Regional Analgesia Through Posterior Quadratus Lumborum Block in Laparoscopic and Robot-Assisted Nephrectomies: A Retrospective Observational Study

Regional analgesia may have a role in laparoscopic nephrectomy reducing opioid requirements and side effects. Transversus abdominis plane (TAP) block has failed to demonstrate efficacy on acute pain reduction after nephrectomies1 and there is risk of pneumothorax with paravertebral block. The quadratus lumborum block (QLB) has recently shown efficacy in nephrectomies using high doses of local anesthetic,2–5 raising concerns about systemic toxicity and lumbar plexus blockade. Our study aims to evaluate whether preoperative low-dose analgesic posterior QLB reduces postoperative pain in traditional or robot-assisted laparoscopic nephrectomy compared to patients with TAP block or no locoregional analgesia (no LRA). METHODS We conducted an observational retrospective study from January 1, 2019, to March 31, 2022, at the Grenoble University Hospital. We included consecuti,ve adult patients who underwent elective laparoscopic nephrectomy and received QLB, TAP or no LRA. Exclusion criteria were language barrier, chronic pain history, sepsis, coagulation disorder, allergy to amide local anesthetics or planned laparotomy. Data were obtained from electronic medical records from anesthetic and ward software. The study design received ethical approval by the French Society of Anaesthesiology and Intensive Care (IRB number: CERAR 00010254-2024-049). According to the French law No. 2012-300 (Decree No. 2016-1537), nonopposition of patients was obtained by an information letter, and the declaration was made to the French Data Protection Authority. Regional analgesia was performed according to international guidelines, after antiseptic cleaning, under ultrasound guidance, using ropivacaine 0.2% up to 40 mL. The primary outcome was the total postoperative morphine equivalent consumption at 24 hours. Secondary outcomes were total morphine consumption at H8 and H48, time to first morphine requirement after extubating, pain score at H0, H3, H6, H8, H24, and H48, nausea or vomiting in the recovery room (PACU), hypoxia in the first 12 hours after the surgery, and length of stay in the PACU. A data analysis and statistical plan was written and filed with the institutional review board before data were accessed. Categorical variables were described by frequency and percentage. Quantitative variables were described by mean and confidence interval. ANOVA was used for quantitative data with normal distribution and the Kruskal–Wallis test otherwise. Qualitative variables were analyzed using Fisher exact test. Groups were compared on gender, age, body mass index, medical history (ASA status, diabetes, cardiovascular diseases, high blood pressure, chronic obstructive pulmonary disease, obstructive sleep apnea and renal function, indication, type (partial or total), approach (robotic or traditional laparoscopy) and duration of surgery, extraction method and perioperative analgesic regimens. If significant differences were found, they were included in a preplanned adjusted regression model to analyze the primary and secondary outcomes. A mixed-effects model analysis of the variation in pain scores and morphine consumption over time was conducted. All statistical tests were 2-sided with a significance level set at 0.05. Only the complete case was considered for analysis. RESULTS Within the study period, 313 patients were screened, 295 patients met inclusion criteria, and 289 patients had no missing value regarding the primary outcome. Among these patients, no LRA was done in 208 patients QLB in 54 patients and TAP block in 33 patients, (flowchart in Supplemental Digital Content 1, Figure 1, https://links.lww.com/AA/F427). Patient characteristics are shown in the Table. We found significant differences for diabetes, cardiovascular diseases, trocars ports infiltration, lidocaine infusion, acetaminophen, surgical indication, type, approach and extraction method (P values not shown), these were added to adjusted regression model. Two hundred eighty patients without missing values were included in the adjusted linear regression (no LRA n = 199 patients, QLB n = 51 patients, TAP n = 31 patients). Table. - Population Characteristics Details QLB (n = 54) TAP (n = 33) No LRA (n = 208) Women, n (%) 26 (48.1) 13 (39.4) 80 (38.5) Age (y), mean [95% CI] 60.3 [56.8–64.2] 58.2 [53.9–63.8] 60.6 [58.7–62.7] BMI (kg.m-²), mean [95% CI] 27 [25.4–28.5] 25.8 [24.4–27.3] 26.8 [26.2–27.4] ASA physical status, n (%) I II III IV 18 (33.3)23 (42.6)12 (22.2)1 (1.9) 11 (33.3)15 (45.4)6 (18.1)1 (3.0) 46 (22.1)100 (48.1)61 (29.3)1 (0.5) Sleep apnea, n (%) 4 (7.4) - 23 (11.1) High blood pressure, n (%) 22 (40.7) 11 (33.3) 95 (45.7) Diabetes, n (%) 6 (11.1) - 37 (17.8) Cardiovascular disease, n (%) 7 (12.9) 1 (3.0) 45 (21.6) COPD, n (%) - - 10 (4.8) Preoperative GFR, (ml.min-1.m-²) mean [95% CI] 87.5 [82.0–93.1] 83.6 [73.3–93.3] 78.2 [74.7–82.0] Postoperative GFR, (mL.min–1.m–²), mean [95% CI] 63.5 [57.5–68.6] 61.5 [51.9–69.9] 68.9 [65.2–72.5] Peroperative diuresis (mL), mean [95% CI] 399 [309–476] 381 [294–467] 412 [358–463] Indication, n (%) Living kidney donor Cancer Functional/malformation, others 15 (27.8)36 (66.7)3 (5.5) 14 (42.4)13 (39.4)6 (18.1) 31 (14.9)161 (77.4)16 (7.7) Type of surgery, n (%) Total nephrectomy Partial nephrectomy 36 (66.7)18 (33.3) 22 (66.7)11 (33.3) 92 (44.2)116 (55.8) Surgical approach, n (%) Standard Robot-assisted 23 (42.6)31 (57.4) 23 (69.7)10 (30.3) 76 (36.5)132 (63.4) Removing method, n (%) Pfannenstiel/Iliac Extended trocars Trocars Others 33 (63.5)17 (32.7)02 (3.8) 21 (65.6)7 (21.9)1 (3.1)3 (9.4) 70 (34.0)114 (55.3)10 (4.9)12 (5.8) Surgery length (min), mean [95% CI] 155 [141–171] 163 [154–175] 156 [151–161] Peroperative antalgic strategies, mean [95% CI] Trocars infiltration, n (%) Lidocaine infusion, n (%) Lidocaine dose (mg), mean [95% CI] Clonidine, n (%) Clonidine dose (μg), mean [95% CI] Ketamine, n (%) Ketamine dose (mg), mean [95% CI] Acetaminophen, n (%) Nefopam, 20 mg, n (%) Ketoprofen, n (%) Ketoprofen dose (mg), mean [95% CI] Dexamethasone 8 mg, n (%) 13 (24.1)24 (44.4)192 [141–244]20 (37)113 [77–149]50 (92.6)40 [36–43]30 (55.5)44 (81.5)22 (40.7)93 [85–101]46 (85.2) 3 (9.1)18 (54.5)206 [145–267]5(15.1)144 [34–255]26 (78.8)40 [32–44]24 (72.7)29 (87.9)6 (18.1)83 [56–110]27 (81.8) 96 (46.1)166 (80.0)369 [339–398]53 (25.5)166 [143–189]186 (89.4)40 [38–42]181 (87.0)164 (78.8)48 (23.1)91 [85–96]162 (77.9) Peroperative analgesic strategies Sufentanil, n (%) Sufentanil dose, mean [95% CI] (μg) Remifentanil, n (%) Remifentanil dose, mean [95% CI] (μg) 49 (90.7)22 [19–24]3 (5.5)1993 [222–3764] 31 (93.9)21 [17–25]6 (18.2)2381 [1442–3319] 176 (84.6)23 [22–25]22 (10.6)1700 [1295–2105] Abbreviations: 95% CI, 95% confidence interval; ASA, American Society of Anaesthesiologists; BMI, body mass index; COPD, chronic obstructive pulmonary disease; GFR, glomerular filtration rate; No LRA, absence of locoregional analgesia; n, number of patients; QLB, quadratus lumborum block; TAP, transversus abdominis block. After adjustment, less morphine total equivalent consumption at H24 was observed in the QLB compared to the TAP group (14.7 [95% CI, 9.9–19.4] mg vs 29.0 [95% CI, 13.2–44.7] mg, P = .015, respectively) and in the QLB compared to the no-LRA group (14.7 [95% CI, 9.9–19.4] mg vs 19.1 [95% CI 15.8–22.5] mg, P = .023, respectively; Figure). At H8, we observed a 12.2 mg (95% CI, 0.5–24.0, P = .040) reduction in morphine total equivalent consumption in the QLB versus the TAP group and 11.4 mg (95% CI 2.5–20.3, P = .012) reduction versus the no-LRA group. This difference was not found at 48 hours (unadjusted morphine consumption at H8, H24 and H48 in Supplemental Digital Content 2, Table 1, https://links.lww.com/AA/F428). There was no significant difference between the 3 groups regarding the time course of pain scores after the surgery, time to first analgesic requirement, hypoxia, nausea and vomiting or PACU length of stay.Figure.: Means and 95% confidence interval of morphine consumption at 8, 24, 48 h after surgery. H8 indicates 8 h after surgery; H24, 24 h after surgery; H48, 48 h after surgery; QLB, quadratus lumborum block; no LRA, absence of locoregional, analgesia; TAP, transversus abdominis block.DISCUSSION This study suggests an association between quadratus lumborum block and reduced 24-hour morphine consumption. This is consistent with the only study on low-dose QLB conducted by Kwak6 where they used a randomized, double-blind design and reported reduced fentanyl consumption at 48hours in the QLB group compared to a sham procedure (H24 QLB 599.5 [95% CI 502.5–696.5] vs 982 [95% CI 809.9–1154.1], P = .001). Our study has several limitations. Due to its retrospective design, physicians chose regional analgesia technique, analgesic regimens, lidocaine infusion or trocars port infiltration, resulting in significant differences between groups and a higher rate of lidocaine and infiltrations in the no-LRA group. The adjusted model tried to alleviate this bias, but we cannot exclude that other confounding factors contribute to our results. As QLB use increased during the study, the anesthetic staff improved their learning curve over this period. There were more partial nephrectomies in the no-LRA group and therefore more robotic procedures, improving analgesia. Finally, morphine consumption is a questionable primary outcome; analyzing the impact of QLB on quality of life would be of interest. Our study suggests an impact of low-dose QLB on morphine consumption after laparoscopic nephrectomies. However, it is a deep block contraindicated in bleeding disorders. ACKNOWLEDGMENTS Regarding the work completed, the authors would like to thank Martin Dupuis, MD, and Alexia Bacci, MD, for the study conception, data collection, and paper writing; Anaïs Adolle, MSc, for study conception, ethical approval process, data management, and article revision; Dimitri Sourd and Antoine Vilotitch, MSc, for study conception, statistical planning and analysis, and paper revision; and Pierre Bouzat, MD, PhD, for his contributions to the study conception, statistical selection, and extensive rewriting. DISCLOSURES Conflicts of Interest: None. Funding: None. This manuscript was handled by: Michael J. Barrington, MBBS, FANZCA, PhD.