisely.

Comparison of Hemodynamic Effects between Dobutamine and Amrinone in the Patients with Pulmonary Hypertension / 대한마취과학회지

BACKGROUND: Dobutamine and amrinone, phosphodiesterase-III inhibitor, are known to have both inotropic and vasodilatory properties. We evaluated the effects of both drugs on systemic and pulmonary hemodynamics in patients with pulmonary hypertension (PH). METHODS: With Institutional Review Board approval, 45 patients whose mean pulmonary arterial pressure was greater than 30 mmHg were studied. After sternotomy under the steady state of anesthesia and controlled ventilation (30 mmHg < PaCO2 < 40 mmHg), patients recieved one of following drugs for 30minutes (min); dobutamine 5.0ug/kg/min (Group I), low dose amrinone (loading dose 1.0 mg/kg, followed by infusion 7.5 g/kg/min, Group II) or high dose amrinone (loading dose 2.0 mg/kg, followed by infusion 10 g/kg/min, Group III). Hemodynamic variables were measured at 10 min and 30 min after start of infusion. RESULTS: Dobutamine didn't decrease pulmonary arterial pressure (PAP) and cause no hemodynamic change while low and high dose amrinone reduced PAP and especcially decrease of PAP in low dose amrinone group was statistically significnat. High dose amrinone increased cardiac index (CI) and decreased both systemic vascular resistance index (SVRI) and central venous pressure (CVP) more significantly than control value. CONCLUSIONS: In patients with chronic right ventricular failure associated with PH, amrinone may decrease the PAP and improve cardiac performance more effectively than dobutamin does. Increment of dosage of amrinone may not result in significant reduction of PAP.