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8 Epidural and Intrathecal Drug Library

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Epidural and Intrathecal Drug Library Stephen F. Eckel and Andrew P. Stivers CHAPTER 8 KEY TERMS1-3 Continuous epidural infusion—mode of drug delivery that provides the patient with a continuous drug dose administered into the epidural space. Within an epidural drug library, this is programmed as milliliters per hour (mL/hr). Delivery limit method—total number of doses that can be administered within a defined period of time. Within an epidural drug library, this can be set as either a delivery limit per time (i.e., total milliliters per time) or as the maximum number of doses per hour. Demand dose or patient-controlled epidural analgesia (PCEA)—mode of drug delivery that allows for administration of a patient-requested dose into the epidural space. The patient controls this dose via a button attached to the epidural pump. Within an epidural drug library, the dose mode for this is milliliters. Demand dose lockout—period of time the patient must wait between administrations of PCEA doses. Within an epidural drug library, this is programmed in minutes. Programmed intermittent epidural bolus (PIEB) or automated mandatory bolus (AMB)—mode of drug delivery that provides an automated bolus dose at a programmable interval administered into the epidural space. This bolus is programmed in advance, during the initiation or titration of the epidural infusion. INTRODUCTION Medications administered via the epidural route are often considered high-alert medica- tions, meaning there is a heightened risk of causing significant harm when used in error. High-leverage risk reduction strategies may minimize the likelihood of error. One such 105 106 / Smart Infusion Pumps strategy is to use an infusion pump with dose error reduction system (DERS) technology. As a risk reduction strategy, the Institute for Safe Medication Practices recommends that acute care facilities use only one type of epidural infusion pump, which is different from general infusion devices used in the organization.4 Although published supportive evidence is limited, it is believed that use of an epidural-specific smart infusion pump drug library has the same benefits of other smart infusion pump drug libraries.5 This chapter will provide recommendations and identify challenges to the development of an epidural infusion pump drug library. PRINCipLES OF EpiDURAL DRUG DELIVERY Administration of anesthetic and analgesic drugs via the epidural route is common in patients requiring analgesia during the postoperative period. Specifically, patients requiring analgesia localized to the lumbar-thoracic region may benefit from this drug delivery mode. Patients undergoing abdominal, gynecologic, obstetric, colorectal, urologic, lower limb (vascular and orthopedic), and thoracic procedures are ideal candidates for epidural analgesia and anesthesia due to the local effects of this route.6 One of several advantages to using the epidural route of drug administration compared to the intravenous route is an effect on several physiologic responses during the postoperative period, including reductions in metabolic and endocrine alterations, reductions in blood loss, reductions in thromboembolic complications, reductions in cardiopulmonary complications, and reduced duration of postoperative ileus.6 Evidence suggests epidural administration of anesthesia reduces the amount of anesthetic and analgesic agents used in the perioperative and postoperative period.7 When this therapy is coupled with an opioid, fewer respiratory depressive adverse events have been shown to occur when compared with opioid use alone. Drug Selection Opioids and local anesthetics, alone or in combination, are the mainstay of epidural drug delivery. Opioids are transported by passive diffusion and vasculature from the epidural space to the spinal cord, where they act on opioid receptors in the dorsal horn. Although opioids inhibit pain transmission, they have no effect on nerve transmission. Highly lipophilic opioids such as fentanyl and sufentanil have a faster onset of action but a reduced duration of action and increased systemic absorption. Alternatively, morphine and hydromorphone, hydrophilic opioids, have a slower onset but longer duration and reduced uptake into the systemic circulation.8 Local anesthetics cross through the epidural space, where they act on axonal nerve membranes, inhibiting nerve transmission. The choice of local anesthetic is predomi- nantly driven by the onset and duration of action. Bupivacaine and ropivacaine are commonly used because of their prolonged duration of action. Chloroprocaine, which is most commonly used in pediatric and neonatal patients, has the shortest duration of action among local anesthetics.9 Concomitant administration of opioids and local anesthetics produce synergistic effects and can be opioid-sparing..
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