What is Bronchopulmonary Dysplasia?
Bronchopulmonary dysplasia is a chronic damage to the lungs in premature babies, which is caused by oxygen and prolonged artificial ventilation of the lungs.
Such a diagnosis is made while maintaining the need for additional oxygen in the newborn, in children who were born prematurely (in the 36th week of gestation), and who have not identified other diseases that may be lacking in oxygen produced by breathing normal air ( congenital heart disease, pneumonia).
Among premature babies, this disease is more common. Also at risk are babies with interstitial pulmonary emphysema, increased airway resistance, high peak inspiratory pressure, high pulmonary artery pressure. It is worth noting that among boys, this disease is more common compared with girls.
Bronchopulmonary dysplasia in premature and full-term babies is suspected if the patient cannot be removed from mechanical ventilation or oxygen therapy. The child has increased hypoxemia, oxygen demand, and hypercapnia increases. Under the latter condition implies, as it were, poisoning of the body with carbon dioxide, this is a special case of hypoxia.
X-ray methods can detect diffuse darkening, which occurs due to the accumulation of exudate. Later, the image is multicystic, has a similarity with a sponge, scars, emphysema and atelectasis develop in the affected areas. There is also a possibility of desquamation of the alveolar epithelium, neutrophils, macrophages and inflammatory mediators, which are found in the tracheal aspirate.
Causes of Bronchopulmonary Dysplasia
Bronchopulmonary dysplasia of infants was first considered by physicians as the negative effect of oxygen and mechanical ventilation. Today, this diagnosis is considered to be a polyetiological disease.
Factors of development of bronchopulmonary dysplasia:
- toxic effect of oxygen
- immaturity lung premature baby
- lung barotrauma
- respiratory disorders
- pulmonary hypertension
- hypovitaminosis A and E
- hereditary factors
- pulmonary edema
Immaturity lung premature baby
The frequency and severity of bronchopulmonary dysplasia correlates with the body weight of the newborn and the period of gestation by the mother. 73% of babies who weighed up to 1 kg at birth were diagnosed with bronchopulmonary dysplasia. The incidence among children born with a mass of from 1 to 1.5 kg, about 40%. Diagnoses, given the period of child rearing (gestational age), speak of bronchopulmonary dysplasia of newborns, if the baby was born before the 28th week.
Toxic effect of oxygen
Oxygen matters in the early stages of the disease. Hypoxic damage to the lungs causes necrotic processes in the epithelium of the child’s respiratory tract, in the endothelium of the lung capillaries, in the transformation of type 2 alveolocytes into type 1. Oxidative attack causes pulmonary hypertension and atelectasis, it is worth noting that mucociliary clearance is also impaired.
Barotrauma of the lungs
When breathing a significant amount of oxygen, a child has epithelial damage, which is a cell barrier, and protein-containing edema develops in the lungs. There is a need to give the child with artificial ventilation even more oxygen. This forms a vicious circle, because the damage to the lungs only aggravates it.
If microorganisms settle in the child’s airway, he or she has a higher risk of developing bronchopulmonary dysplasia. Some pathogens can lead to chorionamnionitis, too early childbirth, lung lesions, for example, bronchial hyperresponsiveness, inflammation of the bronchi, inactivation of surfactant. A secondary infection develops when the hospital-acquired flora enters the lungs during tracheal intubation.
Pulmonary edema can be caused by excessive volume of infusion therapy, the presence of an open arterial duct, and impaired fluid removal.
Pathogenesis during Bronchopulmonary Dysplasia
The pathogenesis begins with the exposure of damaging stimuli, which were named above (for example, overloading the vascular bed with volumetric blood flow, ischemia-reperfusion, etc.). Further, these agents cause local damage, which results in cell destruction and cell death. The body’s signal system responds by triggering an inflammatory process, swelling of the lung tissue occurs.
Alveolitis is resolved in some patients, and in others it persists, which causes bronchopulmonary dysplasia in premature and full-term newborns. Further, in the pathogenesis of the disease under consideration, the entry of mononuclear cells and the proliferation of fibroblasts with subsequent fibrosis follow. together with the processes described above, the structure of the lungs changes – the morphology of the respiratory tract with inflammation, metaplasia, and smooth muscle hypertrophy. The capillary blood flow is reduced with the development of arterial smooth muscle hypertrophy hypersensitive to humoral stimuli.
Symptoms of Bronchopulmonary Dysplasia
A typical symptom is too frequent breathing of the baby. He makes more than 60 breaths / breaths per minute, which is called in science rapid breathing movements. A mother may notice shortness of breath, and in the lungs, doctors listen to weakened or harsh breathing of the lungs. There are also wet rales in the lungs.
If at a bronchopulmonary dysplasia a newborn develops respiratory failure, then auxiliary muscles take part in breathing. When you inhale, the areas between the ribs are drawn in, there is a retraction of the supraclavicular fossa, the inflation of the wings of the nose. Also, blue skin is observed in the area of the nasolabial triangle, then cyanosis of the legs and arms begins, and then the torso.
Diagnosis of Bronchopulmonary Dysplasia
Anamnesis is important for diagnosis. Births for up to 32 weeks, carrying out mechanical ventilation in the neonatal period, indicate a bronchopulmonary dysplasia in a child. Clinical data is also important. The child has a need for oxygen (children up to 28 days of life).
Doctors conduct an examination to record shortness of breath and rapid breathing. It is also necessary to apply auscultation of the lungs, listening to breathing noises and moist rales. A radiograph shows the replacement of connective lung tissue, which is a typical sign of edema and fibrosis. In some cases, consult a pulmonologist.
Treatment of Bronchopulmonary Dysplasia
Supportive treatment includes the following components:
- fluid restriction
- nutritional support
- inhaled bronchodilators (not always)
- diuretic administration
It is important to diagnose and immediately treat respiratory infections in infants up to 28 days. The goal of therapy is to remove the child from artificial respiration and oxygen support as early as possible.
Caloric intake is calculated by the formula: 120 or more kcal per 1 kg of a child’s body per day. Calorie content should be increased compared with the norm, because extra work is given to breathing, and the lungs require recovery and development. Reception baby fluid limit to avoid pulmonary edema and plethora. Doctors may prescribe diuretics: chlorothiazide, 10-20 mg per 1 kg of the patient’s body per day + spironolactone, 1-3 mg / kg 1 time per day or in 2 doses. Furosemide is effective, which is administered intravenously at 1-2 mg / kg, intramuscularly at 1-2 mg / kg or by oral administration at 1-4 mg / kg after 12-24 hours for newborns and after 8 hours for children of older age. It can be used for a short time, because long courses cause hypercalciuria and, as a result, osteoporosis, fractures and the formation of kidney stones. Water electrolyte balance monitoring is required during diuretic treatment.
Severe forms of bronchopulmonary dysplasia of newborns can cause the need for mechanical ventilation and oxygen therapy for several weeks or months. The pressure and fraction of oxygen in the inhaled air (FiO2) should be reduced as quickly as the child can bear, but the child should not be allowed to be in hypoxemia. Constant monitoring of arterial blood oxygenation is needed; a pulse oximeter is used for this; support at the level of greater than or equal to 88% saturation.
When a child is removed from a ventilator, there is a risk of respiratory acidosis, so you can treat it without returning to the previous IVL regimen if the pH remains above 7.25 and the patient does not have severe respiratory failure. To reduce hospitalizations due to RSV, passive immunization with monoclonal antibodies to the respiratory syncytial virus, palivizumab, is performed. But this measure costs a lot of money, it is used mainly for children from high-risk groups.
From November to April, children are given an antiviral drug at a dosage of 15 mg per 1 kg of the child’s body after 1 month, until 6 months have passed after treatment for an acute illness. Children older than 6 months should also be vaccinated against the flu.
Prognosis of bronchopulmonary dysplasia
The prognosis depends on the severity of the disease. The probability of death in children who at 36 weeks of gestation are still on the ventilator is between 20 and 30% in the first 12 months of life. Children with bronchopulmonary dysplasia have 3-4 times higher frequency of growth retardation and neuropsychic development.
In children with bronchopulmonary dysplasia for 3-4 years, there is an increased risk of developing lower respiratory infections. They quickly develop respiratory decompensation, if there is an infectious process in the lung tissue. The child should be hospitalized when a respiratory failure or respiratory infection clinic is detected.
Prevention of Bronchopulmonary Dysplasia
To prevent this disease can be, if you quickly reduce the parameters of mechanical ventilation to a level that is the minimum tolerated by the child. Next you need to remove the child from the ventilator. It is important to use aminophylline as a breath stimulant early in order to avoid intermittent forced ventilation for preterm.
Doctors as a prophylaxis can prenatally assign glucocorticoids. If a baby has a very low body weight at birth, surfactant is prescribed. Important early correction of the open canal duct and the avoidance of large volumes of fluid to reduce the severity and frequency of bronchopulmonary dysplasia. If the child cannot be removed from artificial ventilation of the lungs in tedious periods, nosocomial pneumonia and an open canal of the duct should be excluded.