Peták F, Hayden M J, Hantos Z, Sly P D
Institute for Child Health Research, and Department of Respiratory Medicine, Princess Margaret Hospital, Perth, Australia.
Am J Respir Crit Care Med. 1997 Oct;156(4 Pt 1):1172-7. doi: 10.1164/ajrccm.156.4.9701049.
We previously studied low-frequency respiratory impedance (Zrs) data at an elevated lung volume to separate airway and tissue mechanical properties in normal infants (Am. I. Respir. Crit. Care Med. 1996; 154:161-166). The aim of the present study was to determine the volume dependence of the airway and tissue mechanics by extending Zrs measurements to lower lung volumes. Zrs spectra between 0.5 and 21 Hz were measured in supine sleeping infants (n = 8; 7 to 26 mo of age) at mean transrespiratory pressures (Ptr[mean]) of 20, 10, and 0 cm H2O, during periods of apnea induced by inflating the infants' lungs to a pressure of 20 cm H2O through a face mask. At each inflation pressure, a model containing airway resistance (Raw) and inertance (law) and tissue damping (G) and elastance (H) was fitted to Zrs data. At FRC, the values of Raw, law, G, and H were 20.6+/-4.9 (SD) cm H2O x s/L, 0.037+/-0.014 cm H2O x s2/L, 39.6+/-10.3 cm H2O/L, and 147+/-35 cm H2O/L, respectively. Increase of Ptr(mean) caused a monotonous decrease in Raw (42+/-7% of the value at FRC), while law remained constant. The tissue parameters were minimal at a Ptr(mean) of 10 cm H2O (68+/-10% and 78+/-6% in G and H, respectively) and significantly higher at both 0 and 20 cm H2O. Although Zrs measurements can be made in most infants at lung volumes as low as FRC, an inflation pressure of 20 cm H2O provides a higher success rate and is therefore a more suitable condition for general use.
我们之前在较高肺容积下研究了低频呼吸阻抗（Zrs）数据，以区分正常婴儿气道和组织的力学特性（《美国呼吸与危重症医学杂志》1996年；154:161 - 166）。本研究的目的是通过将Zrs测量扩展到更低肺容积来确定气道和组织力学的容积依赖性。在仰卧睡眠的婴儿（n = 8；7至26月龄）中，通过面罩将婴儿肺部充气至20 cm H₂O压力诱导呼吸暂停期间，测量了平均跨呼吸压力（Ptr[mean]）为20、10和0 cm H₂O时0.5至21 Hz之间的Zrs频谱。在每个充气压力下，将包含气道阻力（Raw）和惯性（law）以及组织阻尼（G）和弹性（H）的模型拟合到Zrs数据。在功能残气量（FRC）时，Raw、law、G和H的值分别为20.6±4.9（标准差）cm H₂O·s/L、0.037±0.014 cm H₂O·s²/L、39.6±10.3 cm H₂O/L和147±35 cm H₂O/L。Ptr（mean）增加导致Raw单调下降（为FRC时值的42±7%），而law保持不变。组织参数在Ptr（mean）为10 cm H₂O时最小（G和H分别为68±10%和78±6%），在0和20 cm H₂O时均显著更高。尽管在大多数婴儿中，即使在低至FRC的肺容积下也能进行Zrs测量，但20 cm H₂O的充气压力成功率更高，因此更适合普遍使用。
