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. Methods: Retrospective review of 10years (1997–2006) data of all in‐patients with cancer pain treated with strong opioids delivered by PCA. Results: 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. Conclusion: 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.