CONTINUOUS INFUSION OF OPIOIDS

Abstract

ontinuous intravenous infusion (CI) of opioid drugs is being used more and more to manage both postoperative and chronic cancer pain(1-9). In fact, 13 percent of terminally ill patients at one institution were given opioids IV before they died(9). Although there are no well-controlled prospective studies, the evidence to date supports the view that CI of opioid drugs is generally safe, particularly for cancer patients whose prior exposure to these drugs provides the protective buffer of opioid tolerance at the start of the infusion. Infusing an opioid throughout a period of progressive deterioration that culminates in coma and death raises ethical issues. Continuing a potentially toxic therapy after stupor develops has been alluded to but not addressed directly in the medical literature(10). If our overriding goal for the terminally ill patient is comfort, then maintaining CI as death approaches is ethical and necessary, despite the likelihood that death may be hastened by this therapy. Thus the terminal phase of deterioration becomes not so much a complication of therapy, but a natural outcome of the disease process itself. Since CI requires an extra step in preparation and a specialized drug delivery system, it carries a small additional risk of contamination and is more expensive than repetitive dosing. Thus, CI is usually started after repetitive iv dosing has failed to provide adequate analgesia. Indications for IV administration include intolerance of IM and PO routes (for example, in severely cachectic patients who develop bowel obstruction); intolerance of Po drugs when the IM route is undesirable; or a need to eliminate absorption time or concern over