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Salbutamol delivery from a hydrofluoroalkane pressurized metered-dose inhaler in pediatric ventilator circuits: an in
J H Wildhaber1, M J Hayden, N D Dore
1Department of Respiratory Medicine, Princess Margaret Hospital for Children, Subiaco, Western, Australia. hannesw@cyllene.uwa.edu.au
Study Objectives:
The aim of our study was to determine the in vitro delivery of salbutamol from a pressurized metered-dose inhaler (pMDI) containing hydrofluoroalkane (HFA) propellant through various delivery devices to four models of a pediatric lung.
Design:
To determine the effect of electrostatic charge, delivery of salbutamol was initially assessed with a multistage liquid impinger (MSLI) through an inline nonchamber device (Baxter MDI Adapter) and a small (Aerochamber MV) and a large (Nebuhaler) inline chamber device. Following this, the delivery was assessed to four lung models appropriate for a child of 70 kg, 50 kg, 15 kg, and 4 kg, with the same three reduced static devices inserted directly into a pediatric ventilator circuit.
Measurements And Results:
Reduction of electrostatic charge improved small particle delivery through holding chambers to the MSLI by 12 to 14%. In the ventilator model, the mean delivery was between 1.9% and 5.4% for the nonchamber device, between 14.3% and 27.2% for the small holding chamber, and between 7.2% and 25.7% for the large holding chamber. Delivery was the least efficient in the 4-kg model compared to the 70-kg, 50-kg, and 15-kg models.
Conclusions:
Salbutamol from an HFA pMDI is delivered efficiently through inline holding chambers with reduced static in pediatric ventilator settings. A large holding chamber has no advantage over a small holding chamber. In addition, salbutamol delivery is more efficient through a holding chamber than through a nonchamber device.