Pediatric cystic fibrosis

Introduction to cystic fibrosis in children Cystic fibrosis (CF), also known as viscous disease or mucovisicidosis, is an autosomal recessive disorder of systemic exocrine gland dysfunction in children and adults. The disease can involve multiple systems, mainly invading the respiratory tract and digestive tract. Among them, the highest incidence and mortality are lung lesions, which can account for about 95%. CF is a chronic invasive progressive disease associated with multiple comorbidities such as viscous mucus secretion, malabsorption and infection. basic knowledge The proportion of sickness: 0.01% Susceptible people: children Mode of infection: non-infectious Complications: bronchiectasis, bronchitis, pneumonia, hemoptysis

The cause of cystic fibrosis in children

Cystic fibrosis is an autosomal recessive hereditary disease, accounting for approximately 70 patients. The disease-causing gene is located on the long arm of the 7th chromosome, generally greater than 250 kb. The gene is a cystic fibrosis composed of 1480 amino acids. A gene encoding a membrane regulatory factor. One of the deletions caused a loss of phenylalanine at the F508 position. It is actually known that about 100 gene mutations can lead to a phenotype of CF. It has been possible to detect heterozygotes and prenatal diagnosis of individuals with F508 deletion. This disease mainly affects epithelial tissues and affects secretion and absorption. Among them, CFTR protein is mainly related to chloride ion transfer. 99% of the patients in this patient have elevated chloride ion concentration in sweat, but some scholars believe that CFTR is a molecule directly or indirectly related to chloride ion permeability. It is not clear how to explain the clinical symptoms of CF with abnormal chloride ion transfusion.

Prevention of cystic fibrosis in children

There is nothing to prevent, mainly early detection of early treatment.

Cystic fibrosis complications in children Complications, bronchiectasis, bronchitis, pneumonia

1. Pulmonary complication, bronchiectasis, bronchitis, bronchiolitis, pneumonia, pulmonary insufficiency, hemoptysis, pneumothorax, nasal polyps, sinusitis, reactive respiratory disease, pulmonary heart disease, respiratory failure, bronchial mucus Plug, allergic bronchopulmonary aspergillosis.

2. Gastrointestinal complication meconium ileus, meconium peritonitis, meconium-like intestinal obstruction-like diseases (non-neonatal obstruction), anal prolapse, intussusception, volvulus, appendicitis, small intestine atresia, pancreatitis, Biliary cirrhosis (hepatic portal hypertension, esophageal varices, splenomegaly and hyperfunction), neonatal obstructive jaundice, hepatic steatosis, gastroesophageal reflux, gallstones, inguinal hernia, growth retardation, vitamin deficiency (vitamins) A, K, E, D) Insufficient insulin, symptomatic hyperglycemia.

3. Other comorbidities edema - hypoproteinemia, dehydration - heat stroke, hypertrophic osteoarthrosis - arthritis, post-puberty, amyloidosis.

Symptoms of cystic fibrosis in children Common symptoms Repeated upper respiratory tract infection, bloating, chronic cough, nausea and vomiting, abnormal frequency of bowel movement, barrel-shaped chest hair, jaundice (toe), shortness of breath

The three clinical features are diffuse chronic obstructive pulmonary disease, pancreatic insufficiency and sodium and chloride concentrations in sweat are 3 to 5 times higher than normal. It can be diagnosed in the neonatal period. About half of the children are diagnosed before the age of one year, and about 80% are diagnosed within the age of five. The first symptoms are mostly stools that are not formed, increased in frequency and weight, or cough with vomiting. The clinical characteristics of 20096 patients with CF were summarized in the United States in 1995, as shown in Table 1.

1. Respiratory performance

More than 90% of children have repeated chronic infections of the upper and lower respiratory tract, including chronic bronchitis, atelectasis and repeated pneumonia. May be associated with empyema, chronic sinusitis and bronchiectasis. Infectious bacteria are more common with Pseudomonas aeruginosa and Staphylococcus aureus, and the positive rate of pathological examination in death cases is over 90%. Cough is the most common symptom, initially a dry cough, gradually accompanied by snoring. Older patients may have a worse cough in the morning and after the activity, and the mucus is mostly purulent. Some patients may have no symptoms for a long time or only show long-term acute respiratory infections. In addition, some people show chronic cough or repeated pneumonia that occurs within 1 week after birth. Bronchiolitis is often accompanied by wheezing, most common within 1 year of age, with coughing, persistent or paroxysmal wheezing and rapid breathing. When the lung lesion progresses or is aggravated repeatedly, the cough persists, the phlegm is more, the sticky is not easy to cough up; the activity intolerance occurs, the shortness of breath and the growth and development are backward. Children are getting thinner due to repeated infections with fever, restless sleep and loss of appetite. Pulmonary heart disease can eventually occur, resulting in death from respiratory failure.

Nasal mucosal inflammation, edema, and nasal polyps can cause nasal congestion and runny nose. Acute sinusitis is not common, and nasal polyps are common in patients aged 5 to 20.

The body can be seen in the barrel chest, shoulders, intercostal and clavicle depressions, clubbing (toe), lips and nails, and shortness of breath. Auscultation has wheezing sounds and dry and wet voices. Due to the increased survival rate and age of survival in recent years, pneumothorax and hemoptysis are more common than in the past. The hemoptysis of the bronchial pulmonary artery divides to form an aneurysm rupture.

X-ray examination is characterized by bronchial obstruction, inflammation and a series of images. Early emphysema and diffuse atelectasis, "finger-like" forked shadows, often with pneumonia lesions and small abscesses. Bronchiectasis is characterized by scattered small sacs. Pulmonary hypertension and pulmonary heart disease occur in the late stage, and pneumothorax can occur repeatedly.

Reduced lung capacity, lower flow rate in the middle of exhalation, later reduced tidal volume, reduced ventilation per minute, increased residual volume and functional residual capacity, decreased lung compliance, increased airway resistance, increased alveolar-arterial oxygen pressure difference, arteries PO2 reduction and CO2 retention. Major or advanced respiratory failure, pulmonary heart disease and right heart failure.

2. Digestive tract performance

In neonatal CF, 15% to 20% of meconium-induced intestinal obstruction and peritonitis are manifested as delayed bloating, vomiting, and delayed delivery of feces. X-ray showed dilated bowel, fluid level and nodule shadow, and the glassy shadow was visible in the middle and lower abdomen. Symptoms of pancreatic insufficiency can be seen in 80% of children. The child has a good appetite. Although he consumes enough milk and complementary food, his weight does not increase, and he often cries because of hunger. The frequency of bowel movements is large, and the amount is large, showing significant steatorrhea and odor. The limbs are thin and the belly is in sharp contrast. Often repeated rectal prolapse. In children with neonatal CF, cholestatic jaundice may occur with liver function, and cirrhosis, portal hypertension, and hypersplenism may occur in elderly children. Fatal gastrointestinal bleeding, pancreatic exocrine deficiency and malabsorption can occur, such as hypoproteinemia, edema, dystrophic anemia, growth retardation, fat-soluble vitamin deficiency, hypolipidemia and hypocholesterolemia disease.

3. Other

Only 2% to 3% of patients have symptomatic biliary cirrhosis, which is characterized by jaundice, ascites, esophageal varices, hematemesis, and hypersplenism. In addition to insufficient pancreatic gland function, it can also have hyperglycemia, diabetes, polyuria and weight loss. Gonadal development is delayed with an average delay of 2 years. About 95% of men have azoospermia because the Wolffian tube is not developing. The incidence of inguinal hernia, scrotal hydrops and testicular undescending is higher than normal. Women can have cervicitis. Young children may lose too much salt due to sweating, "salt cream" on the skin or odor on the skin. This disease can be manifested as hypochlorine alkalosis.

Examination of cystic fibrosis in children

Blood gas analysis

Alveolar-arterial oxygen partial pressure difference increased, arterial PO2 decreased and CO2 retention.

2. Sweat chlorine test patients increased sweat sodium chloride. The method of collecting sweat is the most accurate using the pilocarpine (pilocarpine) ion permeation method. Collect sweat after stimulating sweat glands (at least 0.1 to 0.5 m1). Chlorine is then measured by titration and sodium and potassium are measured by flame photometry. For example, adrenal insufficiency can be ruled out, sweat chlorine value <40mmol / L (40mEq / L) is normal; 50 ~ 60mmol / L (50 ~ 60mEq / L) is suspicious; 60mmol / L (60mEq / L) or above The diagnosis of the disease is necessary for the clinic. Sweat chlorine >60mmol / L (60mEq / L) was positive, requiring two sweat chlorine test positive.

3. Abnormal pancreatic function Duodenal fluid is small and thick, pH is lowered, hydrogen carbonate ion is low, trypsin is lacking or only a small amount, trypsin test is negative, chymotrypsin, pancreatic lipase and amylase are low. 4. Fat malabsorption can be checked by the following methods:

(1) Check whether the urine contains iodine after oral administration of lipiodol: If the iodine is not included, the fat absorption is poor.

(2) Absorption of carotene or vitamin A: If a large amount of vitamin A is orally administered, the carotene or vitamin A is repeatedly measured to determine the pathological condition.

(3) Serum cholesterol content: generally lower than ordinary people, also indicates poor fat absorption.

5. Other tests for bacterial culture separation of lower airway secretions; detection of gene mutations can be detected in prenatal testing and neonatal screening.

X-ray inspection

(1) Chest X-ray: characterized by bronchial obstruction, inflammation and a series of images. Early signs are general emphysema and diffuse atelectasis in both lungs. The atelectasis is lobular or large-leaf, and the latter is more common in small babies, especially in the upper right lobe. The signs of mucus embolism appear as "finger-like" bifurcated shadows that extend outward from the hilar region and are more common in the upper lobe of the lung. Most pneumonia lesions and small abscesses often appear in repeated infections, and can extend to the peripheral part of the lungs. Bronchiectasis is characterized by scattered small sacs. The hilar lymph nodes are often enlarged. Pulmonary hypertension and pulmonary heart disease occur in the late stage, and pneumothorax can occur repeatedly.

(2) Abdominal plain film: visible dilated bowel, liquid level and nodular shadow, visible glassy shadow in the middle and lower abdomen.

2. CT examination showed thickening of the bronchial wall, mucus embolism, local hypergas and early bronchiectasis.

3. Pulmonary function Early lung function abnormalities showed reduced lung capacity, lower exhalation flow rate, reflecting small airway obstruction. Later, see the tidal volume decreased, the ventilation per minute decreased, the residual gas volume and functional residual gas volume increased, lung compliance decreased, and airway resistance increased.

4. Determination of cell potential difference in nasal mucosa.

Diagnosis and diagnosis of cystic fibrosis in children

diagnosis

The diagnostic criteria for CF are:

1. Family history.

2. Typical lung disease (chronic obstructive pulmonary disease).

3. Pancreatic insufficiency.

4. Two sweat tests were positive [sweat chlorine >60mmol/L (60mEq/L)], abnormal pancreatic function, fat malabsorption, and bacterial culture of lower airway secretions.

At least 2 of the above can be diagnosed as cystic fibrosis, but the positive sweat test is necessary for the clinic. New diagnostic criteria such as detection of gene mutations and measurement of nasal mucosal cell potential differences.

Differential diagnosis

The lung lesions of this disease should be differentiated from asthma, whooping cough, chronic bronchitis or recurrent bronchopneumonia, golden pneumonia, bronchiectasis and tuberculosis. The clinical manifestations of the digestive tract should be differentiated from neonatal intestinal atresia, small infant milk allergy, 1-antitrypsin deficiency, celiac disease and loss of protein bowel disease. In addition, it should be distinguished from familial autonomic dysfunction, hypogammaglobulinemia and other immunodeficiency diseases and cirrhosis.

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