Nitrogen dioxide formation during inhaled nitric oxide therapy.
BACKGROUND
Nitrogen dioxide (NO2) is a toxic by-product of inhalation therapy with nitric oxide (NO). The rate of NO2 formation during NO therapy is controversial.


METHODS
The formation of NO2 was studied under dynamic flows emulating a base case NO ventilator mixture containing 80 ppm NO in a 90% oxygen matrix. The difficulty in measuring NO2 concentrations below 2 ppm accurately was overcome by the use of tunable diode laser absorption spectroscopy.


RESULTS
Using a second-order model, the rate constant, k, for NO2 formation was determined to be (1.19 +/- 0.11) x 10(-11) ppm-2s-1, which is in basic agreement with evaluated data from atmospheric literature.


CONCLUSIONS
Inhaled NO can be delivered safely in a well-designed, continuous flow neonatal ventilatory circuit, and NO2 formation can be calculated reliably using the rate constant and circuit dwell time.
Sokol
G M
GM
Department of Pediatrics, Indiana University, Indianapolis, IN 46202, USA.gsokol@iupui.edu
Van Meurs
K P
KP
Wright
L L
LL
Rivera
O
O
Thorn
W J
WJ
Chu
P M
PM
Sams
R L
RL
D000280:Administration, Inhalation; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000378:metabolism* / Q000627:therapeutic use; D006801:Humans; D007231:Infant, Newborn; D007700:Kinetics; D009569:Nitric Oxide / Q000008:administration & dosage / Q000378:metabolism* / Q000627:therapeutic use; D009585:Nitrogen Dioxide / Q000032:analysis / Q000378:metabolism* / Q000633:toxicity; D013053:Spectrophotometry; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000378:metabolism* / Q000627:therapeutic use
D001993:Bronchodilator Agents; D014665:Vasodilator Agents; D009569:Nitric Oxide; D009585:Nitrogen Dioxide