Ishibe T, Sato T, Hayashi T, Kato N, Hata T
Department of Anesthesiology, Tottori University Faculty of Medicine, Japan.
Br J Anaesth. 1995 Sep;75(3):330-3. doi: 10.1093/bja/75.3.330.
Inhaled nitric oxide (NO) is used for the treatment of pulmonary hypertension as a selective pulmonary vasodilator. However, NO is oxidized rapidly to the more toxic nitrogen dioxide (NO2). Elimination of NO2 from inspired gas is essential for safe clinical use NO. We therefore investigated the efficacy of soda lime in absorbing NO2 from NO2-containing gases. Commercially available soda limes (Soda sorb and Wako lime-A), were exposed to the following six gas mixtures containing NO and NO2 in a hypoxic carrier gas for 20 min: No. 1: NO 40 ppm; No. 2: NO 35 ppm and NO2 5 ppm; No. 3: NO 30 ppm and NO2 10 ppm; No. 4: NO 20 ppm and NO2 20 ppm; No. 5: NO 10 ppm and NO2 30 ppm; and No. 6: NO2 40 ppm. Both types of soda lime completely absorbed the NO2 in all samples when it was present (Nos 2-6). NO concentration in these gas mixtures was reduced by an amount equal to the NO2 absorbed by soda lime. NO was absorbed minimally when NO2 was not present in the mixture. Nitrite was detected from the Wako lime-A granules exposed to the test gas by the chemical analysis. These findings suggest that soda lime completely absorbs NO2 by chemical neutralization, but NO is absorbed as simultaneously absorbed NO2 only where NO and NO2 coexist. Therefore, we conclude that soda lime is useful for NO2 absorption during NO inhalation therapy but NO monitoring from a point distal to the soda lime is required for precise control of inspired NO concentration.
吸入一氧化氮（NO）作为一种选择性肺血管扩张剂用于治疗肺动脉高压。然而，NO会迅速氧化为毒性更强的二氧化氮（NO₂）。从吸入气体中消除NO₂对于NO的安全临床应用至关重要。因此，我们研究了碱石灰从含NO₂的气体中吸收NO₂的效果。将市售碱石灰（Soda sorb和Wako lime - A）在低氧载气中暴露于以下六种含NO和NO₂的气体混合物中20分钟：1号：NO 40 ppm；2号：NO 35 ppm和NO₂ 5 ppm；3号：NO 30 ppm和NO₂ 10 ppm；4号：NO 20 ppm和NO₂ 20 ppm；5号：NO 10 ppm和NO₂ 30 ppm；6号：NO₂ 40 ppm。当有NO₂存在时（2 - 6号样品），两种类型的碱石灰都能完全吸收所有样品中的NO₂。这些气体混合物中的NO浓度降低的量与碱石灰吸收的NO₂量相等。当混合物中不存在NO₂时，NO的吸收量极少。通过化学分析从暴露于测试气体的Wako lime - A颗粒中检测到了亚硝酸盐。这些发现表明，碱石灰通过化学中和作用完全吸收NO₂，但只有在NO和NO₂共存的情况下，NO才会作为同时被吸收的NO₂被吸收。因此，我们得出结论，碱石灰在NO吸入治疗期间对NO₂吸收是有用的，但为了精确控制吸入NO浓度，需要在碱石灰远端进行NO监测。
