P248 Assessment of repeatability of structured light plethysmography (slp) technique compared to spirometry

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<h3>Introduction</h3> Structured Light Plethysmography (SLP) is a novel non-invasive, contactless technique utilising only a grid of white light and cameras to track, measure, capture Throraco-Abdominal (TA) displacement and record quiet tidal breathing. Repeatability is used to assess the measurements from two devices for the same test subject when recorded simultaneously. Spirometry is considered to be the gold standard for measuring lung function but requires the application of forceful manoeuvres which might not be attainable by patients, and so SLP could provide an opportunity to evaluate these patients if successfully benchmarked to spirometry data. <h3>Aim</h3> To assess the correlation between SLP recordings with simultaneous spirometry measurement of quiet tidal breathing. <h3>Methods</h3> Quiet breathing in 14 healthy volunteers was simultaneously recorded via SLP ( Thora3Di, Pneumacare Ltd) and by spirometry (Power lab 4/20, AD Instruments Ltd). Statistical analysis using Wilcoxon paired signed-rank test to assess correlation and agreement of these techniques was assessed under three different breathing conditions: Normal, Deep &amp; Shallow. Respiratory rate (RR), inspired, expired and total breathing times were analysed (Ti, Te, Ttot) and duty cycle (Ti/Ttot) was calculated under the three different breathing conditions. There was a good correlation between the techniques under normal and deep breathing conditions. Ethical Approval for the study was approved by Science, Technology, Engineering and Mathematics Ethical Review Committee at the University of Birmingham. <h3>Results</h3> There were only significant differences in shallow breathing measurements (Ti <i>P=</i><i>0.0015</i>, Ti/Ttot <i>P=</i><i>0.0400</i>) (see figure 1 A-E). <h3>Conclusions</h3> SLP shows good correlation with spirometry for all timing indices both under normal quiet breathing as well as deep breathing but showed a significant difference in shallow breathing indicating that it is a reliable technique during normal and deep breathing. However, during shallow breathing probably due to fast breathing the movement detection was disturbed as a result of the high frequency (50–60 bpm) or could be attributed to the effects of the mouthpiece and nose clip.