Pellegrino Riccardo, Gobbi Alessandro, Antonelli Andrea, Torchio Roberto, Gulotta Carlo, Pellegrino Giulia Michela, Dellacà Raffaele, Hyatt Robert E, Brusasco Vito
Allergologia e Fisiopatologia Respiratoria, ASO S. Croce e Carle, Cuneo, Italy;
J Appl Physiol (1985). 2014 May 1;116(9):1175-81. doi: 10.1152/japplphysiol.01339.2013. Epub 2014 Mar 20.
Obesity is associated with important decrements in lung volumes. Despite this, ventilation remains normally or near normally distributed at least for moderate decrements in functional residual capacity (FRC). We tested the hypothesis that this is because maximum flow increases presumably as a result of an increased lung elastic recoil. Forced expiratory flows corrected for thoracic gas compression volume, lung volumes, and forced oscillation technique at 5-11-19 Hz were measured in 133 healthy subjects with a body mass index (BMI) ranging from 18 to 50 kg/m(2). Short-term temporal variability of ventilation heterogeneity was estimated from the interquartile range of the frequency distribution of the difference in inspiratory resistance between 5 and 19 Hz (R5-19_IQR). FRC % predicted negatively correlated with BMI (r = -0.72, P < 0.001) and with an increase in slope of either maximal (r = -0.34, P < 0.01) or partial flow-volume curves (r = -0.30, P < 0.01). Together with a slight decrease in residual volume, this suggests an increased lung elastic recoil. Regression analysis of R5-19_IQR against FRC % predicted and expiratory reserve volume (ERV) yielded significantly higher correlation coefficients by nonlinear than linear fitting models (r(2) = 0.40 vs. 0.30 for FRC % predicted and r(2) = 0.28 vs. 0.19 for ERV). In conclusion, temporal variability of ventilation heterogeneities increases in obesity only when FRC falls approximately below 65% of predicted or ERV below 0.6 liters. Above these thresholds distribution is quite well preserved presumably as a result of an increase in lung recoil.
肥胖与肺容积的显著减少有关。尽管如此，至少在功能残气量（FRC）适度减少的情况下，通气仍保持正常或接近正常分布。我们检验了这样一个假设，即这是因为最大流量增加，推测是肺弹性回缩增加的结果。在133名体重指数（BMI）范围为18至50kg/m²的健康受试者中，测量了经胸气体压缩容积、肺容积校正后的用力呼气流量以及5-11-19Hz的强迫振荡技术。通气异质性的短期时间变异性是根据5至19Hz吸气阻力差异频率分布的四分位间距（R5-19_IQR）估算的。预测的FRC%与BMI呈负相关（r = -0.72，P < 0.001），与最大流量-容积曲线（r = -0.34，P < 0.01）或部分流量-容积曲线的斜率增加也呈负相关（r = -0.30，P < 0.01）。再加上残气量略有减少，这表明肺弹性回缩增加。R5-19_IQR与预测的FRC%和呼气储备容积（ERV）的回归分析显示，非线性拟合模型的相关系数显著高于线性拟合模型（预测的FRC%：r² = 0.40 vs. 0.30；ERV：r² = 0.28 vs. 0.19）。总之，只有当FRC降至预测值的约65%以下或ERV低于0.6升时，肥胖患者通气异质性的时间变异性才会增加。高于这些阈值时，通气分布可能由于肺回缩增加而得到较好的保留。
