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.