The Use of Lumbar Erector Spinae Plane Block for Hip Arthroplasty at the L4 Interspace

Hypothesis: The erector spinae plane block will decrease opioid requirements in patients undergoing hip arthroplasty as compared to patients that do not receive the block. Primary Objective: To compare the opioid consumption in the post-anesthesia care unit (PACU) and at 24 hours postoperative (in morphine equivalents) in patients receiving regional anesthesia with spinal vs. spinal alone. Secondary Endpoints: To evaluate the pain scores at discharge from PACU, at 2 hours post PACU discharge, at 24 hours and at 48 hours postoperative; to evaluate the sensory distribution of the block (T10-L5); to evaluate whether or not patients that receive the block have evidence of quadricep muscle weakness Design and methods This is a randomized, prospective study in patients receiving hip arthroplasty. Patients will be assigned to receive a lumbar erector spinae block versus no block. There will be no change in the primary anesthetic technique (spinal anesthesia with sedation) since these patients routinely get spinal anesthesia for hip arthroplasty. Consent for the study will be obtained in the preoperative area upon arrival for surgery. Patients will then be randomized into one of the two groups above. One group will receive a lumbar erector spinae block at L4 with 30ml of 0.375% ropivacaine with 50 mcg of dexmedetomidine before the procedure using ultrasound guidance. The second group will receive no peripheral nerve block to serve as the control. Patients to receive a nerve block will receive mild sedation (1-2mg midazolam ± ≤100mcg fentanyl). All patients receiving nerve blocks will have a printed image of the block thus to confirm proper spread of local anesthetic both cranially and caudally. Postoperatively, the PACU nurse will be asked to document pain scores according to the Visual Analog Scale (VAS) and total dose of opioids given. The distribution of the sensory block and motor weakness will be documented in the anesthesiologist's PACU discharge note. For patients that receive the block, the Physical therapist note will be assessed for any report of quadriceps muscle weakness (i.e., evidence of buckling while walking). For postoperative data collection, opioid consumption totals and the pain scores at 2 hours post admission, at 24 hours and 48 hours post-procedure will be collected from the electronic medical record (EMR) as documented by nurses on the admitting floor. Additionally, the Acute Pain service, who rounds on all patients that receive nerve blocks, will make a note of the pain scores of the patient and any residual muscle weakness or decreased sensation at 24- and 48-hours post-procedure. All data will then be extracted from the EMR by the research assistant.