Fast Fact and Concept #085: Epidural Analgesia

2nd Edition

Author(s): Deb Gordon, RN and Mark Schroeder, MD

Epidural analgesia with local anesthetics, opioids, and/or alpha-agonists can provide superior regional analgesia over conventional systemic routes (IV or PO). In contrast to drugs administered systemically, drugs administered in the epidural space are extremely potent since the drug is delivered close to the site of action (opioid and alpha receptors in the spinal dorsal horn or local anesthetic blockade of nerve roots). Because of this, systemic side effects such as nausea, sedation, and constipation, are minimized. In palliative care, epidural analgesia may be appropriate for patients with regional pain (e.g. pelvic pain from cervical cancer) and/or patients who do not tolerate or obtain relief from oral/parenteral drugs and non-drug therapies.

Drug Distribution

Drugs administered epidurally are distributed by three main pathways:

• diffusion through the dura into the CSF, then to the spinal cord or nerve roots;
• vascular uptake by the vessels in the epidural space into systemic circulation; and
• uptake by the fat in the epidural space; creating a drug depot from which the drug can eventually enter the CSF or the systemic circulation.

Patient Controlled Epidural Analgesia (PCEA)

Epidural analgesia can be administered by intermittent boluses (by a clinician or by patient controlled epidural analgesia using an appropriate pump); continuous infusion; or a combination of both. PCEA is used to supplement a basal rate, to allow a patient to manage breakthrough pain in order to meet their individual analgesic requirements. Like IV PCA, PCEA can provide more timely pain relief, more control for the patient, and convenience for both the patient and nurse to reduce the time required to obtain and administer required supplemental boluses. Unlike IV PCA, the lockout interval of PCEA varies widely based on the lipid solubility of the opioid administered, from 10 minutes with fentanyl to 60-90 minutes when morphine is used. If local anesthetic is used, the lockout interval should be at least 15 minutes to allow for peak effect of the supplemental local anesthetic dose.

Management

Due to the proximity of drug delivery to its site of action, frequent assessment of pain relief, side effects, and signs or symptoms of technical complications (catheter dislodgement, epidural hematoma or abscess, pump malfunction, etc.) are necessary. This should be done every hour for the first 24 hours, then every 4 hours. Assess and document on the pain management flowsheet:

• patient’s pain rating using patient-specific pain scale (e.g. 0-10), both at rest and with activity
• level of sedation & respiratory rate, preferably by the same nurse during each shift
• side effects: pruritis, nausea, urinary retention, orthostatic hypotension, motor block
• sign of catheter insertion site infection or epidural abscess, e.g., back pain, tenderness, erythema, swelling, drainage, fever, malaise, neck stiffness, progressive numbness, or motor block
• changes in sensory/motor function that may indicate an epidural hematoma including unexplained back pain, leg pain, bowel or bladder dysfunction, motor block

References:

1. Pasero C, Portenoy RK, McCaffery M. Opioid Analgesics. In Pain: Clinical Manual: 2nd Ed. Eds M. McCaffery & C. Pasero, Mosby, 1999, pp161-299.
2. Mann C et al. Postoperative patient-controlled analgesia in the elderly: risks and benefits of epidural versus intravenous administration. Drugs & Aging. 2003;20(5):337-45.
3. Antok E et al. Patient-controlled epidural analgesia versus continuous epidural infusion with ropivacaine for postoperative analgesia in children. Anesthesia & Analgesia. 2003;97(6):1608-11.

Acknowledgement: The Fast Fact is adapted with permission from: D Gordon. Patient Controlled Epidural Analgesia (PCEA);Pain Management Fast Facts- 5 Minute Inservice ; University of Wisconsin Pain Team.

Fast Facts are edited by Drew A. Rosielle MD, Palliative Care Center, Medical College of Wisconsin. For comments/questions write to: drosiell@mcw.edu. The complete set of Fast Facts is available at EPERC: www.eperc.mcw.edu.

Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Gordon D, Schroeder M. Fast Fact and Concept #85. Epidural Anlgesia. 2nd Edition. October 2007. End-of-Life/Palliative Education Resource Center ( www.eperc.mcw.edu).

Disclaimer: Fast Facts provide educational information. This information is not medical advice. Health care providers should exercise their own independent clinical judgment. Some Fast Fact information cites the use of a product in dosage, for an indication, or in a manner other than that recommended in the product labeling. Accordingly, the official prescribing information should be consulted before any such product is used.

Creation Date: 1/2008

Purpose: Instructional Aid, Self-Study Guide, Teaching

Audience(s)

ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Pain>opioids; Pain>non-opioids