Mechanisms of ventilation inhomogeneity during vital capacity breaths standing and supine

Mikael J Grönkvist , Michael J Emery , Per M Gustafsson
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引用次数: 11

Abstract

Overall inhomogeneity of ventilation distribution, as measured by single-breath vital capacity (VC) washout (SBW) is known to be greater supine vs. standing. To establish the underlying mechanisms 13 healthy males performed VC SBW of 4% SF6 and He, standing and supine, with or without a 10 sec breathhold (BH). Overall inhomogeneity, as indicated by normalized phase III slopes, was >50% greater supine (SF6 13.1×10−3; He 10.7×10−3 L−1) than standing (SF6 8.6×10−3; He 6.4×10−3 L−1; P<0.001). The (SF6–He) slope, an index of intraacinar inhomogeneity, did not change with posture. Breathholding, assumed to eliminate convective dependent inhomogeneity within and/or between small lung units, produced twice as great reduction of inhomogeneity when supine vs. standing. After BH inhomogeneity remained significantly greater supine vs. standing. In conclusion, at least two events seem to underlie the increased inhomogeneity when supine: (1) a substantially increased convection dependent non-uniformity between well-separated lung regions; and (2) a somewhat increased convection dependent non-uniformity within and/or between peripherally located lung units.

站立和仰卧呼吸时呼吸不均匀的机制
通过单次呼吸肺活量(VC)冲洗(SBW)测量的通气分布的总体不均匀性已知是仰卧比站立更大。为了建立潜在的机制,13名健康男性进行了4% SF6和He的VC - SBW,站立和仰卧,有或没有10秒屏气(BH)。总体不均匀性,如归一化的III期斜坡所示,仰卧位的不均匀性比仰卧位大50% (SF6 13.1×10−3;他10.7×10−3 L−1)比站立(SF6 8.6×10−3;He 6.4×10−3 L−1;术中,0.001)。(SF6-He)斜率(一种衡量腺泡内不均匀性的指标)不随体位变化。屏气被认为可以消除小肺单元内部和/或之间的对流依赖的不均匀性,仰卧时比站立时产生两倍的不均匀性减少。BH后,仰卧位与站立位的不均匀性仍然显著增加。总之,至少有两个事件似乎是平卧时不均匀性增加的原因:(1)在分离良好的肺区域之间,对流依赖的不均匀性大大增加;(2)外围肺单元内部和/或之间的对流非均匀性有所增加。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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