The nurse reviews the following arterial blood gases and understands that the patient has which acid-base imbalance? pH 7.49, PCO2 41, HCO3 38


• Uncompensated metabolic alkalosis is correct because there is an increase in pH (alkalosis), an increase in HCO3 (metabolic in origin), but the PCO2 is still normal (this tells us the lungs are not yet compensating by retaining PC02 via hypoventilation).

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, which leads to hypoventilation and CO2 retention

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

Metabolic Acidosis:
• Caused by loss of bicarb or buildup of acids: 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

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