Variables of patient‐controlled analgesia: 2. concurrent infusion

The effectiveness of morphine after surgery by patient‐controlled analgesia alone or with a concurrent infusion was studied. The infusion did not reduce the dose of self‐administered analgesic and patients treated in this way received twice as much drug as those who used patient‐controlled analgesia alone. Pain control was similar in both groups. The practice of patient‐controlled analgesia plus infusion requires critical review.