A COMPARISON OF VARIABLE-DOSE PATIENT-CONTROLLED ANALGESIA WITH FIXED-DOSE PATIENT-CONTROLLED ANALGESIA

We examined the effect on the quality of analgesia and side effects of increasing the patient control component offering the patient a choic e of bolus dose sizes. Using a three-button hand piece, patients could choose between 0.5-, 1.0-, and 1.5-mg boluses of morphine (variable-d ose PCA, VDPCA). Successful demands were delivered by a modified Grase by 3400 Anaesthesia Pump controlled by a Toshiba T1900 computer. This system was compared with conventional fixed-dose PCA (FDPCA) (1.0 mg o f morphine) delivered by a Graseby 3300 PCA Pump. Both treatment group s had a 5-min lockout interval. Sixty patients were randomly assigned to receive either VDPCA or FDPCA after major abdominal gynecological s urgery or hip or knee arthroplasty. Treatment groups did not differ in their duration of PCA therapy, total morphine consumption, or time sp ent with mild or severe oxyhemoglobin desaturation. There were no diff erences in their ease of controlling pain, satisfaction with pain cont rol, experience of pain on movement, quality of sleep, severity of nau sea, or incidence of vomiting. Although the more complex VDPCA techniq ue provides adequate postoperative analgesia, it does not offer any ad vantage over conventional FDPCA.