Effect of equipment dead space on multiple breath washout measures. Issue 3 (21st January 2015)

• Record Type: Journal Article
• Authors: Benseler, Anouk; Stanojevic, Sanja; Jensen, Renee; Gustafsson, Per; Ratjen, Felix
• Is Part Of: Respirology. Volume 20:Issue 3(2015)
• Page Start: 459
• Page End: 466
• Publication Date: 2015-01-21
• Subjects: Respiratory organs -- Diseases -- Periodicals; Respiratory organs -- Periodicals; 612.2
• DOI: 10.1111/resp.12470
• Languages: English
• ISSNs: 1323-7799

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <sec id="resp12470-sec-0001" sec-type="section"> <title>Background and objective</title> <p>Multiple breath inert gas washout (MBW) systems are designed to minimize equipment dead space volume (Vd). Animal and infant studies have demonstrated the impact of increased Vd on MBW measurements. In this study, we investigate the effect of Vd of a nitrogen (N<sub>2</sub>) MBW system on MBW measurements in preschool children.</p> </sec> <sec id="resp12470-sec-0002" sec-type="section"> <title>Methods</title> <p>N<sub>2</sub> MBW measurements were performed in healthy adults under standard conditions; Vd was added to match the relationship between Vd and lung volumes observed in preschool children. Subsequently, subjects were measured on a sulfur hexafluoride (SF<sub>6</sub>) MBW system under standard conditions and with Vd added to match that of the N<sub>2</sub> MBW system. Healthy preschool children and children with cystic fibrosis were tested on both the N<sub>2</sub> MBW and SF<sub>6</sub> MBW in random order on the same day. A correction equation was derived based on the adult experiments and tested on the preschool data.</p> </sec> <sec id="resp12470-sec-0003" sec-type="section"> <title>Results</title> <p>Increasing the Vd of the N<sub>2</sub> MBW system resulted in a higher lung clearance index (LCI). A strong non‐linear relationship between N<sub>2</sub> LCI and the Vd/tidal volume was observed. When the Vd was equivalent between systems, LCI measured by the SF<sub>6</sub> MBW system was similar to that measured by the N<sub>2</sub> MBW. LCI was higher on the N<sub>2</sub> MBW than the SF<sub>6</sub> MBW in preschool children. Correcting for the equipment Vd of the N<sub>2</sub> MBW resulted in better agreement.</p> </sec> <sec id="resp12470-sec-0004" sec-type="section"> <title>Conclusions</title> <p>Equipment Vd affects LCI measurements especially in young children where Vd is large relative to lung volumes.</p> </sec> </abstract>