Consequences of not relieving negative internal pressure of a medication vial: A survey and simulation study

The glass vial of acetaminophen as an intravenous preparation (Acelio®, Terumo, Japan) has a strong internal negative pressure. The aim of our study was to determine if this negative pressure could result in medication administration errors if not released prior to connecting to the IV set.

Questionnaire survey and simulation study.

University hospital and its affiliated hospitals.

Fifty-two anesthesiologists in 6 different hospitals in Yokohama.

A questionnaire on current practice was sent to the subjects. The authors then first calculated the internal pressure of the Acelio® vial followed by a simulation set-up. This set-up measured the amount of saline that could be aspirated from a syringe loaded on a syringe pump connected via a secondary IV line when the Acelio® vial was attached to the primary line without prior release of the internal pressure. The volume of aspiration was tested with two syringe sizes and with a fully open IV clamp vs partially closed.

Twenty-nine (56.9%) of 51 anesthesiologists who responded to the survey had connected the Acelio® vial at least once without releasing the internal negative pressure, and 21 experienced consequences such as backflow of the venous blood. The pressure inside the Acelio® vial was 81.8±19.6Torr. With the clamp of the simulated IV line fully open, the amount of saline aspirated before the alarm of the syringe pump went off was 1.5±0.1ml and 3.2±0.3ml when 20ml and 50ml syringes were used, respectively. When the clamp was partially closed to allow 2 drops per second, this value was 1.3±0.1ml and 2.3±0.1ml, respectively. After removing the plunger from the holder of the syringe pump, an additional 7ml (clamp partially closed) or 15-18ml (clamp fully open) was aspirated in the subsequent 1min.

A considerable number of anesthesiologists experienced consequences caused by the negative pressure inside the Acelio® vial. This can also cause aspiration of the contents of the syringe pump.