Pedersen O F, Miller M R, Sigsgaard T, Tidley M, Harding R M
University of Aarhus, Institute of Environmental and Occupational Medicine, Denmark.
Eur Respir J. 1994 May;7(5):991-7.
Little is known about the linearity of portable peak flow meters, or about physical gas factors affecting peak expiratory flow (PEF) readings. We therefore tested five portable peak flow meters of three types in an altitude chamber (sea level to 5,500 m) and in a climate chamber at sea level (7-37 degrees C) to determine the influence of the physical conditions of the gas on the reading of the meters. The nonlinear response of the variable orifice meters was confirmed and, when this was corrected for, the readings of these meters were found to be significantly reduced by higher altitude and lower temperature. The readings from a turbine type of peak flow meter were not affected by altitude but were reduced at low temperature. A mathematical model for the variable orifice meters could correct for both their nonlinear behaviour and the effect of gas density (altitude, temperature and humidity). The model showed that correction is not necessary for the differences in gas conditions between calibration and taking of measurements under normal laboratory conditions. All the meters tested had impedances higher than recommended (0.05 kPa.l-1.s) and this may influence PEF at high flows. The mean uncorrected PEF of six healthy subjects when measured with a Mini Wright peak flow meter at sea level and at 3,000 m fell by 5%, but the mean corrected PEF increased by 12%. This increase in PEF was about 60% of that predicted for fully density-dependent flow and agreed with the findings of other similar studies.(ABSTRACT TRUNCATED AT 250 WORDS)
关于便携式峰值流量计的线性，以及影响呼气峰值流速（PEF）读数的物理气体因素，人们了解甚少。因此，我们在海拔舱（海平面至5500米）和海平面气候舱（7至37摄氏度）中测试了三种类型的五台便携式峰值流量计，以确定气体的物理条件对流量计读数的影响。可变孔口流量计的非线性响应得到了证实，校正后发现，随着海拔升高和温度降低，这些流量计的读数显著降低。涡轮式峰值流量计的读数不受海拔影响，但在低温时会降低。可变孔口流量计的数学模型可以校正其非线性行为和气体密度（海拔、温度和湿度）的影响。该模型表明，在正常实验室条件下，校准和测量时气体条件的差异无需校正。所有测试的流量计的阻抗均高于推荐值（0.05 kPa·l-1·s），这可能会在高流速时影响PEF。六名健康受试者在海平面和3000米处使用Mini Wright峰值流量计测量时，未校正的平均PEF下降了5%，但校正后的平均PEF增加了12%。PEF的这种增加约为完全密度依赖性流量预测值的60%，与其他类似研究的结果一致。（摘要截短于250字）
