The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts

STRATIFICATION OF SUPERSATURATED DISSOLVED OXYGEN SOLUTIONS WITH DEPTH AND TEMPERATURE USING A NOVEL HYPERBARIC TONOMETER.

Daniel J. Grady1, Michael A. Gentile2, John H. Riggs3, Terrence F. Smith1, McCarl Todd1, Ira M. Cheifetz2, Gregg Stashenko1; 1Respiratory Care, Mission Health System, Asheville, NC; 2Pediatric Critical Care Medicine, Duke University Health System, Durham, NC; 3Clinical Research, VentLab, Mocksville, NC

Background: Supersaturated dissolved oxygen solutions may exhibit stratification due to variables such as solvent polarity, molecular mobility, spin exchange between oxygen molecules, container shape, solution temperature, and container depth1. The purpose of this study was to evaluate supersaturated dissolved oxygen concentrations at various solution temperatures and depth levels using a novel hyperbaric tonometer. Methods: The supersaturated dissolved oxygen solution was prepared by bubbling gaseous oxygen at 3 L/min through 2.5 liters of sterile water for 20 minutes. Dissolved oxygen measurements were made at the container bottom, 1, 2, and 3 inches above bottom; and at the solution surface. The dissolved oxygen measurements were made using 3 different groups of solution temperatures (62, 57 and 52 degrees F, which equals 17, 14, and 11 degrees C; respectively) for a total of 15 (n = 15) measurements. Dissolved O2 of the supersaturated solution was measured by a Hanna Instruments HI 98186 Dissolved Oxygen analyzer in units of mg/L under conditions of ATPS. Student’s t-test (alpha = 0.05) determined statistical significance. Results: Slight changes in dissolved oxygen concentration at different depths within the tonometer are shown in the figure below. A statistically significant difference (p = 0.0004) was seen between the supersaturated dissolved oxygen solutions at 11 C (52 degrees F) compared to 14 C (57 degrees F). Also, there was a statistically significant differences ( p = 0.0004), between the dissolved oxygen solutions at 14 C (57 degrees F), compared to 17 C (67 degrees F). Conclusions: This study has demonstrated significant differences in dissolved oxygen in sterile water solutions when solvation occurs at different temperatures. Also, slight stratification of supersaturated dissolved oxygen solutions in sterile water was observed due to changes in depth within the tonometer. With warmer solution temperatures, the highest dissolved oxygen measurements occurred 1 inch above the bottom of the container. At the coldest solution temperature, the highest dissolved oxygen content was observed near the surface. Additional research is needed to determine the efficacy of systems to homogenously mix the supersaturated dissolved oxygen solutions. Sponsored Research - None 1 Moscatelli et al. Oximetry of Oxygen Supersaturated Solutions Using Nitroxides as EPR Probes. J. Phys. Chem. B, 2006, 110, 7574-7578