This webinar reviews acid–base balance, focusing on how the body maintains a stable pH (~7.4) through the carbonic acid–bicarbonate system and the Henderson–Hasselbalch relationship between bicarbonate and CO₂. When pH deviates, the body compensates via respiratory or renal mechanisms, though never fully overcorrecting.
Four primary disorders are outlined:
Respiratory acidosis: Caused by hypoventilation (↑PaCO₂, ↓pH). Kidneys compensate by retaining bicarbonate, more effectively in chronic cases.
Respiratory alkalosis: Due to hyperventilation (↓PaCO₂, ↑pH). Kidneys excrete bicarbonate over time, normalizing pH if persistent.
Metabolic alkalosis: From excess bicarbonate or H⁺ loss (↑pH, ↑HCO₃⁻). Compensation occurs via hypoventilation (↑PaCO₂), though limited by hypoxia risk.
Metabolic acidosis: From bicarbonate loss or acid gain (↓pH, ↓HCO₃⁻). Compensation is hyperventilation (↓PaCO₂), with additional buffering and renal acid excretion. The anion gap helps identify underlying causes.
Key takeaways: extreme bicarbonate values usually indicate metabolic disorders; compensation is predictable but incomplete; and mixed disorders should be suspected when values fall outside expected compensatory ranges.
