A randomised, cross-over trial of upright sitting with or without positive expiratory pressure during nebulised delivery of medication to improve the pattern of aerosol deposition in participants with cystic fibrosis

INTERVENTION: Participants will inhale 4mL technetium‐99m DTPA radioaerosol in random order throughout the nebulisation period of 20 minutes for each of the regimens on two separte days: 1. Standard nebulisation period of 20 minutes, or 2. Nebulisation period of 20 minutes with the addition of a positive expiratory pressure device. The two study days will have a minimum of 48 hours washout between them and not greater than 7 days (to ensure clinical stability). After each nebulisation a gamma camera will perform a 20 minute deposition scan incorporating a transmission scan to outline the three‐dimensional margin of the lung fields. This data will be reconstructed to determine the distribution of the deposited radioaerosol in the lungs. CONDITION: Cystic Fibrosis PRIMARY OUTCOME: The 3‐dimensional map of the lung fields will be divided into unit volumes (voxels). The amount of radioactivity in each voxel will be calculated. The standard deviation of the radioactivity across all voxels within the margins of the lung fields will be used as an index of uniformity of the pattern of deposition for each participant. SECONDARY OUTCOME: The deposition fraction will be calculated as the amount of radioactivity in the lung fields divided by the amount of radioactivity in the nebuliser before inhalation, with correction for decay. The ratio of apical:non‐apical deposition of radioactivity will be determined by the mean number of counts per voxel in the apical one third of the lung field divided by the mean number of counts per voxel in the basal two thirds of the lung field. The ratio of central:peripheral deposition of radioactivity will be determined by the mean number of counts per voxel in the central lung field divided by the mean number of counts per voxel in peripheral the lung field. INCLUSION CRITERIA: INCLUSION CRITERIA: To participate in this study, a person must: 1 be 18 years of age or older with confirmed cystic fibrosis on genetic or sweat testing 2 be able to read, write and comprehend English 3 have stable lung function 4 be willing to inhale a 4mL radioaerosol and undergo a 20‐minute gamma scan, on two occasions.