Infantile diarrhea Yi fluid metabolic disorder

Not difficult to find in clinical practice, diarrhea in children were prone to greater dehydration, electrolyte and acid-base balance disorders, this is primarily determined by physiological characteristics of children.

Normal body out of the water volume and maintain a dynamic balance of body fluids, daily consumption is proportional to the required amount of water and heat. Because children are relatively high amount of water needed each day, so the water requirements calculated according to the weight is also higher than for adults. The daily amount of water required for normal children is about 120ml/100kcal, except a few days after birth, the newborn less access to water, the age of the smaller, out of water (body external water exchange volume) is relatively more. Baby daily water exchange is equal to the extracellular fluid is about 1 / 2, while the adult is only 1 / 7, the baby’s water exchange rate than adults, 3 to 4 times faster, so children, especially infants of water-resistant force worse than adults. In pathological cases, if the water shortage, but a continuous loss of moisture, are more vulnerable to dehydration than adults.

Liquid water exchange mainly through the following three ways to complete:

(1) is not dominant water loss: no loss of water is generally more dominant constant, due to rapid growth and development in children, metabolic exuberant, the required heat larger, their non-dominant loss of water is greater, by weight of the adult rate of about two times, under normal circumstances, an average of 42ml/100kcal, in which cells and skin water loss, respectively 14ml/100kcal and 28ml/100kcal.

(2) The digestive tract of the liquid exchange: a large number of normal daily secretion of digestive juice, plasma volume is about 1 ~ 2 times, or extracellular fluid volume of 2 / 3, most of them being re-absorbed from the feces of the only a small amount, in which children with a daily discharge of water from the stool of about 8ml/100cal. When suffering from severe diarrhea, the water re-absorption of obstacles, so that a large number of water and electrolyte loss and therefore cause dehydration. Smaller children age, the digestive tract fluid exchange (secretion and re-absorption), the more rapidly, more easily than adults because of digestive dysfunction, caused by the loss of water and electrolytes.

(3) kidney micturition: normal urine vary widely, determined by renal solute load and the maximum dilution and concentration ability to make normal adult urine diluted to 50 ~ 100mOsm / L. (Specific gravity 1.003), and concentrated to 1400mOsm / L (ratio 1.035), age, smaller, more immature regulatory function of the kidney. Neonates and infants kidney enrichment capacity is poor, can only make urine concentrated to about 700mOsm / L (ratio 1.020), resulting in excretion of water required for the same amount of solute compared with adults more relatively high urine output. When the water inflow to inadequate or loss of water increases, the ability to easily exceed the limits of the kidney enrichment occurred metabolite retention and hypertonic dehydration. Metabolite retention in the body, the body can occur symptoms of poisoning, known as acidosis. In addition, the neonatal renal excretion of chloride ions, phosphate, hydrogen ions and ammonia production capacity is poor, the blood lactate levels of chlorine and high, HCO3-low, and therefore more prone to acidosis.