About safety parameters for patient-controlled analgesia (PCA) devices

During the course of preparation of an opioid prescription, the nurse in charge became aware that the patient-controlled analgesia (PCA) syringe driver did not permit programming for the delivery as required: a maximum bolus number (Bmax) was indicated but only a maximum cumulative dose (Dcmax) could be programmed. The prescription dose criteria were consistent with the guidelines of the French societies of palliative care, anesthesiology, and reanimation (Société française d'accompagnement et de soins palliatifs [Sfap] and Société française d'anesthésie réanimation [Sfar]). A Dcmax dose simulation was programmed and used in order to test this problem. This highlighted the following four defects: bolus delivery is not controlled, leading to potential overdose. When Dcmax is reached, the continuous flow stops, triggering an end dose failure and a new programming step is needed to restart infusion, increasing the risk of programming errors. Human intervention is required to stop the alarm, identify and solve the problem. Finally, Dcmax leads to random dose delivery in place of the predictability of dose delivery expected for opioid administration. On the other hand, Bmax is a limited dose, administered only as a bolus and regulated by the lockout interval. When the Bmax dose is reached, no alarm is triggered, the basal flow continues, but no additional doses can be delivered. Bmax and Dcmax systems are not interchangeable. No comparative study between Bmax and Dcmax could be found, and Sfap and Sfar guidelines are not precise and did not take into consideration the safety aspects of dose delivery however some facts tend to prefer that Bmax. Most of the syringe driver devices are configured for the Dcmax, but not all of them, and the physician is often forced to use the parameter of the available device restricting the choice between Bmax and Dcmax. This is not justified, whether by scientific evidence, industrial, manufacturing or commercial standards. It becomes only a technical option that does not promote standardization of dose delivery and compromises the main safety feature of PCA.