Case Study: When silent changes in one device cause incompatibility with another

An uncontrolled change in syringe dimensions caused compatibility issues with an infusion pump resulting in overdose, underdose, delay in therapy and delays in occlusion alarms.

An infusion pump is used to deliver controlled amounts of potent, life-saving or life-sustaining medications to patients in a healthcare facility. Some of these pumps utilize syringes from other manufacturers to deliver a specific volume at a controlled rate based on an individual patient profile.

Imagine a trained nurse about to start the infusion of a potent pain-relief medication using a patient controlled analgesia (PCA) module in a popular infusion pump system. This is a routine operation they perform on a daily basis using a certain brand of syringes specifically validated for this infusion pump system. On this particular day, they do everything according to the procedure, using the branded syringe they have routinely used in the past. To their surprise, the pump software does not recognize the syringe and refuses to start the infusion. They check the syringe installation inside the PCA module and everything looks right. They remove it from the PCA module and replace it with a new syringe from a different package. The pump still cannot recognize the syringe and they cannot start the infusion.

They call for a different PCA module, but all of them are currently in use. They consider switching to a syringe pump module to provide immediate relief to the patient who seems to be in a lot of pain. The syringe pump should also work although, unlike the PCA module, it does not allow the patient to control medication delivery on-demand. The nurse would need to supervise the patient and make adjustments as needed.

The syringe module is also validated with the same branded syringe they have been using. They select a 35 mL syringe as listed on the settings page of the point-of-care care unit that controls the syringe pump module. They feel relieved to see that the system recognizes the syringe and they are able to start the infusion. As they monitor the patient, they notice that the medication seems to be going out at a faster rate than anticipated. The patient seems to experience temporary relief, so they stop the infusion, report the incident to their supervisor and continue to monitor the patient.

The above hypothetical scenario is based on a recent safety communication from the FDA which advised healthcare providers to not use Cardinal Health Monoject(TM) syringes with syringe pumps and PCA pumps¹:

In June 2023, Cardinal Health began distributing Monoject syringes branded as “Cardinal Health” Monoject syringes. These new syringes differ from the previously branded “Covidien” Monoject syringes as they have different dimensions (example shown in image below) and are made by a different contract manufacturer. The dimensional changes made to the Cardinal Health Monoject syringes, when used with syringe pumps or PCA pumps, may result in recognition, compatibility, and pump performance issues such as overdose, underdose, delay in therapy, and delays in occlusion alarms.

In a different but related Class I recall announcement², FDA offers more clarity about this issue:

Becton Dickinson (BD)/Carefusion 303 is recalling their Alaris Infusion Pumps due to compatibility issues with Cardinal Health Monoject syringes.

When one of these new syringes is used with the previous syringe settings, the pump may either refuse to operate or incorrectly estimate the volume of liquid in the syringe. This has resulted in over and under infusions, as well as delays in therapy.

Alaris infusion pumps and Monoject branded syringes are some of the most commonly used devices for controlled medication delivery. According to the recall announcement, 220,120 syringe pump and PCA modules, and 867,362 PCU (point-of-care units) modules distributed between June 2004 and September 2023 are affected by this incompatibility issue with the syringe.

Clearly, a seemingly small change in syringe dimensions can have a significant impact on delivery of care and patient safety!

This case highlights a challenging risk management scenario in the post-market phase because it involves components of a system from two different manufacturers. Changes in any part of the system can have a major effect on system safety.

Let us take a closer look.