ontinuous peripheral nerve blockade, also called “perineural local anesthetic infusion,” involves the percutaneous insertion of a catheter directly adjacent to the peripheral nerve(s) supplying a surgical site. Local anesthetic is then infused via the catheter providing site-specific analgesia. Originally the technique was described in 1946 by Ansbro using a cork to stabilize a needle placed adjacent to the brachial plexus to provide a “continuous” supraclavicular block.¹ Subsequent technological advancements in needle and catheter design allowed more mainstream use of continuous blocks. For decades, however, patients were required to remain hospitalized because the available pumps used to infuse local anesthetic were large, heavy and technically sophisticated. It was not until 52 years after Ansbro’s first report that outpatient perineural infusion was described by Rawal et al. using a percutaneous catheter and a small, lightweight, portable infusion pump.²

The application of ambulatory perineural infusion initially focused on providing this technique to improve the postoperative experience of patients already scheduled for outpatient surgery. Multiple case reports and series of ambulatory perineural infusion purporting improved outcomes were described via catheters in various anatomic locations, including paravertebral, interscalene, intersternocleidomastoid, infraclavicular, axillary, psoas compartment, femoral, fascia iliaca, sciatic/Labat, sciatic/popliteal and tibial nerve placement. It was not until 2002, however, that the first of four randomized, double-masked, placebo-controlled studies provided prospective evidence quantifying infusion benefits.^3-6

Outpatient Benefits. In all of these investigations, patients receiving perineural local anesthetic achieved both clinically and statistically significant lower resting and breakthrough pain scores compared with those using exclusively oral opioids for analgesia. In addition they required dramatically fewer oral analgesics to achieve their improved level of analgesia. Preoperatively subjects scheduled for moderately painful procedures had a perineural catheter placed: an infraclavicular catheter for hand/forearm procedures,⁴ a popliteal catheter for foot/ankle surgeries^3,5 or an interscalene catheter for shoulder procedures.⁶ Postoperatively patients received either perineural local anesthetic or normal saline and were followed at home for up to 60 hours. All patients were instructed to use a bolus from their infusion pump for breakthrough pain and oral analgesics if this maneuver failed. In patients with an interscalene catheter following shoulder surgery, the local anesthetic infusion provided analgesia so that 80 percent of patients receiving ropivacaine required one or fewer opioid tablets per day during their infusion and reported average resting pain as less than 1.5 on a scale of 0-10.⁶ Conversely all patients receiving placebo required four or more opioid tablets per day, beginning the evening of surgery, and reported average resting pain scores between 3 and 4. For breakthrough pain, the differences between treatment groups were even more pronounced in all of these four placebo-controlled studies.

Additional benefits related to improved analgesia were experienced by patients who received perineural local anesthetic. Of patients receiving perineural ropivacaine, 0 percent to 30 percent reported insomnia due to pain compared with 60 percent to 70 percent of patients receiving placebo.^4-6 Additionally, awakenings from sleep because of pain averaged 0.0-0.2 times on the first postoperative night compared with 2.0-2.3 times for patients using only oral opioids.^4-6 Using fewer opioid tablets was associated with a lower rate of nausea, vomiting, pruritis and sedation.^3-6 Satisfaction with postoperative analgesia was both clinically and statistically higher for patients receiving local anesthetic.^3-6

Early Hospital Dismissal. The possibility of using ambulatory perineural infusion to allow earlier discharge of inpatients who require potent analgesia has only recently been explored.³ For example criteria for home discharge following knee and hip arthroplasty usually include the requirements that 1) pain is controlled with only oral analgesics and that 2) patients must ambulate at least 30 meters so they may function at home. Consequently the median duration of hospitalization following both of these procedures in the United States is five days. Using ambulatory perineural femoral or lumbar plexus infusion, patients have been discharged home after a single night of hospitalization following total hip and knee replacement.⁷ Additionally total elbow and shoulder replacement have been converted into outpatient procedures.⁸ The potential benefits to individuals include a decreased risk of nosocomial infection and accidental medical error and improved patient analgesia and quality of life. The potential societal cost savings are enormous, with more than 500,000 knee and hip replacements performed annually at a cost of more than $12 billion in the United States alone. These practices, however, have only been recently investigated. Significantly more data are required to define the appropriate subset of patients and assess the benefits and associated incidence of complications.

Additional Applications. Ambulatory continuous peripheral nerve blocks have been described for battlefield management as well as international transport following combat injury in Iraq.⁹ Although a control group was not included, a small series of children with complex regional pain syndrome I experienced complete resolution of their symptoms two months following a Bier block and 96 hours of outpatient perineural local anesthetic infusion.¹⁰

As a result of the relatively recent evolution of outpatient continuous peripheral nerve blocks, illuminating data on many aspects of this analgesic technique are unavailable. In keeping with evidence-based medical practice, we believe the optimal techniques, equipment and patient oversight should be determined by prospective, controlled trials and not merely by institutional preference. Future investigation should include identification of which patients and procedures benefit most from perineural infusion; optimal local anesthetic type, concentration and adjutants; the most advantageous delivery regimen and dosing structure; the optimal catheters (e.g., stimulating versus nonstimulating catheters), placement techniques and infusion pumps; the safest frequency of patient contact and method of catheter removal; and, lastly, whether additional outcomes are affected with ambulatory perineural local anesthetic infusion (e.g., health-related quality of life).


References:

1. Ansbro FP. A method of continuous brachial plexus block. Am J Surg. 1946; 71:716-722.

2. Rawal N, Axelsson K, Hylander J, Allvin R, et al. Postoperative patient-controlled local anesthetic administration at home. Anesth Analg. 1998; 86:86-89.

3. White PF, Issioui T, Skrivanek GD, et al. The use of a continuous popliteal sciatic nerve block after surgery involving the foot and ankle: Does it improve the quality of recovery? Anesth Analg. 2003; 97:1303-1309.

4. 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; 96:1297-1304.

5. 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; 97:959-965.

6. 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; 96:1089-1095.

7. Ilfeld BM, Gearen PF, Enneking FK, et al. Total knee arthroplasty as a 23-hour stay procedure using ambulatory perineural local anesthetic infusion: A prospective feasibility study, abstracted. Reg Anesth Pain Med. 2005; In press.

8. Ilfeld, BM, Wright, TW, Enneking, FK. Total shoulder arthroplasty as an outpatient procedure using ambulatory perineural local anesthetic infusion: A prospective feasibility study, abstracted. Reg Anesth Pain Med. 2005; In press.

9. Buckenmaier CC, McKnight GM, Winkley JV, et al. Continuous peripheral nerve block for battlefield anesthesia and evacuation. Reg Anesth Pain Med. 2005; 30:202-205.

10. Dadure C, Motais F, Ricard C, et al. Continuous peripheral nerve blocks at home for treatment of recurrent complex regional pain syndrome I in children. Anesthesiology. 2005; 102:387-391.

Brian M. Ilfeld, M.D., is Assistant Professor of Anesthesiology, University of Florida, Gainesville, Florida.

F. Kayser Enneking, M.D., is Professor of Anesthesiology and Orthopedics, University of Florida, Gainesville, Florida.