Table 2 Pathophysiology of COPD as assessed by EIT
Spatial lung heterogeneity | |
Pathophysiological variable | EIT parameter |
Regional dynamic hyperinflation/intrinsic PEEP [26]. | Regional decrease of end-expiratory lung volume during decremental PEEP trial [27]. Regional end-expiratory flow not returning to zero before next breath [28]. |
Heterogenous distribution of ventilation within the lungs. | Elevated global inhomogeneity index [29]. Uneven distribution of ventral/dorsal ventilation [30]. |
Temporal lung heterogeneity | |
Pathophysiological variable | EIT parameter |
Heterogeneity of regional start of inflation/deflation—regional differences in time constants. | Out of phase filling and emptying of different regions of the lung [25, 31]. Regional ventilation-delay index [32]. |
Regional pendelluft [33]. | Volume shifts between lung regions during end inspiratory hold. Time difference between global and regional impedance versus time curves [24, 33]. |