CONTINUOUS CATHETER TECHNIQUES

The advantages cited for continuous nerve blockade include prolongation of surgical anesthesia, decreased risk of toxicity because of lower incremental doses, and postoperative pain relief and sympathectomy. Catheter placement using over-needle and through-needle methods have been described. Advances in equipment technology, including the development of stimulating needles and catheters and portable pumps allowing local anesthetic infusion after hospital dismissal have increased the success rate and popularity of continuous peripheral blockade ( Fig. 44-30 ).^{[72] [73]} Although concern regarding accurate catheter placement and maintenance still exists, the use of stimulating catheters and radiographic confirmation may further improve the functionality.^{[40] [74]} Risks of infection, inadequate anesthesia or analgesia and accumulation of local anesthetic (i.e., systemic toxicity) are the major disadvantages. Catheter migration, catheter kinking or coiling, and nerve damage may rarely occur.^{[75] [76]}

Methods of providing continuous brachial plexus anesthesia have been described since at least the 1940s^[77] and frequently offer ingenious solutions for the placement and securing of the needle or catheter. Longer catheters may be easier to secure and provide superior blockade if the tip lies more proximal in the plexus.^[78] This technique is especially applicable to patients with upper extremity or digit replantation, total-elbow arthroplasty, or reflex sympathetic dystrophies, for which prolonged pain relief and sympathectomy are advantageous.^[79] Despite increased use of these techniques, few studies have critically analyzed the benefits and outcomes of brachial plexus catheters for single-injection or conventional methods of postoperative analgesia.

Continuous lower extremity techniques were described decades ago but remained underused compared with continuous upper extremity and neuraxial approaches. For example, Brands and Callanan^[80] placed psoas compartment catheters to provide analgesia for femoral neck fractures in 1978. Reliable, improved success rates and the risk of spinal hematoma after neuraxial techniques led clinicians to again consider continuous lower extremity blocks. Contemporary applications for continuous psoas compartment, sciatic, femoral, and popliteal fossa blockade have been reported.^{[40] [73] [81]} Compared with conventional systemic and neuraxial analgesic methods, continuous lower extremity blocks provide superior analgesia with fewer side effects, improve perioperative outcomes, and accelerate hospital dismissal after major joint replacement.^{[81] [82] [83]}

1714

Figure 44-30 Portable infusion pumps. A, Accufuser (McKinley Medical, Wheat Ridge, CO). B, Sgarlato (Sgarlato Labs, Los Gatos, CA). C, Stryker PainPump (Stryker Instruments, Kalamazoo, MI). D, MedFlo II (MPS Acacia, Brea, CA). E, C-Bloc (I-Flow Corp., Lake Forest, CA). F, Microject PCA (Sorenson Medical, West Jordan, UT). (From Ilfeld BM, Morey TE, Enneking FK: The delivery rate accuracy of portable infusion pumps used for continuous regional analgesia. Anesth Analg 95:1331–1336, 2002.)