Case presentation
The patient was a 73-year-old man with a height of 170 cm and weight of 58 kg. He had a history of diabetes and chronic kidney disease and was being followed up by the nephrology department of our hospital. This time, he was admitted to the coronary care unit for fluid control owing to acute exacerbation of chronic kidney disease and a diagnosis of congestive heart failure. Electrocardiography displayed flat T-waves in the inferior leads (II, III, and aVF leads), and negative T-waves were observed in the precordial leads (V1–V4 leads). Additionally, echocardiography demonstrated a reduced left ventricular ejection fraction of about 30% and diffuse wall-motion abnormalities. On stress myocardial scintigraphy, suspected ischemic findings were observed in the distal region of the left anterior descending artery and the right coronary artery, and coronary angiography (CAG) was performed. The patient was found to have triple vessel disease on the CAG and was scheduled for a CABG. Owing to the patient’s low cardiac function, the strategy of on-pump beating CABG was adopted. In addition, anesthesia management of the patient was considered carefully, and it was decided that drugs that cause minimal circulatory depression should be used as much as possible.
Anesthesia was induced with remimazolam at 12 mg/kg/hr, remifentanil at 0.3 µg/kg/min, and rocuronium at 50 mg. Anesthesia maintenance was performed with remimazolam at 1 mg/kg/hr, remifentanil at 0.25 µg/kg/min, and rocuronium at 20 mg/hr. An 8 mm-endotracheal tube was used for intubation. Phenylephrine (0.05 mg) was administered as needed for hypotension. During the surgery, monitoring was performed with invasive arterial pressure, peripheral blood oxygen saturation, central venous pressure, Patient State Index (PSI), regional oxygen saturation, and transesophageal echocardiography. Continuous monitoring of cardiac output was also performed using the FloTrac™ Sensor (Edwards Lifesciences Co., Tokyo, Japan). (Figure.1) From induction to just before the cardiopulmonary bypass (CPB), the cardiac output and cardiac index remained at about 3.0 to 4.0 L/min and 1.8 to 2.5 L/min/m2, respectively. Stroke volume variation (SVV) remained at about 15%. In addition, administration of the coronary vasodilator nicorandil was started at a rate of 3 mg/hr, and isosorbide dinitrate at a rate of 1 mg/hr from the time of induction. The patient underwent on-pump beating CABG without any significant hemodynamic instability during the CPB. The grafts used were the left internal thoracic artery, left radial artery, and great saphenous vein. Five branches were anastomosed. During separation from the CPB, a continuous infusion of dobutamine at a rate of 0.5 µg/kg/min was administered. The patient’s hemodynamic status remained stable without any significant problems even after weaning off from the CPB, and anesthesia was successfully maintained. After separation from the CPB, remimazolam was continuously administered at a rate of 0.7 to 0.8 mg/kg/hr. We were using the PSI as an indicator of sedation, and PSI values remained at about 30 to 40. Anesthesia time was 8 hours and 32 minutes, surgical time was 7 hours and 20 minutes, and CPB time was 3 hours and 43 minutes. The total amount of fluid administered was 1,550 mL, and the amount of bleeding was 1,090 mL. The patient received a transfusion of 4 units of red blood cell concentrate and 1,000 mL of 5% albumin products. Upon admission to the intensive care unit, the patient was weaned off mechanical ventilation, extubated on postoperative day (POD) 1, and was transferred to a general ward on POD 3. The subsequent course was uneventful, and the patient was discharged on POD 15.