Study design and subjects
This study method is based on Lee’s research [1]. This double-blind, randomized trial was approved by the Clinical Research Ethics Committee of The First Affiliated Hospital of USTC and was registered at http://www.chictr.org.cn (ChiCTR-IOR-16007987, Principal investigator: Chengwei Yang, registration date: 24/02/2016). Transforaminal lumbar interbody fusion (TLIF) is a common surgical method for lumbar disc herniation, using unilateral transforaminal approach, unilateral facet resection, and placement of an interbody fusion cage. Written informed consent was obtained from 80 patients undergoing elective one-level or two-level primary TLIF from 2018 to 2020 who had a primary diagnosis of spondylolisthesis, lumbar spinal stenosis, severe degenerative disc disease or facet arthropathy. The inclusion criteria were as follows: (1) males, (2) 18–64 years old, (3) body mass index (BMI) 18.5 ~ 24.9 kg/m2, and (4) American Society of Anesthesiologists (ASA) physical status I or II. The exclusion criteria were as follows: (1) liver and kidney dysfunction, (2) a history of central nervous system diseases, (3) language barriers or illiteracy, (4) the use of hormones, opioids, sedatives or antiemetic drugs 2 days before surgery, (5) refusal to participate in the study at any stage.
Perioperative management
The eligible patients were randomly assigned into two equal groups (SEVO and TIVA groups) using a random-permuted block randomization algorithm via a web-based response system (www.randomization.com). Blinding was performed using opaque envelopes with number. Each envelope contain a patient’s study protocol. The researchers opened sealed envelopes before anesthesia induction. The preoperative evaluators, follow-up assessors and statisticians were blinded to the group allocation.
All subjects fasted routinely before surgery and received no premedication. Standard monitoring was conducted, which included electrocardiography, arterial blood pressure monitoring, pulse oximetry, airway pressure monitoring, capnography, and evaluation with the bispectral index (BIS VISTATM monitor, Aspect Medical Systems, Norwood, MA). In both groups, general anesthesia was induced using 1.5–2.5 mg kg− 1 propofol, 0.4 μg kg− 1 sufentanil, and 0.6 mg kg− 1 rocuronium. Tracheal intubation was performed in all patients using a 7.5 mm (internal diameter) tracheal tube. Mechanical ventilation was maintained with a tidal volume of 8–10 ml kg− 1, and partial pressure of end-tidal carbon dioxide (PEtCO2) was maintained at 35 to 45 mmHg. The carrier gas flow for both groups consisted of a combination of oxygen and air to a total flow rate of 2 L/min (fraction of inspired oxygen 0.5). Maintenance was achieved with TCI (CP-730TCI; Inc., Beijing SLGO, China) propofol (Marsh pharmacokinetic model), 1.5–3 μg ml− 1 propofol in the TIVA group, and sevoflurane (1.5–3.0%) in the SEVO group. For patients in both groups, analgesia was provided with remifentanil (Minto pharmacokinetic model) and sufentanil, and tropisetron hydrochloride was used as an antiemetic. Neuromuscular blockade was determined by a TOF monitor (Veryark-TOF, Guangxi, China). Rocuronium (0.15 mg/kg) was administered intravenously when T1/Tc values height reached 25%. BIS values were maintained ranging from 40 to 60 to monitor the depth of anesthesia. The mean arterial pressure (MAP) was maintained within 20% of the baseline value [14]. 5 min before suture, 20 ml 0.5% ropivacaine was injected into skin and subcutaneous tissues for postoperative analgesia (i.e.,10 ml per side of the incision line).
Quality of recovery was assessed before surgery and on POD1 and POD2 using the QoR-40, which included five dimensions (physical comfort, emotional state, physical independence, psychological support, and pain). The total QoR-40 score ranges from 40 (poorest quality of recovery) to 200 (best quality of recovery).
When the wound was closed, general anesthesia management for all patients was terminated, and the wake time from anesthesia began. Pain and postoperative nausea and vomiting (PONV) were measured using an 11-point numeric rating score in the postanesthesia care unit (PACU). If the score of each item exceeded 4, flurbiprofen axetil or tropisetron hydrochloride was given in PACU or ward .
In addition, the following data were also collected: perioperative MAP and heart rate (HR), consumption of remifentanil, response time (between the cessation of anesthetic maintenance drugs and the patient’s response to a verbal command), extubation time, the incidence of PONV, PACU and the postoperative hospital stay time.
Statistical analyses
Postoperative QoR-40 score was the primary outcome of this investigation. The calculation of sample size was based on Lee’s research and our pilot study. The mean QoR-40 score of TIVA group was 174 in Lee’s research [1], and the standard deviation (SD) was 14. Based on the assumption that a 10-point difference represents a 15% improvement in the quality of recovery [13], 31 subjects per group were required to achieve a power of 80% with a type 1 error of 0.05. Considering a 20% drop-out rate, 80 subjects were enrolled.
SPSS version 16.0 software (SPSS Inc., Chicago, IL) was used for statistical analysis. Continuous variables are expressed as mean ± standard deviation or median (interquartile range). If the data meet the normality, the t-test was used for inter group comparison. Otherwise, the non-parametric test was used for inter group comparison. A P-value of < 0.05 was considered statistically significant.
