A total of 80 patients scheduled for radical prostatectomy from March 25, 2019 to April 1, 2020 were recruited for this study. Patients with the following conditions were excluded: 1) ropivacaine allergy, 2) psychiatric illness, 3) skin infection at the proposed puncture site, 4) peripheral neuropathy, 5) history of opioid abuse, 6) chronic pain or 7) inability to complete the pain digital rating scorer inability score pain on the numerical rating scale (NRS). Withdrawal criteria were death within 48h postoperatively and major intra- or postoperative bleeding.
This clinical trial was started after obtaining approval from the ethics committee of Shanghai Tenth People’s Hospital. Informed consent was obtained from all patients (or family members).
SPSS 17.0 (SPSS Inc., Chicago, IL, USA) was used for random grouping to conceal the random process using envelopes to seal the random numbers, which were strictly assigned based on the order of patient selection. Patients were randomly divided into QLB and sham block groups in a 1:1 ratio. Randomisation was performed inside the operating room. A sealed envelope containing the randomisation code was opened just before administering anaesthesia. Enrolled patients were randomly assigned to receive either general anaesthesia plus QLB with ropivacaine (QLB group, n = 40) or plus sham QLB, that is, normal saline (NS group, n = 40). A caregiver who was unaware of the experimental protocol prepared the ropivacaine and saline solutions. Subsequently, a preloaded syringe containing 20 ml of the colourless solution was handed over to the anaesthetist. Patients, anaesthesiologists, surgeons and follow-up personnel were blinded of the drugs used.
Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), electrocardiogram (ECG), bispectral index (BIS) and the degree of peripheral capillary oxygen saturation (SpO2) were routinely monitored after the patients entered the operating room. The central venous access was established under local anaesthesia. General anaesthesia was induced with 1.5-2.0 mg/kg of propofol (production batch number: X17052B, AstraZeneca Pharmaceutical Co., Ltd.), 0.4µg/kg of sufentanil (production batch number: 1180414, Yichang Renfu Pharmaceutical Co., Ltd.) and 0.15 mg/kg of cisatracurium (production batch number: 180702AJ, Jiangsu Hengrui Pharmaceutical Co., Ltd.) via tracheal intubation. Intraoperative BIS was maintained at 40–60.
Anaesthesia was maintained with 4–6 mg/kg/h of intravenous propofol (production batch number: NX190, AstraZeneca Pharmaceutical Co., Ltd.), 0.05–0.2 µg /kg/min of remifentanil (production batch number: 80A05081, Yichang Renfu Pharmaceutical Co., Ltd.) and 0.7–1.5 minimum alveolar concentration (MAC) of inhaled sevoflurane (production batch number: 18070531, Shanghai Hengrui Pharmaceutical Co., Ltd.). Cisatracurium at a dose of 4–6 mg/h was administered through intermittent intravenous injection. Remifentanil and sevoflurane concentrations were adjusted based on varied vital signs. For analgesia, all patients were intravenously administered 40 mg of parecoxib (production batch number: W27811, Pfizer Pharmaceutical Co., Ltd.) and 12.5 mg of dolasetron mesylate (production batch number: 18062171, Liaoning Haisi Pharmaceutical Co., Ltd.). The intravenous and inhaled anaesthetics were discontinued when the subcutaneous tissue had been sutured. The endotracheal tube was removed after spontaneous breathing was resumed and consciousness level was returned.
Patients with high SBP (≥ 140 mmHg) for the first 2–3 min intraoperatively were administered sufentanil at a dose of 5–10µg. However, if SBP remained high, 0.3–0.5 mg of perdipine was intravenously infused and readministered as necessary. Patients with low SBP (< 90 mmHg) for the first 2–3 min intraoperatively were intravenously administered 40–80µg of phenylephrine. If there was no response, the same medications were readministered, and 200 ml of colloidal solution was added and rapidly infused. If HR was higher than 100 beats/min, 1 mg/kg of esmolol was intravenously administered and repeated as necessary, whereas if HR was lower than 45 beats/min, 0.5 mg of atropine was intravenously administered and repeated as necessary.
Postoperatively, 150µg of sufentanil dissolved in 100ml NS was intravenously infused at 2 ml/h for analgesia in both groups, and patient-controlled analgesia was achieved with a dose of 0.5 ml and a locking interval of 15 min. Patients with severe postoperative pain (NRS ≥ 7) were administered 50 mg of meperidine intramuscularly.
The QLB group underwent bilateral QLB before the induction of general anaesthesia. The QLB procedure has been previously described . Briefly, patients were placed in the right lateral position and routinely disinfected and draped. A portable, coloured, two-dimensional ultrasound machine (Bothell, FUJIFILM SonoSite, USA) equipped with a low frequency (5 − 2 MHz) convex array probe was used for guidance. First, the probe was placed horizontally above the anterior part of the iliac crest, and the external oblique, internal oblique and transverse abdominis muscles were identified. Subsequently, the probe was moved to the back until the quadratus lumbar muscle, psoas muscle, erector spinae and transverse processes of the vertebrae were visible. A 22-G, 8-cm-long nerve plexus stimulation needle (Béron, USA) was inserted from the dorsal to the ventral side. The needle was advanced until the tip was located to the fascia between the quadratus lumborum and psoas muscles (as indicated by the blue arrow in Fig. 1). Correct needle tip positioning was confirmed by injecting 1 ml of NS. Subsequently, a 20 ml mixture comprising 75 mg of ropivacaine (production batch number: 180611CA, Jiangsu Hengrui Pharmaceutical Co., Ltd.) and 25µg of dexmedetomidine (production batch number: 181012BP, Jiangsu Hengrui Pharmaceutical Co., Ltd.) was injected . The patients were then shifted to the left lateral position, and the procedure was repeated for the left QLB. The same procedure was administered to patients in the NS group; however, 20 ml of 0.9% NS was injected instead of the anaesthetic mixture. All operations were performed by the same group of experienced urologists. All QLBs were performed by the same experienced anaesthesiologist. The average operative time was 12.5 minutes.
The primary end-point was the NRS score at different time points during the first 48h postoperatively. NRS scores at rest and when coughing were recorded at 2, 4, 6, 12, 24 and 48h postoperatively. Secondary end-points included the intraoperative remifentanil and sufentanil doses, subjective comfort, handgrip strength and recovery parameters (first time of exhaustion, first fluid intake time, time to get out of bed and length of postoperative hospital stay). Cumulative doses of sufentanil at the same time points were recorded. Moreover, 50 mg of meperidine was considered equivalent to 5 µg of sufentanil. The degrees of anxiety, thirst, hunger, nausea and fatigue were each scored on a scale of 0 to 10, (0, no discomfort; 1–3, mild discomfort; 4–6, severe discomfort; 7–9, severe discomfort and 10, unbearable discomfort). The total score was used to measure subjective comfort. Handgrip strength was standardised by expressing it as a function of body weight using the following formula: (grip strength [kg] / body weight [kg]) × 100. Handgrip strength was tested on the same upper limb. Subjective comfort, handgrip strength were evaluated preoperatively and at 24, 72 and 168 h postoperatively. The first time of exhaustion (time from the end of the operation to the first exhaust), first fluid intake time (time from the end of the operation to the first fluid intake), time to get out of bed (time from the end of the operation to the first off-bed activity) and postoperative hospital stay (days from the end of the operation to discharge) were recorded. Overall satisfaction was evaluated at 48h postoperatively in both groups and graded as follows: 5, very satisfied; 4, satisfied; 3, somewhat satisfied; 2, dissatisfied and 1, very dissatisfied.
Statistical analysis: The SPSS software, version 17.0, was used for all statistical analyses. Normally distributed continuous data were expressed by means (standard deviation) and comparisons were made between groups using the independent samples t-test. Continuous data of repeated measurements in the same group were compared using repeated-measures analysis of variance (ANOVA). Multivariate ANOVA was used to compare between groups at the same time points. Count data were expressed as percentages and compared using the chi-square test. P ≤ 0.05 was considered statistically significant.