Laboratory evaluation of the Baxter Patient-Controlled Analgesia Infusor System: a disposable patient-controlled analgesia device.

The purpose of this study was to determine the accuracy of bolus-demand volumes obtained from the Baxter Patient-Controlled Analgesia Infusor System, a disposable patient-controlled analgesia device. An automated system was used to make demands in a pattern designed to simulate those made by a patient in the first 24 postoperative hours. Following this, a pattern of varying short interdemand intervals was used to evaluate performance of the device when demands were made near the nominal lockout interval of 6 min. Finally, a prolonged array of short interdemand intervals was used to evaluate performance as the reservoir of the devices became exhausted. Ten devices were tested. One device failed; after 70 min of testing the reservoir burst. The mean delivery of the remaining nine devices for the first 24 h of testing was 92.6% of nominal (SD = 3.9%). Evaluation near the nominal lockout interval revealed a departure of delivered volume from nominal (worst = 73.9% at an interdemand interval of 6 min). As the reservoir became exhausted, delivery increased to a maximum value, ranging from 118% to 137% of nominal, before falling to zero. In general, the devices performed consistently and the departures from nominal delivery were not considered to be of clinical significance.