Rhythmic pattern of PCA opioid demand in adults with cancer pain

Patient-controlled analgesia (PCA) has an established role in managing postoperative pain and has been successfully used in-patients with cancer pain. The variation of opioid requirement over a 24h period for patients with cancer pain is debated with suggestions of reduced need over night.

Retrospective review of 10years (1997-2006) data of all in-patients with cancer pain treated with strong opioids delivered by PCA.

141 patients with cancer pain had a mean cumulative 10day morphine equivalent dose per patient of 671mg (median 470mg; range 10-2170mg). At night (10:01pm to 06:00am) the patient's self administered less bolus doses (69mg, (25%)) than during the other two 8h periods (06:01am to 02:00pm, 91mg (33%) and 02:01pm to 10:00pm, 116mg (42%)). In 8 out of 10days a significant variation in bolus requests was observed with significantly less bolus requests during the night (Friedman test, p<0.05). Furthermore, the median number of delivered bolus requests per patient, at night, was 2-3 compared to the morning and afternoon periods of 3-7 and 3.5-6, respectively.

PCA met individual patient's opioid needs in a safe and effective manner despite a large inter-individual variability in opioid consumption. Moreover, the study indicated a pattern of less opioid requirement at night.