A Descriptive Study of the Percentage of Oxygen Delivered Using the Mercury Tube-Valve-Mask Breathing Circuit at 2 L/min Flow Rates
Final rept. May 2001-Apr 2002
TEXAS UNIV HEALTH SCIENCE CENTER AT HOUSTON SCHOOL OF NURSING
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The purpose of this study was to determine the efficacy of the Mercury tube-valve-mask oxygen delivery system at 2 Lmin, 3 Lmin and 4 Lmin flows using an oxygen concentrator Oxygen 93 USP and Oxygen 99 USP. A descriptive design was used. Eighteen healthy volunteers ages 28-43 were recruited from the students and faculty at the Army Medical Department Center and School in San Antonio, Texas. The trials consisted of the subject breathing through the Mercury tube-valve-mask breathing circuit at 2 Lmin, 3 Lmin and 4 Lmin flow rates using an oxygen concentrator Oxygen 93 USP and Oxygen 99 USP. Each subject was randomly assigned to order of oxygen source and flow rate, received all 6 trials, and served as their own control. The subject breathed from the oxygen source and flow rate selected until a sustained fraction inspired oxygen concentrationFiO2 was determined. Once the sustained FiO2 was determined and there was less than 10 variation in FiO2, a three-minute trial began. Data collection consisted of the subjects FiO2, respiratory rate, tidal volume and minute volume. It was hypothesized that the Mercury tube-valve-mask breathing circuit would deliver a FiO2 of 0.40, 0.50, and 0.60 at flow rates of 2 Lmin, 3 Lmin, and 4 Lmin, respectively. A chi-square goodness-of-fit test was used to determine if 85 of the subjects achieved the desired FiO2 at the predetermined flow rate. The 85 criterion was not reached in any of the conditions tested. The mean FiO2 at 2 Lmin was 0.35 with Oxygen 93 USP and 0.36 with Oxygen 99 USP. The mean FiO2 at 3 Lmin was 0.45 with Oxygen 93 USP and 0.45 with Oxygen 99 USP. The mean FiO2 at 4 Lmin was 0.52 with Oxygen 93 USP and 0.53 with Oxygen 99 USP. Although the predicted values of FiO2 were not met, it was found that the Mercury tube-valve-mask breathing circuit was capable of delivering higher concentrations of oxygen than traditional oxygen delivery systems.
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