Catheter Placement

To place a peripheral nerve catheter, the anesthesiologist inserts a needle into the targeted nerve site, injects incremental doses of local anesthetic to block the desired nerve or nerves, and then threads the catheter through the needle (see Figure 26-1 for the site of lumbar plexus catheter placement). The needle is then removed, the catheter is secured, and the site is dressed. In the inpatient setting, continuous peripheral nerve blocks can be administered by the same infusion devices that are used to administer IV PCA or epidural analgesia. In the outpatient setting, portable disposable pumps (elastomeric or vacuum-driven syringe types) are usually used (Skryabina, Dunn, 2006). These latter pumps offer the benefits of being very small and easily discarded after use, avoiding the need for the patient to return the pump and the hospital to develop a pump tracking system. Some pumps allow patient-controlled capability for breakthrough pain so that PCRA may be administered. Some can be programmed to deliver automated bolus delivery in addition to PCRA capability (Taboada, Rodriguez, Bermudez, et al., 2009). The pumps also have simple mechanisms for stopping the infusion if adverse effects occur or at the end of therapy. Catheters are easily removed by clinicians, patients, or family members (Ilfeld, Enneking, 2002; Rawal, Axelsson, Hylander, et al., 1998; Swenson, Bay, Loose, et al., 2006).

There are a number of excellent resources for detailed information on catheters and the placement procedure for continuous peripheral nerve block. For this, the reader is referred to the texts by Cousins, M. J., & Bridenbaugh, P. O. (Eds.). (1998). Neural blockade in clinical anesthesia and management of pain, Philadelphia, Lippincott-Raven; Miller, R. D. (Ed.). (2005). Miller’s anesthesia, ed 6, Philadelphia, Churchill Livingstone; Sinatra, R. S., de Leon-Casasola, O. A., Ginsberg, B., et al. (Eds.). (2007). Acute pain management, Cambridge, NY, Cambridge University Press; Meier, G., & Buttner, J. (2007). Peripheral regional anesthesia: An atlas of anatomy and techniques, ed 2, English translation available, New York, Thieme; and Waldman, S. (2009). Pain review, Philadelphia, Saunders; as well as any one of the research articles cited in this section. Capdevila and colleagues (2009) offer excellent suggestions for proper sterile technique for placement and site dressing. The various pumps used to administer continuous peripheral nerve blocks have been compared and discussed elsewhere (Capdevila, Macaire, Aknin, et al., 2003; Wedel, Horlocker, 2005).

Nurses are referred to their scope of practice as defined by their individual state board of nursing for their role in the administration of continuous peripheral nerve block, and they should see the American Society for Pain Management Nursing’s Position Paper on the Nurse’s Role in the Management and Monitoring of Analgesia by Catheter Techniques for additional guidance (Pasero, Eksterowicz, Primeau, et al., 2007). See also Box 26-1 for guidelines on the care of patients receiving continuous peripheral nerve block.

Research on the Use of Continuous Peripheral Nerve Block

There is now an impressive body of research supporting continuous peripheral nerve block as a primary analgesic technique for postoperative pain, particularly following orthopedic surgery. The following is a list of case reports, reviews, and placebo-controlled research on the use of this method for a variety of types of pain. Note that continuous peripheral nerve blocks have been used for some types of persistent noncancer and cancer-related pain as well.

Efficacy Compared with Other Analgesic Approaches

A meta-analysis of research (19 randomized controlled trials, 603 patients) comparing postoperative opioid analgesia (variety of agents and routes) and continuous peripheral nerve block (variety of catheter locations and regimens) concluded that the latter provided superior analgesia (approximately a 50% VAS score reduction) at all evaluation time periods through postoperative day 3, fewer adverse effects (e.g., sedation, nausea), and higher patient satisfaction compared with opioid-based analgesic approaches (Richman, Liu, Courpas, et al., 2006). A later randomized controlled study comparing IV PCA alone with continuous peripheral nerve block plus IV PCA following hip arthroplasty observed similar findings (Siddiqui, Cepeda, Denman, et al., 2007). Those who received a continuous lumbar plexus block combined with IV PCA had improved analgesia, reduced opioid requirements and adverse effects, and enhanced patient satisfaction. One patient in the IV PCA-only group experienced clinically significant respiratory depression and required ventilator support for 6 hours. One patient in the continuous nerve block group developed quadricep weakness, which was discovered 4 weeks following surgery. Although the cause of the deficit was not determined, its occurrence led the researchers to speculate that it could have been related to the use of regional anesthesia in the presence of anticoagulation (see following discussion of adverse effects). A later study comparing IV PCA and continuous peripheral nerve block after open shoulder surgery reported better analgesia with the block but no differences in functional outcomes (Hofmann-Kiefer, Eiser, Chappell, et al., 2008).

Epidural analgesia has long been a first-line approach for the management of pain after total knee replacement. A meta-analysis of research comparing peripheral nerve block with epidural analgesia did not distinguish between single-injection and continuous peripheral nerve blocks and emphasized the urgent need for more research comparing the two techniques; the researchers concluded that peripheral nerve blocks appear to represent the best balance between analgesia and adverse effects for major knee surgery (Fowler, Symons, Sabato, et al., 2008). Patients undergoing knee replacement in one study were randomized to receive continuous epidural (ropivacaine + fentanyl) or continuous peripheral nerve block (femoral nerve = ropivacaine + fentanyl; sciatic nerve = ropivacaine) (Zaric, Boysen, Christansen, et al., 2006). Adverse effects, such as sedation and nausea, were more common in the epidural group, but pain was equally well-controlled in both groups, and there were no differences in mobilization and other rehabilitation outcomes or length of hospital stay between the two groups. Another study concluded that IV PCA morphine, continuous femoral nerve block, and continuous epidural analgesia provided similar pain relief, rehabilitation, and hospital stay but recommended continuous femoral nerve block as the best choice following hip arthroplasty given its more favorable adverse effect profile (Singelyn, Ferrant, Malisse, et al., 2005) (see Chapter 17 for IV PCA and Chapter 15 for epidural analgesia). An interesting study used an aggressive multimodal plan that included preoperative and postoperative nonopioid and opioid analgesics; preoperative pericapsular ropivacaine, steroid, and morphine; and epidural anesthesia for patients undergoing total knee arthroplasty (Dorr, Raya, Long, et al., 2008). Patients were given continuous femoral nerve block (N = 35) or continuous epidural analgesia (N = 35) postoperatively. Those receiving continuous peripheral nerve block consumed less oral opioid; walking distance on day 0 and day 1 was better for patients with epidural analgesia; length of stay was comparable between the groups; and adverse effects and complications were minimal in both groups. No patients had ileus or respiratory depression, which the researchers attributed to the avoidance of parenteral opioids in almost all patients in the study.

Other methods of local anesthetic administration have been compared as well. A prospective, randomized study of patients undergoing anterior cruciate ligament repair found that continuous femoral nerve block produced better pain relief during rest and activity and greater nonopioid and opioid dose-sparing effects compared with intraarticular and wound infusions of local anesthetic (see later in the chapter for these methods) (Dauri, Fabbi, Mariani, et al., 2009).

Dosing and Administration Regimens

Continuous peripheral nerve blocks are administered via three basic regimens: continuous infusion only (basal rate only), PCRA with basal rate, and PCRA with bolus doses only (Boezaart, 2006). Similar to PCA by other routes of administration, PCRA allows patients to take an active role in the management of their pain and individualize therapy to meet their unique analgesic needs. Some clinicians prefer to use PCRA with a basal rate rather than use a basal rate-only mode for continuous peripheral nerve block because it allows the lowest effective continuous infusion dose (Ilfeld, Morey, Enneking, 2002b, 2004; Ilfeld, Thannikary, Morey, et al., 2004). Practice varies widely, however (see later in the chapter).

As mentioned, automated bolus doses have been administered in addition to PCRA capability. A study randomized 50 patients to receive a continuous popliteal nerve block by automated bolus doses or a continuous infusion; both had PCRA capability (Taboada, Rodriguez, Bermudez, et al., 2009). The quality of analgesia and need for rescue analgesia were similar among the two groups, but those who received automated bolus doses required fewer PCRA doses and consumed less local anesthetic.

A variety of multimodal strategies are used with continuous peripheral nerve block therapy. Nonopioids, such as acetaminophen and an NSAID, and/or anticonvulsants, such as gabapentin or pregablin (see later in this chapter), may be provided in scheduled doses. IV (opioid) PCA (usually without basal rate) is sometimes used to provide supplemental analgesia for patients receiving continuous peripheral nerve block by basal rate only (i.e., without PCRA capability). Alternately, oral opioid or nonopioid-opioid combination analgesics are provided as needed for breakthrough pain. These are sometimes administered in scheduled doses to prevent breakthrough pain. Supplemental analgesia is also provided prior to ambulation and physical therapy to maximize comfort during these painful activities; when PCRA is used, patients are taught to self-administer a dose prior to these activities to improve their ability to participate.

The most commonly used local anesthetics and concentrations for continuous peripheral nerve block are ropivacaine 0.1% to 0.2% and bupivacaine 0.0625% to 0.125%. (The initial block is established with incremental doses of a higher concentration, usually of the same local anesthetic.) Some clinicians report efficacy with higher concentrations, e.g., a fixed infusion of 0.25% bupivacaine at 5 mL/h (Swenson, Bay, Loose, et al., 2006). One study found that 0.1% ropivacaine provided ineffective analgesia and 0.2% and 0.3% ropivacaine provided similarly effective analgesia (Brodner, Buerkle, Van Aken, et al., 2007). There were no adverse effects among the various concentrations, and the researchers suggested 0.2% concentration at an initial infusion rate of 15 mL/h. Clonidine is sometimes added to peripheral nerve block infusions to enhance the duration and effectiveness of the local anesthetic (Ilfeld, Morey, Enneking, 2003) (see Chapter 22 for more on clonidine).

Randomized studies have evaluated various dosing strategies in an attempt to determine an optimal regimen. It appears to vary depending on type of surgery and location of catheter. One compared 0.2% ropivacaine administered by: (1) a basal rate of 12 mL/h plus a low PCRA bolus dose of 0.05 mL (designated the basal group), (2) a basal rate of 8 mL/h plus a PCRA bolus dose of 4 mL (designated the basal-bolus group), or (3) a low basal rate of 0.3 mL/h plus a large PCRA bolus dose of 9.9 mL (designated the bolus group) in patients following foot or ankle surgery (Ilfeld, Thannikary, Morey, et al., 2004). PCRA bolus doses were available once every hour. The patients in the bolus group (PCRA only) had a higher incidence of inadequate pain control, increased supplemental opioid requirements, and more sleep disturbances compared with the basal groups. The basal-bolus group experienced the best overall outcome. The same mode was recommended following upper extremity surgery at or distal to the elbow (Ileld, Morey, Enneking, 2004). However, another group of researchers found no benefit with the addition of a ropivacaine basal rate, and they recommended PCRA bolus-only mode after major knee surgery (Eledjam, Cuvillon, Capdevila, et al., 2002). Others have conducted similar studies with bupivacaine 0.125%, and recommended PCRA bolus-only following total knee replacement (Singelyn, Gouverneur, 2000) and hip replacement (Singelyn, Vanderelst, Gouverneur, 2001) and a basal rate plus PCRA boluses for shoulder surgery (Singelyn, Seguy, Gouverneur, 1999).

The relationship between concentration and volume has also been studied and varies depending on catheter location. One study recommended a more concentrated solution (0.4% versus 0.2% of ropivacaine) in a smaller volume (4 mL/h versus 8 mL/h) for popliteal sciatic nerve block (Ilfeld, Loland, Gerancher, et al., 2008). Another recommended further research but suggested that a lower concentration in a larger volume provided superior analgesia for interscalene nerve blocks (Le, Loland, Mariano, et al., 2008) and for infraclavicular nerve blocks (Ilfeld, Le, Ramjohn, et al., 2009).

The duration of continuous peripheral nerve block therapy depends on many factors, including type of surgical procedure, location of catheter, and patient status (e.g., NPO, chest tubes still in place). A review of the data of nearly 1500 patients who received continuous peripheral nerve block for inpatient orthopedic surgeries revealed a median duration of 56 hours (Capdevila, Pirat, Bringuier, et al., 2005). Generally, the duration ranges from 24 to 72 hours. A secondary analysis of a double-blind, randomized controlled study found that extending the duration of therapy to 96 hours (4 days) had no effect on patients’ functional status and well-being between 7 days and 1 year following knee arthroplasty (Ilfeld, Meyer, Le, et al., 2009).

Adverse Effects and Complications

The adverse effects of local anesthetics delivered by continuous peripheral nerve block are similar to those by other routes of administration (see Box 26-1 and Chapter 15). Intravascular catheter migration is rare but has been reported (Capdevila, Pirat, Bringuier, et al., 2005) and would produce signs of local anesthetic toxicity, such as metallic taste, perioral numbness, and tinnitus. Patients receiving this technique should be evaluated systematically for these signs, and those who receive continuous peripheral nerve block in the home setting must be given verbal and written instructions that include the signs and symptoms of adverse effects and what to do if detected (see pp. 757-758 at the end of Section V). Intravascular injection and undetected early signs of local anesthetic toxicity can progress to cardiovascular collapse. Lipid emulsion has been used to successfully resuscitate several patients from cardiac arrest from local anesthetic-induced cardiotoxicity (Clark, 2008); however, the effectiveness of this treatment depends on the type of local anesthetic administered. That is, intralipid treatment appears to be effective for bupivacaine-induced but not ropivacaine- or mepivacaine-induced cardiac arrest (Espinet, Emmerton, 2009; Zausig, Zink, Keil, et al., 2009). Large doses of epinephrine are also reported to be required for reversal of bupivacaine-induced cardiotoxicity (Mulroy, 2002).

All local anesthetics produce both motor and sensory blockade (Wilson, 2009). The ability to participate in physical therapy early and effectively during the postoperative course for orthopedic patients is critical. Despite the administration of low concentrations of local anesthetic, motor block can present a problem, but adjustments in dose and technique, multimodal approaches, and the use of assistive devices have contributed to improved outcomes in these patients (Dorr, Raya, Long et al., 2008; Ilfeld, Gearden, Enneking, et al., 2006; Wilson, 2009) (see later discussion of Local Infiltration Analgesia).

As mentioned, opioids and nonopioids are often used for breakthrough pain during continuous peripheral nerve block therapy; however, the significant dose-sparing effects of the therapy reduce the incidence of adverse effects associated with these other analgesics, such as GI disturbances from nonopioids, and nausea, sedation, and respiratory depression from opioids. Research suggests that there is less cognitive dysfunction with this technique as well, which has implications particularly in older adult patients (Hebl, Kopp, Ali, et al., 2005). Still, patients must be assessed for these adverse effects whenever these other analgesics are co-administered with the therapy (see Chapters 6 and 19).

Complications are rare with continuous peripheral nerve blocks (Capdevila, Pirat, Bringuier, et al., 2005; Cuvillon, Ripart, Lalourcey, et al., 2001; Swenson, Bay, Loose, et al., 2006) and are thought to be less common than with single-injection blocks (Boezaart, 2006). Transient or permanent nerve injury can be caused by the nerve block as well as by inadvertent intraoperative or postoperative pressure applied to a nerve or postoperatively from traction injury (Boezaart, 2006) or hematoma compression (Siddiqui, Cepeda, Denman, et al., 2007). Transient nerve damage has been reported most often with interscalene blocks (Capdevila, Pirat, Bringuier, et al., 2005) and axillary blocks (Boezaart, 2006). Low incidences of persistent sensory blockade (3%), persistent motor blockade (2.2%), and paresthesias or dysesthesias (1.5%) during the postoperative period were described in one prospective analysis (Capdevila, Pirat, Bringuier, et al., 2005). All resolved without sequelae.

The use of anticoagulation therapy has significantly improved morbidity and mortality following some major surgeries, such as total knee or hip replacement, but this practice has presented a challenge to those who must find strategies that provide both effective and safe management of the associated pain. Peripheral nerve blocks provide exceptional pain relief but are not without a low risk (0.019% to 1.7%) of nerve damage and deficits from complications (Meier, Buttner, 2007), such as hematoma formation and compression (Siddiqui, Cepeda, Denman, et al., 2007). It is essential that patients be regularly assessed for signs of compression syndrome, such as changes in skin color in the affected area indicating poor circulation or increased numbness, tingling, or weakness in an affected extremity, and to be aware that these may be masked by the effects of local anesthetics (see Box 26-1). The reader is referred to the American Society of Anesthesiologists (ASA) guideline for the use of regional anesthetic techniques in anticoagulated patients, which describes the safe use of peripheral nerve blocks in these patients (Horlocker, Wedel, Benzon, et al., 2003) (see Chapter 15 and Table 15-8 on p. 439).

As with any indwelling catheter technique, there is a risk of infection and localized inflammation with continuous peripheral nerve blocks. Risk factors include a stay in the ICU with a possible association with catheter placement in patients who have sustained traumatic injury, duration of the indwelling catheter for greater than 48 hours, site of catheter (e.g., higher risk with femoral than with popliteal), male sex, and absence of antibiotic prophylaxis (Capdevila, Bringuier, Borgeat, 2009). Capdevila and colleagues (2009) recommend the same maximal sterile precautions used for epidural cathether placement to anesthesia providers placing peripheral nerve catheters (see Chapter 15). A prospective study of the experiences of nearly 1500 patients who had received continuous peripheral nerve blocks provided bacterial analysis of the catheters placed in 68% of the patients (Capdevila, Pirat, Bringuier et al., 2005). Positive bacterial colonization occurred in 28.7% of the cases, most often from the staphylococcus species (staphylococcus epidermidis [61%], gram-negative bacillus [21.6%], and staphylococcus aureus [17.6%]). The reader is referred to this study for a breakdown of the incidence and type of bacteria depending on type of peripheral nerve block. One patient in this study experienced symptomology from a staphylococcus aureus infection that resolved with antibiotic treatment. Another study found a 57% rate of bacterial colonization (primarily staphylococcus epidermidis) of femoral catheters; three transitory bacteremias occurred but resolved with catheter removal and no antibiotics (Cuvillon, Ripart, Llaourcey, et al., 2001). The authors recommended close monitoring of patients for signs of infection but did not recommend systematic bacterial analysis of catheters (see Box 26-1). Subcutaneous tunneling of the catheter is suggested as a means of further reducing risk, but well-controlled research is needed to confirm the effectiveness of this approach for this purpose (Compere, Legrand, Guitard, et al., 2009).

Technical difficulties in placement and maintaining the placement of catheters are reported in nearly every study but are relatively rare (Capdevila, Pirat, Bringuier, et al., 2005; Swenson, Bay, Loose, et al., 2006). As with any therapy that utilizes infusion devices, equipment malfunction is described as well.