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Evaluation of a new system for ventilatory administration of nitric oxide
Author(s) -
STENQVIST O.,
KJELLTOFT B.,
LUNDIN S.
Publication year - 1993
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1993.tb03790.x
Subject(s) - medicine , nitric oxide , ventilation (architecture) , nitrogen dioxide , oxygen , humidity , anesthesia , relative humidity , nitrogen , inhalation , soda lime , chemistry , composite material , materials science , mechanical engineering , physics , organic chemistry , engineering , thermodynamics
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 (NO 2 ) is described. The system was evaluated using three different techniques for NO analysis (infrared, chemi–luminescence 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 NO 2 and will cause falsely low NO 2 values. NO 2 was analysed with ultra–violet methodology. NO 2 is highly toxic and the highest recommended occupational health and safety level for inhalation is 5 ppm. The highest values of NO 2 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 1/min in ventilation, frequency of 30/min). The corresponding value for “adult” respiratory settings (10 1/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 NO 2 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 NO 2 concentration (around 12 ppm) and should be flushed thoroughly before use.