Effects of body posture and tidal volume on inter- and intraregional ventilation distribution in healthy men

Mikael Grönkvist, Eddie Bergsten, Per M. Gustafsson
2002 Journal of applied physiology  
Grö nkvist, Mikael, Eddie Bergsten, and Per M. Gustafsson. Effects of body posture and tidal volume on inter-and intraregional ventilation distribution in healthy men. J Appl Physiol 92: 634-642, 2002; 10.1152/japplphysiol.00161.2001.-The influences of body posture and tidal volume (VT) on inter-and intraregional ventilation inhomogeneity were assessed by normalized phase III slope (Sn III) analysis of multiple-breath washout recordings of SF6 and He in 11 healthy men. Washouts with target VT
more » ... ts with target VT of 750, 1,000, and 1,250 ml were performed standing and supine. A linear-fit method was used to establish the contributions of convection-dependent (interregional) (cdi) and diffusionconvection interaction-dependent (intraregional) inhomogeneity (dcdi). Overall inhomogeneity was defined as the sum of cdi and dcdi. The difference in first-breath Sn III for SF6 vs. He, the (SF 6 Ϫ He)SnIII, served as an index of intra-acinar inhomogeneity. Multiple-regression analysis revealed greater cdi supine vs. standing (P Ͻ 0.001) but no significant effects of posture on dcdi or overall inhomogeneity. Larger VT were associated with greater cdi (P Ͻ 0.001), particularly when supine, but reduced dcdi (P Ͻ 0.001), overall inhomogeneity (P Ͻ 0.001), and (SF 6 Ϫ He)SnIII (P ϭ 0.031). In conclusion, during resting breathing overall and intraregional ventilation inhomogeneities remain unchanged when the supine posture is assumed and improve with larger VT, but supine posture and larger breaths result in greater interregional inhomogeneities. Values are means Ϯ SE. P values from a linear multiple regression model are given displaying the influences of body posture and VT/FRC on the parameters measured. The adjusted R 2 from the regression model is also given. LCI, lung clearance index; 1/0 and 2/0, ratios between moment 0, 1, and 2, respectively, from the moment analysis. For explanation of the parameters see METHODS. GAS MIXING STANDING AND SUPINE
doi:10.1152/japplphysiol.00161.2001 pmid:11796675 fatcat:k4vpvxwi55f6vdmztcf3keefti