Cauberghs M, Van de Woestijne K P
Laboratorium voor Longfunktieonderzoek, Universitaire Ziekenhuizen Gasthuisberg, Leuven, Belgium.
J Appl Physiol (1985). 1989 May;66(5):2274-9. doi: 10.1152/jappl.1989.66.5.2274.
Because of the contradictory statements published about the influence of the shunt properties of the upper airway on the measurements of the respiratory impedence by means of the forced oscillation technique, this influence has been reevaluated. In healthy adults and children and in patients with obstructive lung disease, the total respiratory impedance was measured by applying oscillations at the mouth (conventional technique) or around the head (head generator technique), with the cheeks either supported by the hands or not. In healthy adults the two techniques (conventional cheeks supported and head generator) yield similar results for respiratory resistance (Rrs) and a more pronounced increase of respiratory reactance (Xrs) with frequency with the head generator. In children and in patients with moderate airway obstruction, the negative frequency dependence of Rrs observed with the conventional technique tends to disappear with the head generator. This is not observed in patients with severe airway obstruction. The differences between the two techniques can be explained by the influence of the shunt impedance of the upper airway on Rrs and Xrs. Correction for this influence by subtracting the impedance measured during a Valsalva maneuver is not satisfactory, since the Valsalva maneuver itself modifies the upper airway shunt. The head generator technique reduces the influence of the upper airway shunt but does not suppress it altogether; the residual error is small, however.
由于关于上气道分流特性对通过强迫振荡技术测量呼吸阻抗的影响存在相互矛盾的报道，因此对这种影响进行了重新评估。在健康成人、儿童以及阻塞性肺疾病患者中，通过在口腔施加振荡（传统技术）或在头部周围施加振荡（头部发生器技术）来测量总呼吸阻抗，同时观察脸颊是否由手支撑。在健康成人中，两种技术（传统的脸颊支撑和头部发生器）对于呼吸阻力（Rrs）产生相似的结果，而使用头部发生器时，呼吸电抗（Xrs）随频率的增加更为明显。在儿童和中度气道阻塞患者中，传统技术观察到的Rrs的负频率依赖性在使用头部发生器时往往会消失。在重度气道阻塞患者中未观察到这种情况。两种技术之间的差异可以用上气道分流阻抗对Rrs和Xrs的影响来解释。通过减去瓦尔萨尔瓦动作期间测量的阻抗来校正这种影响并不令人满意，因为瓦尔萨尔瓦动作本身会改变上气道分流。头部发生器技术减少了上气道分流的影响，但并未完全消除；然而，残余误差很小。
