Answer: a, b, c, d Optimizing systemic oxygen delivery in relationship to oxygen requirement is the primary goal of management. Improving oxygenation of the blood itself by improving alveolar inflation is only one of the steps in optimizing oxygen delivery. Equally or more important are treating anemia and optimizing cardiac output. Cardiac output should be optimized to maintain delivery of four to five times consumption. In general, this means avoiding those factors which decrease cardiac output, rather than actively trying to increase cardiac output. Blood pressure should be maintained high enough to provide coronary perfusion (over 50 mm Hg mean pressure) but not so high as to limit left ventricular function (over 90 mm Hg mean arterial pressure). Alveolar collapse is treated by cleaning the airways, avoiding 100% oxygen, and moving fluid from the lung or chest, and finally by the use of positive end exploratory pressure to hold open those alveoli which have been opened by other measures. The optimal level of PEEP is that level that maintains arterial oxygenation but does not decrease venous return or cardiac output. This optimal level is best determined by monitoring mixed venous saturation. Another step in optimizing lung function is to take advantage of the gravitational effects on pulmonary blood flow by turning the patient prone or to a full lateral position to direct blood flow to areas of optimal alveolar function. This step will often result in an opening in the closed posterior alveoli which have been compressed by the weight of the fluid in the lungs. At the same time that oxygen delivery is optimized, oxygen consumption should be decreased to normal or even below normal if necessary. Treating infection, providing adequate sedation, and establishing muscular paralysis decrease oxygen consumption, and decrease the need for oxygen delivery