11.2 Acid-Base Physiology in Children
Most aspects of acid-base physiology in children are the same as for adults and will not be repeated here. Some differences in neonates and infants are briefly indicated below. The most common acid-base problems in neonates are respiratory disorders due to respiratory insufficiency.
Many inherited disorders affecting intermediary metabolism can result in an accumulation of organic acids and these nearly all present during childhood. These are briefly considered below.
11.2.1 General Factors affecting Acid-Base Balance in Infants
depends on Gestational Age
Low Reserve to excrete
an Acid Load
11.2.2 Infantile Metabolic
As mentioned previously, a large number of different inborn errors of metabolism cause a metabolic acidosis. This may be:
Feeding difficulties often in association with tachypnoea are common in neonatal metabolic acidosis.
Some examples of organic acidoses in children are:
Some of these disorders also cause a ketoacidosis.
These inherited conditions, though individually uncommon, should be considered in any child with an acidosis especially if associated with coma. Neurological manifestations are common. Expert advice and investigation is required to sort out these disorders.
[The interested are referred to Ozand & Gascon (1991) for a review of organic acidaemias.]
Lactic acidosis can also result from enzyme defects and present during childhood. For example, pyruvate carboxylase deficiency, fructose-1,6-diphosphatase deficiency and pyruvate dehydrogenase deficiency. The lactic acidosis is not an isolated finding as these children have serious dysfunctions of organ systems esp affecting brain, liver and muscle.
Renal tubular acidosis may be hereditary and cause a hyperchloraemic acidosis in infants. Without treatment, growth retardation occurs in these children.
11.2.3 Other Acid-Base Disorders in Children