In a compensated respiratory acidosis, although the PCO2 is high, the pH is within normal range. The kidneys compensate for a respiratory acidosis by tubular cells reabsorbing more HCO3 from the tubular fluid, collecting duct cells secreting more H+ and generating more HCO3, and ammoniagenesis leading to increased formation of the NH3 buffer. Compensated respiratory acidosis is typically the result of a chronic condition, the slow nature of onset giving the kidneys time to compensate.
- Common causes of respiratory acidosis include hypoventilation due to:
- Respiratory depression (sedatives, narcotics, CVA, etc.) Respiratory muscle paralysis (spinal cord injury, Guillan-Barre, residual paralytics).
- Chest wall disorders (flail chest, pneumothorax) Lung parenchyma disorders (ARDS, pneumonia, COPD, CHF, aspiration)
- Abdominal distension (laporoscopic surgery, ascites, obesity, etc.).
Respiratory acidosis: Compensation