Dehydration in Infancy: Hospital Treatment
Harold E. Harrison MD1
1 Professor of Pediatrics, Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Dehydration of a degree severe enough to require intravenous replacement of water and electrolytes indicates (1) depletion of extracellular fluid sodium and water to such an extent that reduction of plasma volume results or (2) distortion of the composition of extracellular fluid with consequent disturbance of physiologic function. Such distortion may be marked hypernatremia, severe depletion of extracellular bicarbonate, or disturbances of potassium concentration resulting in either hyperkalemia or hypokalemia. In addition, hypocalcemia or hypomagnesemia may require specific replacement of these ions.
EXTRACELLULAR FLUID DEPLETION WITH HYPOVOLEMIA
The most important cause of extracellular fluid depletion in terms of frequency is loss of gastrointestinal secretions through either diarrhea or vomiting. In persons with lower intestinal obstruction, sequestration of gastrointestinal secretions in dilated loops of intestine may be sufficient to cause dehydration in the absence of vomiting. In infants with diarrhea, the onset of vomiting usually is an indication for intravenous replacement of electrolyte and water deficits. Oliguria is also an important item of information, indicating that dehydration is severe enough to require parenteral fluids. It has been estimated that hypovolemia and reduced glomerular filtration with oliguria results when about one third of extracellular fluid volume has been lost. In an infant, the normal extracellular fluid volume is 25% of body weight; therefore, a loss of 8% of body weight as extracellular fluid would result in the manifestation of severe dehydration with reduction of plasma volume.
