Measurement of respiratory mechanics in paediatric intensive care: in vitro assessment of a pulmonary function device

Abstract

Objective: To evaluate a recently developed and manufactured device for monitoring respiratory parameters in mechanically ventilated children.

Design: In vitro study using a lung model.

Setting: University paediatric intensive care unit. MATERIAL AND INTERVENTIONS: Evaluation of the accuracy of volume and pressure measurements, of the determination of respiratory system compliance (10 to 30 ml/cmH2O) and of resistance (20 and 50 cmH2O/l per s) by the inflation technique (volume- and pressure-controlled mode of ventilation); assessment of interobserver agreement for compliance (10, 15 ml/cmH2O) and resistance (20, 50 cmH2O/l per s) determinations (ANOVA, intraclass correlation coefficient).

Measurements and results: The accuracy of volume measurements (No.1 Fleisch pneumotachograph) was < or = 5 % of true volumes up to 11 (Flow: 30 l/min) even after the introduction of an endotracheal tube. The accuracy of pressure measurements up to 70 cmH2O was < or = 2.5% of the true values. Coefficients of variation of volume and pressure measurements were < 2%. The accuracy of compliance and resistance determinations was, respectively, < or = 17 and 25% of the true values. No significant observer effect was found on compliance and resistance determinations. Indeed, mean differences in compliance and resistance determinations by pairs of observers were < 1%. Intraclass correlation coefficients were > 0.98.

Conclusions: The measuring error of volume, pressure, compliance and resistance determined using this monitoring system seems acceptable for monitoring purpose. Moreover, use of this system by members of the medical team can be recommended since results obtained by observers, even untrained ones, were similar. In vivo evaluation is now needed.