Sharafkhaneh A, Goodnight-White S, Officer T M, Rodarte J R, Boriek A M
Assistant Baylor College of Medicine, MED VAMC, 2002 Holcombe Blvd, Houston, Texas 77030, USA.
Thorax. 2005 Apr;60(4):288-92. doi: 10.1136/thx.2004.033589.
Thoracic gas compression (TGC) exerts a negative effect on forced expiratory flow. Lung resistance, effort during a forced expiratory manoeuvre, and absolute lung volume influence TGC. Lung volume reduction surgery (LVRS) reduces lung resistance and absolute lung volume. LVRS may therefore reduce TGC, and such a reduction might explain in part the improvement in forced expiratory flow with the surgery. A study was conducted to determine the effect of LVRS on TGC and the extent to which reduced TGC contributed to an improvement in forced expiratory volume in 1 second (FEV1) following LVRS.
The effect of LVRS on TGC was studied using prospectively collected lung mechanics data from 27 subjects with severe emphysema. Several parameters including FEV1, expiratory and inspiratory lung resistance (Rle and Rli), and lung volumes were measured at baseline and 6 months after surgery. Effort during the forced manoeuvre was measured using transpulmonary pressure. A novel method was used to estimate FEV1 corrected for the effect of TGC.
At baseline the FEV1 corrected for gas compression (NFEV1) was significantly higher than FEV1 (p<0.0001). FEV1 increased significantly from baseline (p<0.005) while NFEV1 did not change following surgery (p>0.15). TGC decreased significantly with LVRS (p<0.05). Rle and maximum transpulmonary pressure (TP(peak)) during the forced manoeuvre significantly predicted the reduction in TGC following the surgery (Rle: p<0.01; TP(peak): p<0.0001; adjusted R2 = 0.68). The improvement in FEV1 was associated with the reduction in TGC after surgery (p<0.0001, adjusted R2 = 0.58).
LVRS decreased TGC by improving expiratory flow limitation. In turn, the reduction in TGC decreased its negative effect on expiratory flow and therefore explained, in part, the improvement in FEV1 with LVRS in this cohort.
胸内气体压缩（TGC）对用力呼气流量产生负面影响。肺阻力、用力呼气动作时的用力程度以及绝对肺容积会影响TGC。肺减容手术（LVRS）可降低肺阻力和绝对肺容积。因此，LVRS可能会降低TGC，而这种降低可能部分解释了手术导致的用力呼气流量改善情况。开展了一项研究以确定LVRS对TGC的影响以及TGC降低在LVRS后1秒用力呼气容积（FEV1）改善中所起作用的程度。
利用前瞻性收集的27例重度肺气肿患者的肺力学数据，研究LVRS对TGC的影响。在基线和术后6个月测量了包括FEV1、呼气和吸气肺阻力（Rle和Rli）以及肺容积等多个参数。使用跨肺压测量用力动作时的用力程度。采用一种新方法来估计校正了TGC影响后的FEV1。
基线时校正气体压缩后的FEV1（NFEV1）显著高于FEV1（p<0.0001）。FEV1较基线显著增加（p<0.005），而术后NFEV1未发生变化（p>0.15）。LVRS使TGC显著降低（p<0.05）。用力动作时的Rle和最大跨肺压（TP(peak)）显著预测了术后TGC的降低（Rle：p<0.01；TP(peak)：p<0.0001；校正R2 = 0.68）。FEV1的改善与术后TGC的降低相关（p<0.0001，校正R2 = 0.58）。
LVRS通过改善呼气流量受限降低了TGC。反过来，TGC的降低减少了其对呼气流量的负面影响，因此部分解释了该队列中LVRS后FEV1的改善情况。
