Stenqvist O, Kjelltoft B, Lundin S
Division of Anaesthesia, Sahlgren Hospital, Göteborg, Sweden.
Acta Anaesthesiol Scand. 1993 Oct;37(7):687-91. doi: 10.1111/j.1399-6576.1993.tb03790.x.
A new system for delivery of nitric oxide (NO) to inspiratory gas consisting of two mass flow regulators and a soda-lime absorber for scavenging of nitrogen dioxide (NO2) is described. The system was evaluated using three different techniques for NO analysis (infrared, chemiluminescence and electro-chemical fuel cell technique). The electro-chemical fuel cell was less sensitive to humidity in the sample and is suitable for clinical routine use. The infrared analyser was very sensitive to humidity and the gas sample must be dried by silica gel, which absorbs NO2 and will cause falsely low NO2 values. NO2 was analysed with ultra-violet methodology. NO2 is highly toxic and the highest recommended occupational health and safety level for inhalation is 5 ppm. The highest values of NO2 in our system were detected before the absorber in the inspiratory limb of the breathing system, being 5 ppm at 100% oxygen and 100 ppm NO using "infant" respiratory settings (3 l/min in ventilation, frequency of 30/min). The corresponding value for "adult" respiratory settings (10 l/min in ventilation, frequency of 15/min) was 3.2 ppm. The absorber reduced these levels to well below 1 ppm. When clinically relevant levels of NO were used (20 ppm), no NO2 could be detected after the absorber, irrespective of oxygen concentration in the breathing gas. It was observed that gas cylinders with NO mixed in nitrogen may initially have a high NO2 concentration (around 12 ppm) and should be flushed thoroughly before use.
描述了一种用于将一氧化氮（NO）输送到吸入气体的新系统，该系统由两个质量流量调节器和一个用于清除二氧化氮（NO₂）的碱石灰吸收器组成。使用三种不同的NO分析技术（红外、化学发光和电化学燃料电池技术）对该系统进行了评估。电化学燃料电池对样品中的湿度不太敏感，适用于临床常规使用。红外分析仪对湿度非常敏感，气体样品必须用硅胶干燥，而硅胶会吸收NO₂并导致NO₂值出现错误的低值。NO₂采用紫外线方法进行分析。NO₂具有高毒性，吸入的职业健康和安全推荐最高水平为5 ppm。在我们的系统中，在呼吸系统吸气支路中的吸收器之前检测到的NO₂最高值，在使用“婴儿”呼吸设置（通气量3 l/min，频率30次/分钟）时，在100%氧气和100 ppm NO的情况下为5 ppm。“成人”呼吸设置（通气量10 l/min，频率15次/分钟）的相应值为3.2 ppm。吸收器将这些水平降低到远低于1 ppm。当使用临床相关水平的NO（20 ppm）时，无论呼吸气体中的氧气浓度如何，在吸收器之后都检测不到NO₂。观察到氮气中混合有NO的气瓶最初可能具有较高的NO₂浓度（约12 ppm），使用前应彻底冲洗。
