Quantifying Delivery Of Radio Labeled Aerosol During Noninvasive Ventilation To Stable Moderate And Severe Asthmatics: A Randomized, Cross-Over Clinical Trial

Introduction: Inhalation therapy has been established as an efficient route to treat asthma exacerbations, but coupled to noninvasive ventilation (NIV) remains quite challenging. Objectives: The aim of this study were to compare radiaoaerosol pulmonary index and radioaerosol mass balance in the different compartments (pulmonary and extrapulmonary) using vibrating mesh nebulizers (VMN) and jet nebulizer (JN) coupled to noninvasive ventilation (NIV). Material and methods: The investigators assessed 10 stable moderate to severe asthmatics in a crossover study. Patients was randomly assigned to participate in both phases of the study: Phase 1(NIV+MN) and phase 2(NIV+JN). DTPA-Tc99m with radioactivity of 25 miC was used to inhaler using JN positioned in the circuit using a "T" piece, particle size generation in a five micron range and oxygen flow tritated at eight L/min and MN was positioned in the mask, particle size generation in a one range and connected to electrical energy. NIV was used a bilevel pressure through a face mask attached with straps and pressure adjusted were 12 cmH2O and 5 cmH2O as inspiratory and expiratory pressures, respectively. After, radioactivity counts were performed using a gama camera and regions of interest were delimited. To calculate aerosol mass balance the investigators considered the amount of radioaerosol deposited into the lungs, upper airways, stomach, nebulizer, circuit, inspiratory and expiratory filters, and mask divided for each of these compartments and represented as a percentage.