The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts


William J Holt RRT. RPFT, Edward Snyder AE, Jay S Greenspan MD, and Michael J Antunes MD. Department of Pediatrics. Thomas Jefferson Medical College and Hospital. Philadelphia, PA.

BACKGROUND: Traditional therapies such as hyper oxygenation, hyperventilation, and intravenous vasodilators have had limited success in reversing persistent pulmonary hypertension of the newborn, and hypoxemic respiratory failure. The recent intr oduction of nitric oxide (NO) as an investigational new drug for the treatment of these disorders has been reported to have beneficial effects. Several regional centers have been granted approval to investigate the effects of NO. Some infants require emergency transportation to a tertiary care center in spite of any benefit from NO. The need to continue NO therapy during transport becomes evident, as these infants deteriorate with its discontinuation. We developed a transport NO delivery system described here. Oxygen and NO (400 ppm balance nitrogen) in 33 ft^{3} aluminum tanks are attached directly to the transport isolette on an aluminum carrier tray. This tray has a back board with mounting brackets for a O bleed anesthesia blender. O_{2} (Mini-Ox III) and NO analyzers (Drager electrochemical), and an O_{2} flow meter. The O_{2} line between the tank and the blender was fitted with check valves to allow for uninterrupted connection to the ambulance O_{2} to conserve the tank supply. The system weighs 60 LB and adds 8 inches to the overall length of the isolette. Methods: Bench testing was performed determine the ability of this system to deliver 20 ppm NO in a high O_{2} concentration, and to determine the duration of the 33 ft^{3} tanks. Testing consisted of 4 one hour runs with a mix of 96% O_{2}, and 20 ppm NO, at 12 LPM continuous flow. The ventilator (Preemiecare 200 Transport) was set to IMV 60, peak inspiratory pressure 40 cmH_{2}O, and 5 cmH_{2}O of PEEP. During each of the 1 hour trials the ventilator gas was monitored at the patient connection of the circuit for NO through electrochemical analysis at 15 minute intervals. Analysis through chemiluminesence (Thermo Environmental model 42H) was also performed for comparison of measurements, and to check for the presence of nitrogen dioxide. The electrochemical analyzer was used to monitor ambient air 12 inches below the exhalation valve of the ventilator between circuit measurements. Results: The gas analysis remained stable throughout each of the 4 one hour trials. O_{2} @ 96 %, NO @ 20 ppm, with no nitrogen dioxide detected in the patient connection of the circuit. We were unable to detect NO in ambient air. The 33 ft^{3} O_{2} tanks lasted 1 hour each with 2200 psig at the beginning of the run. Oxygen tanks were changed at 200 psig. The 33 ft^{3} NO tank pressure declined at rate of 100 psig per hour, extrapolating to a 20 hour tank life. CONCLUSION: This NO transport system has the ability to deliver 20 ppm NO in a high concentration of oxygen at a maximum level of conventional support. The 33 ft^{3} O_{2} tank provides an adequate supply of O_{2} for transport from the nursery to and from the ambulance, and the NO tank provides many hours of NO even at high ventilator support. Further testing in the closed quarters of the ambulance is required to determine if scavenging mechanisms are needed. Reference: OF-96-024