Patient controlled analgesia--assessment of machine feedback to patients

The effect of varying patient-controlled analgesia machine feedback was studied in two groups of patients following a standard surgical procedure using patient controlled analgesia with morphine to control postoperative pain. Analgesic demands, morphine consumption, pain scores and side effects were compared and comments from the patients were noted. There was no significant difference between those whose machines signalled only successful demands compared with those who had every demand acknowledged. The patients in the former group appreciated the extra input and the nursing staff found this machine configuration to be less disturbing to the ward. There was no evidence of a clinically useful placebo effect in the latter group.