Oscillometry to assess ventilation heterogeneity during hospital admission for acute cardiorespiratory illness

Hospitalisation due to exacerbations of cardiorespiratory disease results in reduced lung function and increased airways obstruction. However, traditional measures of lung function require maximal effort which is difficult when patients are unwell (e.g. FEV₁) and may focus on larger airways away from the major part of airways disease (e.g. peak flow). We aimed to measure whole airways function using oscillometry in patients during hospitalisation with cardiorespiratory illness compared with healthy controls.

Participants (n=310) underwent assessment; 263 were admitted to hospital with acute cardiorespiratory illness (asthma (n=80), COPD (n=75), heart failure (n=46) and pneumonia (n=62)) and 47 healthy controls were included. Participants underwent handheld oscillometry measurements within the first 24 h of admission.

Oscillometry measurement was feasible in all patients (n=310). There was a significant difference in both absolute and percentage predicted measures of lung mechanics (p<0.05 for all measures), with significantly worse lung mechanics in patients with COPD. Measures of resistance and reactance were worse in those that were more breathless (p<0.0001), had more wheeze (p<0.001) and had low oxygen saturation (p<0.001). No difference was seen based on modified early warning system score or blood biomarkers (eosinophil count, C-reactive protein and brain natriuretic peptide). There were significant improvements in oscillometry measures in those that attended following recovery from acute illness.

Handheld oscillometry can be feasibly deployed in the acute care setting to obtain information on respiratory mechanics. It demonstrates significant differences in ventilation heterogeneity between patients in the acute care setting and healthy volunteers.