Guenard H
Laboratoire de Physiologie, UER III, Université de Bordeaux II, France.
J Physiol (Paris). 1987;82(2):160-71.
The ratios of ventilatory (V) and perfusion (Q) flow rates in the lung are to a large extent responsible for the efficiency of gas exchange. In a simplified monocompartmental model of the lung, the arterial partial pressure of a given gas (Pa) is a function of several factors: the solubility of this gas in blood, its venous and inspired partial pressures and the V/Q ratio. In a multicompartemental model, the mean arterial partial pressure of the gas is a function of the individual values of Pa in each compartment as well as the distribution of V/Q ratios in the lung and the relationship between the concentration and the partial pressure of the gas. The heterogeneity of the distribution of V/Q results from those of both V and Q. Two factors are mainly responsible for this heterogeneity: the gravity and the morphometric characteristics of bronchi and vessels. V/Q ratios are partially controlled at least in low V/Q compartments since hypoxia in these compartments leads to pulmonary arteriolar vasoconstriction. However lungs V/Q ratios range from 0.1 to 10 with a mode around 1. Age, muscular exercise, posture, accelerations, anesthesia, O2 breathing, pulmonary pathology are factors which may alter the distribution of V/Q ratios.
肺内通气（V）与灌注（Q）流速的比值在很大程度上决定了气体交换的效率。在一个简化的单室肺模型中，特定气体的动脉分压（Pa）是几个因素的函数：该气体在血液中的溶解度、其静脉分压和吸入分压以及V/Q比值。在多室模型中，气体的平均动脉分压是每个室中Pa的个体值以及肺内V/Q比值分布和气体浓度与分压之间关系的函数。V/Q分布的异质性源于V和Q的异质性。造成这种异质性的主要有两个因素：重力以及支气管和血管的形态学特征。至少在低V/Q室中，V/Q比值受到部分控制，因为这些室中的缺氧会导致肺小动脉血管收缩。然而，肺的V/Q比值范围为0.1至10，众数约为1。年龄、体育锻炼、姿势、加速度、麻醉、吸氧、肺部病理情况都是可能改变V/Q比值分布的因素。
