The Science Journal of the American Association for Respiratory Care

2009 OPEN FORUM Abstracts

BACK PRESSURE COMPARISON IN THREE MEDICAL GAS DELIVERY SYSTEMS

Tia Alton1, Steve T. Polston2, Kendra L. Sikes3, In K. Kim3; 1School of Medicine, University of Louisville, Louisville, KY; 2Norton Healthcare, Inc, Louisville, KY; 3Pediatric Emergency Medicine, University of Louisville, Louisville, KY

Oxygen is often administered to patients for various respiratory problems. Systems designed to deliver respiratory gas to patients are subject to back pressure as a result of resistance through the pathway. These back pressures have been anecdotally reported as being high enough to disconnect tubing from gas sources; possibly creating a situation that would be detrimental to the gas delivery systems. To evaluate this problem, we measured back pressures in three gas delivery systems for 100% oxygen at physiological temperature (37∞ C). Varying flow rates were used between 1-15 liters per minute (LPM) with four sizes of nasal cannulae; pediatric, infant, neonate, and premature. A U-tube manometer was used to measure the back pressure in 3 systems: Vapotherm® 2000i, Fisher-Paykel® MR850, and Salter®. The gas delivery circuit consisted of 100% oxygen gas flowing through a respiratory humidifier to a pediatric, infant, neonate, or premature nasal cannulae. Experiments were conducted with 100% oxygen at flow rates of 1 LPM, 2 LPM, 3 LPM, 4 LPM, 5 LPM, 10 LPM, and 15 LPM. For each experiment, three trials were conducted. The results showed that at 1-5 LPM flow rates, all three systems produced minimal back pressures (<25 cm H2O) with the pediatric nasal cannulae. At 1-5 LPM flow rates, the Fisher-Paykel® MR850 system produced minimal back pressures (<25 cm H2O) with the infant and premature cannulae. At 3-5 LPM flow rates, all three systems produced significant back pressures (>50 cm H2O) with the neonate cannulae. At 10 LPM and 15 LPM flow rates, all three systems produced significant back pressures (>50 cm H2O) with all four cannulae sizes. We concluded that flow rates of 10 LPM or 15 LPM produce significant back pressure with all 3 systems. When possible, pediatric sized cannulae should be used for flow rates of 1-5 LPM. For infant and premature cannulae, the Fisher-Paykel® MR850 generates minimal back pressure for flow rates of 1-5 LPM. Further modifications should be considered on neonate size cannulae to decrease back pressure. Sponsored Research - None

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