Lindberg L, Rydgren G
Department of Anaesthesiology and Intensive Care, University Hospital of Lund, Sweden.
Br J Anaesth. 1998 Feb;80(2):213-7. doi: 10.1093/bja/80.2.213.
We have evaluated the kinetics of nitrogen dioxide production in a system for inhalation of nitric oxide. In addition to a small fraction of contamination of nitrogen dioxide in the nitric oxide stock gas, a considerable part of the total concentration of nitrogen dioxide is formed immediately after mixing of nitric oxide and oxygen. This initial build-up of nitrogen dioxide is followed by a linear, time-dependent increase in the concentration of nitrogen dioxide. An equation describing the concentration of nitrogen dioxide in the delivery system is formulated: [NO2] = kA x [NO] + kB x [NO]2 x [O2] + kC x t x [NO]2 x [O2], where nitrogen dioxide [NO2] and nitric oxide [NO] concentrations are in parts per million (ppm), oxygen concentration [O2] is expressed as a percentage and contact time (t) is in seconds. The rate constants are kA = 5.12 x 10(-3), kB = 1.41 x 10(-6) and kC = 0.86 x 10(-6). Calculated nitrogen dioxide values correlated well with measured concentrations. This new finding of an initial build-up of nitrogen dioxide has to be taken into consideration if the conversion of nitric oxide to nitrogen dioxide is to be calculated and in the safety guidelines for the use of nitric oxide.
我们评估了一氧化氮吸入系统中二氧化氮生成的动力学。除了一氧化氮储备气体中存在一小部分二氧化氮污染外，一氧化氮与氧气混合后会立即形成相当一部分的二氧化氮总浓度。二氧化氮的这种初始积累之后是其浓度随时间呈线性增加。我们推导了一个描述输送系统中二氧化氮浓度的方程：[NO₂] = kA × [NO] + kB × [NO]² × [O₂] + kC × t × [NO]² × [O₂]，其中二氧化氮[NO₂]和一氧化氮[NO]的浓度以百万分之一（ppm）为单位，氧气浓度[O₂]以百分比表示，接触时间（t）以秒为单位。速率常数分别为kA = 5.12 × 10⁻³、kB = 1.41 × 10⁻⁶和kC = 0.86 × 10⁻⁶。计算得到的二氧化氮值与测量浓度相关性良好。如果要计算一氧化氮向二氧化氮的转化率以及一氧化氮使用的安全指南，就必须考虑到二氧化氮初始积累这一新发现。
