Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (613 page)

   Caused by chronic obstructive or restrictive conditions:

   Nerve disease (e.g., poliomyelitis).

   Muscle disease (e.g., myopathy).

   CNS disorder (e.g., brain tumor).

   Restriction of thorax (e.g., musculoskeletal, scleroderma, pickwickian syndrome).

   Pulmonary disease (e.g., prolonged pneumonia, primary alveolar hypoventilation).

   Acidosis is not usually severe.

   Beware of commonly occurring mixed acid–base disturbances (e.g., chronic respiratory acidosis with superimposed acute hypercapnia resulting from acute infection, such as bronchitis or pneumonia).

   Superimposed metabolic alkalosis (e.g., due to diuretics or vomiting) may exacerbate the hypercapnia.

METABOLIC ALKALOSIS

Complex disorder: The main event is either loss of H
⁺
or gain of HCO
₃
⁻
. Alkalosis will quickly be corrected by compensatory mechanisms unless some factors are acting to maintain the alkalosis.

   Causes

   Loss of acid:

   Vomiting, gastric suction, gastrocolic fistula

   Diarrhea in mucoviscidosis (rarely)