Neonatal Pneumonia
1. Dr. Zainalieva Bukatcha Janibekovna
2. Arfeen Asghar
3. Hassan Ali
4. Tahir Mehmood
5. Tausif Ansari
6. Juhaib Alam
(Teacher, International Medical Faculty, Osh State University, Kyrgyzstan)
(Student, International Medical Faculty, Osh State University, Kyrgyzstan)
(Student, International Medical Faculty, Osh State University, Kyrgyzstan)
(Student, International Medical Faculty, Osh State University, Kyrgyzstan)
(Student, International Medical Faculty, Osh State University, Kyrgyzstan)
(Student, International Medical Faculty, Osh State University, Kyrgyzstan)
Neonatal Pneumonia
Symptoms of secondary infection in newborns caused by a chemical inflammatory reaction in the lungs after inhaling amniotic fluid, meconium, or breast milk.
This entry was certified by the "Science Popularization China" Science Encyclopedia Entry Writing and Application Project .
Neonatal pneumonia can be classified into two types based on its cause: neonatal aspiration pneumonia and neonatal infectious pneumonia . The former can be further divided into amniotic fluid aspiration pneumonia, meconium aspiration pneumonia , and milk aspiration pneumonia .
1. Neonatal aspiration pneumonia
Neonatal aspiration pneumonia is a collective term for chemical inflammatory reactions / secondary infections of the lungs caused by the inhalation of amniotic fluid, meconium, or breast milk in newborns. Clinically, in addition to airway obstruction and respiratory distress as the main manifestations , chest X-rays show prolonged pulmonary inflammation. The clinical manifestations vary depending on the nature, amount, and depth of inhalation of the aspirated material.
(1) Amniotic fluid aspiration pneumonia refers to the fetus aspirating a large amount of amniotic fluid in utero or during delivery. Generally, it refers to amniotic fluid that is not contaminated, and the clinical severity is related to the amount of amniotic fluid aspirated.
(2) Meconium aspiration pneumonia is caused by the inhalation of a large amount of amniotic fluid mixed with meconium during utero or delivery. It is the most common type of aspiration pneumonia that occurs before or during delivery. It is a syndrome with respiratory distress as the main clinical manifestation. The pathological changes are mechanical obstruction and chemical inflammation of the airway . It is more common in full-term or post-term infants .
(3) Milk aspiration pneumonia refers to the inhalation of milk into the respiratory tract during swallowing, causing symptoms such as suffocation and difficulty breathing. When secondary lung infection occurs, it is similar to bacterial pneumonia . The severity is related to the amount and frequency of inhalation.
2. Neonatal infectious pneumonia
It can occur before, during, or after childbirth.
Etiology
1. Neonatal aspiration pneumonia
Neonatal aspiration pneumonia is a collective term for chemical inflammatory reactions / secondary infections in the lungs of newborns caused by inhaling amniotic fluid, meconium, or breast milk.
(1) Amniotic fluid aspiration pneumonia When fetal distress is caused by obvious intrauterine hypoxia and wheezing occurs, respiratory distress is caused by the obstruction of the terminal airway by the exfoliated epithelial cells in the amniotic fluid , followed by chemical inflammatory changes in the lungs or secondary infection.
(2) Meconium aspiration pneumonia ① In women delivered at gestational age >42 weeks, the incidence of meconium-stained amniotic fluid exceeds 30%, while in women delivered at <34 weeks, meconium is rarely expelled into the amniotic fluid. Meconium-stained amniotic fluid was once used as a synonym for fetal distress , but it is not strongly correlated with Apgar score, fetal heart rate abnormalities , or umbilical cord blood pH. Therefore, meconium-stained amniotic fluid with fetal heart rate abnormalities is a marker of fetal distress and perinatal complications. ② Normal intrauterine respiratory activity of the fetus does not lead to meconium aspiration, but in cases of fetal distress caused by significant intrauterine hypoxia, meconium can enter the small airways or alveoli when wheezing occurs . Clinically, severe meconium-stained amniotic fluid, rapid fetal heart rate, and low umbilical artery pH all suggest the possibility of meconium aspiration and require active intervention. ③ If meconium has been aspirated during utero or if the amniotic fluid is contaminated with meconium, and the meconium is not cleared from the large airways after birth, it can enter the distal airways as breathing is established. Meconium initially causes mechanical obstruction of the small airways, and complete obstruction can lead to atelectasis. When meconium partially obstructs the airway, it can produce a valve-like effect, making it easier to inhale but difficult to exhale, resulting in emphysema, which can further develop into mediastinal emphysema or pneumothorax. Due to the stimulation of the small airways by inhaled meconium, chemical inflammation and interstitial pulmonary edema can occur; in cases of chemical inflammation, emphysema can persist while lung collapse becomes more pronounced. Components in meconium that inactivate surfactant include proteases , free fatty acids , bile salts , lanugo, and other substances that can inactivate pulmonary surfactant. ④ On the basis of asphyxia and hypoxia, atelectasis, lung collapse, chemical inflammatory damage, and secondary inactivation of pulmonary surfactant caused by meconium aspiration can further aggravate lung collapse, inadequate ventilation , and hypoxia. This causes the pulmonary blood vessels to become unable to adapt to the postnatal environment, resulting in a decrease in blood pressure and a sustained increase in blood pressure, known as neonatal persistent pulmonary hypertension. This condition occurs in approximately one-third of affected infants.
(3) Milk aspiration pneumonia: Premature infants or those with bronchopulmonary dysplasia are most prone to aspiration of gastric contents ; milk aspiration is also likely to occur in infants with swallowing disorders , esophageal atresia or tracheoesophageal fistula , severe cleft palate or cleft lip , or excessive feeding amounts at each feeding. Before aspiration, local irritation causes the epiglottis to close protectively, resulting in respiratory arrest , clinically manifested as airway obstruction symptoms; after aspiration, respiratory distress and corresponding pulmonary infiltrates on X-ray are observed, and the clinical manifestations are often difficult to distinguish from infectious pneumonia. Due to pulmonary edema , hemorrhage, etc., which reduce lung compliance , secondary bacterial infection may also occur. In milk aspiration pneumonia, milk or lipid- containing macrophages can be seen in the tracheal aspirate .
2. Neonatal infectious pneumonia
Prenatal and intrapartum infections are transmitted through amniotic fluid or blood. The pathogenic microorganisms are similar to those causing pneumonia caused by inhalation of contaminated amniotic fluid in utero. Bacterial infections are mostly caused by Gram-negative bacilli, but also by group B streptococci , chlamydia trachomatis , ureaplasma urealyticum, and viruses such as CMV (cytomegalovirus ) . Postnatal infections are easily transmitted to newborns when those in direct contact with the infant have respiratory infections. In cases of omphalitis , skin infections , and sepsis , pathogens can spread to the lungs via the bloodstream, causing pneumonia. Inadequate sterilization of medical incubators, suction devices , nebulizers , and endotracheal tubes, poor aseptic technique among healthcare workers, infrequent handwashing, and the transfusion of blood products containing viruses such as CMV and HIV can all lead to infection. High-risk factors for iatrogenic infections include: ① birth weight <1500g; ② prolonged hospitalization; ③ overcrowded wards and inadequate sterilization procedures; ④ insufficient nurses; ⑤ poor aseptic technique among healthcare workers; ⑥ antibiotic overuse; ⑦ cross-infection from ventilator use; ⑧ multiple invasive procedures, endotracheal intubation for more than 72 hours, or multiple intubations. The most common pathogenic bacteria are Staphylococcus aureus and Escherichia coli . Many opportunistic pathogens , such as Klebsiella pneumoniae , Pseudomonas aeruginosa , Citrobacter, Staphylococcus epidermidis , and Acinetobacter , can also cause disease in newborns. In recent years, the positive rate of Staphylococcus epidermidis in newborns with pneumonia and sepsis in China has been increasing. In addition, anaerobic bacteria , Chlamydia trachomatis, and deep fungal infections are on the rise and should also be given attention. Respiratory syncytial virus (RSV ) and adenovirus infections are common, especially in late-term newborns. Epidemics are common, often accompanied by secondary bacterial infections. CMV infection can also occur after birth, but the condition is milder than intrauterine infection . Other pathogens, such as Pneumocystis carinii , Ureaplasma urealyticum, and Chlamydia, can also cause pneumonia.
Clinical manifestations
1. Neonatal aspiration pneumonia
(1) After resuscitation from amniotic fluid aspiration pneumonia , respiratory distress and cyanosis will appear. Fluid or foam may flow from the mouth. Moist rales can be heard on lung auscultation. The general symptoms and signs last for more than 72 hours.
(2) The severity of symptoms of meconium aspiration pneumonia is related to the nature (thin or thick) and amount of aspirated amniotic fluid. Clinically, it can range from mild respiratory distress to severe respiratory distress. After neonatal resuscitation, shallow and rapid breathing (>60 breaths/min), nasal flaring , three-recession sign , grunting, and cyanosis appear. In severe cases, respiratory failure may occur. The chest wall bulges and becomes barrel-shaped. In the early stage, coarse moist rales are heard in both lungs , followed by fine moist rales . The above symptoms and signs are more obvious 12 to 24 hours after birth. When pneumothorax or mediastinal emphysema occurs, respiratory distress suddenly worsens and breath sounds are significantly reduced; when persistent pulmonary hypertension occurs, it manifests as persistent severe cyanosis and no response to general oxygen therapy; when heart failure occurs , the heart rate increases and the liver enlarges. Clinically, respiratory distress often lasts for several days to several weeks after birth.
(3) Milk aspiration pneumonia: Sudden respiratory arrest, cyanosis, or choking after breastfeeding , with milk being aspirated from the airway; sudden onset of respiratory distress, three-recession sign, and increased moist rales in the lungs, with symptoms and signs lasting for more than 72 hours; presence of the underlying disease that caused the aspiration. Pay attention to the clinical manifestations of complications, such as secondary infection and heart failure.
2. Neonatal infectious pneumonia
In pneumonia, due to reduced gas exchange area and the effects of pathogens, varying degrees of hypoxia and toxic symptoms of infection can occur, such as hypothermia, poor responsiveness, coma, convulsions, and respiratory and circulatory failure . It can be caused by toxins , inflammatory cytokines , hypoxia, metabolic disorders , and immune dysfunction. Hypoxia can be caused by the following factors: thickening of small airways due to inflammation and edema, narrowing of the lumen, or even blockage. Complete blockage of small bronchi can lead to atelectasis. Pathogens invading and damaging the alveoli promote the production of inflammatory mediators and anti-inflammatory factors, exacerbating tissue damage, increasing fibrotic factors, and causing pulmonary fibrosis . Inflammation reduces the production and increases the inactivation of PS ( phosphatidylserine ), which can lead to microatelectasis and decreased alveolar ventilation . The formation of hyaline membrane , alveolar wall inflammation, cell infiltration, and edema cause alveolar membrane thickening, leading to expiratory respiratory failure. When cells are hypoxic, tissues cannot fully absorb and utilize oxygen. In addition, newborn fetuses have high hemoglobin and low 2,3-DPG (2,3 -diphosphoglycerate ), which easily leads to tissue hypoxia and acid-base imbalance . The intracellular enzyme system is damaged and cannot maintain normal function, which can cause inflammatory reactions and dysfunction in multiple organs, leading to multiple organ failure.
1. Neonatal aspiration pneumonia
(1) Amniotic fluid aspiration pneumonia may appear as a patchy shadow with a light density on X-ray examination, and may be accompanied by mild or moderate emphysema.
(2) Meconium aspiration pneumonia ① X-ray examination: X-ray changes are more obvious 12-24 hours after birth. Typical manifestations include scattered coarse granular or patchy, cloud-like shadows with increased density in both lungs, or accompanied by segmental atelectasis and emphysema, which may be complicated by pneumothorax and/or mediastinal emphysema; when combined with PPHN ( neonatal persistent pulmonary hypertension ) , the bronchial shadows decrease and the lung transparency increases; when combined with ARDS ( adult respiratory distress syndrome ), characteristic X-ray changes of hyaline membrane disease can be seen . The severity of chest X-ray and clinical manifestations may not be proportional. ② Blood gas analysis: Arterial blood gas shows hypoxemia, hypercapnia , and metabolic or mixed acidosis. If hypoxemia is very obvious and disproportionate to the degree of lung lesions or respiratory distress, pay attention to whether there is persistent pulmonary hypertension.
(3) X-ray examination of milk aspiration pneumonia may show widening of the hilar shadow, thickening of lung markings or patchy shadows, and may be accompanied by emphysema or atelectasis. Repeated aspiration may lead to interstitial pneumonia and even fibrosis.
diagnosis
Broadcast
1. Neonatal aspiration pneumonia
(1) Amniotic fluid aspiration pneumonia ① Medical history: history of fetal distress in utero or asphyxia after birth; ② Clinical manifestations; ③ X-ray examination.
(2) Meconium aspiration pneumonia ① Medical history: There is often a clear history of hypoxia, such as fetal distress (abnormal fetal movement and/or fetal heart rate), intrapartum asphyxia, or chronic intrauterine hypoxia; there is evidence of meconium contamination of amniotic fluid, such as meconium mixed in the amniotic fluid, placenta , and fetal fingernails , toenails, skin, umbilical cord, and meconium in oral and nasal aspirates; meconium can be seen in the aspirates at the glottis or in the trachea during endotracheal intubation. ② Clinical manifestations. ③ Relevant examinations.
(3) Milk aspiration pneumonia ① Medical history: There are often precipitating factors. It is more common in premature infants, especially those with bronchopulmonary dysplasia, swallowing coordination dysfunction, gastroesophageal reflux ; esophageal atresia or tracheoesophageal fistula; and severe cleft lip and palate. ② Clinical manifestations. ③ X-ray manifestations.
2. Neonatal infectious pneumonia
Medical History: Pay attention to inquiring about high-risk factors. These include: intrauterine infection – maternal infection history during pregnancy (primarily viral in the early stages, bacterial in the later stages), amniocentesis , chorioamnionitis , and premature rupture of membranes ; intrapartum – fetal distress, prolonged labor , foul-smelling amniotic fluid, or placental debris; postnatal – contact with patients with respiratory infections, omphalitis, skin infections, and high-risk factors for nosocomial infections such as birth weight <1500g, prolonged hospitalization, mechanical ventilation exceeding 72 hours, invasive procedures, and prolonged intravenous nutrition . Clinical Manifestations: Intrauterine infections usually present with symptoms within 3 days of birth, while intrapartum or postnatal infections usually develop after 3 days. Clinical severity varies. Mild cases only present with increased respiratory rate, while severe cases show significant respiratory distress, accompanied by groaning, frothing, irregular breathing rhythm , or apnea. Fever or hypothermia , poor responsiveness, poor feeding, and other symptoms of infection and poisoning may also be present. Moist rales may be heard in the lungs . Severe cases often present with complications such as heart failure , disseminated intravascular coagulation (DIC ), shock, persistent pulmonary hypertension, and pulmonary hemorrhage . X-ray examination is an important diagnostic basis . X-ray characteristics vary depending on the pathogen. Viral infections only show coarse lung markings or scattered patchy shadows; bacterial infections show patchy areas of increased density in both lung fields , which may be accompanied by bullae and pneumothorax . Chest X-ray changes in early-onset group B hemolytic streptococcal pneumonia are difficult to distinguish from RDS. Blood tests : In bacterial infections , neutrophils increase with a left shift, and platelets may decrease. Umbilical cord blood IgM may be elevated. Serum CRP ( C-reactive protein ) is often elevated in bacterial infections . Pathogen detection: Tracheal secretion smears and cultures, and blood cultures when necessary. Smears and cultures of gastric juice within 1 hour of birth and tracheal secretions within 8 hours of birth can indicate the pathogen causing intrauterine infection . Serum- specific IgM and pathogen PCR ( polymerase chain reaction ) detection. Blood gas analysis : To determine the type and nature of respiratory failure.
treat
Broadcast
1. Neonatal aspiration pneumonia
(1) Amniotic fluid aspiration pneumonia Symptomatic treatment: Choose head hood oxygen therapy or mechanical ventilation according to the degree of hypoxia ; Prevention and control of infection: Select broad-spectrum antibiotics against Gram-negative bacteria .
(2) The key to meconium aspiration pneumonia is to improve ventilation and oxygen therapy support. Clear the airway : For newborns with meconium- stained amniotic fluid and intrauterine distress, it is necessary to immediately assess their "vitality". "Lack of vitality" means no breathing or gasping breathing, low muscle tone , and/or heart rate <100 beats/min. Before breathing occurs after delivery, endotracheal intubation and suction should be performed immediately. Note that gastric contents should also be suctioned to avoid aspiration . For viable newborns, it is necessary to monitor them for signs such as respiratory distress and cyanosis. Monitoring and observation items: Monitor body temperature, respiration, heart rate, blood pressure, urine output , and oxygen saturation . Closely observe respiratory distress symptoms and signs, and reduce unnecessary stimulation. Chest X-ray to monitor lung lesions, and pay attention to whether there is pneumothorax or mediastinal emphysema . Oxygen therapy: When PaO2 < 60 mmHg or TcSO2 < 90%, oxygen therapy should be administered according to the degree of hypoxia, ideally maintaining PaO2 at 60–80 mmHg or TcSO2 at 92%–97%. For mild cases, nasal cannula or head mask oxygenation is recommended. When FiO2 > 0.4, CPAP ( continuous positive airway pressure ) can be used, with PEEP ( positive end-expiratory pressure ) at a pressure of 4–5 cmH2O . Caution should be exercised when clinical findings and chest X-rays indicate lung overinflation ; the pressure should not be too high. When PaO2 < 50 mmHg and PaCO2 > 60 mmHg, SIMV ( Synchronized Intermittent Mandatory Ventilation ) is commonly used . If chest X-ray shows predominantly atelectasis or blood gas analysis shows predominantly hypoxemia , the initial peak inspiratory pressure can be slightly higher by 25–30 cmH2O, the inspiratory time can be appropriately prolonged, the inspiratory/expiratory ratio can be 1:1–1.2, and the respiratory rate can be 35–40 breaths/min. If chest X-ray shows predominantly emphysema or blood gas analysis shows predominantly elevated PaCO2 , the initial peak inspiratory pressure should be slightly lower by 20–25 cmH2O , the inspiratory/expiratory ratio can be 1:1.2–1.5, and the respiratory rate can be 40–45 breaths/min. For patients who do not respond to conventional frequency ventilator use or have air leaks such as pneumothorax or interstitial emphysema , high-frequency oscillatory ventilation (8–10 Hz) may be more effective. When persistent pulmonary hypertension is present , high-frequency (>60 breaths/min) conventional ventilation can be used to maintain pH 7.45–7.55, PaCO2 25–35 mmHg, PaO2 80–100 mmHg, and TcSO2 97 %–99%. Alkalizing the blood can reduce pulmonary artery pressure and is a classic and effective clinical treatment. In addition, NO inhalation, high-frequency oscillatory ventilation, and extracorporeal membrane oxygenation ( ECMO ) have also achieved certain therapeutic effects.
(3) Milk aspiration pneumonia ① Clear the airway: Immediately suction with a suction tube or endotracheal tube to maintain airway patency. ② Improve ventilation and oxygen supply: Select the oxygen inhalation method according to the degree of hypoxia. Monitor lung lesions with chest X-ray, and pay attention to whether there is pneumothorax or mediastinal emphysema. ③ Prevent and control infection: Use broad-spectrum antibiotics, and collect tracheal secretions for bacterial culture and drug sensitivity testing . ④ Symptomatic treatment: Ensure nutrition. Mild cases can be fed small amounts frequently, while severe cases that cannot be fed require intravenous infusion, and parenteral nutrition may be necessary. Treat any complications promptly .
2. Neonatal infectious pneumonia
① Respiratory management: Nebulized inhalation , postural drainage , regular turning and back percussion, timely suctioning of oral and nasal secretions, and tracheal lavage for severe atelectasis. ② Oxygen supply : Maintain blood gas PaO2 between 50 and 80 mmHg . Mild cases are given oxygen via head mask; when hypoxia does not improve and blood gas analysis shows predominantly hypoxemia, CPAP therapy can be used; for those with blood gas PaCO2 ≥70 mmHg, or FiO2 > 0.8, PaO2 ≤50 mmHg, or recurrent apnea, mechanical ventilation is required. Because pneumonia is often accompanied by emphysema, the initial parameters should be adjusted to PIP (peak inspiratory pressure) around 20 cmH2O , PEEP 3-4 cmH2O , and respiratory rate 40-50 breaths per minute. ③ Infection control: When bacterial infection is suspected but the pathogen is unknown, third-generation cephalosporins are the first choice , and combined use may be necessary. Ampicillin can be used for group B hemolytic streptococcal infection or Listeria pneumonia . For chlamydia trachomatis and ureaplasma urealyticum pneumonia, erythromycin is the first-line treatment . For cytomegalovirus pneumonia, ganciclovir is the first-line treatment. ④ Actively treat all complications. ⑤ Provide supportive care to ensure adequate calorie and physiological needs . Feed small amounts frequently to avoid aspiration. For those unable to eat, administer intravenous fluids. Be careful not to administer fluids too quickly or too much to avoid heart failure . Intravenous immunoglobulin can be administered for 3-5 days to enhance the body's immune function .
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