Chronic lung disease of prematurity (CLD),
formerly (and still in the USA) known as bronchopulmonary dysplasia (BPD). Advances in neonatal medicine have led to improved survival of premature babies with immature lungs and respiratory disease. Babies born at lower gestational ages are surviving into adulthood, due to therapy with antenatal steroids to prevent respiratory distress syndrome and the use of artificial surfactant to decrease the surface tension of the neonatal alveolar membrane. There have also been improvements in ventilatory techniques, and CLD usually occurs in babies who have been mechanically ventilated. Most long-term studies have been on patients before these improvements in management.
Usually caused by
barotrauma from prolonged ventilation, high-pressure ventilation, and/or ventilation with high O2 concentrations.
Premature baby remaining O2-dependent after 36 weeks post-conceptional age. Infrequent in those born at 30+ weeks and weighing >1, 200g. Mortality 25–30% with severe CLD. May require prolonged home O2 therapy, up to 1y or beyond. 50% of infants will need hospital re-admission during their first year with respiratory infection. Some have significant pulmonary sequelae during childhood and adolescence: airways hyperreactivity, persistent wheeze, chronic hypoxia, and PHT. Duration of O2 dependence predicts long-term sequelae. Majority of children with CLD do not have significant ongoing respiratory symptoms. Children may have disabilities associated with prematurity such as cerebral palsy or learning difficulties.
Cytokine-mediated scarring and repair. Early inflammatory phase: bronchial necrosis, alveolar destruction, capillary permeability, and associated obliterative bronchiolitis. Subacute fibroproliferative phase: type II pneumocyte hyperplasia, bronchial and bronchial smooth muscle hypertrophy, and interstitial and perialveolar fibrosis. Chronic fibroproliferative phase: airway remodelling for up to 1y and bronchial wall thickening. Prior to surfactant use, these changes were more severe.
Functional respiratory abnormalities persist with increased airway resistance and airway hyperresponsiveness. RV and RV/TLC are raised, indicative of air trapping. Air trapping improves over 3–4y as lung growth occurs; however, small airway abnormalities persist, at least until the age of 10. Expired NO levels are usually not raised, indicating a non-eosinophilic-driven process.
Persisting mild to moderate abnormalities, multifocal areas of reduced lung attenuation and perfusion, bronchial wall thickening, and decreased bronchus/pulmonary artery diameter ratios on CT. Radiological abnormalities correlate with physiological evidence of air trapping.
occurs commonly when persistent lung disease; complex pathophysiological factors. Tends to improve with age.
A controversial area. Wheezing is common in infants and toddlers and is often due to viral respiratory tract infections, causing a viral-induced wheeze. This has been found to be associated with passive cigarette smoke exposure, contact with other children, and not being breastfed. This transient early wheezing is distinct from childhood asthma and is presumably non-eosinophilic in origin. The children are not atopic and have no family history of such. The wheeze has resolved usually by the age of 3, although they may persist in having airway hyperactivity for many years. Children with asthma tend to have a family history of eczema with concomitant atopic dermatitis and develop their symptoms at any age, but usually slightly later (by the age of 5). Half of them have mild symptoms, which regress by puberty. Those with more severe disease, requiring regular inhaled steroids, often have disease that persists into adult life. Treatment for young children is based on persistent symptoms and atopy. Drugs which may be effective include inhaled corticosteroids and leukotriene receptor antagonists.
Gough A et al. General and respiratory health outcomes in adult survivors of bronchopulmonary dysplasia: a systematic review. Chest 2012;141:1554–67.Find this resource:
Sigurs N et al. Asthma and allergy patterns over 18 years after severe RSV bronchiolitis in the first years of life. Thorax 2010;65:1045–52.Find this resource:
Floppy trachea, usually associated with oesophageal atresia (but can occur with CLD). Rarely will require intubation or tracheostomy.
Congenital lobar emphysema
Overinflation of a lobe due to localized bronchomalacia or bronchial obstruction. May cause wheeze or produce chest deformity. Often resolves spontaneously.
A diaphragmatic defect, causing bowel to be present in the chest. This may cause respiratory distress soon after birth and may have been detected during the antenatal period by USS, or it may be completely asymptomatic and found incidentally on CXR, with bowel seen in the chest. There are two types. Bochdalek hernia is the congenital absence of posterolateral part of diaphragm, with associated hypoplastic lung due to bowel limiting growth. Treatment is with surgical repair of the diaphragmatic defect, but survival rate is only 50% due to underlying lung problems. Morgagni hernia is anteromedial herniation through the foramen of Morgagni, which is more commonly found in adulthood. It may be asymptomatic or cause symptoms of fullness, tightness, or pain in the anterior chest; it does not cause intestinal obstruction. CXR shows a cardiophrenic angle density. Surgical repair is difficult and is usually not necessary.
Cystic adenomatoid lung
Excessive overgrowth of bronchioles with multiple cysts occurring in a section of lung. Commonly affects left lower lobe. Can be diagnosed antenatally. Can present in the same way as congenital lobar emphysema. May be mistaken for diaphragmatic hernia. Treatment is by resection of the affected lobe, but there may be space-occupying effects of the abnormal lobe that can cause morbidity and mortality, e.g. due to vena caval obstruction.
Pulmonary sequestration/sequestrated segment
Segment of lung parenchyma, with no bronchial connection, that is unventilated. May be supplied by aberrant artery from the aorta and have anomalous pulmonary drainage to the right atrium. Can be intralobar, sharing pleura with the rest of the lung, or extralobar, which is separated from the lung by a lining of pleural tissue. Mostly left-sided; 75% are situated between the diaphragm and left lower lobe. Often associated with other congenital abnormalities. Can be a chance finding on CXR at any age, when cystic change may be seen in this area. Contrast CT or MRI may aid diagnosis. Surgical resection may be necessary if there is repeated infection in this segment.
MacLeod’s (or Swyer–James or Brett’s) syndrome
Hyperlucency of lung or lobe, due to parenchymal and vascular underdevelopment (obliterative bronchiolitis), following childhood bronchitis or bronchiolitis. Usually asymptomatic and is diagnosed on CXR, which shows a hypertranslucent lung with reduced vascular markings and a small pulmonary artery.