Hypertonic dehydration, also known as primary dehydration or hypernatremia with reduced extracellular fluid, is characterized by more water loss than sodium loss, a serum sodium concentration of 150 mmol/L, and a plasma osmolality of 310 mOsm/L. When there is more water deficiency than sodium deficiency, the osmolality of extracellular fluid increases, antidiuretic hormone secretion is increased, renal tubular reabsorption of water is increased, and urine output is decreased. Aldosterone secretion increases, and sodium and water reabsorption increases to maintain blood volume. If water deficiency continues, the osmolarity of extracellular fluid increases further, intracellular fluid moves to the extracellular level, and eventually the degree of intracellular water deficiency exceeds that of extracellular fluid deficiency, which can eventually lead to brain cell dehydration and cause brain dysfunction. Prevention and care of high serum sodium concentration with more water loss than sodium loss: 1. Observe the vital signs, if there is irritability, rapid pulse rate, rapid respiration, etc., be alert to whether there is too much infusion or too fast infusion rate, heart failure and pulmonary edema, etc. Observe dehydration, pay attention to the child’s mental state, dryness of skin and mucous membranes, thirst, degree of sunken eye sockets and fontanelle, urine volume, number and amount of vomiting and diarrhea, etc. Compare the changes before and after treatment to determine whether dehydration is reduced or aggravated. 3.Observe the performance of acidosis, observe the color of the child’s face and breathing changes, and the presence of depression in small infants. Note that after acidosis is corrected, low calcium convulsions may occur due to plasma dilution and lower ionized calcium. 4.It is not necessary to fast, feed the child to give easily digestible liquid or semi-liquid diet, such as rice porridge, noodles, to reduce the burden of the stomach and intestines. 5, should be timely hydration, frequent diarrhea will cause rapid loss of water and nutrients in the body, resulting in acute dehydration. At home, parents can add two level spoons of sugar or half a beer bottle cap of salt to 500 ml of boiling water (or rice soup) to make oral rehydration solution to prevent dehydration. 6, you can take some drugs, such as bifidobacteria powder or capsules, to regulate the micro-ecological balance in the intestine to improve the immunity of children. 7, please do not abuse antibiotics, in fact, more than half of pediatric diarrhea is caused by viruses or due to improper diet, antibacterial drugs are not only ineffective, but will kill the normal flora in the intestine, aggravating diarrhea.