Nitrogen dioxide (NO2) production for different doses of inhaled nitric oxide (NO) during mechanical ventilation with different tidal volumes using two prototypes for the administration of NO

• Background Although low concentrations of inhaled nitric oxide may by therapeutic, both nitric oxide and its oxidation product nitrogen dioxide are potentially toxic. The threshold limits for time-weighted average concentrations of nitric oxide and nitrogen dioxide issued by the American Conference of Governmental Industrial Hygienists are 25 and 3 ppm, respectively. The concentrations of these gases in the breathing space of hospital personnel during administration of nitric oxide to adult patients have not been reported.• Methods Air was sampled from the breathing zone of intensive care unit nurses via collar-mounted tubes during the nurses’ routine duties attending patients who were receiving inhaled nitric oxide at 5 or 20 ppm. The exhaust ports of the mechanical ventilators were left open to the room. Nitric oxide and nitrogen dioxide were chemically assayed as nitrite from sorbent tubes by using spectrophotometry. Ambient nitric oxide levels were measured at sequential distances from the ventilator by using chemiluminescence.• Results The time-weighted average concentrations of inspired gas for nurses during inhaled nitric oxide treatment were 0.45 ppm or less for nitric oxide and less than 0.29 ppm for nitrogen dioxide. Nitric oxide levels at the ventilator during delivery at 20 ppm were 9.2 ppm, but dropped off markedly beyond 0.6 m (2 ft), to a mean of about 30 ppb.• Conclusion Inhaled nitric oxide therapy at doses up to 20 ppm does not appear to pose a risk of excessive occupational exposure to nitric oxide or nitrogen dioxide to nurses during routine delivery of critical care.

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Analysis of Medical Resource Utilization and Outcome of Inhaled Nitric Oxide in Patients Undergoing Mechanical Ventilation

International Journal of Gerontology ◽

10.1016/j.ijge.2014.03.010 ◽

2015 ◽

Vol 9 (1) ◽

pp. 46-51 ◽

Cited By ~ 1

Author(s):

Yueh-Chih Chung ◽

Shian-Chin Ko ◽

Chin-Li Lu ◽

Mei-Chen Huang ◽

Kuo-Chen Cheng

Keyword(s):

Nitric Oxide ◽

Mechanical Ventilation ◽

Resource Utilization ◽

Inhaled Nitric Oxide ◽

Medical Resource ◽

Medical Resource Utilization

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Nitrogen Dioxide Production during Mechanical Ventilation with Nitric Oxide in Adults

Anesthesiology ◽

10.1097/00000542-199505000-00020 ◽

1995 ◽

Vol 82 (5) ◽

pp. 1246-1254 ◽

Cited By ~ 51

Author(s):

Masaji Nishimura ◽

Dean Hess ◽

Robert M. Kacmarek ◽

Ray Ritz ◽

William E. Hurford

Keyword(s):

Nitric Oxide ◽

Mechanical Ventilation ◽

Nitrogen Dioxide ◽

Residence Time ◽

Rate Constants ◽

Minute Ventilation ◽

Test Lung ◽

Mechanical Ventilators ◽

Lung Volumes ◽

Air Inlet

Background Inhaled nitric oxide (NO) may be useful in the treatment of adult respiratory distress syndrome and other diseases characterized by pulmonary hypertension and hypoxemia. NO is rapidly converted to nitrogen dioxide (NO2) in oxygen (O2) environments. We hypothesized that in patients whose lungs are mechanically ventilated and in those with a long residence time for NO in the lungs, a clinically important [NO2] may be present. We therefore determined the rate constants for NO conversion in adult mechanical ventilators and in a test lung simulating prolonged intrapulmonary residence of NO. Methods NO (800 ppm) was blended with nitrogen (N2), delivered to the high-pressure air inlet of a Puritan-Bennett 7200ae or Siemens Servo 900C ventilator, and used to ventilate a test lung. The ventilator settings were varied: minute ventilation (VE) from 5 to 25 l/min, inspired O2 fraction (FIO2) from 0.24 to 0.87, and [NO] from 10 to 80 ppm. The experiment was then repeated with air instead of N2 as the dilution gas. The effect of pulmonary residence time on NO2 production was examined at test lung volumes of 0.5-4.0 l, VE of 5-25 l/min, FIO2 of 0.24-0.87, and [NO] of 10-80 ppm. The inspiratory gas mixture was sampled 20 cm from the Y-piece and from within the test lung. NO and NO2 were measured by chemiluminescence. The rate constant (k) for the conversion of NO to NO2 was determined from the relation 1/[NO]t-1/[NO]o = k x [O2] x t, where t = residence time. Results No NO2 was detected during any trial with VE 20 or 25 l/min. With N2 dilution and the Puritan-Bennett 7200ae, NO2 (< or = 1 ppm) was detected only at a VE of 5 l/min with an FIO2 of 0.87 and [NO] > or = 70 ppm. In contrast, [NO2] values were greater with the Servo 900C ventilator than with the Puritan-Bennett 7200ae at similar settings. When NO was diluted with air, clinically important [NO2] values were measured with both ventilators at high [NO] and FIO2. Rate constants were 1.46 x 10(-9) ppm-2.min-1 when NO was mixed with N2, 1.17 x 10(-8) ppm-2.min-1 when NO was blended with air, and 1.44 x 10(-9) ppm-2.min-1 in the test lung. Conclusions [NO2] increased with increased FIO2 and [NO], decreased VE, blending with air, and increased lung volumes. Higher [NO2] was produced with the Servo 900C ventilator than the Puritan-Bennett 7200ae because of the greater residence time. With long intrapulmonary residence times for NO, there is a potential for NO2 production within the lungs. The rate constants determined can be used to estimate [NO2] in adult mechanical ventilation systems.

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