Post hypercapnic alkalosis (PHA) is frequently overlooked as a complication of acutely intubated & mechanically ventilated patients with COPD exacerbations.
HOW DOES IT WORK?
Post hypercapnic alkalosis refers to patients who are hypercapnic (chronic CO2 retainers) and develop a compensatory metabolic alkalosis due to renal bicarbonate (HCO3) retention. After they are intubated, their Pco2 is corrected rapidly, however their chronically elevated bicarbonate remains. This generates a metabolic alkalosis that is typically slow to fall.
B F Palmer and R J Alpern. Metabolic alkalosis. JASN. September 1, 1997 vol. 8 no. 9 1462-1469
Banga A., Khilnani GC. Post-hypercapnic alkalosis is associated with ventilator dependence and increased ICU stay. COPD. 2009 Dec;6(6):437-40.