Definition Initially described in 1967 by Northway using clinical, radiographic, and histologic lung changes in the preterm infant who had been treated with oxygen and ventilator therapy. (Average age 34 wks, wt 2.2 kg.)
Definition Definition initially required an oxygen requirement at 28 days and an abnormal chest radiograph. Currently, most authors define BPD as an oxygen requirement at 36 wks CGA because of the increasing survival of the ELBW infant.
Incidence A review of Surfactant trials demonstrated a significant differences in incidence depending on the institution and definition used (17-57%).
Incidence The incidence however changes dramatically with BW/GA increasing from @7% in the 1001-1250 gm BW infant to @64% in the 501-750 gm BW infant.
Risk Factors Major risk factors Prematurity Genetic predisposition (male, white, family history of atopy and asthma, HLA-A2) Fluid overload Patent ductus arteriosus Infection Inflammation Air leak Mechanical ventilation Oxygen Malnutrition
Pathophysiology BPD is a mutifactorial disorder beginning with an acute lung injury in a susceptible host followed by continued injury and abnormal repair.
Pathophysiology Lung injury can occur as a result of any of the following.
Pathophysiology Surfactant deficiency Results in collapse of saccules Distention of distal alveolar ducts Maldistribution of ventilation
Pathophysiology Pulmonary Edema Almostalways present in RDS Worsened by hypoproteinemia and increased pulmonary blood flow (think PDA)
Pathophysiology Oxygen Exposure Prolonged exposure to high [ ] can lead to epithelial and endothelial cell damage, cilliary dysfunction, decreased lung lymph flow, altered surfactant synthesis, and inhibition of lung growth
Pathophysiology Oxygen Free Radicals Inadequate concentrations of antioxidants may predispose the premature infant to cell membrane destruction and the unraveling of nucleic acids
Pathophysiology Mechanical Ventilation Volutrauma (Thought to provoke a complex inflammatory cascade that ultimately leads to BPD) Barotrauma (Increased pressure is transmitted to terminal bronchioles and alveolar ducts, dissects into the interstitium where it is trapped, resulting in PIE)
Pathophysiology Mechanical Ventilation How many breaths do you deliver to a newborn infant at a rate of 30 bpm? (commonly seen in the NICU…)
Pathophysiology Mechanical Ventilation Important to note that there is ample evidence demonstrating that excessive airway pressures associated with large tidal volumes can trigger the inflammatory cascade in the lungs – the overdistention of the lungs induces increased pulmonary vascular resistance with retention of neutrophils and release of inflammatory mediators
Pathophysiology Infection Often seen following the “honeymoon” period (the several days after exogenous surfactant treatment when often minimal or no oxygen supplementation is needed Increased risk of BPD seen in babies of mothers who have chorioamnionitis
Pathophysiology Infection Neutrophils, macrophages, leukotrienes, platelet-activating factor, interleukin-6, interleukin-8, and tumor necrosis factor have all been found in high concentrations in infant who developed BPD
Pathophysiology Infection Inconsistent reports that colonization with Ureaplasma urealyticum may predispose and infant to BPD
Pathophysiology Inflammation The inflammatory process begins with an initial stimulus, (oxygen free radicals, pulmonary barotrauma, infectious agents, etc…) and progresses with leukocyte infiltration and a cascade of destruction and abnormal repair – leading to the development of chronic lung disease
Pathophysiology Nutrition The sick premature infant has an increased nutritional requirement because of increased metabolic needs and rapid growth requirements – if the needs are not met the infant will develop a catabolic state, probably a major contributing factor in the pathogenesis of BPD
Pathologic Changes Early changes include areas of altelectasis filled with proteinacious fluid alternating with areas of overexpansion
Pathologic Changes Continued airway injury is seen as a loss of epithelium and cilia
Pathologic Changes Late findings include interstitial fibrosis, cystic dilatation, atelectasis, intersitial edema, and lymphatic distention
Diagnosis BPD is predominately a disorder of the surviving extremely premature infant, although it can be seen in the term infant with respiratory failure.
Diagnosis Often preceded by significant oxygen requirements and need for mechanical ventilation beyond the first week of life.
Diagnosis Physical Examination Worsening respiratory status manifested by increased WOB, increased O2 requirement, increased incidence of apnea-bradycardia Retractions, diffuse rales, prolonged expirations Possible RV heave, single S2, or prominent P2, signifying cor pulmonale
Diagnosis Physical Examination Enlarged liver secondary to right heart failure, or displacement secondary to hyperinflation
Diagnosis Laboratory and Radiographic Studies ABG may reveal CO2 retention (although pH is often normal with chronic lung disease - ) Abnormalities in the electrolytes may be the result of the retained CO2 (elevated bicarbonate), diuretic therapy (hypo-Na, hypo-K, and hypo-Cl), and fluid restriction (elevated BUN & Cr)
Diagnosis Laboratory and Radiographic Studies Chest X-ray can be quite variable from diffuse haziness and hypoinflation to streaky interstitial markings, altelectasis, cysts, and hyperinflation
Management The management of BPD includes the preventive measures to decrease the incidence of the disease and treatment modalities once it is present
Management Treatment Beta-2 agonist for acute exacerbations of CLD Nutrition
Prognosis Depends on the degree of pulmonary disease and the presence of other medical conditions
Prognosis Pulmonary outcome Although there is a significant risk of needing rehospitalization within the first year (@30%) and many infant with BPD have increased airway resistance and reactivity, the pulmonary outcome is good
Prognosis Neurodevelopmental outcome Children with BPD increased risk for adverse outcome compared to infants without BPD Increased hearing impairment Increased ROP Increased incidence of learning disabilities, ADHD, and behavioral problems
Which of the following CXR findings are consistent with stage 4 of BPD?A) lung appears cystic with areas of hyperinflation & areas of atelectasisB) fibrosis and edema with areas of consolidation & areas of overinflationC) low volumes with diffuse fine granular opacitiesD) opaque lung fields with air bronchograms & possibly interstitial airE) normal
Which of the following organisms have been implicated in the pathogenesis of BPD?A) MycoplasmaB) UreaplasmaC) Group B strepD) Borrelia burgdorferiE) Moraxella catarrhalis
Which statement about long term survivors with BPD (school-age) is true?A) They have an increased incidence of asthma.B) They have airway hyper-responsiveness.C) They have an increased incidence of atopy.D) They have an increased incidence of hospital admissions.
Which of the following treatments for Chronic Lung Disease has been shown to improve the long term outcome of this population (Need for ventilatory support, length of hospital stay, long term neurodevelopmental outcome)?A) BronchodilatorsB) Thiazide DiureticsC) Loop DiureticsD) Inhaled CorticosteroidsE) None of the above
Which of the following is NOT a risk factor for bronchopulmonary dysplasia?A. PrematurityB. Female sexC. Patent ductus arteriosusD. Air leakE. Mechanical ventilation
How many breaths are delivered via positive pressure toan infant on SIMV at a rate of 30 per day?• 432• 4,320• 43,200• 432,000• 4,320,000• 4.32 x 107• 4.32 x 108• 4.32 x 109