A patient presents to the ER after being found unconscious and not breathing. Before endotracheal intubation, you get an arterial blood gas with which of the following results:


•Because the patient went some time without breathing, PCO2 will be elevated do to retention, causing respiratory acidosis.

Respiratory Acidosis:
•Respiratory system is the cause, for ex. hypoventilation
•Increase in PCO2, decrease in pH
•Compensation - Kidneys reabsorb Bicarb (HCO3)

Metabolic Acidosis:
•Caused by loss of bicarb or a build up of acids, for ex. lactic acidosis, diarrhea, renal failure, ketones, ammonium intoxication. Not caused by respiration.
•HCO3 decreases, pH decreases
•Compensation - hyperventilation to eliminate CO2

Respiratory Alkalosis:
•Caused by excessive ventilation
•Decrease in PCO2, increase in pH
•Compensation - Kidneys excrete HCO3

Metabolic Alkalosis
•Acid (H+) lost from emesis, diuretics. Retention of HCO3 from medications, hyperaldosteronism
•Increase in HCO3, Increase in pH
•Compensation - Respiratory centers are not stimulated, this leads to hypoventilation and CO2 retention

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