In vitro evaluation of a spacer in a pediatric model of mechanical ventilation

The objective of this study was to evaluate the mass of salbutamol delivered by a pMDI or a mesh nebulizer using a spacer in a pediatric model of mechanical ventilation. For the use with pMDI (Ventoline, 100µg/puff, GlaxoSmithKline, France) the spacer (Combihaler, Laboratoire Protec9Som, France) was compared with a T-piece. For the nebulization of salbutamol (2.5mg/2.5ml), a mesh nebulizer (Aeroneb Solo, Aerogen, Ireland) was used with a T-adapter or a spacer. In this study, a respirator (Volume controlled, Vc = 155mL, f = 25/min, PEEP = 6, P max = 8, ratio between the inspiratory time and the expiratory time = 50/50) and a model of lung Dual TTL model 5600i (Michigan Instruments) were used. A filter was placed after the 5.0 mm endotracheal tube. The concentration of salbutamol was measured by spectrophotometry after the use of the pMDI and after nebulization Values, expressed as mean +/- SD, were compared using one-way ANOVA. With pMDI, the mass of salbutamol deposited on the filter was twice higher with the spacer compared with the T-piece (19 ± 1.5 µg vs 8.2 ± 1.7 µg). After nebulization, salbutamol aerosol delivery increased withspacer in comparison with the T-adapter (32.7 ± 3.5 % vs 22.1 ± 2.0 %). In addition, the use of a spacer reduces the mass of salbutamol deposited between the Y-piece and the endotracheal tube compared with the T-adapter. In pediatric conditions, the spacer increase the amount of salbutamol deposited by 2.3 compared with the T-piece. Concerning the nebulization, the deposition of salbutamol is increased by 1.5 with the spacer compared with T-adapter.