Breath-by-breath: unmasking cardio-respiratory conditions through capnography waveforms - the general breathing record study

Background In an increasingly global comorbid population, there are significant challenges to diagnosing the cause of breathlessness. Furthermore, once chronic respiratory conditions have been diagnosed, there is considerable difficulty in detecting deterioration early enough to provide timely, effective intervention. Current methods of diagnosing and monitoring conditions that cause breathlessness, such as asthma and chronic heart failure, can be extensive and difficult to perform.Methods This observational, proof-of-concept study explored the potential of high-resolution capnography to differentiate respiratory and cardiac conditions causing breathlessness. Using an early model of the N-Tidal device, we analysed capnography waveforms from participants with severe asthma, chronic heart failure, and pneumonia, and compared them to healthy baseline controls.Results A moderate correlation was observed between alpha angle and spirometry metrics in asthma (r2 = 0.48 for FEV1/FVC), along with a moderate association between alpha angle and left ventricular ejection fraction in heart failure (r2 = 0.46). Pneumonia recovery was marked by a 12.6% median increase in end-tidal CO2.Conclusion These results suggest that high-resolution capnography may offer promise for non-invasive diagnosis and monitoring of cardiorespiratory conditions.Trial registration NCT03356288 (registered on 7 September 2017)