Chapter 79. Organization of an Acute Pain Management Service Incorporating Regional Anesthesia Techniques

The field of acute pain management has changed substantially in recent years. In the past, acute pain management consisted primarily of opioids given intermittently by intramuscular injection. In addition to pain on injection, this lead to undesirable “analgesic gaps” or periods of inadequate pain control between peak and trough opioid levels. Consequently, patients were often reluctant to request pain medications ordered “as needed.”

To provide more continuous analgesia, intravenous patient controlled analgesia (IVPCA) was introduced in the 1980s, leading to the development of specialized pain management teams, most often under the direction of anesthesiologists. The application of intrathecal opioids and epidural analgesia for postoperative pain management heralded the first pain service in the United States.1 In Europe, Narinder Rawal presented his experience introducing the role of nurses as valued members of the acute pain management team.2 By the early 1990s, 40% of US hospitals had acute pain services.3

The American Society of Anesthesiologists (ASA) Task Force first established practice guidelines for acute pain management in 1995.4 These guidelines were revised in 2004, and the reader is encouraged to review this document.5 The Joint Commission of Accreditation of Healthcare Organizations (JCAHO) established standards (Table 79–1) for pain management in January 2001.6 These standards provided an impetus for hospitals to have an institution-wide commitment for policies and procedures to support effective pain management. This effort promoted the concept of pain as the “fifth vital sign” and established the patient's right to pain management. It also became evident that an effective pain management program can only be achieved with a strong institutional commitment. The revised ASA guidelines of 2004 highlighted the importance of multidisciplinary collaboration among anesthesiologists, surgeons, nurses, pharmacists, and other members of the healthcare team.

Early advances on this topic focused on safe application of aggressive techniques utilizing protocols and standing orders with the monitoring available on the ward. However, it is the PCA services that paved the way for the development of true acute pain management services providing on-demand systemic as well as epidural and intrathecal analgesia. The US model focused on physician management; the European model put a greater emphasis on the nursing role.

In recent years, regional anesthesia has gained popularity because if its contribution to postoperative pain management. Single and continuous peripheral neural blockade is increasingly practiced in both the inpatient and outpatient setting. However, effective application of these techniques requires adequate expertise, surveillance, and organization, not simply placing the particular block or catheter. Multidisciplinary acute pain teams can monitor and titrate these techniques to maximize pain relief and safety while minimizing side effects.

More aggressive techniques such as IVPCA, epidural analgesia, intrathecal opioids, and peripheral blocks find their best results when launched as part of a multimodal analgesic approach that incorporates nonsteroidal antiinflammatory agents (NSAIDs) and cyclooxygenase-2 (COX-2) inhibitors as well as other means of nonpharmacologic means to acute pain management (see Chapter 77, The Role of Nonopioid Analgesic Techniques in the Management of Postoperative Pain, for more information on nonpharmacologic means to pain management).7,8 True multimodal analgesia targets multiple mechanisms of pain to effectively relieve both rest and dynamic pain.

A dedicated acute pain management team enhances implementation of these techniques for pain management. The primary goals of an acute pain management service are to offer a wide variety of services, provide a high level of patient surveillance, and integrate these services into the overall hospital setting. Optimal analgesia requires judicious dose adjustment to maximize the benefits and minimize the side effects of therapy. This can only occur if the patient is adequately monitored.

The purpose of this chapter is to provide strategies for effective postoperative pain management while enhancing safety and facilitating delivery of services. An organizational model for a nursing-based acute pain service is presented. Standard orders and protocols are also provided to facilitate implementation of the suggested principles and approaches. Finally, we provide many of the organizational tools and concepts we have found useful in the organizational design of our acute pain service.

IVPCA is commonly used as part of a multimodal approach to postoperative pain control. Sechzer9 and Forrest10 popularized the concept of PCA. Patients self-administer small doses of intravenous opioid at predetermined intervals (lockout), to maintain a minimum effective analgesic concentration (MEAC). This titration of the opioid provides a more constant plasma level of analgesic11 and more consistent analgesia.12 Maintaining opioid plasma levels within a tight range improves analgesia while reducing unwanted side effects that can occur with larger boluses. PCA pumps can be programmed to deliver opioids either by intermittent patient-controlled bolus doses alone or with a continuous background (or basal) infusion. PCA pumps are programmed to set the demand dose, lockout interval, hourly total dose, and basal infusion. Importantly, before starting PCA, analgesia must be established with an initial loading dose of opioid.13 Without front loading, MEAC is not achieved for at least three elimination half-lives.14 PCA is intended to maintain a level of pain control, not to initiate satisfactory analgesia. Therefore, if the PCA process is interrupted by pump failure, a faulty intravenous, or inadequate patient dosing, the patient will require bolus titration to achieve comfort before reinitiating PCA.

PCA advantages over intermittent injections include fewer analgesic gaps, maintaining analgesia with less total opioid consumption (thus with fewer side effects), less use of nursing staff time, and improved patient satisfaction. Patients can anticipate and proactively manage their pain, particularly before moving or coughing. There is also a psychological advantage because of the shortened interval between perception of pain and administration of medication.

In the opioid-naïve patient, the addition of a basal infusion to IVPCA has been shown not to improve analgesia, but increases the risks of this technique.15 Without a basal infusion, the risk of clinically significant respiratory depression is generally low. Patients maintain normal levels of arterial CO2 in the early postoperative period while receiving PCA therapy. Postoperative respiratory functions (forced expiratory volume, functional residual capacity, and peak flow rates) are not significantly different from those in patients receiving intramuscular injections of opioids.16,17

The most common problem associated with IVPCA use is operator error, the most common cause of which is programming error and incorrect drug concentration.18 When a medication error involves a PCA pump, the risk of patient harm increases 3.5 times.19 The FDA's Manufacturer and User Facility Device Experience (MAUDE) Database for 2004 identified 21 deaths involving IVPCA pumps; 16 deaths were related to large-volume infusion pumps (LVP). Given that there are approximately 10 times as many LVPs as PCA pumps, it appears that the risk of a severe respiratory event from a PCA pump is at least 10 times greater than with an LVP.20 To avoid these errors the nursing staff must understand the basis for therapy and be knowledgeable about the operational aspects of PCA pumps.

Patient-related PCA problems include failure to understand PCA therapy, intentional analgesic abuse, underutilization because of unwarranted fears of addiction, and PCA by proxy (operation by an individual other than the patient). Patients should be educated about PCA before surgery; the education should be frequently reinforced throughout treatment.

Morphine is the most commonly used PCA opioid. Hydromorphone and fentanyl are also favored because of their favorable metabolite profile. Meperidine has little place as an analgesic because of its neurotoxic metabolite, normeperidine. Table 79–2 summarizes the commonly used IVPCA equianalgesic opioid solutions.

An iontophoretic, transdermal drug-delivery system (ITS) has demonstrated the ability to provide needle-free patient-controlled delivery of fentanyl. This patient-controlled transdermal analgesia (PCTA) system is a preprogrammed and self-contained device about the size of a credit card. Clinical trials have demonstrated analgesic efficacy similar to that from standard morphine IVPCA.21

When converting between opioids, these conversion doses should be considered as an approximation because of incomplete cross tolerance. Patient responses may vary when converting from one opioid to another. Similar rules apply when converting the IV opioid therapy to the oral opioid analgesic therapy (Table 79–3).

Safe and effective use of PCA requires institution-wide protocols and standard orders (Figures 79-1, 79-2, 79-3, and 79-4). Clinicians must have a thorough understanding of equianalgesic opioid doses (see Table 79–2).

Peripheral nerve blocks are useful in providing surgical anesthesia and postoperative analgesia22,23 with an acceptable side effect profile.23,24 Single-injection techniques are limited in duration but can be extremely useful in the immediate postoperative period. Continuous catheter techniques can extend the duration of analgesia to the desired length of time. The greatest hindrance to the catheter technique was the unavailability of appropriate equipment both for catheter insertion and drug delivery. Both of these obstacles have now been overcome. There are commercially available catheter insertion kits and drug delivery systems. The infusion pumps now available are small, portable, and lightweight. There is a large variety of commercially available PCA pumps with different characterists.25 The introduction of these lightweight, portable infusion pumps has made home infusion possible, and it has been shown to be effective in randomized, double-blind, placebo-controlled studies.26–28

Numerous approaches have been described to the lumbar, sacral, and brachial plexuses and in the paravertebral space. The planned surgical procedure will determine the peripheral nerve block needed for postoperative analgesia. A brief example of common indications is listed in Table 79–4. The reader should refer to the respective chapters on individual nerve block techniques for in-depth discussion on indications and technical aspects of their use. In general, the peripheral nerve block techniques are indicated in patients expected to have moderate-to-severe postoperative pain that is not easily controlled with opioids or when opioid side effects are problematic.

Possible modes of local anesthetic infusion through these catheters include intermittent bolus, continuous infusion, or continuous infusion with PCA boluses. Infusion mode is often a matter of clinician preference. Continuous infusions and continuous infusion with PCA have been shown to be superior to the intermittent bolus technique.29

In an ambulatory setting, patient selection is critical. Only patients who are capable of accepting the additional responsibility of the catheter and infusion pump should be selected. Since some degree of cognitive dysfunction may occur in the early postoperative period, patients will benefit from a caregiver at home for the first 24–48 h who can participate in patient care. To decrease the risk of local anesthetic toxicity, patients with hepatic or renal insufficiency should not be sent home with continuous catheters if they do not have a caregiver at home. Hence, patients without a caregiver, with baseline cognitive difficulties, with certain underlying medical problems, or patients living a distance from the medical facility may be poor candidates for ambulatory infusion techniques.

Recommendations for local anesthetic injection volume and catheter infusion rates are provided in the respective chapters. The reader should note that the suggested doses, volumes, concentrations, and infusion rates are only general guidelines and must be adjusted for individual patients. More in-depth discussion on these variables can be found in Chapters 10 (Local Anesthetic Solutions for Continuous Nerve Blocks) and 64 (Continuous Peripheral Nerve Blocks in Outpatients).

The successful use of peripheral catheters in the ambulatory setting requires patient education that should start in the preoperative area and extend into the postoperative period. Both patients and their caregiver must be involved. Instructions should be both verbal and written and include pager numbers and telephone numbers of responsible healthcare providers who will be available around the clock if problems occur. Although the surgeon is responsible for the overall care of the patient, the anesthesiologist providing the continuous regional technique must be responsible and available for catheter-related problems.

Key elements of patient instructions include:

• Protect the operative limb for the duration of the block.
• Keep the catheter site clean and dry.
• Do not operate machinery or drive a vehicle for the duration of the block.
• Approximate duration/resolution of the surgical block.
• Use of supplemental oral analgesics/opioids.
• Portable pump instructions.
• When and how to remove the catheter.
• Look for signs of catheter/local anesthetic infusion complications.
• Observe catheter site for swelling, tenderness, and drainage.

Careful follow-up is necessary with any continuous catheter technique. Visiting nurses may be helpful. Patients may benefit from daily telephone contact with specific questions about quality of analgesia, local anesthetic side effects, and possible catheter site infection. Documentation of these patient contacts should be made.

Patients may remove their peripheral infusion catheters at home, may return to the medical facility to have them removed, or a visiting nurse may remove the catheter. This may depend on the patients' abilities, the distance they must travel from the hospital, and their degree of mobility. Reusable infusion pumps may be mailed to the surgical facility in a padded envelope. With proper selection and education of patients, the incidence of injury to the blocked limb is very low.30

Complications of Continuous Catheter Techniques

1. Local anesthetic toxicity is a potential complication that can occur when large volumes or high concentrations of local anesthetics are used. Intravascular placement of catheters can be detected with epinephrine-containing local anesthetic test doses. Low concentrations of a long-acting local anesthetic with an acceptable safety profile are advisable. Ropivacaine, in 2 mg/mL concentration, infused in a continuous interscalene (brachial plexus) catheter at 6 to 9 mL/h has demonstrated safety.31,32

2. Patients should be instructed to look for signs of local infection at the catheter site, local tenderness, redness, and fever. These should be immediately reported to the healthcare providers. Even though infection at catheter sites is uncommon, one study reported 57% of femoral catheters showed bacterial colonization at 48 h.33

3. Although a rare occurrence, catheter migration must always be considered. Catheter failure is the most common sign of migration. Since the actual location of the local anesthetic infusion cannot be determined, failed catheters should always be removed promptly. Catheters may migrate into the intravascular compartment. Patients should be provided with a list of signs of intravascular infusion of local anesthetics: tinnitus, metallic taste in the mouth, and anxiety. Intramuscular migration of the catheter will result in either a decrease or complete cessation of analgesia. The infusion should be stopped since there is a theoretical risk of myocitis.34

4. Careful dressing of the catheter site and use of surgical tape can reduce catheter dislodgment. Clear dressings are advantageous since they permit visualization of the insertion site. Commercially available skin preparations (similar to ostomy site skin preps) may increase adhesion while reducing skin breakdown. Adhesive surgical strips may be beneficial in regions that are difficult to secure. Catheters can also be secured by suturing or tunneling. This may be helpful for longer term placement.

5. Many varieties of infusion pumps are available for either continuous infusions or with patient-controlled boluses. The pump selection should be based on its accuracy of delivery, simplicity of use, and ability to allow for patient-initiated boluses. Cost should also be evaluated. Use of disposable pumps in the ambulatory setting is preferred, as patients are not required to return the equipment. Use of large-volume (250–400 mL) pumps will provide longer periods of analgesia. However, larger volumes of local anesthetic may increase the risk of systemic toxicity.

Successful use of peripheral nerve catheter infusions requires an infrastructure consisting of anesthesiologists, surgeons, pharmacists, and nurses:

• A group of anesthesiologists with additional training in regional anesthesia.
• Around-the-clock coverage of the service by an anesthesiologist.
• Surgeons familiar and supportive of these techniques.
• Pharmacists familiar with the range of local anesthetic concentrations and infusion rates.
• Specially trained nurses to help maintain catheter infusions and provide patient education.
• Policies supporting attentive patient follow-up.
• Availability of infusion pumps.
• Proper patient selection and education.
• Institutional commitment to provide trained staff and equipment.
• Organizational tools, including standardized procedure note, order sets, and documentation records.

Multimodal analgesia produces optimal pain relief by targeting pain at multiple pathways.35 Combining analgesic techniques and drugs has a synergistic or additive effect and decreases the requirement for individual medication, thereby reducing the incidence of side effects.36

The surgical stress response produces endocrine and metabolic responses in the body. These pathways can be targeted pharmacologically at specific levels by adopting a multimodal approach to pain control.37 The focus of the multimodal approach to acute postoperative pain management is to facilitate the patient's rehabilitation. Multimodal approaches combined with accelerated recovery protocols can reduce length of hospital stay.38 This has been shown to work when the surgical team, anesthesiologists, nurses, and patients work together within established clinical pathways.39

Chronic pain has been identified as a consequence of surgery and poorly controlled acute pain.40 Multimodal techniques may reduce central sensitization, improve pain control, and ultimately reduce long-term sequelae. The concepts of preemptive analgesia are discussed in Chapter 76 (Preemptive Analgesia, Regional Anesthesia, and the Prevention of Chronic Postoperative Pain). Local anesthetics and regional anesthesia techniques are critical components of multimodal analgesia. Potential uses are described in the following sections and in Table 79–5.

Opioids and nonsteroidal antiinflammatory drugs (NSAIDs) act both centrally and peripherally to decrease afferent impulses to the dorsal horn of the spinal cord. Ketamine, an N-methyl-d-aspartate (NMDA) receptor antagonist, when used in small doses (0.5–0.15 mg/kg IV) has been shown to improve pain relief if administered with opioids intravenously or epidurally.41,42

With appropriate patient selection, NSAIDs can be very effective. However, in some patients and situations NSAIDs can exert an antiplatelet effect that can cause surgical bleeding. They may also cause renal dysfunction. NSAIDs have an opioid-sparing effect43 and can be administered orally or parentally. COX-2 inhibitors do not have an antiplatelet effect, making them desirable for postoperative pain management. Concern for cardiovascular problems has led to the withdrawal of certain COX-2 inhibitors from the market. However, this risk is associated with a duration of use longer than is indicated for most acute pain situations.

Use of continuous epidural infusions of local anesthetic with or without opioids has become a cornerstone of multimodal analgesia.44 The use of dilute local anesthetic solutions has been shown to decrease the incidence of deep venous thrombosis in the postoperative period.45 It is an effective weapon in attenuating the endocrine metabolic response to surgical stress and to provide dynamic pain relief.46 The epidural catheter must be functional and cover the dermatomal distribution of the surgical incision to be effective. Epidural catheters are best inserted at the middermatome of surgical trauma. Care must also be taken to advance between 3 and 5 cm of epidural catheter into the epidural space. A shallower insertion results in greater incidence of catheter dislodgement, whereas an excessive length of catheter reduces efficacy and increases risk of catheter knotting. The routinely used nylon epidural catheters are difficult to direct in the epidural space, regardless of the direction of the epidural needle bevel. Hence, it is best to target a short length of catheter at the precise spinal cord level to cover surgical pain.

In a meta-analysis comparing epidural analgesia with parenteral opioids, epidural analgesia was found to provide more effective pain control.47 Epidural opioids or local anesthetics either alone or in combination demonstrated superiority. Hence, when surgical pain is of high intensity and likely to last at least 48 h, epidural analgesia deserves consideration. Side effects of epidural analgesia include motor block, nausea and vomiting, pruritus, urinary retention, sedation, and respiratory depression. Epidural catheters in the presence of anticoagulation may increase the risk of epidural hematoma.

A number of other agents have demonstrated analgesic efficacy when administered by the epidural route either alone or in combination with other agents. These agents include anticholinergics, NMDA receptor antagonists (eg, ketamine) and α2-adrenergic agonists. Epidural epinephrine, clonidine,48 and dexmedetomidine49 have demonstrated analgesic efficacy.

A standard epidural order form (Figures 79–5 and 79–6) and epidural procedure note (Figure 79–7) enhances documentation and reduces medication errors.

Commonly used solutions for epidural infusion and rates of administration are detailed in Tables 79–6 and 79–7.

The preprinted epidural analgesia forms are of vital importance to the efficacy, safety, time efficiency, and surveillance of the epidural analgesia program (Table 79–8).

Common problems and clinical dilemmas that occur during epidural infusion are presented in a decision-tree fashion in Figures 79-8, 79-9, 79-10, 79-11, and 79-12. These decision-tree algorithms can be used to troubleshoot most of these issues on the ward.

Peripheral Nerve Blocks (& Multimodal Analgesia)

Peripheral neural blockade works best when it is part of a multimodal approach to pain control.50 It may offer advantages over continuous catheter-based epidural analgesia in lower limb procedures, particularly when anticoagulation is required for venous thromboembolism (VTE) prophalaxis. For single-injection techniques, adding epinephrine 1:200,000 or clonidine enhances the duration of the block. Since clonidine can cause sedation, bradycardia, and hypotension, it may not be a suitable agent for use in the ambulatory setting.

Infiltration with Local Anesthetics

Injecting the operative site with local anesthetic is a simple way to enhance pain control.51 Local anesthetics can be injected or infused into joint spaces, surgical wounds, or in the vicinity of nerves near the surgical site. Local anesthetics are relatively inexpensive and remain the most useful and safe component of multimodal analgesia.

Acute Pain in the Patient with Chronic Pain

Patients with chronic pain present special challenges in the perioperative period. Their pain is typically poorly controlled by the routine administration of opioids alone. It is critical that such patients are identified in the preoperative period and an analgesia plan established before surgery52 to avoid unnecessary prolonged periods of severe uncontrolled postoperative pain. Evidence from the literature supports that the opioid requirement in these patients can be much higher than in opioid-naïve patients.53 These patients may present with a history of chronic opioid use, often at high doses and perhaps in conjunction with a variety of other pain medications. Following identification, these patients require careful assessment in the preoperative phase to fully describe the nature of their chronic pain, to quantify opioid requirements, and to document all current medications. Then, an analgesic plan must be formulated with the patient as an active participant.54Table 79–9 details practical approach to postoperative pain management in the patient with history of chronic pain.

Opioid-Tolerant Patients

Opioid-dependent patients may include patients with chronic pain,55 active opioid abusers, or former addicts enrolled in long-term methadone maintenance programs. All of these patients have a high tolerance to the antinociceptive effects of opioids,56 are pain-intolerant,57 and can have opioid-induced hyperalgesia.58

It is important to identify these patients in the preoperative period and establish a sound pain management strategy before surgery. In the postoperative period these patients will often require more than twice their stable opioid dose. This rapid increase in opioid requirement has been termed acute tolerance. Patients should receive their daily maintenance opioid dose the morning of surgery. Even if regional anesthesia techniques are used, these patients must receive their minimum opioid requirement to prevent opioid withdrawal symptoms. In the immediate postoperative period, consider higher than routine doses of IVPCA with morphine or hydromorphone. (Hydromorphone and sufentanil are regarded as higher efficacy opioids and may be more helpful in opioid-tolerant patients.) With opioid tolerance, adding a basal IV opioid infusion to PCA may improve analgesia. The basal infusion may be dose-equivalent to a significant portion of the patient's maintenance requirement.

Regional analgesia with local anesthetic and systemic opioid is a more efficient way of providing pain control than parenteral opioids alone. Use of an opioid with high intrinsic efficacy, such as sufentanil, is more effective59 in the setting of opioid receptor down-regulation.60 These patients may benefit from the regional anesthesia, epidural, or parenteral opioids for a longer period of time than opioid-naïve patients.

In the postoperative period, converting opioid-tolerant patients to oral opioids can be quite challenging. One approach is to calculate the patient's 24-h opioid requirement from IVPCA and give two thirds that amount in the form of a long-acting oral opioid and one third in the form of a short-acting oral opioid to be used as needed. Table 79–8 provides an equianalgesic opioid conversion chart.

Baseline opioid doses should be tapered slowly to prevent withdrawal. Addition of other adjuncts such as α2-adrenergic receptor agonists like clonidine, dexmedetomidine, NMDA receptor antagonists, and COX-2 inhibitors all help to decrease opioid need and improve analgesia. Tricyclic antidepressants may help with neuropathic pain, although these agents usually require several weeks to achieve efficacy. Membrane-stabilizing agents (eg, gabapentin) can be extremely helpful during the perioperative period in the presence of neurogenic or neuropathic pain. Routine doses of these agents should be continued. Surgery can cause new nerve injury and pain that may benefit from these agents.

Before and after hospital discharge, referral to a pain specialist can be very helpful in treating the opioid-dependent patient to help optimize pain management during rehabilitation and facilitate opioid dose tapering. Whenever possible, the pain specialist familiar with the patient's history should be involved in the postdischarge pain management. With patients chronically treated with opioids, patients may be better served by having a single opioid prescriber.

Considerations for managing the opioid-tolerant patient are presented in Table 79–10.

Extended-release epidural morphine (EREM) (DepoDur, Endo Pharmaceuticals, Chadds Ford, PA) was approved by the US Food and Drug Administration in 2004 for postoperative pain management following major surgery. EREM is an extended-release formulation of morphine in a liposomal carrier, intended for epidural administration. EREM is approved for the treatment of postoperative pain by single-dose administration into the lumbar epidural space before major surgery or following umbilical cord clamping during cesarean section. EREM is not intended for intravenous, intrathecal, or intramuscular administration.

Recently published studies have demonstrated the safety and efficacy of EREM in a variety of surgical models. In a hip arthroplasty study, EREM provided analgesia for up to 48 h after surgery with a side effect profile similar to that for standard epidural opioid analgesia.61 EREM demonstrated a marked reduction in the need for supplemental analgesia and delayed the time for first analgesic rescue. No additional analgesia was needed in 25% of EREM patients. Similarly, in the lower abdominal surgery study, EREM reduced the need for supplemental opioid analgesia and reduced pain scores.62

In a cesarean section study, EREM was compared with a standard epidural morphine dose of 5 mg.63 Patients who received EREM at the 10- and 15-mg dose had both superior pain relief and extended analgesia for 48 h with less need for supplemental analgesia. To measure functionality of patients, an instrument was created to assess the effect of pain on common patient functions (resting in bed, sitting, waking, and using the rest room). Pain had significantly less impact on functional ability for 48 h after surgery in patients who received EREM at the 10- or 15-mg dose.

One must bear in mind that the doses in these initial studies employed opioids alone for analgesia. Consequently, opioid side effects were observed. In practice, most clinicians utilize multimodal analgesic techniques to reduce opioid requirements and their related side effects while optimizing pain relief. If clinicians use similar techniques with EREM, it is quite likely that lower doses may provide adequate analgesia while reducing typical opioid side effects, such as nausea, pruritus, sedation, and respiratory depression.

The potential of providing extended analgesia without an epidural catheter and epidural pump or IVPCA pump is very desirable. External pump technology is cumbersome for the patient, time-consuming for the nursing staff, and is associated with medication errors and pump programming errors. In many surgical settings, anticoagulation to prevent venous thromboembolis is now standard management. Consequently, indwelling epidural catheters may increase the risk of epidural hematoma formation. EREM may provide extended analgesia without the need for indwelling epidural catheters and without the difficulties associated with current epidural and IVPCA pumps.

Nurses are a key component of an acute pain service. The pain nursing team may be composed of acute pain management nurses, pain resource nurses, and floor nurses. Acute pain management nurses are dedicated to promoting and providing care for patients in pain. In most settings, acute pain nurses work in collaboration with the department of anesthesiology. Acute pain management nurses operate best within an established framework of hospital-approved protocols and guidelines and through decision trees. Guidelines and protocols are intended to establish the basic standard of care and provide consistency in management.64 Protocols prescribe methods of care in a less flexible way then guidelines,65 but neither is a substitute for personal knowledge. Thoughtful application is essential if guidelines and protocols are to be safe and effective.

A nurse-driven acute pain service consists of a physician director and the nursing team. The physician determines the appropriate analgesic technique. The care team, consisting of an attending physician, resident, and an acute pain nurse, assesses patients on morning rounds and develops a comprehensive management plan. A standard daily clinical note will facilitate documentation (see Figures 79–3 and 79–4). The roles of the various team members are described in Table 79–11.

The pain management plan is communicated and coordinated by the acute pain nurse to the other members of the patient care team. The pain resource nurse is a floor nurse with special training in the assessment of pain and technical expertise in the various infusion devices. Optimally, every nursing unit has a pain resource nurse to provide peer support to other floor nurses and provide basic troubleshooting and assessment. Standard documentation sheets for pain assessment, epidural, and PCA are helpful (see Figures 79–3, 79–4, and 79–6).

A very specific process is followed so that protocols can be considered, approved, and eventually become part of a standard order set. The proposed protocols are then reviewed by the pharmacy and therapeutics (P&T) committee that makes recommendations resulting from evidence-based practice. The P&T committee is a multidisciplinary group composed of physicians, pharmacists, administrators, and nurses. Standard order sets then typically require the approval of a medical executive committee. Where computer physician order entry is employed (CPOE), standard order sets must be configured to maintain all necessary order details of the protocol. Thus, physicians are able to order a protocol of decision trees that allow the acute pain nurses to follow a defined path in the management of specific pain management scenarios.

With a nurse-driven acute pain service, the pain nurse is the first to respond to calls for the patient's pain issues. Pain nurses must possess astute assessment and critical thinking skills. This requires a background in critical care or postanesthesia care. Utilizing decision trees and critical thinking, pain nurses are called on to manage pain and side effects of pain therapies, troubleshoot epidural and peripheral block catheters, titrating and bolusing as needed, and removing catheters when indicated. Pain nurses must be well trained at assessing hypotension, motor block, and excessive sedation. All actions and interventions of the pain nurse are entirely within the scope of institutional protocols. Figures 79-8, 79-9, 79-10, 79-11, and 79-12 provide a number of practical decision trees for troubleshooting common clinical scenarios.

Pain nurses are the critical link in providing education and peer support to the various members of the nursing service. Nurse-driven acute pain services function proactively, closely monitoring and anticipating problems. The visible presence of pain nurses increases patient satisfaction, improves pain control and safety, and may improve patient outcome. Busy acute pain services utilizing aggressive regional anesthesia/analgesia techniques and opioid therapies may benefit from an organizational design that places nurse in key patient management positions. A nurse-driven acute pain service integrates the treatment of these patients into the overall hospital milieu and helps facility institutional consistency in the management of all pain issues within the facility.

A pharmacist offers a unique perspective when establishing or expanding an acute pain service using regional anesthesia/analgesia techniques. Pharmacists have extensive training in pharmacology, pharmacokinetics, and pharmacoeconomics. In addition to the traditional role of the pharmacist in compounding and dispensing medications, a pharmacist can be a valued team member who provides clinical services in the areas of safe, rationale, and cost-effective drug therapy. Pharmacists may provide patient education and instruction, drug information, and alternative therapy options. Pharmacists may also be included in quality assurance data collection, proper pump selection, proper medication labeling, safety considerations, and the development of policies and procedures. Pharmacists can also be involved in hospital formulary medication decisions and have an important role in evaluating new products for formulary addition.

Pharmacy Considerations with Epidural Delivery

When the technique of epidural and intrathecal administration was developed, it was standard practice to administer medication as a single bolus or multiple as-needed bolus injections. Anesthesiologists generally prepared and administered the doses. This technique, however, may result in periods of inadequate pain control and has been associated with a higher frequency of adverse effects resulting from temporary peak levels of medications creating unwanted side effects.66 Development of protocols for initial bolus doses followed by continuous infusions with or without patient-controlled epidural analgesia (PCEA) has revolutionized pain management.65 Continuous infusions of epidural opioids or local anesthetics (or both) avoid the peaks and valleys of pain control and the need for multiple bolus injections.66–68 Studies comparing continuous infusions and intermittent bolus administration have shown that continuous administration provides better analgesia with lower total doses administered.67

Pharmacists should be involved in the procurement and preparation of the epidural continuous infusion solutions. The preparation of epidural infusions must follow strict aseptic techniques outlined by the new standard of practice for compounding sterile preparations, published in Chapter 797 in the United States Pharmacopeia.69 Epidural solutions are considered a “moderate risk level” for microbial contamination based on the fact that the solution contains no preservatives.69 Appropriate labeling of epidural solutions and concentrations of commonly used epidural additive drugs are detailed in Tables 79–12 and 79–13.

Peripheral Nerve Blocks and Catheters

Peripheral anesthetic techniques have increased in popularity for the management of acute and chronic pain conditions. Studies have shown that patients who receive peripheral nerve blocks experience reduced postoperative pain and analgesia requirements and report more satisfaction with their pain management.70 These techniques involve either bolus or intermittent doses, or continuous infusions of local anesthetics through a catheter near or around the nerve or nerve plexus that supplies the surgical area.71,72

A perineural placement of catheters for continuous local anesthetic is growing in popularity.73–75 This technique of continuous peripheral nerve blocks or perineural local anesthetic infusions involves the percutaneous insertion of a catheter directly adjacent to the peripheral nerves or plexuses supplying an affected surgical site.76 In the hospital setting, local anesthetic infusions can be prepared by the pharmacy, and the continuous infusion be accomplished with an infusion pump. In recent years, smaller electronic infusion pumps, syringe pumps, elastomeric pumps, and spring–powered pumps have been designed for use in the ambulatory setting. Because of the inherent risks of sending a patient home with an infusion device, most published studies limit ambulatory use of the pumps to patients expected to have moderate-to-severe postoperative pain of a duration more than 24 h and who will have difficulty managing the pain with oral opioids.76 In addition, special consideration must be given to the caregiver's capability for managing the pump or the need for home care or visiting nurses to monitor, regulate, or discontinue the infusion.

An alternative to continuous regional blocks is continuous infusion of local anesthetic directly into the wound site.77 A pump is attached to a catheter inserted near an incision site. The pump infuses a continuous flow of local anesthetic and may include the capability for patient control. For wound instillation devices, the local anesthetic may be added to the device in the sterile environment of the operating room or added into the device by pharmacy personnel using aseptic technique.

With the capability of infusing local anesthetics epidurally, intrathecally, peripherally, and topically, guidelines must be established for all healthcare providers to be aware of the type and route of local anesthetic administration. Unintentional administration of local anesthetic via two different routes may increase the risk for systemic toxicity. To prevent double administration, all local anesthetic administration should be documented in the patient chart. If CPOE is available, all orders should be entered into the computer. A warning screen should appear if duplicate local anesthetic orders are entered for a patient.

With the evolution of multimodal therapy, anesthesiologists and surgeons must communicate regarding all pain management therapy. In addition, pharmacists must review medication profiles and be aware of all local anesthetics dispensed and administered to patients. Pharmacists play a crucial role in monitoring the overall pharmacologic management of the patient.

Infusion Devices

Pharmacist involvement in the selection of infusion devices will offer a unique perspective on the advantages and disadvantages of various pumps. Many factors must be considered to determine the optimal device for a given clinical situation. Infusion devices should be safe, accurate, reliable, easy to use, and compatible with the drug delivery systems available.68 For the management of acute pain, an external pump is standard. Several external devices are available on the market, including syringe pumps, peristaltic devices, and elastomeric reservoir pumps. When selecting a pump, several factors should be considered, including the acceptable infusion rate accuracy, PCA bolus capability, and total local anesthetic volume required.

Syringe pumps are used to deliver the contents of a syringe over a given period.68 These devices can be programmed to deliver the contents of a syringe over several hours to several days. These pumps are commonly used for the delivery of opioids for IVPCA. Prefilled morphine and meperidine syringes are commercially available. Pharmacy personnel must compound other opioids or differing concentrations of commercially available products. Most of these devices must be locked to prevent patient manipulation and to prevent diversion of a controlled substance.

Peristaltic devices deliver a drug from a flexible reservoir via administration tubing that is mechanically squeezed.68 These pumps are traditionally used to administer intravenous fluids. Some peristaltic devices have locked chambers to secure solutions. This would be of benefit for opioid infusions. Peristaltic pumps can accommodate larger volumes of solution. Flow rate capabilities range from 0.1 to 999 mL/h. Newer pumps have more sophisticated programming, allowing for minimum and maximum rates of any drug programmed into the device. Some programs also calculate infusion rates based on the patient's weight and the amount of drug to be administered per minute or hour. This new technology was developed to help prevent potential medication errors.

Elastomeric reservoir pumps force fluid through a flow regulator via elastomeric pressure of a balloon reservoir.68 Depending on the brand, the reservoir volume varies, allowing for varying rates and length of therapy. This technology is used for continuous delivery of local anesthetics for continuous peripheral blocks or instillation directly into the wound.

Regardless of the type of infusion pump used, the maximum reservoir volume must be considered when establishing the use of epidural solutions or continuous nerve infiltrations. In addition, the range of administration rates is a critical factor in epidural delivery of medications.68 Epidural infusion rates vary depending on the location of the epidural catheter and the drugs administered into the epidural space. Rates greater than 20 mL/h are generally not indicated. Table 79–7 provides a general guideline for epidural administration rates based on the placement of the epidural catheter.77Tables 79–12 and 79–13 provide useful information on epidural orders, labeling, and solutions. Figure 79–5 is a sample epidural order form.

When choosing an infusion device, consideration should be given to devices that allow for safe and secure administration of solutions while maximizing the time between refills or the interval between bag, syringe, or cassette changes. The potential for pump misidentification or confusion is ever-present, leading to medication errors or error in route of deliver. From a systems standpoint, rigorous policies are needed to prevent medication errors. This may include special labeling, route-specific tubing, and dedicated pumps for specific techniques, color-coding of labels and tubing, and two practitioner pump set-up checks. Representatives from the departments of biomedical engineering, nursing, anesthesiology, and pharmacy should all be involved in pump selection.

Solution Preparation, Stability, and Sterility

As described previously, pharmacists offer many valuable services to all areas of patient care. In regard to regional anesthesia, the most important contributions include accurate preparation and assurance of sterility and stability for all solutions prepared.

Any drug administered into the epidural or intrathecal space must be free of neurotoxic preservatives.67,78 Agents containing preservatives such as methylparaben, benzyl alcohol, methylhydroxybenzoate, propylhydroxybenzoate, phenol, and formaldehyde must be avoided.67,78 Standard epidural preparations guidelines call for the use of preservative-free solutions.

Although infection of the epidural or intrathecal space is rare, it can be fatal. Preparation of all epidural solutions must be performed with strict adherence to sterile aseptic technique. As of January 1, 2004, JCAHO officially surveyed accredited organizations for compliance with the United States Pharmacopeia (USP) general Chapter 797, Pharmaceutical Compounding-Sterile Preparations.69 USP Chapter 797 details the procedures and requirements for compounding sterile preparations and sets standards that are applicable to all practice settings in which sterile preparations are compounded. Based on these guidelines, because epidural solutions contain no preservatives, they are considered to be a medium risk for microbial contamination. Certified pharmacy personnel using a laminar flow hood should prepare epidural, intrathecal solutions as well as solutions for continuous peripheral neural blockade.

The stability of morphine, fentanyl, hydromorphone, and fentanyl mixed with various local anesthetics in a variety of syringes and reservoirs has been studied.79–82 Solutions studied maintained potency for at least 12 days. However, the risk of microbial contamination in preservative-free solutions is problematic. Current guidelines from the Centers for Disease Control and Prevention (CDC) recommend that preservative-free infusion solutions be completely used or discarded within 24 h of preparation when not refrigerated.67,83,84 CDC guidelines also recommend that preservative-free solutions be stored under refrigeration for no more than 7 days.83 Refrigeration must be continuous and occur immediately after mixing the solution. After the product is dispensed for patient use, a 24-h expiration date must be applied. USP Chapter 797 gives a medium risk level to preparations 30 h at room temperature and 7 days under refrigeration.69 According to USP Chapter 797, if the product is not made in a laminar flow hood, it will be considered high risk and should be used within 24 h.69 It would be prudent for institutions administering epidural, intrathecal, and continuous peripheral local anesthetic solutions to have the solutions prepared in accordance with USP Chapter 797.

Standardization of Regional Anesthesia Continuous Solutions

Standardizing epidural solution volumes, medications used, and drug concentrations are important considerations when establishing an epidural program. Consistency in prescribing and preparing epidural, intrathecal, and continuous peripheral local anesthetic solutions helps to reduce the potential for medication errors and simplifies the preparation process.85–87 Having a limited number of concentrations for epidural solutions will prevent medication errors in prescribing, preparing, and administering epidurals. Pharmacists should work with anesthesiologists to determine dosing ranges for epidural drugs. Pharmacists should be familiar with the dosing ranges and should question orders that deviate from established guidelines. It would be beneficial to minimize the size of the solution bag for epidurals. If the rate of an epidural is mistakenly increased, a limited amount of epidural solution would be infused at the incorrect rate.

When initially establishing standard epidural solutions, physician preference and stability considerations should be assessed.87 Decisions regarding standard epidural preparations must also take into consideration safety, cost, time, narcotic accountability, and reservoir volume of the infusion device.85–87 When possible, using whole rather than partial ampules and vials and using available package sizes of the drugs will help to minimize waste.87 This is beneficial in helping to keep narcotic inventories as simple as possible. Although standard epidural solutions are usually adequate for most patients, it should be noted that these standard preparations might not be suitable for every patient. There may be instances when a patient requires a specialized preparation. The patient may have an allergy to one of the standard epidural components, or the patient may have a history of opioid tolerance and will require higher concentrations. If a nonstandard epidural is ordered, highlighting the concentrations may help to prevent confusion and errors.

Standardization of epidural solutions may allow for batch preparation. Batch preparation helps to prevent a delay in starting an epidural. In addition, depending on the infusion rate, more than one infusion bag may be needed per day. If an infusion is running dry, having batched solutions available prevents the possibility of interrupting continuous pain therapy. Batching puts less stress on pharmacy personnel preparing solutions and on nurses in a need of a new solution bag. However, maintenance of continuous pain relief therapy for the patient is the most important benefit. To provide the maximum expiration dating, certified individuals should do batch preparation of epidural solutions without preservative under strict aseptic conditions. Storage should be in accordance with the CDC and USP Chapter 797.69

Some pharmaceutical manufacturers provide compounding services for epidural and other solutions. Others manufacture standard concentrations. Expiration dating is extended beyond 7 days based on stability studies conducted by the pharmaceutical manufacturers. Institutions handling a large number of surgical and obstetric cases may find this service of use because compounding large amounts of epidurals requires additional staffing, supplies, and time. Therefore, the cost of the compounded products should be weighed against pharmacy considerations associated with preparing the solutions.87

Safety Considerations

Medication errors related to the use of opioid infusions and epidurals are among the most frequently reported.85 To help prevent medication errors, it is imperative that all epidural solutions be labeled in a clear, concise, consistent manner. Table 79–12 provides suggestions for the appropriate labeling of epidural solutions.84 Labels should be legible and permanently affixed to the infusion bag or syringe in a manner that makes it easily readable.84 The patient's name, date of preparation, and solution expiration should be clearly stated. The medication contents should be distinctly labeled with the name of the drugs and volumes used to prepare the solution. In addition, the final concentration and total volume should be clearly marked on the bag in bold lettering. Last, a bright auxiliary label reading “For Epidural Use Only" should be affixed to the bag or syringe.

Drugs intended for intravenous administration have been accidentally administered into the epidural or intrathecal space.67,85–86 An error in the route of administration could have catastrophic consequences. The route of administration must be clearly noted on all order forms. Drug concentrations vary dramatically between intravenous, continuous peripheral block, epidural, and intrathecal routes. If an intravenous solution of morphine 1 mg/mL is administered epidurally, respiratory depression and death may result. In addition to anesthesiologists, nurses and pharmacists should be familiar with dosing ranges and standard concentrations for epidural and intrathecal preparations.

Proper labeling of the epidural tubing is also imperative. It is recommended that the distal ends of epidural and intravenous lines be labeled to clearly differentiate them.85 A line dedicated to the administration of epidurals with port-free tubing should always be used to prevent accidental epidural administration of drugs intended for intravenous use.85–86 It is also helpful to use single-chamber pumps dedicated to epidural infusions. Infusion pumps should also be labeled “For Epidural Use Only." If a multiple-chamber pump must be used for epidural administration, the other chambers should not be used for the infusion of any other medications. If an adjustment in rate or another medication is administered to the patient, nurses should always trace the tubing from the insertion site to a pump. If more than one pump is being used, placing the IV pump on the opposite side of the patient's bed from the epidural pump may help to prevent mistakes.85

Healthcare practitioners should be aware of the potential for error with hand-written orders. Only proper abbreviations should be accepted and clarification of any order completed prior to processing. The use of preprinted order forms has helped to reduce these types of errors. The ASA Task Force on Pain Management has established guidelines for the use of preprinted order forms in acute pain management.88 The key elements for epidural analgesia preprinted order forms are listed in Table 79–8.

If a patient is receiving an epidural opioid, prescribing other sedative agents should be done with extreme caution. The service or anesthesiologist managing the epidural should be the only service prescribing other sedatives. If another service prescribes another sedative, the pharmacist should intervene and notify the service managing the opioid epidural. If CPOE is available, a warning screen should be displayed if a sedative is ordered.

The pharmacist's role in regional anesthesia may include reviewing patients' drug therapy, optimizing medication selection, and developing policies and procedures. Pharmacists also supervise and evaluate solution preparation, stability, storage, and safety issues. Additionally, the pharmacist can provide information on the cost of different mediation modalities, offering suggestions for the most cost-effective choices.

Anesthesiologists, surgeons, pharmacists, and various members of the nursing team all have important roles when considering the organization of an acute pain service. Acute pain management requires a multimodal and multidisciplinary approach with a clear organizational framework. Regional anesthesia techniques for surgical anesthesia are a highly effective component of acute pain management. Maximizing the contributions of regional anesthesia to acute pain management requires integrating these techniques into the larger framework of patient care. Clinicians must regard their efforts as extending beyond the operating room and postanesthesia care unit. This requires an organizational framework that includes all members of the healthcare team, standard order sets, assessment and documentation forms, and institutionwide policies and procedures for the management of aggressive pain techniques. Strong institutional commitment is imperative.