PT  - JOURNAL ARTICLE
AU  - Bradford Smith
AU  - Jason Bates
TI  - Dynamic pressure-volume loops as predictors of long-timescale derecruitment in the lung
DP  - 2013 Sep 01
TA  - European Respiratory Journal
PG  - P654
VI  - 42
IP  - Suppl 57
4099  - http://erj.ersjournals.com/content/42/Suppl_57/P654.short
4100  - http://erj.ersjournals.com/content/42/Suppl_57/P654.full
SO  - Eur Respir J2013 Sep 01; 42
AB  - The tendency of the injured lung to derecruit with time is reflected in its increases in elastance during a few minutes of mechanical ventilation immediately following a recruitment maneuver. This procedure is inconvenient for clinical use, however, so we investigated whether the dynamic pressure-volume (PV) loop obtained during a single large breath can be used to estimate lung derecruitability.Anesthetized, paralyzed, tracheostomized BALB/c mice were subjected, at zero end-expiratory pressure, to 16.5 min periods of over-ventilation (tidal volume, Vt = 1.0,1.1,1.2,1.3 ml) during which PV loops were recorded every 5.5 min. Lung derecruitability (Vt = 0.25ml) was assessed for 4.5 min between each over-ventilation epoch. The mice were exposed to alternating derecruitability tests and over-ventilation epochs for up to 4 hrs.Each derecruitability test provided an initial value of lung elastance (H1) and a subsequent mean rate of change of elastance (DRate). Each dynamic PV loop provided a measure of lung elastance (H0.2ml) at the 0.2 ml point during inspiration. Both H1 (Fig. 1a) and DRate (Fig. 1b) exhibited strongly correlated sigmoidal relationships with H0.2ml. This suggests that the long timescale derecruitability of the lung, encapsulated in H1 and DRate, is also reflected in the shape of the dynamic PV relationship, quantified by H0.20ml. The latter may thus be a clinically useful measure of derecruitability.