The use of infusion devices for epidural or intrathecal administration of spinal
opioids is described. The risks of
infection and mechanical
catheter complications, the need for escalating doses, reservoir volume,
drug stability, and cost are practical considerations associated with use of both external and internal infusion systems. Use of patient criteria to identify suitable candidates for intraspinal administration of
pain medication helps ensure successful management. The criteria for intraspinal delivery pumps are safety, accuracy, reliability, ease of management by the patient and the health-care professional, and compatibility of the
drug with the pump components. The primary factors to consider when comparing pumps to be used for intraspinal delivery of
pain medication are the volume and flow rate requirements of the devices. External portable infusion devices are classified according to the mechanism of operation into three primary groups: syringe pumps, peristaltic mechanisms, and elastomeric reservoir pumps. Portable
patient-controlled analgesia pumps that have syringes, flexible reservoir bags, and elastomeric reservoirs have been developed. Implanted systems with flow rates that are preset at the factory make
pain management more difficult when the patient requires changes or escalations in doses over time. A programmable implanted pump is available. Two advantages of continuous epidural or intrathecal infusion are (1) the peaks and valleys of
pain relief with bolus
injections are eliminated and (2) the need for multiple
injections is reduced.
Patient-controlled analgesia (PCA) pumps enhance the efficacy of continuous infusions by allowing the patient to administer bolus doses to control
acute pain.