The three methods for administering intraspinal analgesia are: (1) bolus (administered by the clinician), (2) continuous infusion or basal rate (administered by a pump), and (3) patient-controlled epidural analgesia (PCEA) (administered by the patient using a pump).
For some surgical procedures, a single intraspinal morphine bolus provides sufficient pain control for several hours. For example, an epidural or intrathecal bolus of morphine often is administered to manage pain that does not warrant the placement of a catheter, such as after cesarean section and some gynecologic, orthopedic, and urologic procedures (Pasero, Quinn, Portenoy, McCaffery, & Rizos, 2011). A single epidural morphine dose is capable of providing analgesia for 24 to 48 hours depending on the formulation used. Single bolusing is also used when indwelling epidural catheters are contraindicated, such as in some patients who require anticoagulant therapy (Pasero, Quinn, Portenoy, McCaffery, & Rizos, 2011).
Analgesic infusion pumps are used to deliver continuous epidural analgesic infusions (basal rate). Supplemental bolus doses are prescribed for breakthrough pain and can be administered using the clinician-administered bolus mode available on most infusion pumps.
Patient-controlled epidural analgesia permits patients to treat their pain by self-administering doses of epidural analgesics to meet their individual analgesic requirements. When PCEA is administered, a basal rate usually provides most of the patient’s analgesic requirement and the PCEA bolus doses are used to manage breakthrough pain. If a basal rate is not provided, it is especially important to remind patients to “stay on top of the pain” by maintaining a steady neuraxial analgesic level and self-administering bolus doses before the pain is severe and out of control (Pasero, Quinn, Portenoy, McCaffery, & Rizos, 2011).