Validation of Structured Light Plethysmography (SLP) in patients with asthma, in patients with acute asthma; an observational study in healthy participants and during patients' clinical investigation of broncho-reversibility in the asthma groups.

A non-randomised observational study to validate Structured Light Plethysmography in three groups of participants: those with stable asthma and those with acute asthma, who are undergoing routine clinical investigation of broncho-reversibility using spirometry. We will also observe a normal healthy group who will receive no clinical intervention. SLP data capture and spirometry (as part of the patients clinical care) will be performed before and after a Bronchodilator reversibility test which is part of the patients normal clinical care (except in the normal healthy group where no bronchodilator will be given). The data collected from this study will allow us to examine the effect of bronchodilators on breathing patterns in these patients and also compare breathing patterns in asthma patients to those in healthy individuals.

The participant will wear a plain white t-shirt. Alternatively, the measurement can be taken on bare skin or with the participant (if female) wearing a plain material white bra. The participant is asked to sit down on a chair or lie down with their neck in a neutral position and their back as straight as possible in front of the SLP device (Thora-3Di, Pneumacare Ltd). The projector is lined up to project the grid of light over the participant's chest and upper abdomen. and will be instructed to perform a period of 5 minutes of tidal breathing, They will otherwise be asked to remain as still as possible throughout the measurement. During the sequence of breathing, thoracoabdominal wall movements will be captured by the device.

participant on completion of their Bronchodilator Challenge within the Lung Function Department or clinic

The SLP measurement is repeated on completion of their Bronchodilator reversibility test within the Lung Function Department or clinic.

Inclusion Criteria:

• Aged between 2 and 80 years

Exclusion Criteria:

• Patients with significant co morbidities resulting in clinical instability (assessed by the clinician at screening only):
• obstructive sleep apnea, Apnoea hypopnoea index > 30 (if known)
• An acute or chronic condition that, in the investigator's opinion, would limit the patient's ability to participate in the study
• BMI > 40
• Inability to consent/comply with trial protocol

100 participants between the ages of 2 and 80 with stable asthma who are undergoing routine clinical investigation of broncho-reversibilty.

100 participants between the ages of 2 and 80 with acute asthma who are undergoing routine clinical investigation of broncho-reversibilty.

100 participants between the ages of 2 and 80 with no history of respiratory disease ('Normal'). These participants will not undergo a bronchodilator challenge.