Aspiration of meconium in childbirth

Aspiration of meconium in childbirth can cause the development of chemical pneumonitis and mechanical bronchial obstruction, resulting in the development of respiratory failure. At inspection reveal tachypnea, wheezing, cyanosis or desaturation.

The diagnosis is suspected if, after childbirth with meconium stained amniotic fluid, the child develops a respiratory insufficiency, the diagnosis is confirmed by chest x-ray. Treatment of aspiration of meconium during childbirth involves suctioning the contents from the mouth and nose immediately after birth before the baby takes the first breath, and then, if necessary, respiratory support is provided. The prognosis depends on the underlying physiological stressors.

[1], [2], [3], [4]

The causes of aspiration of meconium in childbirth

Physiological stress during labor and delivery (due to hypoxia caused by compression of the umbilical cord or placental insufficiency or infection) can cause meconium to escape into the amniotic fluid before the birth of the child; departure of meconium is noted in about 10-15% of births. During childbirth, about 5% of children who have left meconium, aspirate meconium, provoking lung damage and the development of respiratory failure, which is called meconium aspiration syndrome.

Displaced children born in conditions of malnutrition are at risk of more severe forms of the disease, because less dilute meconium more often causes airway obstruction.

Predisposing factors:

• preeclampsia, eclampsia;
• arterial hypertension;
• pregnancy overstretch;
• diabetes maternal diabetes;
• decreased motor activity of the fetus;
• intrauterine growth retardation;
• smoking of mother;
• chronic diseases of the lungs, cardiovascular system.

The mechanisms by which aspiration induces the development of a clinical syndrome likely include cytokine release, airway obstruction, inactivation of the surfactant, and / or chemical pneumonitis; the underlying physiological stressors can also make a difference. If there is complete bronchial obstruction, as a result, atelectasis develops; partial blockade leads to the emergence of an air trap, when inhaling air enters the 
alveoli, and when exhaled it can not leave, which leads to overgrowth of the lungs and the possible appearance of pneumothorax with the development of the pneumomediastenum. Continuing hypoxia can lead to persistent pulmonary hypertension in newborns.

Also, during delivery, babies can aspirate the original lubricant, amniotic fluid or blood of the mother or fetus, and then respiratory failure and signs of aspiration pneumonia on the chest X-ray may develop.

Treatment is supportive; if you suspect a bacterial infection, you should make crops and start antibacterial therapy.

Pathogenesis

Hypoxia and other forms of intrauterine fetal stress provoke an increase in the intestinal peristalsis, relaxation of the external anal sphincter and the departure of meconium. With increasing gestational age, this effect is enhanced. That is why when OPV staining with meconium in the case of the birth of a premature baby, it should be considered that he suffered a more severe hypoxia than a born babe.

Appearance of hypoxia in the fetus of convulsive breaths in the ante- or intranatal periods can lead to aspiration of the meconial waters. The penetration of meconium into the distal parts of the respiratory tract causes their complete or partial obstruction. In areas of the lungs with complete obstruction, atelectasis is formed, with partial obstruction, the formation of "air traps" and the overgrowth of the lungs (valve mechanism), which increases the risk of air leakage to 10-20%.

In the development of aspiration pneumonia, two factors play a role: bacterial - due to the low bactericidal effect of mechanical OPV - and chemical - due to mechanical effects on the mucous membrane of the bronchial tree (pneumonitis). There is edema of bronchioles, narrowing the lumen of small bronchi. Uneven ventilation of the lungs due to the formation of areas with partial airway obstruction and associated pneumonia cause pronounced hypercapnia and hypoxemia. Hypoxia, acidosis and bloating cause an increase in vascular resistance in the lungs. This leads to right-left shunting of blood at the level of the atria and arterial duct and further deterioration of oxygen saturation of blood.

Symptoms of aspiration of meconium in childbirth

Symptoms of meconium aspiration can be different, it depends on the severity of hypoxia, the amount and viscosity of aspirated amniotic fluid. As a rule, children are born with a low rating on the Apgar scale. In the first minutes and hours of life, oppression of CNS functions associated with perinatal hypoxia is noted.

Aspiration of a large amount of amniotic fluid in a newborn causes acute airway obstruction, which is manifested by deep convulsive breaths, cyanosis and gas exchange disorders.

When aspiration by amniotic fluid in the distal parts of the respiratory tract without complete obstruction develops SDR, which is due to increased resistance to the airways and the formation of light "air traps". The main symptoms of this condition are tachypnea, swelling of the wings of the nose, intercostal involvement and cyanosis. In some children without acute airway obstruction, clinical manifestations of meconium aspiration may appear later. In such cases, immediately after birth, an easy SDR is noted, the manifestations of which grow after a few hours as the inflammatory process develops. When the "air traps" are formed in the lungs, the anteroposterior size of the thorax considerably increases. Auscultation is determined by different-calibrated wet wheezing and stridor breathing.

With a favorable current even in the case of massive aspiration, the radiograph is normalized to the 2nd week, but increased pneumonia of the lungs, fibrosis areas, pneumatology can last several months. Mortality in aspiration of meconium in case of untimely sanation of the tracheobronchial tree reaches 10% due to complications (air leakage, infection).

Symptoms of meconium aspiration include tachypnea, swelling of the wings of the nose, traction of the pliable areas of the chest, cyanosis and reduced saturation, wheezing and greenish-yellow staining of the umbilical cord, nail bed and skin. Meconial staining can also be noticeable in the oropharynx and (with intubation) in the larynx and trachea. Newborns with the development of an air trap may have a barrel chest, as well as symptoms and signs of pneumothorax, interstitial emphysema and pneumomediastinum.

Diagnosis of meconium aspiration in childbirth

The diagnosis is suspected if the newborn has signs of respiratory failure during childbirth with meconial staining of amniotic fluid, and is confirmed by chest radiography, revealing hyperventilation with areas of atelectasis and flattening of the diaphragm. You can see the fluid in the interlobar regions and the pleural cavity, as well as detect air in the soft tissues and mediastinum. Since meconium can provoke bacterial multiplication, and meconial aspiration syndrome is difficult to distinguish from bacterial pneumonia, blood and aspirate from the trachea should also be sown.

[5], [6], [7]

Treatment of meconium aspiration in childbirth

The emergency treatment shown to all newborns in the amniotic fluid staining of meconium includes vigorous suction of contents from the mouth and nasopharynx using the De Lee apparatus immediately after the head eruption and before the baby takes a first breath and screams. If, during suction, there are no traces of meconium in the contents, and the child looks active, observation is shown without further intervention. If the child has difficulty breathing or has respiratory depression, muscle tone is reduced or bradycardia is noted (less than 100 beats / min), tracheal intubation with a 3.5 or 4.0 mm tube should be performed. The meconium aspirator connected to the electric pump is connected directly to the endotracheal tube, which later serves as a suction catheter. Suction is continued until the endotracheal tube is removed. Repeated intubation and CPAP are indicated with persistent respiratory failure, afterwards, if necessary, the child is transferred to the ventilator and placed in the intensive care unit. Because the ADSP increases the risk of pneumothorax, regular check-ups (including physical examination and chest radiography) are important to detect these complications; they should first of all be thought of in children with intubation of the trachea, whose blood pressure, microcirculation or oxygen saturation suddenly deteriorate.

Additional treatment for meconium aspiration in childbirth may include the surfactant of children in IVL with a high oxygen demand, which may reduce the need for extracorporeal membrane oxygenation. Antibiotic therapy is indicated for aspiration of meconium, as it promotes bacterial growth. Begin with cephalosporins and aminoglycosides. Often in children with meconium aspiration, pulmonary hypertension, hypovolemia, pathological acidosis, hypoglycaemia, hypocalcemia, etc. Are noted in the first day of life. It is necessary to control the level of glycemia, acid-base state (CBS), ECG, arterial pressure, basic electrolytes with their subsequent correction. As a rule, children are not fed on the first day; from the 2nd day of life, it is advisable to begin enteral feeding with the help of a nipple or probe, depending on the severity of the condition. If enteral feeding is not possible, infusion therapy is performed.

Treatment of air leakage syndrome, complications of the air trap, is discussed below.

Prevention

Prevention begins with the identification of the foregoing predisposing factors and their correction. During labor with a high risk of fetal hypoxia, the fetus is monitored. If the results of the assessment indicate a critical condition of the fetus, delivery is indicated in the most appropriate way (caesarean section, obstetric forceps).

Dispensary supervision

Clinical follow-up of children who have undergone meconium aspiration is performed by a district pediatrician (once a month), a neurologist and an oculist (once every 3 months).

[8], [9]

What prognosis does meconium aspiration in childbirth have?

Aspiration of meconium in labor usually has a favorable prognosis, although there are differences depending on the underlying physiological stressors; the overall mortality rate is slightly increased. Children with meconium aspiration syndrome may be at increased risk of developing further asthma.