Hypoxemia metabolic acidosis with

M (metabolic acidosis and hypoxemia with tactic acidosis)... 

Conditions that result in increased production of metabolic acids include lactic acidosis and diabetic ketoacidosis. Lactic acidosis occurs with anaerobic metaboUsm in the presence of severe hypoxemia (i.e., Pao < 36 mm Hg). Any condition that prevents adequate oxygenation resulting in hypoxemia, such as respiratory failure or lung cancer, as well as any condition causing a decrease in perfusion to body tissues, such as heart failure or shock of any form, will result in anaerobic metabolism and lactic acid buildup. In diabetic ketoacidosis, the lack of insulin to move glucose into the cells results in a form of starvation and the production and accumulation of ketoacids (i.e., ketosis) owing to the use of lipids for fuel. 

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