Powles A C, Jones N L
Comput Biol Med. 1982;12(2):163-73. doi: 10.1016/0010-4825(82)90025-7.
A pocket calculator program is described which facilitates rapid evaluation of pulmonary function at rest and during exercise. It embodies the Fick Principle applied to carbon dioxide; mixed venous carbon dioxide tension is measured by rebreathing, obviating the need for central venous or pulmonary artery catheterisation. The program is in two parts, Gas Phase and Blood Phase, which may be used separately. The variables calculated include tidal volume, CO2 production, oxygen consumption, respiratory quotient, alveolar ventilation and dead space: tidal volume ratio (Gas Phase); bicarbonate concentration, base excess, veno-arterial CO2 content difference, cardiac output, mixed venous oxygen saturation and pulmonary venous admixture (Blood Phase). Use of the program enables these variables to be calculated rapidly and accurately. Accuracy is improved by the application of equations which correct for alveolar-to-blood tension differences, effects of differing hemoglobin concentrations, arterial oxygen saturations and acid-base abnormalities; these calculations are otherwise very lengthy, time consuming and prone to error. The program allows simple noninvasive measurements to be applied to patients with a wide variety of metabolic, cardiac and pulmonary abnormalities in rest and exercise.
本文描述了一种袖珍计算器程序，该程序有助于快速评估静息和运动期间的肺功能。它体现了应用于二氧化碳的菲克原理；通过重复呼吸测量混合静脉血二氧化碳分压，无需进行中心静脉或肺动脉插管。该程序分为气相和血相两部分，可以单独使用。计算的变量包括潮气量、二氧化碳产生量、耗氧量、呼吸商、肺泡通气量和死腔：潮气量比值（气相）；碳酸氢盐浓度、碱剩余、静脉 - 动脉二氧化碳含量差、心输出量、混合静脉血氧饱和度和肺静脉混合血（血相）。使用该程序能够快速准确地计算这些变量。通过应用校正肺泡与血液张力差异、不同血红蛋白浓度、动脉血氧饱和度和酸碱异常影响的方程式提高了准确性；否则这些计算非常冗长、耗时且容易出错。该程序允许对静息和运动时患有各种代谢、心脏和肺部异常的患者进行简单的无创测量。
