The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

TITRATION OF DELIVERED F_{1}O_{2} USING INCREMENTAL CHANGES IN SUPPLEMENTAL OXYGEN IN THE QUANTUM PSV^{TM} NON-INVASIVE POSITIVE PRESSURE VENTILATOR

Jonathan B. Waugh, Ph.D., RRT, Randy M. De Kler, M.S., RRT. Georgia State University, Cardiopulmonary Care Sciences Department, Atlanta, Georgia.

INTRODUCTION: Ventilators used for NIPPV do not have an oxygen control setting so practitioners typically "bleed-in" 100% oxygen into the patient circuit. The purpose of this study was to measure the effect of manipulating supplemental oxygen flow rates on F_{1}O_{2} delivered to the patient. Methods: A Quantum-PSV NIPPV (Healthdyne Technologies, Marietta, GA) was used with the constant settings of a rise time = 0.5 seconds, percent inspiratory time = 25%, and frequency = 10 bpm. The Quantum NIPPV was connected to a Manley test lung (Ohmeda, Madison, WI) set at a system compliance of 50 mL/cm H_{2}O and an airway resistance of 2.0 cm H_{2}O/L.sec. The mean delivered F_{1}O_{2} was measured at the nasal mask while varying the oxygen flow rates and the site at which oxygen flows were added. Results:

O_{2}Lpm Delivered F_{1}O_{2} mean±SD Delivered F_{1}O_{2} mean±SD

(bleed-in at machine) (bleed-in at mask)

1 25.6±0.1 --

2 32.3±0.1 26.7±0.2

3 38.4±0.2 --

4 44.7±0.1 36.4±0.2

6 57.9±0.1 45.6±0.4

8 69.8±0.3 --

10 85.8±0.2 80.5±0.2

Supplemental O_{2} added into the patient circuit next to the NIPPV yielded significantly higher delivered F_{1}O_{2} values than the mask site (p = 0.016 by repeated measures ANOVA). Supplemental O_{2} with CPAP levels of 4-10 cm H_{2}O with spontaneous rate of 10 bpm and a V_{T} of 300 mL produced mean F_{1}O_{2} values of 0.71-0.48 @ 10 Lpm O_{2} and 0.98-0.70 @ 15 Lpm O_{2}. Conclusions: Mean delivered F_{1}O_{2}'s increased 6-8% for each liter per minute increase in supplemental O_{2} introduced at the site most distal from the patient for these study conditions. Introducing supplemental oxygen into the patient circuit at the site most distal from the patient appears to provide higher delivered F_{1}O_{2} values than near the patient mask. Oxygen flow rates of 10-15 Lpm are sufficient to deliver a high F_{1}O_{2} at modest tidal breathing in CPAP mode.

Reference: OF-96-051

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