What is a primary cause of metabolic acidosis?

Metabolic acidosis is typically characterized by a decrease in bicarbonate concentration in the blood or an increase in acid. Sepsis is a primary cause because it can lead to the production of lactic acid due to tissue hypoperfusion and hypoxia. When the body is unable to adequately supply oxygen to tissues, anaerobic metabolism occurs, resulting in increased levels of lactic acid which contribute to acidosis. Additionally, sepsis can also disrupt renal function and lead to impaired acid-base regulation, further promoting metabolic acidosis.

In contrast, the other options relate to conditions that do not directly result in metabolic acidosis in the same way. Pneumothorax primarily affects pulmonary function and can lead to respiratory problems rather than a direct metabolic disturbance. Neurological injury may impact respiratory drive or metabolic function, but it does not inherently cause metabolic acidosis. Rapid breathing typically is a compensatory mechanism in response to acidosis rather than a cause of metabolic acidosis itself. This distinction is important for understanding the physiological processes involved in metabolic acidosis and its relevant causes.