Clinical evaluation of a screen pneumotachograph as an in-line filter

Abstract

The American Thoracic Society/European Respiratory Society Task Force underlined that the use of in-line filters during respiratory function tests ''is an area of controversy''. The aim of the present study was to measure the contamination occurring during forced expiration downstream from a screen pneumotachograph (SP) with and without an in-line filter (Pall PF30S). A total of 40 healthy subjects performed eight consecutive maximal expiratory manoeuvres into four sterile apparatuses (A1: no filter, no SP; A2: filter-only; A3: SP-only; A4: filter and SP) in random order. A blood agar plate was fixed downstream from the apparatus. Colonyforming units (CFUs) were counted after 24 h incubation at 37uC. Of the 40 plates obtained with each apparatus, 13 were sterile with A1 (range 0-679 CFUs), 25 with A2 (0-49 CFUs), 30 with A3 (0-35 CFUs) and 39 with A4 (one CFU in the only positive plate). A1 versus A2 and also A3 versus A4 gave different values for the CFU number, but A2 and A3 showed similar contamination levels.The authors conclude that: 1) the in-line filter does not perform better than a screen pneumotachograph; 2) it does not eliminate the need to decontaminate the pneumotachograph; and 3) equipment placed downstream from an in-line filter and a screen pneumotachograph is almost protected from contamination.

Airflow dynamics and exhaled-breath temperature following cold-water ingestion

“…We presently report a baseline EBT in our healthy cohort of ~33.8 ± 0.4 •C, which mirrors data from Svensson et al (2012), and corroborates the general consensus. As such, to mitigate unnecessary errors in spirometric measurement, we concur with others who suggest that the BTPS correction factor for expiratory gas should be adapted to the actual gas conditions in the pneumotachograph (Normand et al, 2007).…”

Computational Fluid Dynamics Modeling in Respiratory Airways Obstruction: <i>Current Applications and Prospects</i>

“…These approaches detect impairment in the airway through the use of Force Oscillation Technique (FOT) [13], the pneumotachograph technique [14] and dynamic spirometry [15]. However, the above-mentioned techniques of assessing respiratory disorders have limitations which are discussed by Joe et al [16][17][18][19][20][21]. Therefore, recent studies have taken advantage of advanced scientific computations such as CFD, which closely mimic the human airways to deduce airflow behavior in the human respiratory system.…”