Résumé
Spinal fusion surgery induces moderate to severe postoperative painrelief. The lumbar Erector Spinae Plane Block (ESPB) is a recent block. Its diffusion and efficacy remain debated. After anatomical study (dye diffusion), this prospective, randomized, double-blinded, versus placebo, clinical trial evaluated the efficacy of lumbar ESPB on postoperative morphine consumption. Methods: for the anatomical study, three cadavers were injected with color solution using ultrasound approach at the level L3 (20 mL each side). Dissections were performed to describe metameric and spinal diffusion. After CPP approval (Clinical trial: NCT 04473508), 50 patients were randomized from November 2019 to July 2021: saline vs ropivacaïne groups. After standardized general anesthesia, patients were placed in ventral position and a lumbar ESPB was performed under ultrasound approach at L3 (left and right sides). A total dose of 40 mL of ropivacaïne 3.75 mg/mL or saline solution were injected. Similar IV multimodal analgesia was used for both groups: paracetamol (1g), ketoprofene (100mg), nefopam (20mg), ketamine (0.5mg/kg), dexamethasone (8mg). Morphine rescue titration in PACU (VAS pain score >3 on 10) followed by IV PCA morphine (24h) was given to patients. Patients were evaluated (pain scores, side effects) over time until upon discharge and at 3 months (DN4, EQ5SL and VAS pain score). Primary endpoint was morphine consumption at 24H. Results: for anatomical study, we noted a coloration of the dorsal ramus of the spinal nerves at the level of injection. A caudal and rostral diffusion (2-3 metameres) was observed without diffusion in the spinal space. For clinical study, no difference was observed between groups at baseline. Morphine consumption was reduced in Ropivacaïne group, 7.3mg [3.7-19], with no statistical difference with Saline group, 12.5mg [3.5-26] p=0.51 (mean reduction IC (95%): 5mg). In PACU, similar VAS pain scores and morphine titration were recorded between groups. Over time, both groups presented similar VAS pain scores, adverse events (NVPO, urinary retention and confusion), surgical complication and length of stay. At 3 months, VAS pain score at rest and mobilization, DN4 and EQ5D-5L score were not difference between groups. Conclusion: in this study, using multimodal analgesia, lumbar ESPB reduced morphine consumption after spinal fusion surgery without clinical or statistical benefit compared with the saline group, whereas the anatomic study showed the potential benefit of its wide distribution.