◊ 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).
◊ Reviewed by A. Borgeat, MD, PhD
Professor / chief of the department, Orthopedic University Hospital Balgrist/Zurich, Switzerland
Ilfeld and colleagues [1] evaluated in this prospective, randomised, triple-masked clinical study the usefulness of a continuous 4-day femoral nerve block with 0.2% ropivacaine to decrease the time until three specific criteria for discharge were reached (1. adequate analgesia; 2. independence from intravenous analgesics; 3. ambulation of at least 30 m). A secondary endpoint was the 6-minute ambulatory distance on the afternoon after surgery. Patients receiving perineural 0.2% ropivacaine needed 25 h to achieve the three criteria for discharge compared to 71 h in patients of the placebo group. Differences between groups in secondary endpoints including pain score, intravenous morphine requirements, and total ambulatory distance were small.
The study confirms results already published by the same group, using quite similar methods with perineural catheters placed at different locations [2-4]. Results are also in accordance regarding earlier mobilisation [5-6] or shorter rehabilitation time[5] with those from previous studies using femoral catheters. Therefore, the novelty of the study is limited. However, some points deserve to be commented.
The overall positive conclusion of the study is compromised by some issues. First, the “minimal” decrease of the postoperative pain in the treatment group is disappointing and points at the need for a more appropriate multimodal analgesic treatment. Second, the capacity to achieve 30 m ambulation has been impaired in 45% of the patients of the ropivacaine group due to a motor block (quadriceps muscle weakness). A motor block is a major concern in patients discharged home under this analgesic regimen since there remains the risk of a fall. In this context wound infusion could be a more appropriate alternative. Indeed, Andersen et al [7,8] have shown that local and intraarticular infiltration after hip arthroplasty was associated with reduced consumption of narcotics, shorter hospital stay, and improved mobilisation without motor block. A comparison of the outcome of these two techniques would be of great interest. Finally, as pointed out by the authors, the femoral nerve block in the control group was not accomplished by single injection, but was continued overnight. This practice has without any doubt influenced the results of this study.
Thus, a continuous femoral nerve block can improve postoperative pain treatment and shorten hospital stay, but at the expense of serious side effects. These results confirm those of Capdevila [5] and Singelyn [6]. The authors performed a great work, but the treatment protocol used in this investigation appears not ideal for ambulatory postoperative analgesia. A next challenge will be to perform studies investigating improvements in long-term functional recovery and a decrease in the occurrence of chronic pain. These results could provide new impulses for the development of continuous analgesia through perineural catheter.
[1] Ilfeld BM, Le LT, Meyer RS, Mariano ER, Vandenborne K, Duncan PW, Sessler DI, Enneking FK, Shuster JJ, Theriaque DW, Berry LF, Spadoni EH, Gearen PF.
Ambulatory continuous femoral nerve blocks decrease time to discharge readiness after tricompartment total knee arthroplasty: a randomized, triple-masked, placebo-controlled study. Anesthesiology 2008; 108: 703-13
[2] Ilfeld BM, Morey TE, Enneking FK.
Continuous infraclavicular brachial plexus block for postoperative pain control at home: a randomized, double-blinded, placebo-controlled study. Anesthesiology 2002; 96: 1297-304
[3] Ilfeld BM, Morey TE, Wang RD, Enneking FK.
Continuous popliteal sciatic nerve block for postoperative pain control at home: a randomized, double-blinded, placebo-controlled study. Anesthesiology 2002; 97: 959-65
[4] Ilfeld BM, Morey TE, Wright TW, Chidgey LK, Enneking FK.
Continuous interscalene brachial plexus block for postoperative pain control at home: a randomized, double-blinded, placebo-controlled study. Anesth Analg 2003; 96: 1089-95
[5] Capdevila X, Barthelet Y, Biboulet P, Ryckwaert Y, Rubenovitch J, d'Athis F.
Effects of perioperative analgesic technique on the surgical outcome and duration of rehabilitation after major knee surgery. Anesthesiology 1999; 91: 8-15
[6] Singelyn FJ, Deyaert M, Joris D, Pendeville E, Gouverneur JM.
Effects of intravenous patient-controlled analgesia with morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg 1998; 87: 88-92
[7] Andersen KV, Pfeiffer-Jensen M, Haraldsted V, Soballe K.
Reduced hospital stay and narcotic consumption, and improved mobilization with local and intraarticular infiltration after hip arthroplasty: a randomized clinical trial of an intraarticular technique versus epidural infusion in 80 patients. Acta Orthop 2007; 78: 180-6
[8] Andersen LJ, Poulsen T, Krogh B, Nielsen T.
Postoperative analgesia in total hip arthroplasty: a randomized double-blinded, placebo-controlled study on peroperative and postoperative ropivacaine, ketorolac, and adrenaline wound infiltration. Acta Orthop 2007; 78: 187-92
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