Learn with Med Nuggets: Metabolic and Respiratory Acidosis and Alkalosis

Introduction

• Slight variances outside normal pH can be life-threatening.
• Kidneys and lungs work together to correct pH imbalances.
  • Kidneys compensate for lungs, and vice versa.
• Blood pH:
  • Normal: 7.35 - 7.45
  • Acidic: < 7.35
  • Alkaline: > 7.45

Role of Lungs in pH Regulation

• Lungs regulate pH by controlling partial pressure of carbon dioxide (pCO2).
• Respiratory Compensation:
  • Fast process (minutes).
  • Regulates pCO2 by changing respiration rate/depth.
  • Decrease in respiration leads to carbon dioxide retention → Respiratory Acidosis.
  • Increase in respiration removes CO2 → Respiratory Alkalosis.

Conditions Affecting Respiratory Rate

• Increase in Respiratory Rate (Respiratory Alkalosis):
  • Panic attacks.
  • Pulmonary embolism.
  • High altitude.
  • Drug overdoses (e.g., salicylates).
• Decrease in Respiratory Rate (Respiratory Acidosis):
  • Airway obstruction.
  • Lung diseases.
  • Sedatives and opioids.
  • Strokes, diaphragm dysfunction.

Role of Kidneys in pH Regulation

• Kidneys regulate pH by altering bicarbonate ion concentration.
• Renal Compensation:
  • Slow process (days).
  • Absorb bicarbonate if blood is acidic.
  • Excrete bicarbonate if blood is alkaline.

Metabolic Acidosis

• Causes:
  • Buildup of hydrogen ions or removal of bicarbonate.
  • Ingestion of substances (e.g., ethylene glycol).
  • Diabetic ketoacidosis.
  • Chronic kidney disease (CKD).
  • Severe diarrhea.
  • Addison's disease.
  • Diuretic use (e.g., spironolactone).
  • Normal saline and total parenteral nutrition.
• Compensation: Respiratory alkalosis.

Metabolic Alkalosis

• Causes:
  • Loss of hydrogen ions or retention of bicarbonate.
  • Prolonged vomiting or nasogastric suctioning.
  • Diuretic use.
  • Hypokalemia.
  • Renal tubular disorders.
• Compensation: Respiratory acidosis.

Conclusion

• Upcoming topic: Analysis of ABG (Arterial Blood Gas) results.