Neonatal Parenchymal Diseases Overview

Neonatal Parenchymal Diseases

• Neonatal parenchymal diseases are a broad category encompassing various conditions impacting the lung tissue of newborns
• These diseases are commonly associated with prematurity and/or complications related to ventilation

Bronchopulmonary Dysplasia (BPD)

• First described by Northway et al. in 1967

• Formerly known as Chronic Lung Disease of Infancy (CLDI)

• Most common chronic lung disorder in children

• Primarily affecting premature infants

• Characterized by low birth weight and prolonged mechanical ventilation

• Exposure to high oxygen concentrations during mechanical ventilation often contributes to BPD

• Presence of chronic respiratory signs, persistent oxygen requirement, and abnormal chest radiograph at 1 month or 36 weeks postconceptional age.

• Diagnostic criteria involve gestational age, time of assessment, and need for specific oxygen levels.

• Specific time points (36 weeks gestation or discharge, 28 days or age) with need for specific oxygen concentration (e.g., <30% O2 in mild BPD)

• Criteria are tailored based on gestational age (<32 weeks vs >32 weeks)

Risk Factors for BPD

• Prematurity (pulmonary immaturity) is the primary risk factor
• Hyperoxia
• Ventilator-induced lung injury
• Inflammation
• Infection

Pathogenesis of BPD

• Factors like genetic predisposition, hyperoxia exposure, inflammation, and infections all contribute to BPD.
• Disruption of key signaling pathways is central in the development of disease
• Key factors including premature birth, prenatal factors (e.g., chorioamnionitis, pre-eclampsia) and infection, ventilator-induced injuries, and hyperoxia all play significant roles.

Signs and Symptoms of BPD

• Tachypnea (rapid breathing)
• Mild retractions (inward pulling of skin between ribs/chest)
• Rales/wheezing (abnormal breath sounds)
• Peripheral edema (swelling in extremities)
• Hepatomegaly (enlarged liver)
• Jugular venous distention (increased pressure of blood in neck)
• Poor weight gain

Diagnostic Tests for BPD

• Arterial blood gas analysis (measuring oxygen and carbon dioxide levels in the blood): can show hypercapnia or hypoxemia
• Pulmonary function alterations: can include elevated minute ventilation, low tidal volume, increased airway resistance, and decreased lung compliance
• Chest CT scan
• Chest X-ray

CXR Findings in BPD

• Hyperinflation
• Low diaphragm
• Atelectasis
• Cystic changes

Diagnosis of BPD

• Based on positive pressure ventilation during the first two weeks of life for at least three days
• Clinical signs of abnormal respiratory function
• Need for supplemental oxygen beyond 28 days of age to maintain PaO2 levels above 50 mm Hg
• Chest radiograph showing diffuse abnormal findings consistent with BPD

Treatment for BPD

• Neonatal intensive care unit (NICU) monitoring and management for an average duration of 120 days
• Detailed oxygen monitoring to prevent hypoxia or hyperoxia, preventing further lung injury
• Mechanical ventilation (including nCPAP/high flow nasal cannulas and endotracheal intubation)
• Corticosteroids to reduce inflammation
• Lung fluid control: fluid restrictions, diuretics to avoid fluid buildup
• Bronchodilators
• Antibiotics to manage infections
• Nutritional support, including supplemental formulas and intravenous feedings

Complications of BPD

• Cor pulmonale (right heart failure)
• Pulmonary hypertension (high blood pressure in the lungs)

Wilson-Mikity Syndrome (WMS)

• Respiratory disease affecting premature infants, first described in 1960.
• Insidious onset over a few days to weeks following birth
• Increased severity correlates with decreased maturity

Etiology of WMS

• Pulmonary dismaturity (immature lungs)
• Abnormal ventilation/perfusion secondary to premature lung characteristics
• Microscopic examination reveals abnormalities including thickened alveolar septa, cystic emphysema, histiocytes and mononuclear cells in alveolar spaces, and incomplete capillary network development

Clinical Manifestations of WMS

• Significant cyanosis
• Tachypnea (rapid breathing)
• Retractions (chest wall inward movement)
• Wheezing (abnormal sounds during breathing)
• Cough

CXR findings in WMS

• First week: may be normal
• Acute stage: lucent foci with reticular pattern or coarse nodular appearance
• Intermediate stage: coarse streaks dominate X-ray.
• Final stage: lung fields return to normal appearance

Treatment for WMS

• Oxygen if needed
• Antibiotics if infection is present
• Steroids (as necessary)
• Digitalization in cases of congestive heart failure

Pulmonary Hemorrhage

• Acute bleeding from the lung arising from systemic or pulmonary circulation
• Can be localized or diffused

Incidence of Pulmonary Hemorrhage

• 1 in 1000 live births
• 10% of cases affecting extremely premature infants
• High mortality rate (30-40%)

Causes of Pulmonary Hemorrhage in Children

• Infection: Bronchitis, bronchiectasis, lung abscess, pneumonia
• Vascular Disorders: Pulmonary embolism, thrombosis, arteriovenous malformation, hemangioma
• Trauma: Airway laceration, lung contusion, artificial airway, suction injuries, foreign bodies, inhalation injuries
• Coagulopathy: Von Willebrand's disease, thrombocytopenia, anticoagulants
• Congenital Malformations: Sequestration, congenital pulmonary airway malformations, or bronchogenic cyst
• Miscellaneous: Catamenial, factitious, or neoplasm

Etiology of Pulmonary Hemorrhage in Neonates

• Acute pulmonary infection
• Severe asphyxia
• Respiratory distress syndrome (RDS)
• Assisted ventilation
• Patent ductus arteriosus (PDA)
• Congenital heart disease
• Erythroblastosis fetalis
• Hemorrhagic disease of the newborn
• Thrombocytopenia
• Inborn errors of ammonia metabolism
• Surfactant treatment
• Disseminated intravascular coagulation

Clinical Manifestations of Pulmonary Hemorrhage in Neonates

• Hemoptysis or blood in the nasopharynx
• Respiratory distress (similar to RDS)
• Onset: at birth or delayed
• Cardiovascular collapse
• Poor lung compliance
• Prolonged cyanosis
• Hypercapnia

CXR in Neonatal Pulmonary Hemorrhage

• Varied or non-specific: minor streaking or patchy infiltrates to massive consolidations

Treatment strategies for Neonatal Pulmonary Hemorrhage

• Blood replacement (hypovolemic shock)
• Airway clearance (suctioning)
• Intra-tracheal administration of epinephrine
• Exogenous surfactant administration
• Massive hemoptysis requires intubation and mechanical ventilation with high positive end-expiratory pressure (PEEP 8-10cmH2O)
• Unilateral double-lumen endotracheal tube, allowing for airway occlusion on affected side to facilitate ventilation of the unaffected side
• Bronchial artery embolization (treatment of choice)
• Addressing underlying etiologies

Neonatal Pneumonia

• Respiratory disease characterized by infection or inflammation of the lung
• Usually caused by viruses, bacteria, or irritants
• More common in premature infants than full-term infants
• Early-onset: occurs within hours of birth, part of generalized sepsis.
• Late-onset: occurs after the first week of life; commonly seen in neonatal intensive care units (NICU) among infants requiring prolonged endotracheal intubation.

Etiological Agents of Neonatal Pneumonia

• Neonates (<3 weeks): Group B Streptococcus, Enteric gram-negative bacteria, Streptococcus pneumoniae, Haemophilus influenzae type b, and viral agents (CMV, HSV, enteroviruses, Rubella).
• 3 weeks - 3 months: Chlamydia trachomatis, Ureaplasma urealyticum, Respiratory syncytial virus (RSV), human metapneumovirus (hMPV), Parainfluenza virus type 3 (PIV type 3), and Bordetella pertussis
• 4 months – 4 years: Respiratory syncytial virus (RSV), human metapneumovirus (hMPV), Parainfluenza virus type 3 (PIV type 3), Influenza A and B viruses, Rhinoviruses, Adenoviruses, Streptococcus pneumoniae, Hemophilus influenzae, Staphylococcus aureus, and Moraxella catarrhalis
• Older Children and Adults: Influenza A & B viruses, Adenoviruses, Streptococcus pneumonia, Mycoplasma pneumonia, and Chlamydia pneumonia

Transmission of Neonatal Pneumonia

• Perinatal/Transplacental: Hematogenous (CMV, Rubella) or transmitted from birth canal
• Ascending: vagina, amniotic fluid
• Nosocomial: fomites, secretions (Klebsiella, pseudomonas, candida)
• Community-acquired

Risk Factors of Neonatal Pneumonia

• Prematurity
• Existing lung disease (such as BPD)
• Congenital heart disease
• Environmental exposure to irritants (like smoke or wood smoke)
• Large number of siblings
• Low socioeconomic status
• Birth near RSV season
• Maternal infection

Pathogenesis of Viral Pneumonia

• Virus attaches to respiratory epithelium, directly causing injury.
• Results in swelling, secretions, debris leading to airway obstruction
• Atelectasis, interstitial edema, and ventilation-perfusion mismatch contribute to hypoxemia

Pathogenesis of Bacterial Pneumonia

• Bacteria enters lungs and causes damage and inflammation
• Organisms proliferate, spreading to adjacent areas
• This eventually leads to focal or lobar involvement

Clinical Presentation of Neonatal Pneumonia

• Increased respiratory rate
• Suprasternal, intercostal, or subcostal retractions
• Nasal flaring
• Mild/moderate dehydration
• Grunting
• Cyanosis
• Fever (in half of cases)
• Respiratory failure
• Physical examination reveals inspiratory crackles (and expiratory wheezing in viral pneumonia)

Diagnosis of Neonatal Pneumonia

• Physical examination (respiratory distress, tachypnea, secretion appearance)
• Chest X-ray (infiltrates, reticular/granular appearance, consolidation)
• Blood culture
• Pleural fluid culture and/or cultures of tracheal aspirate/nasopharynx
• ABG, Complete Blood Count (CBC) with WBC and platelet count
• Gram stains
• Serum antibodies (for viral pneumonia)

Treatment for Neonatal Pneumonia

• Antimicrobial medications (antiviral if appropriate)
• Oxygen therapy
• Airway clearance (suctioning)
• Blood transfusions if needed
• Intravenous fluids
• Adequate nutrition
• Airway management
• Mechanical ventilation

This quiz covers neonatal parenchymal diseases, focusing on bronchopulmonary dysplasia (BPD), a common chronic lung disorder in premature infants. Learn about its causes, diagnostic criteria, and characteristic features. Understand the implications of preterm birth and mechanical ventilation on lung health in newborns.