Gerstmann D R, Fouke J M, Winter D C, Taylor A F, deLemos R A
Southwest Foundation for Biomedical Research, San Antonio, Texas 78228.
Pediatr Res. 1990 Oct;28(4):367-73. doi: 10.1203/00006450-199010000-00013.
To study the effect of different high-frequency oscillatory ventilation parameters on airway pressure, we measured oscillatory pressure amplitude ([Paw[) and mean airway pressure (Paw) at three sites in open-chested normal rabbits: proximal, trachea, and alveolus. Five animals were studied to test a new pleural capsule design, which was then used in two groups of animals to measure right upper (n = 4) or middle (n = 5) lobe alveolar pressures. Animals were randomly sequenced through combinations of frequency (10, 15, and 20 Hz) and fractional inspiratory time (Ti) (0.3 and 0.5) while normoxic and eucapnic. During capsule testing, we noted that alveolar pressures increased (p less than 0.05) with increasing capsule mass, suggesting that compressive forces from the capsule may alter the capsule measurement. We thus used a low-mass (430 mg) transducer system in the rabbit high-frequency oscillatory ventilation experiments. Using multifactorial analysis of variance, we found significant main effects of Ti on Paw, and of measurement site on both [Paw[ and Paw (all p less than 0.009). Frequency did not influence variations in either [Paw[ or Paw. For both Ti settings, alveolar upper lobe Paw was lower compared with that of the middle lobe (p less than 0.0005). Lengthening Ti (0.3 to 0.5) increased tracheal Paw in each capsule group (p less than 0.0005). At Ti = 0.5, tracheal Paw exceeded Paw measured proximally (p less than 0.05). Our data support in vivo alveolar Paw inhomogeneity and demonstrate significant changes in pressures within the lung related to Ti during high-frequency oscillatory ventilation.
为研究不同高频振荡通气参数对气道压力的影响，我们在开胸正常兔的三个部位测量了振荡压力幅度（[Paw[）和平均气道压力（Paw）：气管近端、气管和肺泡。对5只动物进行研究以测试一种新的胸膜囊设计，然后将其用于两组动物，测量右上叶（n = 4）或中叶（n = 5）的肺泡压力。在动物处于常氧和正常碳酸血症状态下，使其随机接受频率（10、15和20 Hz）和吸气时间分数（Ti）（0.3和0.5）组合的测试。在胸膜囊测试期间，我们注意到随着胸膜囊质量增加，肺泡压力升高（p < 0.05），这表明来自胸膜囊的压缩力可能会改变胸膜囊测量值。因此，我们在兔高频振荡通气实验中使用了低质量（430 mg）的传感器系统。通过多因素方差分析，我们发现Ti对Paw有显著的主要影响，测量部位对[Paw[和Paw均有显著影响（所有p < 0.009）。频率对[Paw[或Paw的变化均无影响。对于两种Ti设置，上叶肺泡Paw均低于中叶（p < 0.0005）。延长Ti（从0.3至0.5）会使每个胸膜囊组的气管Paw升高（p < 0.0005）。在Ti = 0.5时，气管Paw超过近端测量的Paw（p < 0.05）。我们的数据支持体内肺泡Paw的不均匀性，并证明在高频振荡通气期间，肺内压力与Ti相关的显著变化。
