A Multicenter, Randomized, Triple-Masked, Placebo-Controlled Trial of The Effect of Ambulatory Continuous Femoral Nerve Blocks on Discharge-Readiness Following Total Knee Arthroplasty In Patients on General Orthopaedic Wards
Brian M. Ilfeld, MD, MS, Associate Professor,1 Edward R. Mariano, MD, MAS, Associate Clinical Professor,2 Paul J. Girard, MD, Assistant Clinical Professor,3 Vanessa J. Loland, MD, Assistant Clinical Professor,4 R. Scott Meyer, MD, Associate Clinical Professor,5 John F. Donovan, MD, Assistant Clinical Professor,6 George A. Pugh, MD, Chair,7 Linda T. Le, MD, Assistant Professor,8 Daniel I. Sessler, MD, Professor and Chair,9 Jonathan J. Shuster, PhD, Research Professor,10 Douglas W. Theriaque, MS, Director of Informatics,11 and Scott T. Ball, MD, Assistant Clinical Professor12Knee
A continuous femoral nerve block (cFNB) involves the percutaneous insertion of a catheter adjacent to the femoral nerve, followed by a local anesthetic infusion, improving analgesia following total knee arthroplasty (TKA). Portable infusion pumps allow infusion continuation following hospital discharge, raising the possibility of decreasing hospitalization duration. We therefore used a multicenter, randomized, triple-masked, placebo-controlled study design to test the primary hypothesis that a four-day ambulatory cFNB decreases the time until each of three predefined readiness-for-discharge criteria (adequate analgesia, independence from intravenous opioids, and ambulation ≥ 30 meters) are met following TKA compared with an overnight inpatient-only cFNB. Preoperatively, all patients received a cFNB with perineural ropivacaine 0.2% from surgery until the following morning, at which time they were randomized to either continue perineural ropivacaine (n=39) or switch to normal saline (n=38). Patients were discharged with their cFNB and portable infusion pump as early as postoperative day three. Patients given four days of perineural ropivacaine attained all three criteria in a median (25th–75th percentiles) of 47 (29–69) hours, compared with 62 (45–79) hours for those of the control group (Estimated ratio=0.80, 95% confidence interval: 0.66–1.00; p=0.028). Compared with controls, patients randomized to ropivacaine met the discharge criterion for analgesia in 20 (0–38) vs. 38 (15–64) hours (p=0.009), and intravenous opioid independence in 21 (0–37) vs. 33 (11–50) hours (p=0.061). We conclude that a four-day ambulatory cFNB decreases the time to reach three important discharge criteria by an estimated 20% following TKA compared with an overnight cFNB, primarily by improving analgesia.
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