Abstract
Background:
Electrical impedance tomography (EIT) provides a noninvasive means of assessing posture-related end-expiratory lung impedance and the regional distribution of ventilation. However, the physiological effects of specific bedside postures, including the hands-on-knees and tripod positions, have not been fully characterized using EIT in spontaneously breathing individuals. We aimed to compare the end-expiratory lung impedance and regional ventilation distribution of healthy volunteers across a range of postures as a physiological proof-of-concept to inform future clinical investigations.
Methods:
The regional end-expiratory lung impedances (ΔEELI) of 20 healthy male subjects who adopted the 6 following postures were compared: supine, prone, sitting, tripod, hands-on-knees, and standing. The distribution of ventilation between the dorsal and ventral lung regions was also analyzed for each posture. The Wilcoxon test with the Holm–Bonferroni correction was used to compare the datasets.
Results:
Compared with the supine posture, the hands-on-knees posture was associated with the highest global ΔEELI (3.58 units, 95% CI: 2.81–4.58, P < .001), followed by the tripod position (2.16 units, 95% CI: 1.69–3.47, P < .001). With respect to the regional ventilation, dorsal ventilation was significantly better for all other postures versus the supine posture, particularly for the hands-on-knees and tripod position (ΔEELI in the dorsal region 2.77 units, 95% CI: 2.02–3.33, and 2.02 units, 95% CI: 1.35–2.64, respectively; both P < .001).
Conclusions:
In healthy men, the hands-on-knees and tripod postures were associated with greater global and dorsal end-expiratory lung impedance and a more dorsal ventilation distribution. Whether these physiological observations might translate to clinically meaningful improvements in patients with respiratory disease warrants further investigation in clinical studies.
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