An In Vitro Comparison of Albuterol Delivery to a Spontaneously Breathing Pediatric With Different Airway Resistance and Lung Compliance During Noninvasive Ventilation

Abstract

Background:

Delivery efficiency of nebulizers has been described with noninvasive ventilation. However, albuterol delivery to patients with different airway resistance (Raw) and lung compliance (CL) has not been quantified. The purpose of this study is to compare albuterol delivery during noninvasive ventilation of a simulated pediatric with different levels of Raw and CL.

Methods:

A collecting filter at the bronchi of a teaching manikin was attached to a passive test lung (QuickLung, Ingmar Medical) to simulate a spontaneously breathing pediatric. A ventilator (Trilogy 202, Philips) with a single limb circuit (S/T mode, inspiratory pressure: 6 cm H₂O, expiratory pressure 8 cm H₂O, respiratory rate: 30 breaths/min and I:E ratio 1:2) was connected to a pediatric upper airway manikin via the standard oronasal mask (AF541, Respironics). Albuterol sulfate (2.5 mg/3 mL) was delivered with jet (MistyMax10) and mesh (NIVO) nebulizers at Raw of 5 and 20 cm H₂O/L/s and CL of 10 and 20 L/cm H₂O during noninvasive ventilation (n = 5). Descriptive statistics and Mann Whitney U test were used for data analysis (P < .05).

Results:

The table below shows inhaled dose% delivered (mean ± SD) distal to the trachea. The mesh nebulizer delivered up to 3-fold more drug than the jet nebulizer in all conditions tested in this study. Regardless of the type of nebulizer used, no significant difference was found between Raw 5 and Raw 20 at CL of 10 L/cm H₂O while reducing Raw from 20 cm H₂O/L/s to 5 cm H₂O/L/s significantly improved aerosol delivery using jet (P = .030) and mesh (P = .040) nebulizers at CL of 20 L/cm H₂O. Although aerosol deposition obtained with the mesh nebulizer was not statistically different with CL 10 and 20 L/cm H₂O at Raw 20 (P = .55), its delivery efficiency increased with an improvement in lung compliance at Raw 5 (P = .041). Aerosol delivery with the jet nebulizer significantly increased with CL 20 L/cm H₂O compared to CL 10 L/cm H₂O at Raw 5 (P = .003) and Raw 20 (P = .031).

Conclusions:

At low CL such as 10 L/cm H₂O, a significant increase in Raw does not impact aerosol delivery regardless of the type of nebulizer used during NIV while there is an inverse relationship between aerosol deposition and Raw at CL of 20 L/cm H₂O. Aerosol delivery with jet and mesh nebulizers improved with an increase in CL during pediatric noninvasive ventilation.

NEBULIZERS	Raw	CL 10 L/cmH2O	CL 20 L/cmH2O	p value
Mesh Nebulizer	5 cmH2O/L/s	14.4 ± 0.7%	17.6 ± 1.8%	0.041
 	20 cmH2O/L/s	14.0 ± 1.1%	14.5 ± 0.6%	0.55
 	p value	0.632	0.040	 
Jet Nebulizer	5 cmH2O/L/s	4.65 ± 0.2%	6.3 ± 0.3%	0.003
 	20 cmH2O/L/s	4.39 ± 0.5%	5.56 ± 0.3%	0.031
 	p value	0.487	0.037