[Benchmark of a high-frequency jet ventilator, the Monsoon™]

To test a high-frequency jet ventilator, the Monsoon™ (Acutronic laboratory) on a lung model with regard to delivered tidal volume and tracheal pressure measured through the injector.

Benchmark study.

The jet ventilator was tested with seven commercially available catheters associated with their connecting line. Recorded data were: the injected volume per minute, the pressure measured in the connecting line between the ventilator and the injector and the difference between the end expiratory pressures (EEP) measured by the ventilator through the injector and the tracheal pressure. Measurements were performed by varying the driving pressure (P(w): 1 to 3 bar), inspiratory time/ventilatory cycle duration ratio (I/T: 0.25 to 0.35 %) and respiratory rate (RR 60 to 300 c/min).

Whatever the injection catheter used, minute volume increased proportionally with P(w). For each injector and for a given P(w) and I/T, it was possible to determine a RR threshold upon tracheal pressure and EPP gradient largely increased: RR less than 3Hz for I/T less than 0.35 % and P(w) of 3 bar with adult catheters except for Leadercath(®) (RR 2Hz). All the paediatric catheters could be used at a P(w) less than 2 bar, a RR 120 c/min and I/T less than 0.35 %.

Use of a dedicated injector line and a range of settings (RR and I/T rapport) are required to measure an actual EPP through the injector.