Aida A, Miyamoto K, Saito S, Nakano T, Nishimura M, Kawakami Y, Omori Y, Ando S, Ichida T, Ishibe Y
First Department of Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Nihon Kyobu Shikkan Gakkai Zasshi. 1995 Mar;33(3):306-11.
Although inhaled nitric oxide (NO) has attracted attention as a pulmonary vasodilator, little heed has been given to its potential toxicity. Nitric oxide is known to be rapidly oxidized to nitrogen dioxide (NO2), which may damage pulmonary tissue. We examined the effects of temperature and humidity on the production of NO2 from NO. We also evaluated the amount of NO2 absorbed by soda lime, which is usually placed in the inspiratory line. For this purpose, we measured changes over time in the concentrations of NO and NO2 in mixtures that included NO, oxygen, and nitrogen in various concentrations, and at different temperatures and humidities. We confirmed that the formation of NO2 from NO follows the equation: -d[NO]/dt = 2 k[NO]2 [O2], where k is the rate constant. We found that k was significantly smaller at 37 degrees C than at 25 degrees C but was not influenced by humidity (0%, 40% or 90%). Although soda lime was very effective in absorbing NO2 from the inspiratory line, NO was simultaneously absorbed at the same molar ratio when the two gases existed together in the line. We thus conclude that inhalation of NO at 37 degrees C is more desirable than inhalation at room temperature, to suppress the production of NO2. When soda lime is used in the inspiratory line, attention should be paid to the reduction in the concentration of NO in the line.
尽管吸入一氧化氮（NO）作为一种肺血管扩张剂已引起关注，但其潜在毒性却很少受到重视。已知一氧化氮会迅速氧化为二氧化氮（NO₂），这可能会损害肺组织。我们研究了温度和湿度对由NO产生NO₂的影响。我们还评估了通常放置在吸气管道中的碱石灰吸收的NO₂量。为此，我们测量了在不同温度和湿度下，包含不同浓度的NO、氧气和氮气的混合物中NO和NO₂浓度随时间的变化。我们证实，由NO生成NO₂符合以下方程：-d[NO]/dt = 2k[NO]²[O₂]，其中k是速率常数。我们发现，37℃时的k值明显小于25℃时的k值，但不受湿度（0%、40%或90%）影响。尽管碱石灰在从吸气管道中吸收NO₂方面非常有效，但当两种气体同时存在于管道中时，NO会以相同的摩尔比同时被吸收。因此，我们得出结论，在37℃吸入NO比在室温下吸入更可取，以抑制NO₂的产生。当在吸气管道中使用碱石灰时，应注意管道中NO浓度的降低。
