Sentinel - Triaging Acute Breathlessness Using Multi-Modal Biomarkers

Inclusion Criteria: * Aged 18-90 years. * Has experienced episode of breathlessness during the past 12 months triggering interaction with a health care professional. Self-reported breathlessness using any of the following words to describe symptoms will qualify as a presentation of breathlessness regardless of aetiology or severity of symptoms: shortness of breath, tight chest, trouble breathing, breathlessness, dyspnoeic, breathless, asthmatic, suffocating, wheezing, fighting for breath or any equivalent word. Breathlessness does not have to be the primary presenting symptom. * Deemed clinically sufficiently stable to participate according to health care practitioner. Exclusion Criteria: * Inability to understand written local language at a year 5 level. * Not being confident in use of digital technology (smartphone and/or tablet). This will become evident through an inability to use the system. * Inability to enter required study sample data due to diminished consciousness and/or physical or mental capacity regardless of whether this is associated with the breathlessness event. * Received an investigational medical product in the context of a Clinical Trial during the 28 days prior to first probe administration.