Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

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Thesis ( M.S. ) -- University of Texas at Arlington, 2008.

Thesis (M.Ag.Sc.)--University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 1999. / Bibliography: leaves 69-78.

Thesis (doctoral)--Lunds Universitet, 1990.

Thesis (doctoral)--Lunds Universitet, 1990.

A recently developed therapy for treatment of acute respiratory failure requires that the patient's metabolic carbon dioxide production be eliminated by a membrane oxygenator operated in an extracorporeal blood circuit. In conjunction with peripheral cannulation, the oxygenator should be optimised for CO₂ removal at low blood flow rates of 1.5 ℓ/min or less for adults. An extensive literature survey revealed that very few publications dealt with oxygenator CO₂ performance at low flow rates. Two commercial devices, the Terumo CAPIOX II (1.6 m² and 3.3 m² membrane areas) hollow fibre oxygenator and the Travenol TMO (2.25 m² membrane area) parallel-plate oxygenator were evaluated in relation to the new therapy. A theoretical model describing carbon dioxide transfer in membrane oxygenators was used to correlate the experimental data. The Terumo CAPIOX II 3.3 m² unit was the only device capable of satisfying the carbon dioxide removal requirements necessary for the new therapy at the low blood flow rates stipulated. Effects of blood and gas flow maldistribution were also studied in the TMO and CAPIOX II units respectively. Non-uniform blood flow was not a major factor contributing to the decline in CO₂ transfer performance compared with theory. This was confirmed in experiments with a modified TMO unit. Comparison with theory indicated that the membrane resistance was the controlling factor for CO₂ transfer in the CAPIOX II device. A method was developed to assess the CO₂ transmission rate (Gco₂) through oxygenator membranes under gas-membrane-liquid contact conditions. This forms the basis for the selection of suitable membrane materials for oxygenators. Although the GCO₂ values for homogeneous silicone rubber membranes were consistent with the results of previous workers, significantly higher values were obtained for microporous polypropylene membranes. For microporous membranes under liquid contact conditions a 5-fold reduction in GCO₂ is obtained in this study compared to gas-membrane-gas tests, indicating that micropore wetting imposes a significant resistance to CO₂ transfer.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 112-122).

The purpose of this investigation was to examine the change in pulmonary ventilation (V_E), ventilatory equivalent of oxygen (VE_O_2) and lactic acid (LA) in relation to oxygen uptake (V_O_2) as predictors of the lactate threshold (LT). Eight healthy male (21.9 ± 3.0 years) subjects conducted three incremental-load tests. In each test the initial work rate consisted of 4 minutes of unloaded pedaling ("0" load) followed by incremental-load work of 360 Kgm • min^-1 at 60 rpm for trial I and trial II, while during trial III the work rate consisted of 540 Kgm • min^-1 of incremental-load work at 90 rpm. Work load was increased every third minute until the subject reached voluntary exhaustion. Blood samples from a forearm vein were collected during trial II (60 rpm) and trial III (90 rpm) and analyzed for lactic acid. In our subjects the measured (x̄ ± SD) lowest VE_O_2 for O_2 in relation to V_O_2 for trial I of 22.9 ± 1.9 occurred at a V_O_2 of 1.27 ± 0.8 L • min^-1. For trial II the VE_O_2 of 22.4 ± 1.3 occurred at a V_O_2 of 1.30 ± 0.09 L • min^-1, while for trial III a VE_O_2 of 24.4 ± 2.5 occurred at a V_O_2 of 1.84 ± 0.15 L • min^-1. The lowest VE_O_2 and onset of LA accumulation as calculated from individual exponential equations relating V_E to V_O_2 yielded V_O_2 values at 1.77 ± 0.18 L • min^-1 and 1.74 ± 0.25 L • min^-1 for trial II, and 1.83 ± 0.19 L • min^-1 and 2.02 ± 0.53 during trial III. Utilizing ln[LA]-ln V_O_2 equations, the LT occurred at a V_O_2 of 1.30 ± 0.07 L • min^-1 during trial II and 1.85 ± 0.12 L • min^-1 during trial III. It was concluded that during the 60 rpm test that the lactate threshold was best predicted by measured lowest VE_O_2 and the plot of the In[LA] to In V_O_2 relationship. The methods used in this study provide a valid and reliable estimate of the lactate threshold and support the use of measured lowest VE_O_2 , a respiratory gas exchange measure, as an indirect measure of the lactate threshold.