Luft U C, Loeppky J A, Mostyn E M
J Appl Physiol Respir Environ Exerc Physiol. 1979 Mar;46(3):534-40. doi: 10.1152/jappl.1979.46.3.534.
In view of uncertainties about the best way to estimate mean alveolar gases in patients with ventilation-perfusion inequalities, three different methods were evaluated on 54 patients. 1) O2 and CO2 were recorded by mass spectrometer on an O2 (x)-CO2 (y) diagram. The coordinates at the intersect of the expiratory record with the mixed expired R line (RE) ives the mean alveolar values (PAo2 and PAco2. 2)pa'co2 was calculated with the Bohr equation using a predicted anatomic dead space and PA'o2 was derived with the alveolar equation. 3) End-tidal (ET) P02 were averaged over 1 min at rest in steady state. Mean RET calculated from 3 was identical with RE. Mean values for PAco2, PA'CO2. and PETco2 differed by less that 1 Torr, but the variance was least with the end-tidal method. There was a highly significant correlation between delta aAPco2 using PETco2 and VD/VT, better than with either of the other methods. The end-tidal measurement appears to give the best approximation of mean alveolar gas in pulmonary patients.
鉴于在估计通气-灌注不均患者的平均肺泡气体的最佳方法方面存在不确定性，对54例患者评估了三种不同方法。1）通过质谱仪在O₂（x）-CO₂（y）图上记录O₂和CO₂。呼气记录与混合呼出R线（RE）交点处的坐标给出平均肺泡值（PAO₂和PACO₂）。2）使用预测的解剖无效腔通过玻尔方程计算Pa'CO₂，并通过肺泡方程推导PA'o₂。3）在静息稳态下1分钟内平均呼气末（ET）P0₂。由3计算出的平均RET与RE相同。PAco₂、PA'CO₂和PETco₂的平均值相差不到1托，但呼气末法的方差最小。使用PETco₂的δaAPco₂与VD/VT之间存在高度显著的相关性，优于其他任何一种方法。呼气末测量似乎能最好地近似肺部患者的平均肺泡气体。
