Measurement of functional residual capacity by modified multiple breath nitrogen washout for spontaneously breathing and mechanically ventilated patients

Abstract

The modified multiple breath nitrogen washout method for FRC measurement provides improved precision and equivalent accuracy and repeatability compared with existing methods during ventilation with variable ventilation patterns. Further study of the novel N₂ washout method is needed.

Two steps forward in bedside monitoring of lung mechanics: transpulmonary pressure and lung volume

“…For example, rapid and/or irregular respiratory rates with large variations in tidal volume may alter FRC values and/or prevent gas-automated methods from performing the measurement [27]. Abnormal metabolic states because of high fever and/or agitation, as well as neurological conditions that alter respiration may also influence FRC measurements by varying CO 2 production and breathing patterns [27,28]. …”

Two Steps Forward in Bedside Monitoring of Lung Mechanics: Transpulmonary Pressure and Lung Volume

“…For example, rapid and/or irregular respiratory rates with large variations in tidal volume may alter FRC values and/or prevent gas-automated methods from performing the measurement [27]. Abnormal metabolic states because of high fever and/ or agitation, as well as neurological conditions that alter respiration may also infl uence FRC measurements by varying CO 2 production and breathing patterns [27,28].…”

Modelling mixing within the dead space of the lung improves predictions of functional residual capacity

“…Early methods relied on mass spectrometers (Gothard et al, 1980;Mitchell et al, 1982;Sivan et al, 1990;Williams et al, 1997), but they are bulky, temperamental and becoming harder to source (Arieli, 2010;Hahn, 1996;Horsley et al, 2014), so have not been used in clinical practice. More recently, several methods which do not use mass spectrometers have been proposed (Brewer et al, 2011;Olegård et al, 2005;Weismann et al, 2006), but further validation is needed before they are recommended for routine clinical use (Rouby et al, 2013).…”

“…©2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Many methods have relied on a small number of observations per breath (Brewer et al, 2011;Gavaghan and Hahn, 1996;Gothard et al, 1980;Hahn, 1996;Hahn et al, 1993;Mitchell et al, 1982;Olegård et al, 2005;Weismann et al, 2006), for example each breath only yielding one data point: the end-expired concentration. Here methods that use the entire expired signal are presented, which may increase the information extracted from the data.…”