Not all syringes are equal – the comparative performance of syringes in propofol target-controlled infusions

Abstract

Background: Syringe infusion pumps are used for target-controlled infusions (TCI) and total intravenous anaesthesia (TIVA). Modern pumps compatible with third-party syringes require user input for the syringe type loaded. Within public hospitals in Johannesburg, South Africa, the supply of programmed, validated 50/60 ml syringes is inconsistent, with various non-programmed syringes substituted. These syringes are used for infusions when programmed variants are unavailable. This study aimed to compare the TCI propofol volume output of the non-programmed syringes to their programmed counterparts.

Methods: A contextual, quasi-experimental study was performed. The study site consisted of four academic anaesthesiology hospital departments in Johannesburg, South Africa. A syringe audit, description, and estimation of their measurements were performed, along with an assessment of syringe options across the available infusion pumps. An experimental bench test assessing the gravimetric propofol output of TCIs was conducted. The non-programmed syringes’ propofol output was compared to four different, named, programmed syringes.

Results: Five different TCI-enabled syringe pumps and four different non-programmed syringes were found across the hospitals. The three non-programmed variants were Luer-slip types and one Luer-lock type. Non-programmed syringes using the BD Plastipak™ option delivered between 17.6% and 21.3% more than the BD Plastipak™ syringe. The B. Braun Original-Perfusor^® Syringe (OPS^®) option breached the 5% cut-off for overdosage with two non-programmed syringes. Inappropriate infusion endalarms and premature infusion cessation occurred with all four non-programmed syringes using the B. Braun OPS^® option. All four non-programmed syringes delivered volumes within ± 2% when using two programmed syringe options (Injectomat^® and Terumo^®).

Conclusions: Over-delivery of propofol may have significant sequelae, such as cardiac instability, inappropriate anaesthesia depth, and rarely, propofol-related infusion syndrome (PRIS). Inappropriate alarms and infusion cessation could lead to accidental awareness during TCI/TIVA. Recommendations were made for programmed syringe procurement and the safe use of nonprogrammed syringes.