Severe Metabolic Alkalosis: Diagnosis and Management

Definition and Measurement

• Base excess represents the amount of acid or base that would need to be added to a blood sample to normalize the pH to 7.4 at a PCO2 of 40 mmHg, providing an indirect estimation of global tissue acidosis or alkalosis due to impaired perfusion or metabolic disturbances 1, 2
• Normal base excess range is typically between -2 and +2 mEq/L; values outside this range indicate metabolic acid-base disturbances 2

Clinical Significance and Consequences

• Base excess >30 indicates extreme metabolic alkalosis, which is much more severe than the threshold for intervention mentioned in guidelines (BE > -10) 3, 4
• This degree of alkalosis can cause significant physiological dysfunction, including decreased tissue oxygen delivery due to leftward shift of the oxyhemoglobin dissociation curve 5
• Hypoventilation can occur as a compensatory mechanism 6

Management and Treatment

• Identify and treat the underlying cause of metabolic alkalosis, and restore intravascular volume with normal saline if volume depletion is present 3, 4
• Monitor arterial blood gases frequently to assess response to therapy 3, 4