The effect of milrinone on metabolism after cardiopulmonary bypass.

AIM: The aim of this study was to examine the effects of milrinone on tissue metabolism perioperatively in cardiac surgery patients using extracorporeal circulation, in comparison to adrenaline and placebo. These effects were measured indirectly by measuring serum lactate, base excess and glucose levels at standard intervals. METHODS: Seventy-seven consecutive patients, who underwent elective cardiac surgery, were allocated in 3 groups. Inotropic support was initiated coming off CPB (cardiopulmonary bypass) if there was evidence of hypotension (mean arterial pressure [MAP] <60 mmHg), after adequate preload (pulmonary capillary wedge pressure [PCWP] >10 mmHg). Milrinone was used in patients with pulmonary hypertension (MPAP >20 mmHg). Group 1 (N.=26) received no inotropes, placebo. Group 2 (N.=32) received adrenaline. Group 3 (N.=19) received adrenaline + milrinone at 0.5 microg/kg/min infusion. Adrenaline was infused at a variable dose (0.01-0.02 microg/kg/min) to achieve a MAP >60 mmHg. The serum lactate, base excess and glucose levels were measured at standard intervals in all 3 groups. Diabetic, hepatic or renal failure patients (serum creatinine >2 mg/dL), were excluded from the study. Patient demographic and clinical characteristics were similar in all 3 groups. RESULTS: Repeated measure analysis of variance between groups showed significantly lower serum lactate levels and higher base excess in the milrinone group (P<0.05), after 2 to 4 hours of treatment. Serum glucose levels were higher in the adrenaline group (P=0.01). There were no immediate complications, morbidity or mortality in the study groups. CONCLUSION: These findings suggest that milrinone has a beneficiary effect on aerobic tissue metabolism after extracorporeal circulation, reflected on serum lactate, base excess and glucose levels, possibly due to a combination of positive inotropic and peripheral vasodilatory effect of the drug.

Reliability of continuous jugular venous bulb hemoglobin oxygen saturation during cardiac surgery.

OBJECTIVE: To evaluate the accuracy and reliability of continuous measurement of jugular venous bulb hemoglobin oxygen saturation (SjvO2) with a fiberoptic catheter (SjvO(2OX)) during cardiac surgery versus simultaneous paired measurements of hemoglobin oxygen saturation by the Hemoximeter (SjVO(2HEM); Radiometer, Copenhagen, Denmark) and indirect estimations of hemoglobin oxygen saturation from measurements of partial pressure of oxygen in blood gases (SjVO(2BG)). DESIGN: A prospective study. SETTING: American Hellenic Educational Progressive Association General Hospital, University Hospital of Thessaloniki, Greece. PATIENTS: Thirty patients undergoing elective aortocoronary artery bypass surgery. INTERVENTIONS: In addition to routine pressure monitoring, a 4F fiberoptic catheter was placed in the left jugular bulb by a retrograde internal jugular vein approach and SIvO(2OX) was continuously measured. Before insertion, each catheter was calibrated in vitro. MEASUREMENTS AND MAIN RESULTS: One hundred twelve simultaneous paired recordings between SjvO(2OX) and SjVO2BG were performed to define the accuracy of SjVO(2OX) to SjVO(2BG). Sixty-one of 112 simultaneous paired recordings between SjvO(2OX) and SjVO(2HEM) and SjVO(2HEM) and SjVO(2BG) were performed to define the accuracy of SjvO(2OX) to the reference SjVO(2HEM) and the reliability of the SjVO(2BG) measurement to SjVO(2HEM). The fiberoptic catheter readings varied from underestimating to overestimating hemoglobin saturation by a mean of -5.35% to +9.67% and of -3.22% to +7.81% versus Blood Gas Analyzer (Ciba-Corning) and Co-Oximeter (OSM 2b Hemoximeter, Radiometer) values, respectively. The mean underestimation and overestimation of Co-Oximeter versus Blood Gas Analyzer values were -3.18% and +4.17%, respectively. CONCLUSION: SjvO2 values obtained continuously from a jugular venous bulb fiberoptic catheter may give relatively accurate readings provided they are duly interpreted and errors caused by wall artifact or blood sampling are avoided.