The Effect of Source Gas Pressure and Flow on Respirable Dose of Budesonide and Dornase Alpha

Abstract

Background: Patients have expressed that they could feel a difference in the effectiveness of breathing treatments given in the hospital from a flow meter versus those at home with a compressor. This made us question if there was a difference in respirable dose (RD) between compressors and flow meters. The purpose of this study was to determine if compressors could produce a nebulizer efficiency for Budesonide (B) and Dornase Alpha (DA) that had previously been determined. The research question was, is there a correlation between nebulizer/flow meter flow and pressure, and RD and what was nebulizer efficiency? Methods: A breath-enhanced nebulizer with either a unit dose of B or DA connected to either an air-flow meter or a compressor, was operated until sputter. Spontaneous breathing was simulated by a test lung connected to a breath simulation module, to produce a V_T of 155 mL, f of 25 breaths/min, and a T_I of 0.5 s, consistent with a pediatric breathing pattern. During nebulization, the flow and pressure of the compressor or flow meter was measured by bourdon gauge and liter meter. The RD was calculated by weighing a filter before and after the treatment. The nebulizer efficiency was calculated by dividing the RD by the nominal dose. Pearson’s r was used to determine the correlation between flow/nebulizer RD and pressure/nebulizer RD for each drug. Significant correlations = P < .05. Results: For DA (40 trials), the nebulizer efficiency was 9.16%-18.24%, while the nebulizer efficiency for B (42 trials) was 1.15% – 21.45%. There was a significant correlation between the flows produced by the compressors and/or the air-flow meter for both DA (r = 0.1414, P = .02) and B (r = 0.1163, P = .03) and RD. However, there was no correlation between the compressor/flow meter pressure and the RDs for both drugs. Certain compressors had greater efficiency. Conclusions: Clinicians may need to know the efficiency of the compressor/nebulizer combination they are using, since there is a relationship between flow and RD. Since others have shown that the Parineb can achieve > 50% efficiency, the burden falls to the gas supply. None of the compressors we tested provided a nebulizer efficiency of 50% or more. These were all compressors that were off the shelf, common practice in the respiratory therapy department. Perhaps the RT department should have means of verifying compressor efficiency when high efficiency aerosol delivery is desired.