选择性最小平方拟合法用于压力支持通气中呼吸努力的无创性评估

Noninvasive assessment of respiratory effort during pressure support ventilation by selective least square fitting

目的以呼吸运动方程为依据，通过动态监测气道压力（Paw）、流量（v’）和容量（V）的变化，探讨选择性最小平方拟合法（SLSF）无创性监测压力支持通气（pressum supportventilation，PSV）中呼吸肌肉压力（Fmuse）的可行性和效率。方法12例机械通气患者在PSV水平分别为5、10、15和20emH2O各通气15min，最后将PSV水平调到大于或等于加cmH2O通气15min，使患者达到“接近放松”状态。分别以非选择性最小平方拟合法（NSISF）和SLSF分析“接近放松”状态时的Paw、V’和V数据，得到患者的呼吸系统弹性（Ers）和阻力（Rrs），将Ers和呼气末压力（EEP）代入到呼吸运动方程中，分别计算NSLSF法和SLSF法得到的呼吸肌压力曲线nsPmuse（t）和sPmuse（t），比较sPmuse以及msPmuse与食道囊管法测得的矫正食道压力（Peso）之间的相关性。结果在PSV水平分别为5、10、15和20cmH2O时，sPmuse与PeSO间的相关系数分别为0．987、0．970、0．914和0．752，nsPmuse与Peso之间的相关系数分别为0．928、0．820、0．677和0．409。结论SLSF法比NSLSF法更适合用于PSV通气时呼吸努力的无创性评估，随着PSV水平的增加，sPmuse和nsPmuse无创性评估PSV通气患者呼吸努力的适用性均降低。

Objective To investigate the feasibility and efficiency of noninvasive monitoring respiratory muscle effort during pressure support ventilation （PSV） with selective least square fitting （SLSF） by the dynamical monitoring of airway pressure （Paw）, flow （V＇）, volume （V） on the basis of respiratory motion equation. Method Twelve patients mechanically ventilated were enrolled in this study. The patients were ventilated at PSV level of 5, 10, 15 and 20 cmH2O in a period of 15 minutes respectively and then ventilated at a PSV level of no less than 20 cmH2O in a period of 15 minutes to reach to a so. called near-relaxation state. The non-selective least square fitting （NSLSF） method and the SLSF method were used to analyze the Paw, V＇ and V data at the near - relaxation state to get elastance and resistance of respiratory system （Ers/Rrs） respectively. Then the average Ers and Rrs obtained from SLSF and NSLSF as well as end-expiratory pressure （EEP） were substituted into the equation of respiratory motion to calculate sPmuse （from SLSF） and nsPmuse （from NSLSF） respectively, Correlation analyses were made among esophageal pressure （Peso） and sPmuse, nsPmuse. Results At PSV level of 5, 10, 1 5 and 20 cmH2O, the correlation coefficients between Peso and sPmuse were 0.987, 0, 970, 0.914 and 0.752 respectively, whereas for nsPmuse the correlation coefficients were 0.928, 0.820, 0.677 and 0.409 respectively.Conclusion SLSF method is more preferable than NSLSF in noninvasive assessment of respiratory effort in PSV as the PSV levels increasing, the applicability of both sPmuse and nsPmuse for noninvasive assessment of respiratory effort during PSV decreases.