The importance of post marketing quality control: The case of the adjustable pressure-limiting valve performance

A previously published study reported on the nonlinear behaviour for airway pressure and tidal volume of the adjustable pressure-limiting (APL) valve of the Aisys CS² anaesthesia machine (GE Healthcare, Madison, Wisconsin, USA) during manual bag ventilation. In co-operation with the manufacturer, an adapted APL valve was developed.

To test and characterise the performance of an adapted APL valve and assess its clinical usability.

Two-stage study, consisting of an in-vitro testing of an adapted APL valve in a baby and adolescent lung model, followed by a clinical experience survey of anaesthesia personnel after the official implementation of the new APL valve into clinical routine.

Anaesthesia Department at the University Children's Hospital Zurich.

Airway pressures and inspiratory tidal volumes during opening and closure of the APL valve at different settings. Likert scale assessment of performance expectance, effort expectance, behavioural intention and safety of the APL valve during clinical use.

In contrast to the original APL valve of the GE Aisys CS², the adapted APL valve showed a nearly linear increase in airway pressures as well as in the tidal volumes measured. Most importantly, the measured pressures never exceeded the set pressures. Based on the experimental findings, all original APL valves of the GE Aisys CS² were replaced by the adapted APL valve. Two months later, an anonymised and standardised questionnaire was handed out to all employees working with the adapted APL valve. Analysis of the questionnaire indicated that the adapted APL valve is easier and more precise to handle in the daily routine than the original one.

The newly adapted APL valve for the GE Aisys CS² has considerably improved its linearity at lower pressures and supports our institution's bag mask ventilation practices.