Weinmann G G, Mitzner W, Permutt S
J Appl Physiol Respir Environ Exerc Physiol. 1984 Sep;57(3):881-7. doi: 10.1152/jappl.1984.57.3.881.
Tidal volumes used in high-frequency ventilation (HFV) may be smaller than anatomic dead space, but since gas exchange does take place, physiological dead space (VD) must be smaller than tidal volume (VT). We quantified changes in VD in three dogs at constant alveolar ventilation using the Bohr equation as VT was varied from 3 to 15 ml/kg and frequency (f) from 0.2 to 8 Hz, ranges that include normal as well as HFV. We found that VD was relatively constant at tidal volumes associated with normal ventilation (7-15 ml/kg) but fell sharply as VT was reduced further to tidal volumes associated with HFV (less than 7 ml/kg). The frequency required to maintain constant alveolar ventilation increased slowly as tidal volume was decreased from 15 to 7 ml/kg but rose sharply with attendant rapid increases in minute ventilation as tidal volumes were decreased to less than 7 ml/kg. At tidal volumes less than 7 ml/kg, the data deviated substantially from the conventional alveolar ventilation equation [f(VT - VD) = constant] but fit well a model derived previously for HFV. This model predicts that gas exchange with volumes smaller than dead space should vary approximately as the product of f and VT2.
高频通气（HFV）中使用的潮气量可能小于解剖无效腔，但由于气体交换确实会发生，生理无效腔（VD）必定小于潮气量（VT）。我们使用玻尔方程，在三只犬的肺泡通气量恒定的情况下，当VT从3 ml/kg变化至15 ml/kg且频率（f）从0.2 Hz变化至8 Hz时（该范围涵盖正常通气以及高频通气），对VD的变化进行了量化。我们发现，在与正常通气相关的潮气量（7 - 15 ml/kg）下，VD相对恒定，但当VT进一步降至与高频通气相关的潮气量（小于7 ml/kg）时，VD急剧下降。随着潮气量从15 ml/kg降至7 ml/kg，维持恒定肺泡通气所需的频率缓慢增加，但当潮气量降至小于7 ml/kg且分钟通气量随之迅速增加时，频率急剧上升。在潮气量小于7 ml/kg时，数据显著偏离传统的肺泡通气方程[f(VT - VD) = 常数]，但与先前推导的高频通气模型拟合良好。该模型预测，使用小于无效腔的气量进行气体交换时，其变化应大致与f和VT2的乘积成比例。
