High Concentration Oxygen in Bronchiectasis

INTERVENTION: 50% oxygen administration for 30 minutes via a full‐face continuous positive airway pressure mask without positive airway pressure. Followed by a 30 minute washout period. CONDITION: Bronchiectasis PRIMARY OUTCOME: Transcutaneous carbon dioxide level, as measured by a TOSCA monitor. SECONDARY OUTCOME: Alveolar minute ventilation, calculated using data from a flow sensor attached to the expiratory port of the participant's mask and volumetric capnography. Alveolar volume, calculated using data from a flow sensor attached to the expiratory port of the participant's mask and volumetric capnography. Change in transcutaneous carbon dioxide greater than or equal to 10mmHg, as measured by a TOSCA monitor. Change in transcutaneous carbon dioxide greater than or equal to 4mmHg, as measured by a TOSCA monitor. Effect of baseline transcutaneous carbon dioxide, spirometry and CT findings on all outcomes. Heart Rate, measured from the TOSCA Minute Ventilation, calculated using data from a flow sensor attached to the expiratory port of the participant's mask. Oxygen saturations, as recorded on the TOSCA via continuous electronic recording data download. Respiratory Rate, measured from capnography equipment Tidal volume, calculated using data from a flow sensor attached to the expiratory port of the participant's mask and volumetric capnography. Transcutaneous carbon dioxide level as measured by a TOSCA monitor. Volume of dead space to tidal volume, calculated using data from a flow sensor attached to the expiratory port of the participant's mask and volumetric capnography. Volume of dead space, calculated using data from a flow sensor attached to the expiratory port of the participant's mask and volumetric capnography. INCLUSION CRITERIA: Bronchiectasis diagnosed by a doctor and confirmed on CT scanning.