Study terminated/withdrawn due to the prolonged timeline since initial ethical approval (without starting) and the number of significant changes to the management and structure of the study deemed appropriate for continuation due to the delays.

This is an observational, controlled, single-centre study to validate the Thora3Di™ against standard practice in patients who are undergoing investigation for disproportionate breathlessness. The core methodology involves capturing of data during a short period of measurement of breathing using SLP.

Cohort A: This study is a pilot study with four study visits (Screening, Baseline, week 13 and week 26) to generate data to characterise the tidal breathing patterns and parameters with Thora3Di™. Subjects will have a screening visit within 0 to 14 days prior to the first study visit. For each study visit, subjects will be seen in the clinical research facility and have two 5-minute SLP measurements (at rest and on exertion). The SLP measurement should be performed prior to standard lung function tests with minimal impact on clinical time and not change to hospital attendance. Also, each visit subjects will be asked to report concomitant medications and adverse events, and fill several questionnaires forms as outlined in the SOAs.

Cohort B: Healthy subjects will have only one visit for this study. After signing the informed consent form, subjects will undergo two 5-minutes SLP measurements (at rest and on exertion).

Inclusion Criteria:

• • Cohort A: Any adult who is presenting with controlled disproportionate breathlessness will be considered for inclusion as a diseased subject (with excluded comorbidities as cause of breathlessness e.g. uncontrolled asthma (GINA 2019 guidelines), uncontrolled cardiac disease, ILO).

  • Cohort B: Any adult who is in good respiratory health will be considered for inclusion as a normal in the study.

Exclusion Criteria:

• Subject unable to sit in an upright position for required period

  • Subjects with significant co morbidities (assessed by the clinician at screening only):
  • Chest wall or spinal deformity e.g. scoliosis OSA, Apnoea hypopnoea index > 30 (if known)
  • Any other significant disease or disorder which, in the opinion of the investigator, may either put the participants at risk because of participation in the study, or may influence the result of the study, or the participants' ability to participate in the study
  • BMI > 40
  • Height > 194 cm
  • Female participant who is pregnant, lactating or planning pregnancy during the course of the study
  • Inability to consent/comply with trial protocol

Cohort A: Any adult who is presenting with controlled disproportionate breathlessness will be considered for inclusion as a diseased subject (with excluded comorbidities as cause of breathlessness e.g. uncontrolled asthma (GINA 2019 guidelines), uncontrolled cardiac disease, ILO).

• Cohort B: Any adult who is in good respiratory health will be considered for inclusion as a normal in the study.