Jones T A, Petsonk E L, Frazer D G
Department of Surgery, Easton Hospital, PA 18042, USA.
Respir Physiol. 1996 Oct;106(1):47-55. doi: 10.1016/0034-5687(96)00041-2.
The objective of this study was to determine if the effect of temperature on excised lung pressure-volume (P-V) hysteresis during various P-V maneuvers would be consistent with predicted effects based on the recruitment-derecruitment (R-D) model of lung P-V hysteresis. Three sets of P-V curves were recorded for excised rat lungs at (1) 24 degrees C, (2) either 42 degrees or 45 degrees C, and (3) 24 degrees C. After full inflation of the lung, deflation-inflation (D-I) cycles were performed between total lung capacity (30 cmH2O) and successively decreasing end-expiratory pressures (EEPs). Normalized hysteresis (K) was plotted vs EEP. K remained relatively constant at EEPs > or = +5 cmH2O at 24 degrees C and 42 degrees C and > +5 cmH2O at 45 degrees C. Large increases in K occurred as the EEP was further reduced, with the relationship of K vs EEP being shifted to the right at 42 degrees C and 45 degrees C relative to 24 degrees C, with the greater shift occurring at 45 degrees C. Previous work has shown that the R-D of lung units contributes to P-V hysteresis and is EEP-dependent, increasing at EEPs < or = +4 +/- 1 cmH2O at room temperature (Cheng et al., 1995). This study suggests that at increased temperatures, R-D of lung units is initiated at higher EEPs and is more extensive than at room temperature.
本研究的目的是确定在各种压力-容积（P-V）操作过程中，温度对离体肺压力-容积滞后现象的影响是否与基于肺P-V滞后现象的募集-解募集（R-D）模型所预测的效应一致。对离体大鼠肺记录了三组P-V曲线，分别在（1）24℃、（2）42℃或45℃以及（3）24℃下进行。肺完全膨胀后，在总肺容量（30 cmH₂O）和逐渐降低的呼气末压力（EEP）之间进行放气-充气（D-I）循环。将归一化滞后现象（K）与EEP作图。在24℃和42℃时，当EEP≥+5 cmH₂O，以及在45℃时当EEP＞+5 cmH₂O时，K保持相对恒定。随着EEP进一步降低，K大幅增加，相对于24℃，在42℃和45℃时K与EEP的关系向右移动，在45℃时移动幅度更大。先前的研究表明，肺单位的R-D导致P-V滞后现象，且依赖于EEP，在室温下当EEP≤+4±1 cmH₂O时增加（Cheng等人，1995年）。本研究表明，在温度升高时，肺单位的R-D在更高的EEP时开始，且比室温时更广泛。
