Brown L K, Schwartz J, Miller A, Pilipski M, Teirstein A S
Department of Medicine, Mount Sinai Medical Center, New York, NY 10029.
Respir Physiol. 1990 May-Jun;80(2-3):231-43. doi: 10.1016/0034-5687(90)90086-e.
Chest wall inertance (Iw) constitutes a mechanical load which is small in normal individuals, but increases in the morbidly obese. The effect of increased Iw on respiratory drive and pattern has not previously been investigated. We studied this effect by measuring rebreathing CO2 response in 10 normal subjects with and without a 45.5 kg inertial load. Changes in inspiratory occlusion pressure (P0.1), ventilation, respiratory rate, mean inspiratory flow (VT/TI) duty cycle (TI/TT), inspiratory and expiratory times, and [P0.1/(VT/TI)] were assessed. The P0.1 vs. PETCO2 response shifted to the left during inertial loading, while the slope remained unchanged (x-intercept = 36.7 +/- 4.9 mm Hg unloaded vs. 32.7 +/- 7.5 mm Hg loaded, P less than 0.05), increasing P0.1 from 18.5 +/- 8.0 to 21.0 +/- 7.6 cm H2O at PETCO2 = 6.5 mm Hg (P less than 0.005). Respiratory pattern was unchanged with the inertial load except for a slight decrease in tidal volume. The inspiratory transfer characteristic [P0.1/(VT/TI)] at PETCO2 = 65 mm Hg increased significantly (8.3 +/- 2.0 to 10.5 +/- 2.9 cm H2O.(L.sec-1)-1, P less than 0.025) illustrating the strategy of maintaining similar ventilation by increasing inspiratory force against the load.
胸壁惯性（Iw）构成一种机械负荷，在正常个体中较小，但在病态肥胖者中会增加。此前尚未研究过增加的Iw对呼吸驱动和模式的影响。我们通过测量10名正常受试者在有和没有45.5千克惯性负荷情况下的重复呼吸二氧化碳反应来研究这种影响。评估了吸气阻断压（P0.1）、通气量、呼吸频率、平均吸气流量（VT/TI）、占空比（TI/TT）、吸气和呼气时间以及[P0.1/(VT/TI)]的变化。在施加惯性负荷期间，P0.1与呼气末二氧化碳分压（PETCO2）的反应向左偏移，而斜率保持不变（空载时x轴截距 = 36.7±4.9毫米汞柱，加载时为32.7±7.5毫米汞柱，P<0.05），在PETCO2 = 6.5毫米汞柱时，P0.1从18.5±8.0厘米水柱增加到21.0±7.6厘米水柱（P<0.005）。除潮气量略有减少外，呼吸模式在施加惯性负荷时未发生变化。在PETCO2 = 65毫米汞柱时，吸气传递特性[P0.1/(VT/TI)]显著增加（从8.3±2.0增加到10.5±2.9厘米水柱·（升·秒-1）-1，P<0.025），这说明了通过增加对抗负荷的吸气力量来维持相似通气量的策略。
