Comparison of Postoperative Recovery between Balanced and Total Intravenous Anesthesia in Patients Undergoing Off-Pump Coronary Artery Bypass (OPCAB) Surgery: A Prospective, Single-Blind Randomized Study

2.1. Methods

This prospective, randomized, single-blind, controlled study was performed between March 2020 and August 2021 in single tertiary care hospital. The study protocol was approved by the Institutional Review Board of Chonnam National University Hospital (Approval number: CNUH-2020-015), and the study was registered at the Clinical Research Information Service of the Korea National Institute of Health (trial number: KCT0004726). All participants provided written informed consent before enrollment in accordance with the principles of the Declaration of Helsinki. Patients aged 20–79 years, corresponding to American Society of Anesthesiologists (ASA) physical status I–IV, and who were undergoing off-pump coronary artery bypass graft surgery (OPCAB) were enrolled in the study. Patients who were taking any sedatives, opioids, or sleep aids and those with a history of allergic reactions to any of the study drugs were excluded. Patients with physical disabilities, those who were illiterate, those who underwent conversion to coronary artery bypass grafting (i.e., cardiopulmonary bypass (CPB)), those with severe left ventricular dysfunction (ejection fraction < 30%), those who suffered from major organ failure before surgery (creatinine ≥ 2 mg/dL, AST/ALT ≥ 3 times higher than normal before surgery and showing a progressive increase, and neurological abnormalities), or who required continuous mechanical ventilation assistance after surgery were also excluded.

Pre-anesthesia visits and evaluations were conducted on the day before, or day of, surgery to confirm the patient’s general condition, preoperative test results, and medications. In addition, demographic information, height, weight, comorbidities, EuroSCORE II, and the number of affected coronary vessels were extracted from the patients’ medical records. At this time, a blinded investigator used the QoR-40K questionnaire to obtain baseline values for all patients. The patients were divided into two groups according to anesthesia method, i.e., a total intravenous anesthesia group (Group T) and balanced anesthesia group (Group B). The group assignment process was performed based on a computer-generated list of random numbers by a researcher who did not participate in the administration of anesthesia. Researchers investigating the QOR-questionnaire were unaware of the assignment.

After entering the operating room, each patient was monitored by 5-lead electrocardiography, pulse oximetry, and noninvasive blood-pressure monitoring. Before inducing anesthesia, we implanted a 22 or 20 G catheter into the radial artery and began continuous arterial blood-pressure monitoring. After recording the baseline vital signs, 8 L/min of oxygen was applied via a face mask and sufentanil (0.3 μg/kg) was infused.

Group T received target-controlled infusion of propofol (2% Fresofol^®; Fresenius Kabi Korea Ltd., Seoul, Korea) with the target plasma concentration set to 1.5–2.0 μg/mL. Infusion was increased in increments of 0.5 μg/mL until reaching a target bispectral index (BIS) of 40–60. In Group B, a bolus (1–1.5 mg/kg) of propofol (1% Fresofol^®; Fresenius Kabi Korea Ltd.) was administered slowly until the target BIS was reached. Sufentanil infusion was started at the beginning of anesthesia and was then infused continuously with a mean arterial pressure (MAP) of 70–90 mmHg in both groups. After loss of consciousness was confirmed, rocuronium (0.8–1.0 mg/kg) was administered intravenously to facilitate intubation. During maintenance of anesthesia, propofol or sevoflurane administration was adjusted according to the target BIS of 40–60. Fluids and vasopressors were used if necessary. In addition, capnography parameters, pulmonary artery pressure, transesophageal echocardiography parameters, and body temperature were monitored for all patients.

The surgery was performed via median sternotomy by the same surgical team (led by one surgeon). During surgery, body temperature was maintained within the normal range using an external heated mattress. Anesthetic management information, such as surgery time, anesthesia time, sufentanil dose, infused fluid volume, transfusion units, inotropic drug usage, and number of anastomotic vessels, was recorded. Blood pressure and heart rate (HR) were recorded at each time point after anesthesia induction, skin incision, sternotomy, anastomosis, protamine injection, and arrival at the intensive care unit (ICU) or general ward. After the operation, 0.075 mg of palonosetron was administered to all patients and they were transferred to the surgical ICU while maintaining mechanical ventilation. Extubation was performed by the attending physician if the patient met the criteria for extubation (responsive, negative inspiratory force > 20 mmHg, core temperature > 36.5 °C, arterial pH > 7.3, and absence of uncontrolled arrhythmia). Postoperative pain control was achieved using an intravenous patient-controlled analgesia (PCA) device (fentanyl; basal 6 μg/h; bolus 6 μg; lockout 10 min). Tramadol (50 mg) was administered intravenously as an additional analgesic if the patient complained of pain (numeric rating scale (NRS) score ≥ 4). Postoperative nausea and vomiting (PONV) scores were recorded (0: no PONV, 1: nausea, 2: retching, and 3: vomiting). Rescue antiemetics were injected in patients with PONV scores ≥ 3.

The primary outcome was the QoR-40K score 24 h after extubation. Secondary outcomes were the QoR-40K score 48 h after extubation; peri-operative vital signs (MAP and HR); total amounts of sufentanil, fluid, and blood products administered during surgery; use of inotropics; time to extubation after surgery; length of stay in the ICU; and length of stay in the hospital. Pain score (NRS), use of rescue analgesics, post-operative fentanyl consumption, post-operative nausea and vomiting (PONV), and use of rescue antiemetics were also measured as secondary outcomes at the time of extubation and 24 and 48 h thereafter. All researchers in this study were anesthesiologists.

The patient’s HR and blood pressure at the time of extubation and 24 and 48 h thereafter, pain at the surgical site, the amount of fentanyl used in the pain-control device, the use of additional analgesics, and the use of antiemetics were determined from the medical records. The number of transplanted vessels was confirmed based on the operation records. At 24 and 48 h after extubation, the questionnaires were completed by the participants themselves or by responding to what the researcher read to them.