Late neonatal metabolic acidosis

Introduction to metabolic acidosis in the late neonatal period Healthy newborns develop metabolic acidosis 2 to 3 weeks after birth, called late metabolic metabolicosis (newborn). Its pathogenesis is related to the quality and quantity of protein in the diet, as well as imperfect renal function development and excessive renal acid load. Typical late-stage metabolic acidosis can occur in preterm infants without other problems 2 to 3 weeks after birth, characterized by unsatisfactory weight gain associated with metabolic acidosis (BE < -8 mmol/L) (daily Weight gain <10g), these children may be asymptomatic or only excitatory, the BE value is usually between -10 ~ -16mmol / L, may also affect the growth and development of the child and the body's resistance, and even due to other serious The disease is life-threatening. basic knowledge The proportion of the disease: the incidence rate of newborns is about 0.01%-0.03% Susceptible people: children Mode of infection: non-infectious Complications: metabolic acidosis

Causes of late metabolic acidosis in neonates

(1) Causes of the disease

The production of late-stage acid is mainly caused by the imbalance between endogenous acid production and renal acid secretion, that is, the positive balance of acid production. This imbalance can be caused by the abnormal increase of endogenous protein synthesis acid. Abnormal renal acid secretion or both.

1. The quality and quantity of protein in the diet: When the total protein content in the formula is increased, the content of sulfuric acid is also increased, and the possibility of ingesting the net acid when the protein is ingested is increased; the formula with high calcium content affects the balance. It causes more hydrogen ions to be released into the body fluid. At the same time, when the synthetic alkali in the diet is increased, the net acid absorption in the intestine increases accordingly. The protein base contained in the milk protein is higher than the formula containing less protein, which is more likely to cause acidosis. The protein contains high levels of phenylalanine and methionine. In the intestines of newborns, especially in the intestines, there is a lack of enzymes that convert these two amino acids, such as casein-based milk or formula, which can make these two acids. In the blood concentration increased, blood urea nitrogen and blood ammonia also increased significantly, and acidosis, in addition, small intestinal mucosal cell disaccharidase deficiency, resulting in increased intestinal lactic acid after milk food, lactic acid absorbed into the body, Caused by lactic acidosis.

2. Insufficient acid-dissipating capacity of the kidney: Insufficient renal development in neonates, especially premature infants, plays an important role in the formation of late-stage metabolic acidosis. Premature infants have poorer ability to handle acid load within 1 to 3 weeks after birth. The reason is:

(1) Compared with normal term infants, the threshold of sodium bicarbonate in premature infants is low, premature infants <19mmol/L, term infants>21mmol/L.

(2) Premature infants have poor compensatory ability to lose sodium bicarbonate.

(3) The renal tubules excrete hydrogen ions, and the ability to lower the pH of urine is poor.

The ability of the kidney to regulate acid-base imbalance gradually increases from 4 to 6 weeks after birth, so the incidence of late metabolic acidosis in preterm infants is significantly higher than that in term infants, and the incidence of very low birth weight infants is higher.

(two) pathogenesis

Phosphorus or sulfur-containing proteins are metabolized in the body to produce a certain amount of non-volatile acids (phosphoric acid, sulfuric acid). These acids are rapidly buffered in the extracellular fluid, causing the alkali reserve HCO3 to decrease, and finally the renal tubules produce new ones by discharging H+. HCO3-(H2CO3HCO3-H+), in order to achieve acid-base balance, neonatal, especially low birth weight infants, renal dysfunction H+ ability is poor, 2 to 3 weeks after birth, children's food intake increases, such as excessive intake of phosphorus containing casein, Excessive acid load can not be excreted by the kidney, which can cause metabolic acidosis. Some people use different milk to feed the newborn. As a result, the milk and the formula of milk powder and the casein are higher, which makes the low birth weight. The incidence of late-stage metabolic acidosis (LMA) increased, whereas breast milk and Prenan formula, the protein concentration and casein ratio were lower, and the incidence of late metabolic acidosis (LMA) was lower.

Neonatal late metabolic acidosis prevention

1. Advocate breastfeeding, early feeding should promote breastfeeding for newborns, especially premature infants.

2. Choose the right dairy product: use milk powder from premature infants. If you have to use artificial feeding, you should choose protein with whey protein-based formula. Studies have shown that changing the ingredients of formula milk health search, such as increasing potassium citrate Calcium chloride and calcium carbonate health search or calcium lactate, or low-phosphorus formula can reduce the net acid excretion of kidneys in premature infants [net acid excretion, urinary anion (chloride phosphate sulfate, The difference between the total amount of organic acids and the total amount of cations (Na, K, Ca, Mg)], thereby effectively preventing or reducing the occurrence of late metabolic acidosis.

3. In the case of insufficient breast milk secretion, LMA still has a certain incidence rate in formula feeding with premature infants. Because, for premature infants born 2 to 3 weeks, once the weight does not increase or the growth is slow, blood gas examination should be done as soon as possible, in order to timely treatment.

Neonatal complications of metabolic acidosis Complications metabolic acidosis

Can affect the growth and development of the baby and the body's resistance, and even life-threatening due to other serious diseases.

Late neonatal metabolic acidosis symptoms common symptoms sleepiness, loss of appetite, metabolic acidosis, skin pale muscle tension reduction

Late metabolic acidosis (LMA) can be asymptomatic and can only be found in blood gas analysis. Heavier patients usually develop symptoms 2 to 3 weeks after birth, often as follows:

1. History: artificial feeding, a history of high intake of casein, especially premature infants.

2. Weight does not increase: Although the intake of calories has reached 150kcal/kg, the protein has reached 5g/kg, but the weight of sick children has increased slowly or not, especially in low birth weight infants.

3. Low response: low spirits, low crying, low appetite, pale skin, blue mouth and slightly lower muscle tone; very low birth weight infants can show drowsiness and apnea.

4. Deep breathing: In addition to some serious acidosis, the general breathing depth is not obvious.

Examination of late neonatal metabolic acidosis

The diagnosis must be based on blood gas analysis: BE often <-7mmol / L, HCO3- <15mmol / L, PCO2 compensatory slightly reduced, the pH can be reduced to <7.35 in decompensation.

1. Regular chest X-ray examination: except for lung infections.

2. Regular B-ultrasound and ECG examination: except for heart, liver, kidney and other diseases.

Diagnosis and identification of metabolic acidosis in late neonatal

Neonates with clinically healthy appearance, especially those born artificially, have an unexplained growth retardation 2 to 3 weeks after birth, blood pH <7.30, and alkali residual below -7.0 mmol/L. Metabolic acidosis in late childhood, but metabolic acidosis may occur due to infectious diseases and respiratory diseases. Therefore, the diagnosis of late metabolic acidosis (LMA) should be cautious, and the quality of protein intake should be analyzed. Whether the amount is easy to cause late metabolic acidosis; should be necessary to check, except for other possible causes; after correcting acidosis, observe whether the symptoms are improved, such as correcting the symptoms after rapid acidosis, can confirm the diagnosis of metabolic acidosis .

Because the symptoms of metabolic acidosis in the late neonatal period are non-specific, similar symptoms can occur in neonates with infectious diseases or other diseases, and metabolic acidosis can occur. Therefore, the diagnosis must be considered after other causes. This disease, such as attention to the identification of neonatal infectious diseases, respiratory diseases and so on.

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