Ambulatory Continuous Femoral Nerve Blocks Decrease Time to Discharge Readiness after Tricompartment Total Knee Arthroplasty
Brian M. Ilfeld, M.D., M.S., Associate Professor,* Linda T. Le, M.D., Fellow,† R. Scott Meyer, M.D., Associate Clinical Professor,‡ Edward R. Mariano, M.D., Assistant Clinical Professor,§ Krista Vandenborne, Ph.D., P.T., Associate Professor and Chair,∥ Pamela W. Duncan, Ph.D., P.T., Professor,# Daniel I. Sessler, M.D., Professor and Chair,** F. Kayser Enneking, M.D., Professor,†† Jonathan J. Shuster, Ph.D., Research Professor,‡‡ Douglas W. Theriaque, M.S., Director of Informatics,§§ Linda F. Berry, R.N., Patient Care Resource Manager,∥∥ Eugene H. Spadoni, P.T., Clinical Therapist,## and Peter F. Gearen, M.D., Associate Professor and Chair***Knee
Background
The authors tested the hypotheses that, compared with an overnight continuous femoral nerve block (cFNB), a 4-day ambulatory cFNB increases ambulation distance and decreases the time until three specific readiness-for-discharge criteria are met after tricompartment total knee arthroplasty.
Methods
Preoperatively, all patients received a cFNB (n = 50) and perineural ropivacaine 0.2% from surgery until the following morning, at which time they were randomly assigned to either continue perineural ropivacaine or switch to perineural normal saline. Primary endpoints included (1) time to attain three discharge criteria (adequate analgesia, independence from intravenous analgesics, and ambulation of at least 30 m) and (2) ambulatory distance in 6 min the afternoon after surgery. Patients were discharged with their cFNB and a portable infusion pump, and catheters were removed on postoperative day 4.
Results
Patients given 4 days of perineural ropivacaine attained all three discharge criteria in a median (25th–75th percentiles) of 25 (21–47) h, compared with 71 (46–89) h for those of the control group (estimated ratio, 0.47; 95% confidence interval, 0.32– 0.67; P <0.001). Patients assigned to receive ropivacaine ambulated a median of 32 (17–47) m the afternoon after surgery, compared with 26 (13–35) m for those receiving normal saline (estimated ratio, 1.21; 95% confidence interval, 0.71–1.85; P = 0.42).
Conclusions
Compared with an overnight cFNB, a 4-day ambulatory cFNB decreases the time to reach three important discharge criteria by an estimated 53% after tricompartment total knee arthroplasty. However, the extended infusion did not increase ambulation distance the afternoon after surgery. (ClinicalTrials.gov No. NCT00135889.)
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