This study will test the use of a new handheld device (called the N-Tidal C), that measures a person's tidal breath carbon dioxide, in diagnosing the cause of someone's breathlessness. It will also evaluate whether this device can detect when a person's breathing problem is getting worse.

When a person breathes out, they exhale carbon dioxide (CO2). The CO2 levels in breath change as they breathe out and this makes a specific pattern, or "waveform". This waveform can tell a clinician a lot about the underlying health of a person. There are disease specific CO2 waveforms for common breathing conditions such as Asthma and Chronic Obstructive Pulmonary Disease (COPD). However up until this point there has been no accurate and non-invasive method of measuring the tidal breath CO2 waveform.

This study will test the N-Tidal C, a new handheld device that accurately measures this waveform, and whether it can differentiate different causes of breathlessness; namely asthma, heart failure, pneumonia, breathing pattern disorders and motor neurone disease.

Inclusion Criteria:

Asthma Cohort:

• A confirmed clinical diagnosis of asthma for ≥ 6months
• Moderate to severe asthma defined as British Thoracic Society stages 3-5
• 2 or more exacerbations in the previous 12 months with at least 1 exacerbation within the last 6 months.
• Exacerbation free for 2 weeks (defined as no increased dose or course of oral corticosteroids or antibiotics).

Breathing Pattern Disorder Cohort

• A Clinical diagnosis of a Breathing Pattern Disorder (BPD)

Chronic heart failure Cohort:

• A confirmed clinical diagnosis of chronic heart failure with both of the following:

  1. A Left Ventricular Ejection Fraction <40% on most recent imaging within the last 12 months.
  2. New York Heart Association Class 2-4

• Admitted with an acute decompensation of their heart failure to hospital within the last 6 months

Motor Neurone Disease Cohort:

• A confirmed clinical diagnosis of Motor Neurone Disease
• Forced Vital Capacity (FVC) of less than 60% of predicted, sleep disordered breathing or daytime hypercapnia.
• Established on Home Non-Invasive Ventilation.

Pneumonia Cohort:

• A confirmed clinical diagnosis of Pneumonia supported by evidence of consolidation on a chest X-ray (CXR) or computed tomography (CT) imaging.

Healthy Cohort:

• No known history of lung, cardiac or neuromuscular disease (defined as no current clinical diagnosis of, or be receiving treatment for, a lung, cardiac or neuromuscular disease). A Body Mass Index of less than 40. A Non-smoker, or an ex-smoker with less than a 5 pack year history.

Exclusion Criteria:

• Known other lung, chest wall, neuromuscular, cardiac or other comorbidity or abnormality that would affect spirometry and/or other measures of lung function or Tidal Breath Carbon Dioxide measurements.
• In the opinion of the clinical investigator, the participant would have difficulty completing the study procedures consistently over the course of 6 months.

The healthy Cohort will be made up of healthy volunteers. The Disease Cohorts will be selected from hospital outpatient clinic lists and inpatient wards.