Dall'ava-Santucci J, Armaganidis A, Brunet F, Dhainaut J F, Chelucci G L, Monsallier J F, Lockhart A
Department of Physiology, Hôpital Cochin Port-Royal, Paris, France.
J Appl Physiol (1985). 1988 Jan;64(1):42-9. doi: 10.1152/jappl.1988.64.1.42.
Respiratory pressure-volume (PV) curves are commonly obtained in paralyzed patients by relating airway pressure to volume changes of a syringe (Vsyr). This is based on the implicit assumption that changes in thoracic volume (Vtho) and Vsyr are equal. We undertook to verify this assumption through simultaneous measurements of Vtho by respiratory inductive plethysmography and Vsyr in six comatose, paralyzed, intubated patients. At any constant Vsyr, Vtho fell and was smaller on deflation than on inflation during inflation-deflation (ID) cycle. The rate of fall was 110 +/- 64 (SD) ml/min. During ID cycles lasting 76 +/- 7 s, thoracic PV curves showed less hysteresis and a larger compliance on deflation than PVsyr curves (12 +/- 2 vs. 18 +/- 6% and 73 +/- 13 vs. 67 +/- 12 ml/cmH2O, P less than 0.05). With PVsyr curves, hysteresis increased and compliance on deflation decreased with increasing rate of fall of Vtho. We submit that the difference between changes in Vsyr and Vtho is best explained by gas exchange and should be taken into account when performing PV curves with a syringe in paralyzed patients.
呼吸压力-容积（PV）曲线通常是在瘫痪患者中通过将气道压力与注射器容积变化（Vsyr）相关联来获得的。这基于胸廓容积（Vtho）和Vsyr变化相等的隐含假设。我们通过对6名昏迷、瘫痪、插管患者同时使用呼吸感应体积描记法测量Vtho和Vsyr来验证这一假设。在任何恒定的Vsyr下，在充气-放气（ID）周期中，Vtho下降，且放气时比充气时小。下降速率为110±64（标准差）ml/分钟。在持续76±7秒的ID周期中，胸廓PV曲线显示出比注射器PV曲线更少的滞后现象，且放气时顺应性更大（12±2对18±6%，73±13对67±12 ml/cmH2O，P<0.05）。对于注射器PV曲线，随着Vtho下降速率增加，滞后现象增加，放气时顺应性降低。我们认为，Vsyr和Vtho变化之间的差异最好用气体交换来解释，并且在对瘫痪患者使用注射器进行PV曲线测量时应予以考虑。
