Graham B L, Buchanan P R, Withy S J, Harris E A
Clin Phys Physiol Meas. 1985 Feb;6(1):17-25. doi: 10.1088/0143-0815/6/1/002.
Although various methods have been used to correct the output of a respiratory mass spectrometer for the delay and rise time in its response, thereby reducing the error in measured gas concentrations, there are additional considerations in the case of a multiplex mass spectrometer. The measured signal from the detector is a series of discrete samples of the concentration of several different gases rather than a continuous monitor of a single gas concentration as generated by other types of mass spectrometer. If the time constant of the mass spectrometer is of the same order as the interval between samples of a gas in the multiplex mode, correction techniques based on continuous-time analysis would not be as valid as those based on discrete-time analysis. Such correction techniques were compared to the use of a simple time shift. For multibreath gas washout analysis with simulated worst-case 'square wave breathing' it was found that, because of the complex nature of the response of the mass spectrometer, a simple time shift provided a reduction in error nearly equal to that of an additional first order response correction, and that such further corrections may be unnecessary or even invalid under some circumstances.
尽管已经采用了各种方法来校正呼吸质谱仪响应中的延迟和上升时间的输出，从而减少测量气体浓度的误差，但对于多道质谱仪而言还有其他需要考虑的因素。来自检测器的测量信号是几种不同气体浓度的一系列离散样本，而不是像其他类型的质谱仪那样对单一气体浓度进行连续监测。如果质谱仪的时间常数与多道模式下气体样本之间的间隔处于同一量级，基于连续时间分析的校正技术就不如基于离散时间分析的校正技术有效。将此类校正技术与简单的时间偏移的使用进行了比较。对于模拟最坏情况“方波呼吸”的多次呼吸气体洗脱分析，发现由于质谱仪响应的复杂性，简单的时间偏移减少的误差几乎与额外的一阶响应校正相同，并且在某些情况下这种进一步的校正可能是不必要的甚至是无效的。
