Occupational exposure during nitric oxide inhalational therapy in a pediatric intensive care setting

Objective: To determine the amount of occupational exposure to nitric oxide (NO) and nitrogen dioxide (NO₂) during NO inhalational therapy. Design: In a standard pediatric intensive care room, 800 ppm NO was delivered to a high-frequency oscillator and mixed with 100% O₂ to obtain 20 ppm NO in the inspiratory gas flow. NO and NO₂ concentrations in room air were measured using a chemiluminescence analyzer. Air samples were taken from a height of 150 cm at a horizontal distance of 65 cm from the ventilator in a nonventilated and in a well-ventilated room with and without an expiratory gas exhaust under normal intensive care environmental conditions. Setting: Pediatric intensive care unit in a university children's hospital. Mesaurements and results: Maximal concentrations of NO and NO₂ were reached after 4 h NO use. Without exhaust, in a nonventilated room, environmental NO and NO₂ concentration rose to a maximum of 0.462 and 0.064 ppm, respectively. With the use of an expiratory gas exhaust, NO and NO₂ concentrations were 0.176 and 0.042 ppm, respectively. With normal air-conditioning, these values were 0.075 and 0.034 ppm, respectively, without the use of an expiratory gas exhaust. With expiratory gas exhaust added to normal air-conditioning, values for NO and NO₂ were 0.035 and 0.030 ppm, respectively, Conclusions: The use of 20 ppm NO, even under minimal room ventilation conditions, did not lead to room air levels of NO or NO₂ that should be considered toxic to adjacent intensive care patients or staff. Slight increases in NO and NO₂ concentrations were measurable but remained within occupational safety limits. The use of an exhaust system and normal room ventilation lowers NO and NO₂ concentrations further to almost background levels.