Feedback information from flow volume curves to the practice

To investigate whether the use of feedback information provided by viewing flow volume (F/V) curves during spirometry performed by practice assistants improves spirometry test quality.

Randomised controlled single session crossover study. Eight practice assistants performed spirometry in healthy subjects (n=47). Two measurement conditions were applied, one allowing viewing of F/V curves during the tests ('unblinded') the other not ('blinded'). Outcomes were differences in FEV₁, FVC, FEV₁/FVC ratio, PEF, FEV₁ repeatability and number of manoeuvres per test. Two lung function technicians indicated their preference for either the blinded or unblinded F/V curve.

Higher PEF values were observed for the unblinded condition (0.43 L/s, 95% CI 0.08, 0.77). The other outcomes showed no differences. One lung function technician judged that in 62% (p=0.012) of the pairs the F/V curve from the unblinded condition was better, the other technician judged so in 51% (p=0.349).

This study in healthy subjects showed that the use of information from F/V curves leads to a modest quality improvement of spirometric tests performed by practice assistants and can therefore be recommended for use in general practice.