Pneumonia is a common disease in newborns and an important cause of neonatal death. According to statistics, perinatal infectious pneumonia has a mortality rate of about 5-20%. It can occur in utero, during delivery or after birth, and is caused by different pathogens such as bacteria, viruses, and mycobacteria.
I. Etiology
1, intrauterine infectious pneumonia (also known as congenital pneumonia)
The main pathogens are viruses, such as rubella virus, cytomegalovirus, herpes simplex virus, etc. It is often caused by primary infection or latent infection reignited during the mother’s pregnancy, and the pathogen infects the fetus through the placenta via the bloodstream. Infections such as maternal bacteria (E. coli, Klebsiella, Listeria), protozoa (Toxoplasma gondii) or mycoplasma can also infect the fetus through the placenta, but it is less common.
2. Infectious pneumonia during delivery
(1) premature rupture of the fetal membranes for more than 24 hours or pathogens in the maternal birth canal infect the amniotic membrane, causing amniotic chorioamnionitis and infectious pneumonia when the fetus inhales contaminated amniotic fluid.
(2) The fetus inhales contaminated amniotic fluid or the mother’s cervical secretions through the birth canal during delivery. The common pathogens are Escherichia coli, Streptococcus pneumoniae, Klebsiella, Listeria and group B hemolytic streptococcus, etc., but also viruses and mycoplasma. Premature birth, stalled labor, and excessive inspection of the birth canal are more likely to induce infection.
3, postnatal infectious pneumonia
(1) respiratory route: contact with patients with respiratory infections.
(2) Blood-borne infection: often part of sepsis.
(3) Medical route: infectious pneumonia due to poor disinfection of medical instruments such as aspirators, nebulizers, oxygen supply masks, tracheal intubation, etc., or prolonged use of ventilators, or transmission through the hands of medical personnel. The pathogens are mostly Staphylococcus aureus and Escherichia coli. In recent years, opportunistic pathogens such as Klebsiella, Pseudomonas, Staphylococcus epidermidis, and Citrobacter have increased in infection. Viruses such as respiratory syncytial virus, adenovirus, Chlamydia trachomatis and Mycoplasma urealyticum should also be taken seriously. The use of broad-spectrum antibiotics for too long is prone to Candida pneumonia.
Second, the clinical manifestations
1, intrauterine infectious pneumonia: clinical manifestations vary greatly. Most of the onset within 24 hours after birth, there is often a history of asphyxia at birth, and after resuscitation there can be shortness of breath, moaning, dyspnea, unstable body temperature, poor response. Breath sounds on lung auscultation may be coarse, diminished, or wet rales may be heard. Severe cases may present with respiratory failure, heart failure, DIC, shock, or persistent pulmonary hypertension. Those with bloodstream infection often lack pulmonary signs and show multisystem involvement such as jaundice, hepatosplenomegaly and meningitis. There is also progression to chronic pneumonia several months after birth. Peripheral blood leukocytes are mostly normal, but may be decreased or increased. The diagnosis of prenatal infection is made by cord blood IgM >200mg/L or increased specific IgM. X-ray chest radiographs often show interstitial pneumonia changes, while bacterial pneumonia is manifested as bronchopneumonia.
2. Infectious pneumonia during delivery: The onset varies depending on the pathogen, generally from a few days to a few weeks after birth, with bacterial infections developing 3-5 days after birth, herpes virus type II infections mostly 5-10 days after birth, and chlamydial infections with an incubation period of up to 3-12 weeks. Gastric fluid smear immediately after birth to look for leukocytes and pathogens, or blood specimens, tracheal secretions, etc. for smear, culture and convective immunoelectrophoresis tests can help in pathogenic diagnosis.
3, postpartum infectious pneumonia: manifestation of fever or temperature does not rise, shortness of breath, nasal flapping, cyanosis, spitting, trismus signs; pulmonary signs are often not obvious in the early stage, the course of the disease may appear fine wet rales in both lungs. Respiratory syncytial virus pneumonia may present as wheezing, and croup may be heard on auscultation of the lungs. Bacterial culture of nasopharyngeal secretions, virus isolation and fluorescent antibodies, and serum-specific antibody tests are useful for pathogenetic diagnosis. Staphylococcus aureus pneumonia is easily combined with pneumothorax, and large pulmonary alveoli can be seen on X-ray.
III. Treatment
1, respiratory management: nebulized suction, postural drainage, regular turning, patting back, timely aspiration of oral and nasal secretions to keep the respiratory tract unobstructed.
2, oxygen supply: when there is hypoxemia, nasal catheter, mask, hood or nasal plug CPAP can be used to administer oxygen, in case of respiratory failure, mechanical ventilation is feasible to maintain the arterial blood PaO2 at 6.65-10.7kPa (50-80mmHg).
3, anti-pathogen therapy: bacterial pneumonia can be referred to sepsis selection of antibiotics. Listeria pneumonia available ampicillin; Chlamydia pneumonia preferred erythromycin; herpes simplex virus pneumonia available acyclovir; cytomegalovirus pneumonia available ganciclovir.
4, supportive therapy: correct circulatory disorders and water, electrolyte and acid-base balance disorders, the total daily infusion of 60-100ml/kg, the infusion rate should be slow to avoid heart failure and pulmonary edema; ensure adequate energy and nutrition supply, as appropriate, intravenous infusion of plasma, albumin and immunoglobulin, to improve the body’s immune function.