Evaluation of nitrogen dioxide scavengers during delivery of inhaled nitric oxide

Abstract

We have analysed the ability of three nitrogen dioxide absorbing materials (soda lime, noXon and zeolite) to act as nitrogen dioxide scavengers during delivery of inhaled nitric oxide. Different mixtures of gas were produced in a ventilator (Servo Ventilator 300) and passed through an inspiratory tube. Concentrations of nitrogen dioxide and nitric oxide were measured in the distal part of the tube, with and without the gas having passed through a canister containing the different filter materials. Our findings indicated that nitrogen dioxide was absorbed effectively by all filter materials but that there was re-formation of nitrogen dioxide from nitric oxide and oxygen in or immediately after the canister. This initial production of nitrogen dioxide was very rapid and could not be prevented by the use of scavengers. Thus soda lime and zeolite had no practical effect as scavengers in this delivery system, and the effect of noXon was very slight.

An Evaluation of Nitric Oxide and Nitrogen Dioxide Absorbers and Filters

“…There are numerous reports on the ability of various materials to filter either NO, NO 2 or both from ventilator circuits. Absorbers such as sodalime and its variations [4][5][6][7][8][9][10][11][12][13][14][15][16] , and charcoal 7,14,17,18 have been extensively studied. Other materials such as the molecular sieve 5A 6,15,19 and noXon 15 have also been investigated.…”

“…Absorbers such as sodalime and its variations [4][5][6][7][8][9][10][11][12][13][14][15][16] , and charcoal 7,14,17,18 have been extensively studied. Other materials such as the molecular sieve 5A 6,15,19 and noXon 15 have also been investigated. These studies have tended to concentrate on anaesthetic applications, where the aim is to maintain NO levels but prevent toxic build up of NO 2 .…”

“…Previous work with sodalime has determined its ability to absorb NO 2 . When white-violet (W-V) or (P-W) pink-white indicators are used, sodalime is a good absorber of NO 2 5,9,[11][12][13][14][15] but its absorption of NO is limited by the amount of NO 2 present 9,11,12,15 . In order to absorb NO as well, sodalime must have another agent added to it.…”

“…Other, more sophisticated filters have also been tested as NO and NO 2 scavengers. Materials such as molecular sieve 5A 6,15 , noXon 15 and the HgCONO filter 7 have been shown to be excellent filters of NO and NO 2 . None of the three Stackhouse filters (ILF100, ILF150 and ILF200) which we tested showed adequate absorption.…”

A novel, cassette-based nitric oxide delivery system with an advanced feedback control algorithm accurately delivers nitric oxide via the anesthesia machine independent of fresh gas flow rate and volatile anesthetic agent

“…Anesthesia circuits contain a carbon dioxide (CO 2 ) absorber and gas reservoir system that are essential for rebreathing to occur safely. The anesthesia semi-closed circuit was primarily designed to conserve volatile anesthetic agent use by allowing low FGFs [7,8].…”