"Ventilatory efficiency" is widely used in cardiopulmonary exercise testing to make inferences regarding the normality (or otherwise) of the arterial CO₂ tension (P_aCO2) and physiological dead-space fraction of the breath (V_D/V_T) responses to rapid-incremental (or ramp) exercise. It is quantified as: 1) the slope of the linear region of the relationship between ventilation (V'_E) and pulmonary CO₂ output (V'_CO2); and/or 2) the ventilatory equivalent for CO₂ at the lactate threshold (V'_E/V'_CO2 ) or its minimum value (V'_E/V'_CO2min), which occurs soon after but before respiratory compensation. Although these indices are normally numerically similar, they are not equally robust. That is, high values for V'_E/V'_CO2 and V'_E/V'_CO2min provide a rigorous index of an elevated V_D/V_T when P_aCO2 is known (or can be assumed) to be regulated. In contrast, a high V'_E–V'_CO2 slope on its own does not, as account has also to be taken of the associated normally positive and small V'_E intercept. Interpretation is complicated by factors such as: the extent to which P_aCO2 is actually regulated during rapid-incremental exercise (as is the case for steady-state moderate exercise); and whether V'_E/V'_CO2 or V'_E/V'_CO2min provide accurate reflections of the true asymptotic value of V'_E/V'_CO2, to which the V'_E–V'_CO2 slope approximates at very high work rates.

“通气效率”广泛用于心肺运动测试，以推断动脉 CO ₂张力 ( P _{aCO 2} ) 和呼吸的生理死腔分数 ( V _D / V _T ) 的正常（或其他）反应快速增量（或斜坡）运动。量化为： 1）通气量（_V'E）与肺CO 2_输出量（_{V'CO 2} ）线性区域的斜率；和/或 2) CO ₂在乳酸阈值 ( V '_E / V'CO ₂ _ _{_} ) 或其最小值 ( V ' _E / V ' _{CO 2}分钟), 其发生后不久 但在呼吸代偿之前。尽管这些指数通常在数值上相似，但它们并不同样稳健。也就是说，V ' _E / V ' _{CO 2的值很高} 和V ' _E / V ' _{CO 2} min 提供了当已知（或可以假定）要调节_{PaCO 2}时_升高的V D _/ V T_{的严格指标。}相比之下，高V ' _E – V ' _{CO 2}斜率本身不会，因为还必须考虑相关的通常为正的和小的V ' _E截距。解释因以下因素而变得复杂：P _{aCO 2}实际上在快速增量运动期间受到调节（如稳态适度运动的情况）；以及是否V ' _E / V ' _{CO 2} 或V ' _E / V ' _{CO 2}分钟提供V ' _E / V ' _{CO 2}的真实渐近值的准确反映，V ' E _– V ' CO _2斜率在非常高的工作率下接近该值。