The overall study design is based on the assumption that the maximum increase in red blood cells and their effect often does not occur while a subject is in the ICU and acutely ill. The study hypothesis is that a higher hemoglobin (red blood cells) carries more oxygen and delivers oxygen to the tissues. This should increase the ability of the injured subject to tolerate the physical exertion involved in the recuperative process and thus recover earlier than someone with a lower hemoglobin.