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A portable nitric oxide scavenging system designed for use on neonatal transport
J S Dhillon1, J B Kronick, N C Singh
1Paediatric Critical Care Unit, Department of Paediatrics, Children's Hospital of Western Ontario, London, ON, Canada.
Objective:
To evaluate a portable scavenging system for nitric oxide and its oxides, designed for use on neonatal transport.
Design:
A prospective evaluation of the nitric oxide scavenging system, using a neonatal transport incubator ventilator and a test lung.
Setting:
Laboratory of a tertiary care children's hospital.
Interventions:
The scavenging system was tested, using a neonatal transport incubator with attached ventilator, ventilator circuit, and a neonatal test lung. Nitric oxide was administered on the inspiratory limb, and nitric oxide and its oxides were measured in the expiratory gas after passing through the scavenger.
Measurements And Main Results:
A modified scrubber assembly was filled with 50% activated charcoal and 50% aluminas potassium permanganate pellets (3). Three wire meshes were placed before, in between, and after the two chemicals to facilitate gas flow. Using the maximum FIO2, with a nitric oxide concentration of 120 parts per million (ppm), the test lung continuous flow ventilation (FIO2 of 0.86, peak inspiratory pressure of 30 cm H2O, positive end-expiratory pressure of 6 cm H2O) and respiratory rate of 60 breaths/min) was performed for 4 hrs with each of four freshly prepared scavenging systems. A fifth scavenging system was tested for a 12-hr period. The mean composition of the exhaled gases for 4 hrs were: nitric oxide 0.01 +/- 0.03 (SD) ppm, nitric dioxide 0.06 +/- 0.06 ppm, and other oxides 0.05 +/- 0.09 ppm. After 12 hrs of 120 ppm of inhaled nitric oxide, the fifth scavenger system had undetectable nitric oxide, nitric dioxide, and other oxides in the exhaled gas. Normal room air contained between 0.0 and 0.03 ppm of nitric oxide, 0.0 and 0.02 ppm of nitric dioxide, and 0.0 and 0.02 ppm of other oxides.
Conclusion:
Nitric oxide, nitric dioxide, and other dioxides can be safely scavenged by this portable scavenging system, allowing safe administration of nitric oxide free from environmental contamination with nitric oxide and its oxides.