Introduction
In the postoperative period, fluid shifts in patients on cardiopulmonary bypass are common. These can often be treated with vigorous diuresis, but when patients have depressed myocardial function or acute injury, diuretic refracturiness may occur as the response to loop diuretics and is related to cardiac output and renal perfusion. This report describes the use of our system in a patient that suffered a perioperative myocardial infarction with depressed ejection fraction and pulmonary edema.

Case Report
A 71-year-old diabetic male presented with unstable angina pectoris and after cardiac catheterization, was found to have left main coronary disease and an associated high-grade anterior descending coronary lesion. The patient underwent three-vessel bypass surgery the day following angiography with saphenous vein graft to the LAD diagonal branch and the obtuse marginal branch, as well as an internal mammary artery bypass to the LAD. At the time of surgery, when the anterior descending artery was opened, thrombus was noted in the artery. The patient was readily weaned from cardiopulmonary bypass; but required significant inotropic support on the first postoperative night. Electrocardiography the morning following surgery showed a new Q wave in V-2, 3 and 4 and troponins were as high as 400. He was extubated the day following surgery. On the evening of the second postoperative day, the patient developed marked tachypnea, decreasing oxygen saturations, and respiratory fatigue. His pulmonary artery diastolic pressure went from 20 to 33 mmHg and required re-intubation. On the fourth postoperative day, the patient was hemodynamically stable and had decreasing oxygen needs on the ventilator. He was awake and alert and responding well to diuresis. On the fifth postoperative day, however, the patient had decreasing urinary responses to diuretics. The PAD was 21 mmHg. The CVP was 16 torr. The BUN had risen to 36 mg% and the creatinine to 1.7 mg% from a baseline 22 mg% and 1.4 mg%. He also had hypochloremic, hypokalemic, metabolic alkalosis related to loop diuretic utilization.   Alif -1 Eboo Safe was prescribed at a fluid removal rate of 300 to 500 cc per hour for a period of up to eight (8) hours. A total of 2 liters of free water was removed over 4.4 hours. The patient’s oxygenation improved and he was extubated on the following day.

Comment
Over diuresis occurs commonly, manifested by arteriolar intravascular volume contraction, increased systemic vascular resistance, and decreased renal perfusion particularly in the case of myocardial damage in which the cardiac output may be diminished or fixed. Intravascular volume as measured by the central venous pressure will remain increased. Pulmonary edema will then be refractory. Patients develop problems with electrolyte imbalance, induced arrythmias, particularly atrial fibrillation and enhanced activity of the neurohormonal axis. The use of our system, a form of veno-venous filtration, reduces this fixed preload without impacting hemodynamics or electrolyte concentrations. Pulmonary edema can readily resolve and patients can be more easily removed from mechanical ventilatory support.

Case history courtesy of:

Co-Director of Cardiac Surgery

Minnesota