通气/灌流指数在呼吸监护中的应用价值

Clinicaal Effects of PaO_2/FiO_2 in Respiratory Monitoring

对158例慢性阻塞性肺疾患患者作呼吸监护，测定P(A-a)O2，RI，PaO2／FiO2（通气／灌流指数），比较上述三个肺换气效率指标在临床上的应用价值。结果表明，（1）P(A－s)O2，RI，PaO2／FiO2三项指标都能反映慢支肺气肿组，慢支伴Ⅰ型呼衰组肺换气效率，可用于病情动态观察；（2）P(A-a)O2，RI值受通气功能影响。Ⅱ型呼衰时，此值用作病情动态观察的参比性差，对抢救并无指导意义；（3）PaO2／FiO2值在呼吸监护中的意义优于P(A-a)O2、RI值，在各种情况下都能反映肺换气效率，Ⅱ型呼衰者对测定值影响较小，且可提示肺功能受损的程度。根据FiO2可在床旁计算，指导抢救。测定上述各项指标必须注意吸氧方法正确、氧流量表正确和采血方法正确。

158 patients under respiratory momtoring were observed with P(A-s)O2,RI andPaO2/FiO2. The clinical value of the three pulmonaary function parameter was detected Theresults show that:1. P(A-a)O2,RI and PaO2/FiO2 reflect the pulmonary gas exchange efficacy and seriousness ofpulmonary impairment of both emphysema of lungs group and type I respiratory failuregroup consistently, and can be well used in observation of developments of the disease;2.P(A-a)O2 and RI can be influenced by ventilatory function. Therefore, in case of type Ⅱ respiratory failure, it is of low comparability, and of little instructive significance in emergency;3. PaO2/FiO2, is a better value in respiratory monitoring than PaO2 and RI. This is because:(1)It can reflect gas exchange efficacy well in various conditions especially in type Ⅱ respiratory failure; (2)It can determine severity of impairement of pulmonry function; (3)PaO2/FiO2can be easily calculated by recording inhaled O2concentration when drawing blood, or simplyconvertting SaO2 to PaO2, than calculate with FiO2% by O2 flowmeter in bedside; (4)Correctmethod of inhaling oxygen is needed. O2 flowmeter must well worked. the inhaling of thesame concentration of O2 for 30 minutes must be insured. If possible, inhale air while drawing blood. It can assure less error and measure a more dependable PaO2/FiO2.