Neonatal Cold Injury Syndrome
Introduction
Introduction to neonatal cold injury syndrome Neonatal cold injury syndrome (coldinjurysyndrome), referred to as neonatal cold injury, also known as neonatal sclerosis (scleredemaofnewborn), is a comprehensive symptom, mainly caused by cold damage, mainly characterized by hypothermia and multiple organ function damage, serious The skin appears hard and swollen, more common in premature infants and cold seasons, can also occur in severe sepsis, characterized by skin, subcutaneous adipose tissue sclerosis, edema, premature, asphyxiated, infected newborns are common, severe Multiple organ dysfunction can occur. basic knowledge The proportion of illness: 0.0025% Susceptible people: children Mode of infection: non-infectious Complications: shock, diffuse intravascular coagulation
Cause
Causes of neonatal cold injury syndrome
Body factor (20%):
In neonates, especially premature infants, the body temperature regulation function has not yet fully developed, the body surface area is relatively large, the skin is thin, the blood vessels are distributed more, it is easy to dissipate heat, the subcutaneous fat is less (<1500g very low body weight children have very little subcutaneous fat), and the lack of saturated fatty acids An enzyme that becomes an unsaturated fatty acid, has a high content of saturated fatty acids in subcutaneous fat tissue, 29% of palmitic acid, and 3% of stearic acid. It is easily condensed at a slightly lower temperature, and premature infants mainly produce heat from brown fat metabolism, but This fat is not stored enough and is easily depleted.
Cold environment (15%):
Cold causes the peripheral blood vessels to contract, norepinephrine secretion increases, causing brown fat to decompose, increasing heat production to maintain body temperature, cold time is long, brown fat is depleted, chemical heat production capacity drops sharply, leading to cold injury of newborns, heart and lung function The malignant cycle of inhibition, the body temperature drops with room temperature after the delivery of the fetus; asphyxia, anesthesia, maternal sedatives, infection and birth injury and other factors can affect the body temperature regulation, and more likely to occur hypothermia.
Insufficient intake (20%):
Insufficient caloric intake in premature infants, combined with a small amount of neonatal glycogen reserves, limited sources of heat production.
Disease (10%):
Pneumonia, sepsis, diarrhea, asphyxia, severe congenital heart disease or malformation affect neonatal metabolism and circulatory function, especially in severe infections, can cause microcirculatory disorders and DIC, hypoxia, acidosis, shock can inhibit neurotransflex regulation and Brown fat produces heat.
Pathogenesis
In recent years, there has been a further understanding of the pathophysiological changes caused by low temperature. Foreign scholars have suggested that when most cells are exposed to cold, the structure of cells and intracellular membranes changes severely. Lipids first coagulate and separate from the components of the membrane, making the membrane The structure loses the permeability barrier, so the cold damage has a wide impact on the body. Domestic scholars have proposed microcirculatory disorders in the scleredema, shock and DIC pathological processes, which have changed the metabolism and function of the main organs.
1. Obstacles to body temperature regulation: After the body temperature drops to 20-25 °C, the central nervous system is inhibited.
2. Cardiovascular system: cold makes sinus node inhibition, heart rate is slow, body temperature is <28 °C, prone to arrhythmia; vasoconstriction, increased blood viscosity, increased pulmonary circulation and systemic circulation, central venous pressure rise; limb blood flow map shows affected area Blood flow amplitude drops and blood flow decreases.
3. Respiratory system: respiratory rate, ventilation and tidal volume decrease in proportion to body temperature, apnea occurs when body temperature is 16-20 °C; body temperature <25 °C pulmonary vascular tone decreases, pulmonary blood volume increases, pulmonary vascular bed decreases with body temperature And expansion, pulmonary edema and pulmonary hemorrhage.
4. Central nervous system: hypothermia causes cerebral vasoconstriction, blood flow decreases, sensation and movement disorder gradually appear, pupil dilated, coma, EEG waveform disappears when body temperature drops to 18-20 °C.
5. Blood system: As body temperature decreases, hematocrit gradually increases, plasma volume decreases, platelets and leukocytes decrease, red blood cells deform, broken red blood cells increase, red blood cell surface charge decreases, aggregation occurs easily, blood oxygenation curve shifts to the left, body temperature <29 Prothrombin time is prolonged at °C, AT-III, VII factor concentration is decreased, and fibrinolytic activity is increased to cause coagulopathy and diffuse intravascular coagulation.
6. Renal function: decrease in renal blood flow with body temperature, leading to oliguria, no urine, and increased serum creatinine.
7. Gastrointestinal tract: Intestinal peristalsis is weakened, liver detoxification function and phagocytic phagocytic activity are decreased, leukocyte chemotaxis, phagocytosis and peroxidase product function are significantly reduced, infection is likely to occur, catalase concentration is decreased, kidney, heart LDH The isozyme activity is relatively increased.
8. Metabolism: Oxygen uptake and oxygen consumption decrease in parallel with the core temperature, the respiratory quotient is lower than normal. When the core body temperature is 30 °C, the respiratory quotient drops to 0.65; the glucose metabolic rate decreases, the utilization is reduced, and hypoglycemia is easy to occur; the tissue blood flow is reduced. Oxygen-induced lactic acid accumulation, resulting in metabolic acidosis; inhibition of the respiratory center, reducing CO2 emissions, respiratory acidosis.
Prevention
Neonatal cold injury syndrome prevention
Prevention is more important than treatment.
1. Do a good job in perinatal health: do a good job in perinatal care (especially in rural areas) and education, strengthen prenatal checkups, prevent pregnancy complications, avoid premature birth, low birth weight infants and birth injuries.
2. Keep warm: In the cold season and the area, warm equipment should be assembled for the delivery room. Once the newborn is delivered, it should be wrapped with pre-warmed towels to keep warm, so that the newborn's body temperature is stable, especially for high-risk children. Enough heat.
3. Active treatment of infection: Active treatment of underlying diseases that cause scleredema, such as infection, intracranial hemorrhage, deformity, asphyxia, birth injury and so on.
Complication
Neonatal cold injury syndrome complications Complications, diffuse intravascular coagulation
Severe scleredema often occurs in shock and diffuse intravascular coagulation (DIC), low blood pressure, low heart sounds, oliguria or even no urine; often lung, digestive tract, skin mucosa and other bleeding before dying.
Symptom
Neonatal cold injury syndrome symptoms Common symptoms Scleredema edema jaundice neonatal response low shock heart failure sepsis suffocation
History
Most occur in the cold season; early neonatal and premature infants are more common; there are premature birth, asphyxia, birth injury, infection, lack of calorie supply and other medical history, most of the summer is caused by severe infection and hypoxia.
2. Symptom
(1) hypothermia: body temperature (5cm temperature in the anus) often drops to 35 ° C, severe <30 ° C, only about 26 ° C.
(2) General performance: low response, weak or low crying, difficulty in sucking, cold body and limbs, superficial breathing, weak pulse.
(3) hard swelling: the body part of the subcutaneous fat accumulation can appear hard swelling, edema or hard but not swollen, touch like rubber, common on the sides of the thigh, buttocks, calf outside, shoulders, can spread back, chest, Abdominal and buccal, severe hand and foot can also be hard, start skin redness like cooked crab color, if accompanied by hypoxia can be purple, bleeding, circulatory disorder is pale gray, with jaundice is pale yellow like wax, the condition According to the standards set by the Second National Conference on Neonatal Infants in 1999, see Table 1. Organ function changes include no eating, no crying, low response, slow heart rate or ECG, blood biochemical abnormalities, etc. Organ failure refers to shock, Heart failure, DIC, pulmonary hemorrhage, renal failure, etc., calculation of hard swelling range, 20% of head and neck, 18% of upper limbs, 14% of chest and abdomen, 14% of back and lumbosacral region, 8% of buttocks, double 26% of the lower limbs, when the body temperature <35 °C, the negative temperature difference of the sputum-anal indicates the body's heat-producing failure, 0 or positive value is not exhausted.
(4) Infection: coexisting infection often involves pneumonia, sepsis.
Examine
Examination of neonatal cold injury syndrome
1. Blood routine: There is no significant change in the total number of peripheral white blood cells. The total number of white blood cells and neutrophils may increase or decrease in different degrees. If the neutrophils are significantly increased or decreased, the prognosis is poor, and DIC is involved. Platelets are significantly reduced.
2. DIC screening test: prolonged prothrombin time of severe coagulopathy, prolonged thromboplastin time with DIC, positive 3P test, decreased fibrinogen, and the following six tests should be performed for patients with critical cirrhosis: 1) Platelet count: The platelet count is often progressively decreased, and the platelet count of about 2/3 children is <100×109/L (100,000/mm3).
(2) Prothrombin time: prolonged prothrombin time in severe cases, 20s in 4 days after birth, and 15s in day 5 and above.
(3) Time of thromboplastin: Partial thromboplastin time in white clay is >45s.
(4) Plasma thrombin time: the normal value of neonates was 19-44 s (16. s older), which was more diagnostic than the control group of the same age > 3 s.
(5) Fibrinogen: fibrinogen <1.17 g / L (117 mg / dl), < 1.16 g / L (160 mg / dl) has a reference value.
(6) 3P test (plasma protamine paracoagulation test): 65% of normal newborns have 65% fibrinolytic activity, and may have fibrin degradation products (FDP), so 3P test can be positive, still positive after 24h It is not normal, but the DIC late 3P test can be turned negative.
3. Blood biochemistry: due to refusal of milk at low temperature, increased glycogen and energy consumption, blood sugar often decreased; creatinine, non-protein nitrogen increased.
4. Blood gas analysis: With acidosis as the main performance, due to hypoxia and acidosis, blood pH decreased, PaO2 decreased, and PaCO2 increased.
5. Ultra-micro-erythrocyte electrophoresis time measurement: due to the increase of blood viscosity, the red blood cell electrophoresis time is prolonged.
6. Electrocardiogram: Some cases may have ECG changes, mainly showing prolonged QT time, low voltage, low or inverted T wave, and ST segment falling.
7. Chest X-ray: Pseudo-pneumonia can be seen scattered in patchy shadows.
Diagnosis
Diagnosis and diagnosis of neonatal cold injury syndrome
diagnosis
According to the medical history, clinical manifestations and laboratory tests can make a diagnosis, according to the extent of hard swelling, general condition, body temperature, and whether there is no shock, pulmonary hemorrhage is divided into light, moderate and severe.
1. Diagnosis of hard skin swelling
According to the size of the skin, the size of the skin is light, medium and heavy, mild: mild swelling range is less than 30%; moderate: hard swelling range is 30% to 50%; severe: hard swelling range is greater than 50%.
2. Hard swollen subcutaneous fat toughness diagnostic indexing
I degree: subcutaneous fat is slightly hard, skin color is slightly red; II degree: edema is more obvious, subcutaneous fat elasticity is basically disappeared, skin color is slightly dark red; III degree: edema is obvious, subcutaneous fat elasticity disappears, rubbery hardness, dark complexion red.
3. Diagnostic criteria for critical scleredema
According to the Trial Program for Critical Case Scoring Method prepared by the Office of Children's First Aid Project of the Ministry of Health of the Ministry of Health, the following two indicators are specified:
(1) The temperature of the anus is below 30 °C, and the degree of hard swelling is more than 2 degrees, regardless of the size.
(2) The rectal temperature is below 33 °C, the hard swelling is above 2 degrees, and the range is over 60%.
Anyone who meets one of the above two conditions can be diagnosed as critically ill.
Differential diagnosis
1. Neonatal edema: This disease needs to be differentiated from neonatal edema, neonatal edema in congenital heart disease, insufficiency, neonatal hemolysis, hypoproteinemia, hypocalcemia and vitamin B1, vitamin E deficiency is prone to occur, Newborn girls may have temporary partial labial edema. Sometimes normal newborns, especially premature babies, may occur in the back of the foot, scalp, orbital edema, and are associated with insufficient sodium and chlorine excretion.
2. Subcutaneous gangrene: It also needs to be differentiated from subcutaneous gangrene and subcutaneous fat necrosis.
