Ethical approval
This study was approved by the ethics committee of Drum Tower Hospital Affiliated with the Nanjing University Medical School (reference number: 2019-304-01).
Methods
The medical information of the patients undergoing PCNL was retrieved from the electronic charter system (Medisystem, Suzhou, China) in our Nanjing Drum Tower Hospital from Jan/2019 to Jun/2019. Query used the following criteria:(a) anesthesia start time within the specified date/time parameters;(b) surgical procedure equal to PCNL;(C) patient has a completed pain assessment procedure form indicating the performance of QLB-L or QLB-TM. This is a retrospectively comparative study comparing the analgesic effect of ultrasound-guided QLB with two different approaches (QLB-L group, QLB-TM group) versus routine practice (control group) on postoperative pain following PCNL.
Participants
Those eligible patients with age> 18 years old, ASA physical status classification Ⅰ-Ⅲ scheduled to undertake the selective PCNL procedure were included in this retrospective study. The patients with the history of severe hypertension (systolic blood pressure >180 mmHg), diabetes mellitus with neuropathic pain, hepatic cirrhosis, renal function insufficiency, depressant condition, alcohol addiction, chronic intake of oral NSAIDS or analgesics, or with incomplete/loss of clinical data were excluded in this study.
Anesthesia and perioperative management
Implement of Quadratus lumborum block prior to general anesthesia
QLB-L technique: QLB-L technique (schematic illustration in Fig-1a, b): The patient was placed securely in the lateral decubitus position. A low-frequency curvilinear probe (SonoSite Edge, transducer C60x/5 2MHz, Fujifilm Sonosite Inc, US) was attached above the iliac crest. Under the guidance of ultrasound, the 18 gauge 10-cm needle (Stimuplex® D, B. Braun Medical Inc., Germany) was applied to puncture from dorsal to ventral direction aiming at the anterolateral margin of the junction of QL and transversalis fascia, and 5 ml saline solution was injected to confirm the correct position by hydro-dissection phenomenon. [13] The block was completed with the 0.375% ropivacaine at a volume of 0.5 ml/kg thereafter. The range of sensory block was tested 30 min after the procedure. Patients whose block plane of abdominal wall between T10-L1 level 30 min after the block were considered to have achieved effective blockade.
QLB-TM technique: QLB-TM technique (Fig-1c and d): The patient was placed on the same position as the QLB-L technique. The ultrasound probe was vertically attached above the iliac crest. The transverse process of second lumbar vertebra (L2) and typical shamrock image were identified, and the needle was inserted from the edge of the probe and proceeded further into the fascia between the QLM and psoas major muscle. The local anesthetics were injected into the accurate interfascial plane between these two muscles.
Induction and maintenance of anesthesia
All patients received standard general anesthesia monitoring and intravenous infusion commenced with Lactate Ringer’s solution at the rate of 400 ml/h to replace the fluid loss owing to 8 h fasting and no drinking. Anesthesia was induced with intermittent bolus injection of (midazolam 0.01 mg/kg), propofol (2 mg/kg), sufentanil (0.2 ug/kg), and cisatracurium (0.2 mg/kg) facilitated in tracheal intubation. The mechanical ventilation was commenced to maintain the end tidal PCO2 at 40 mmHg. General anesthesia was obtained by total intravenous anesthesia with continuous infusion of propofol (4-6 mg/kg/min), cisatracurium (2 μg/kg/min) to ensure appropriate sedation (BIS at the range of 40-60), substantial analgesia and muscle relaxation respectively. The invasive arterial pressure monitor was established via left radial artery cannulation with a transducer connected to Philips (IntelliVue MP60, Bothell, Washington, United States) prior to surgery. Intermittent sufentanil (0.1 ug/kg) was given if the HR, blood pressure or both increased more than 20% of the baseline. At 10 minutes before the beginning of the surgical procedure, 50 mg of flurbiprofen dissolved in 100ml saline were intravenously administered. The hemodynamic parameters and oropharyngeal temperature were recorded automatically by Medisystem electronic charter database (Suzhou, China) in our department.
Postoperative care and pain management
At the end of the operation, the patient was transferred to the post-anesthesia care unit (PACU) and the tracheal tube was removed after full emergence from anesthesia. The patient was discharged from the PACU to the ward once Steward Scale score was higher than 5 assessed by an experienced physician in PACU. The VAS scores were assessed by a well-trained doctor at 30 min immediately after extubation, every other 4 hours thereafter till 48 h post-surgery in the ward. When the VAS score of patients was over 3, 50 mg flurbiprofen was titrated to free of pain. If VAS score over 5, dizocine (0.1 mg/kg) was administrated for pain control as a rescue dose. The maximal dose of flurbiprofen or dizocine is 200 mg, 0.2mg/kg daily respectively.
Data collection
Preoperative and intraoperative demographic variables included the following: age (years); gender; BMI(kg/m2); American Society of Anesthesiologists(ASA); underlying diseases (Diabetes, Coronary artery disease, Hypertension); duration of operation (minutes); anesthesia time (defined as the time spent in the operating room in minutes); categories of drugs used for general anesthesia; Intraoperative mean arterial pressure (MAP) and heart rate (HR);dosage of intraoperatively administered narcotics. Postoperative variables included the following: additional analgesic requirement (NSAIDS, Dizocine); pain intensity assessed on visual analog scales (VAS); the incidence of postoperative nausea and vomiting (PONV), itching, respiratory depression, the time for the first defecation, and the length of hospital stay (LOS).
Outcome measurements
The primary outcome was VAS scores of patients at rest at 30 min post-extubation, 24 and 48 h after surgery respectively. Secondary outcomes comprised of blood pressure and HR of patients recorded at the following time-points: arrival at the operating room (T0), beginning of surgery (T1), the end of surgery (T2), immediate post-extubation (T3), and leaving PACU (T4); the duration of operation, intraoperative opioid (sufentanil) consumption; LOS; postoperative additional analgesic requirement within 48 h after PCNL as well as the adverse effects (such as PONV, itching, respiratory depression,the time for the first defecation) were recorded for further analysis.
Statistical analysis:
Power analysis was based on results of preliminary estimation of the difference in VAS at 24 h after PCNL procedure among various treatment groups from our electronic charter database; specifically, power was set at 0.8, significance criteria was set at 0.05, sigma was at 0.74. This yielded a sample size of 17 for each group. A Shapiro-Wilk test was used to evaluate whether or not the data are normally distributed; The distribution of each continuous variable was summarized by its mean±standard deviation and/or median with range (R)/ interquartile range (IQR). The distribution of each categorical variable was summarized in terms of its frequency and percentage. One-way analysis of variance using LSD correction for multiple comparisons of parametric variables and the Mann-Whitney U test is used for the non-parametric variables followed by Dunn’s test for multiple comparisons. Repeated measurement analysis of variance was used to analyze repeated measurements. The test of chi-square or Fisher’s exact test is applied for the categorized data. A P value of <0.05 is accepted as statistically significant. The analysis of the data was carried out using the IBM SPSS 21.0 statistical package software.