The Science Journal of the American Association for Respiratory Care

2000 OPEN FORUM Abstracts

NITRIC OXIDE DELIVERY WITH THE AERONOX®

Khaled Sedeek MD, Robert M. Kacmarek PhD RRT FAARC, Dean Hess PhD RRT FAARC. Respiratory Care, Massachusetts General Hospital and Harvard Medical School, Boston, MA

Background: Inhaled NO is FDA approved for treatment of hypoxic respiratory failure of the newborn. NO delivery systems should provide a constant [NO] with changes in ventilatory pattern. We evaluated the Aeronox® NO delivery system (Pulmonox, Tofield, Alberta CA).

Methods: The Aeronox® was calibrated, adjusted, and connected to the ventilator circuit as recommended by the manufacturer. NO was delivered into the inspiratory limb of the ventilator circuit near the ventilator outlet. Gas was sampled downstream from the point of injection near the Y-piece. At the same sample site, gas was aspirated for analysis using a Sievers NOA rapid-response analyzer (Sievers, Boulder CO). The output of the Sievers was digitized at 1000 Hz (Windaq, Akron OH). The Aeronox® and Sievers were calibrated simultaneously with the same gas mixture. We evaluated 3 [NO] (1, 5, and 20 ppm). The ventilators were attached to an infant lung model (Michigan Instruments TTL). We evaluated the Bird VIP ventilator in time and volume controlled modes. In the time controlled mode, we adjusted respiratory rate (20, 30, and 40/min), inspiratory time (0.3, 0.5, and 0.8 s), peak inspiratory pressure (15, 25, and 35 cm H2O), and flow (10 and 15 L/min). In the volume controlled mode, we adjusted respiratory rate (20 and 30/min), tidal volume (50 and 150 mL), and flow (10 and 20 L/min). We also evaluated the Sensormedics HFO using a flow of 20 L/min with adjustments in frequency (5, 10, and 15 Hz), mean airway pressure (15, 20, and 25 cm H2O), and amplitude (20, 30, and 40 cm H2O). The 100% O2 setting on the ventilator was used to evaluate NO2 production.

Results: See figures for results at 20 ppm. A bias was noted between the [NO] measured by the Aeronox® and the Sievers, but this is too small to be clinically important. For each set of conditions, the fluctuation in delivered [NO] as measured by the rapid response Sievers NO analyzer was small, indicating adequate mixing within the ventilator circuit and a stable delivered dose throughout inspiratory phase. The [NO2] was always < 1 ppm. Experience: Our only experience with this device is in the laboratory setting. We found it easy to calibrate and use. The only difficulty was in the delivery of 1 ppm under some conditions because the Aeronox® was unable to be adjusted to a flow low enough.

Conclusions: Our evaluation suggests that the Aeronox® delivers a constant [NO] with minimal [NO2] using the ventilators and settings evaluated in this study. (study sponsored by INO Therapeutics, Clinton NJ) (See Original for Figure)

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