Acid-Base Imbalances: Respiratory Acidosis & Alkalosis

• Arterial blood gas (ABG) results: pH 7.30, PaCO2 50 mmHg, HCO3- 24 mEq/L indicates respiratory acidosis.
• Respiratory acidosis: Decreased pH (<7.35) and elevated PaCO2 (>45 mmHg) with normal HCO3- suggest a respiratory origin.
• Chronic obstructive pulmonary disease (COPD) is a likely cause of respiratory acidosis.
• Hypoventilation, as seen in COPD, causes CO2 retention, leading to respiratory acidosis.
• Bradycardia and hypotension are the most concerning symptoms in a patient with respiratory acidosis.
• Severe acidosis can depress cardiac function, leading to bradycardia and hypotension.
• For a patient hyperventilating due to anxiety the nurse should expect ABG findings of: pH 7.48, PaCO2 30 mmHg, HCO3- 24 mEq/L.
• Hyperventilation leads to respiratory alkalosis, characterized by increased pH and decreased PaCO2.
• Hyperventilation is the primary compensatory mechanism for metabolic acidosis.
• The lungs compensate by increasing CO2 excretion through rapid breathing.
• Salicylate poisoning can cause metabolic acidosis.
• Salicylates increase acid production, leading to metabolic acidosis.
• For a patient with metabolic alkalosis administer potassium supplements.
• Hypokalemia often accompanies metabolic alkalosis and requires correction.
• Prolonged vomiting is a cause of metabolic alkalosis.
• Loss of gastric acid through vomiting increases bicarbonate concentration, leading to metabolic alkalosis.
• ABG results: pH 7.38, PaCO2 52 mmHg, HCO3- 30 mEq/L indicates fully compensated respiratory acidosis.
• In fully compensated respiratory acidosis a normal pH with increased PaCO2 and increased HCO3- indicates full compensation.
• Kussmaul respirations are most indicative of metabolic acidosis.
• Deep, rapid breathing (Kussmaul respirations) is a hallmark of metabolic acidosis.
• A lab value that supports a diagnosis of metabolic alkalosis: pH 7.50, PaCO2 48 mmHg, HCO3- 32 mEq/L
• Increased pH and increased HCO3- indicate metabolic alkalosis.
• In metabolic acidosis, the lungs hyperventilate to blow off CO2.
• The lungs compensate by increasing CO2 excretion.
• ABG values indicating partially compensated metabolic acidosis: pH 7.29, PaCO2 30 mmHg, HCO3- 18 mEq/L.
• Low pH confirms acidosis and low HCO3- confirms metabolic origin.
• The low PaCO2 suggests partial respiratory compensation.
• A patient with metabolic acidosis due to diabetic ketoacidosis (DKA) will most likely exhibit ABG result of: pH 7.28, PaCO2 30 mmHg, HCO3- 18 mEq/L. A decreased pH, decreased HCO3-, and compensatory decrease in PaCO2 indicate metabolic acidosis with respiratory compensation.
• Instruct the patient to breathe into a paper bag as a nursing intervention for a patient with respiratory alkalosis due to hyperventilation.
• Breathing into a paper bag increases CO2 levels, helping correct respiratory alkalosis caused by hyperventilation.
• Nasogastric suctioning is most likely to cause metabolic alkalosis
• Loss of gastric acid through suctioning or vomiting can lead to metabolic alkalosis.
• ABG results of a patient with a pH of 7.31, PaCO2 of 40 mmHg, and HCO3- of 18 mEq/L indicates metabolic acidosis.
• Low pH and decreased HCO3- indicate metabolic acidosis.
• ABG values: pH 7.45, PaCO2 30 mmHg, HCO3- 20 mEq/L indicates fully compensated respiratory alkalosis.
• In fully compensated respiratory alkalosis the pH is normal but on the alkaline side, the PaCO2 is low, and the HCO3- is low, indicating full compensation.
• When a patient with metabolic acidosis due to renal failure is receiving sodium bicarbonate therapy, assess for symptoms of fluid overload.
• Sodium bicarbonate therapy can cause fluid overload due to sodium retention.
• Pulmonary embolism is one of the conditions that can cause respiratory alkalosis.
• A pulmonary embolism can lead to hyperventilation, resulting in CO2 loss and respiratory alkalosis.

This lesson covers the interpretation of arterial blood gas (ABG) results, focusing on respiratory acidosis and alkalosis. It explains the underlying mechanisms, such as hypoventilation in COPD leading to CO2 retention, and hyperventilation as a compensation for metabolic acidosis. Also highlights the importance of recognizing symptoms like bradycardia and hypotension.