The impact of delirium on the circadian distribution of breakthrough analgesia in advanced cancer patients

Most cancer patients will experience pain requiring opioid therapy during t heir illness. Standard opioid therapy includes fixed scheduled doses and so -called "rescue" doses for breakthrough pain. Circadian rhythms seem to inf luence the expression of pain and the responsiveness to analgesic medicatio n. Delirium is a common complication in advanced cancer patients and it als o may modify the expression of pain and the rise of analgesic medication. W e reviewed the circadian distribution of breakthrough analgesia (BTA) doses in 104 advanced cancer patients who were part of a Prospective study of ti le occurrence of delirium. We found that the circadian distribution of BTA is significantly different from a random distribution in the case of patien ts with and without delirium. Patients without delirium tended to use more BTA (P < 0.001) in the morning, whereas patients with delirium tended to us e more BTA in the evening and at night (P = 0.02). We conclude that deliriu m is associated with changes in the circadian distribution of BTA, which is possibly related to reversal of the normal circadian Myth Pit. (C) U.S. Ca ncer Pain Relief Committee, 2001.