MONTREALDelirium in patients with advanced cancer appeared to be associated with changes in the circadian distribution of analgesia for breakthrough pain and may be due to a reversal of the normal circadian rhythm in these patients, reported Bruno Gagnon, MD, of McGill University and Montreal General Hospital.
The study was conducted as part of a prospective study of delirium in advanced cancer patients in the acute palliative care unit at Grey Nuns Community Hospital & Health Centre, Edmonton, Alberta. The patient charts were retrospectively analyzed for breakthrough analgesia use; however, the patients, nurses, and physicians were blinded to the fact that the review would be carried out.
Breakthrough analgesia use was divided into three time periods: 11:30 pm to 7:30 am (night); 7:30 am to 3:30 pm (day), and 3:30 pm to 11:30 pm (evening), corresponding to the length of the nursing shifts.
The study included 104 eligible patients categorized into three groups based on delirium status: Group 1 (n = 33) had no delirium on admission or during their hospital stay; group 2 (n = 22) had terminal or nonreversible delirium; and group 3 (n = 49) had a changing delirium status (at least one period of delirium in addition to one or more delirium-free periods).
A total of 1,677 patient admission days were analyzed for circadian distribution of breakthrough analgesia doses: 1,254 days without delirium and 423 days with delirium. The researchers found that the circadian distribution of breakthrough analgesia doses differed significantly from a random distribution in both patients with and without delirium (J Pain Symptom Manage 22:826-833, 2001).
During delirium-free days, patients required more breakthrough analgesia doses during the daytime, compared with a random distribution, whereas when delirium was present, more breakthrough analgesia was used during the evening and at night (see Table).
Similarly, the group 2 patients (terminal delirium) received more breakthrough analgesic doses during the evening, compared with the group 1 (no delirium) patients. Furthermore, among the group 3 patients (changing delirium status), the highest breakthrough analgesia use was during the evening when delirium was present and during the day when delirium was absent.