Metabolic alkalosis is a metabolic condition of increased alkaline substances in extracellular fluid and/or elevated pH due to loss of hydrogen ions (H⁺), and is characterized by an increase in plasma bicarbonate (HCO₃-). It may result in a compensatory elevation of arterial partial pressure of CO₂ (PaCO₂), which is rarely greater than 55 mmHg. However, the upper limit of PaCO₂ compensation can exceed 60 mmHg in severe metabolic alkalosis, though at present there are few such reports at home and abroad. In this article, we reported the successful rescue for a case of extreme metabolic alkalosis so as to raise the awareness of this rare clinical phenomenon.