The primary study endpoint is the difference in plasma cytokines between the hypoxia and normoxia group, and between the hyperoxia and normoxia group. Secondary objectives include HIF-1α protein and mRNA, aHIF mRNA expression in circulating leukocytes, measures of ROS, leukocyte phagocytosis, and cytokine production by leukocytes stimulated ex vivo with various inflammatory stimuli, and measurement of basic hemodynamic and ventilatory parameters and temperature.