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Bronchopulmonary Bronchopulmonary Dysplasia (BPD) Dysplasia (BPD) Dr Varsha Atul Shah

Broncho pulmonary dysplasia(bpd)

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Page 1: Broncho pulmonary dysplasia(bpd)

Bronchopulmonary Bronchopulmonary Dysplasia (BPD)Dysplasia (BPD)

Dr Varsha Atul Shah

Page 2: Broncho pulmonary dysplasia(bpd)

Back groundBack ground

Develops in neonates treated with O2 & PPV . Originally described by Northway in 1967 using

clinical , radiographic & histologic criteria . Bancalari refined definition using ventilation

criteria , O2 requirement @ 28days to keep PaO2>50mmhg & abnormalities in chest x –ray .

Page 3: Broncho pulmonary dysplasia(bpd)

Back groundBack ground

Shennan proposed in 1988 criteria of O2 requirement @ 36 weeks corrected GA .

Antenatal steroids , early surfactant Rx & gentle modes of ventilation minimize severity of lung injury .

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PathophysiologyPathophysiology

Multifactorial Major organ systems - lungs & heart Alveolar stage of lung development - 36wks GA

to 18 months post conception Mechanical ventilation & O2 interferes with

alveolar & pulmonary vascular development in preterm mammals .

Severe BPD Pulmonary HT & abnormal pulmonary vascular development .

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Stages of BPDStages of BPD

Defined by Northway in 1967 Stage 1 - similar to uncomplicated RDS Stage 2 - pulmonary parenchymal opacities

with bubbly appearance of lungs Stage 3 & 4 – areas of atelectasis ,

hyperinflation & fibrous sheaths Recently CT & MRI of chest – reveals

more details of lung injury

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Frequency of BPDFrequency of BPD

Dependent on definition used in NICU . Using criteria of O2 requirement @ 28 days

frequency range from 17% - 57% . Survival of VLBW infants improved with

surfactant Actual prevalence of BPD has increased .

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Mortality/Morbidity of BPDMortality/Morbidity of BPD

Infants with severe BPD Increased risk of pulmonary morbidity & mortality within the first 2 years of life .

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Pulmonary Complications of Pulmonary Complications of BPDBPD

Increased resistance & airway reactivity evident in early stages of BPD along with increased FRC .

Severe BPD Significant airway obstruction with expiratory flow limitations & further increased FRC secondary to air trapping & hyperinflation

Page 9: Broncho pulmonary dysplasia(bpd)

Volume trauma & Volume trauma & BarotraumaBarotrauma

Rx of RDS – surfactant replacement , O2 , CPAP & mechanical ventilation .

Increased PPV required to recruit all alveoli to Px atelectasis in immature lungsLung injuryInflammatory cascade .

Trauma secondary to PPV-Barotrauma VolumetraumaLung injury secondary to

excess TV from increased PPV .

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Volume trauma & Volume trauma & BarotraumaBarotrauma

Severity of lung immaturity & effects of surfactant deficiency determines PPV .

Severe lung immaturityAlveolar number is reducedincreased PP transmitted to distal bronchioles .

Surfactant deficiencysome alveoli collapse while others hyper inflate .

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Volume trauma & Volume trauma & BarotraumaBarotrauma

Increased PPV to recruit all alveoliCompliant alveoli & terminal bronchioles ruptureleaks air in to interstiumPIEIncrease risk of BPD

Using SIMV compared to IMV in infants <1000g showed less BPD .

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O2 & AntioxidantsO2 & Antioxidants

O2 accept electrons in it’s outer ringForm O2 free radicalsCell membrane destruction

Antioxidants(AO)Antagonise O2 free radicals

Neonates-Relatively AO deficient Major antioxidants – super oxide dismutase ,

glutathione peroxidase & catalase

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O2 & AntioxidantsO2 & Antioxidants

Antioxidant enzyme level increase during last trimester .

Preterm birthIncreased risk of exposure to O2 free radicals

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InflammationInflammation

Activation of inflammatory mediatorsIn acute lung injury

Activation of leukocytes by O2 free radicals , barotrauma & infectionDestruction & abnormal lung repairAcute lung injuryBPD

Leukocytes & lipid byproducts of cell membrane destructionActivate inflammatory cascade

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InflammationInflammation

Lipoxigenase & cyclooxigenase pathways are involved in the inflammatory cascade

Inflammatory mediators are recovered in tracheal aspirate of newly ventilated preterm who later develops BPD

Metabolites of mediatorsvasodilatationincreased capillary permeabilityalbumin leakage & inhibition of surfactant functionrisk of barotrauma

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InflammationInflammation

Neutrophils – release collegenase & elastasedestroy lung tissue

Hydroxyproline & elastin recovered in urine of preterms who develops BPD

Di2ethylhexylphthalate(DEHP) degradation product of used ET tubeslung injury

A study in 1996 found that increased interleukin 6 in umbilical cord plasma

Page 17: Broncho pulmonary dysplasia(bpd)

InfectionInfection

Maternal cervical colonization/ preterm neonatal tracheal colonization of U.urealyticum associated with high risk of BPD

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NutritionNutrition

Inadequate nutrition supplementation of preterm compound the damage by barotrauma , inflammatory cascade activation & deficient AO stores

Acute stage of CLDincreased energy expenditure

New born ratsnutritionally depriveddecreased lung weight

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NutritionNutrition

Cu , Zn , Mn deficiencypredispose to lung injury

Vit A & E prevent lipid peroxidation & maintain cell integrity

Extreme prematurity – large amounts of H2O needed to compensate loss from thin skin

Page 20: Broncho pulmonary dysplasia(bpd)

NutritionNutrition

Increased fluid administration increased risk of development of PDA & pulmonary edema(PE)

High vent settings & high O2 needed to Rx PDA & PE

Early PDA Rx – improve pulmonary function but no effect on incidence of BPD

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GeneticsGenetics

Strong family history of asthma & atopy increase risk of development & severity of BPD

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CVS ChangesCVS Changes

Endothelial cell proliferation Smooth muscle cell hypertrophy Vascular obliteration Serial EKG – right ventricular hypertrophy Echocardiogram – abnormal right

ventricular systolic function & left ventricular hypertrophy

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CVS ChangesCVS Changes

Persistent right ventricular hypertrophy/ fixed pulmonary hypertension unresponsive to supplemental O2 leads to poor prognosis

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AirwayAirway

Trachea & main stem bronchi - abnormalities depend on duration & frequency of intubation & ventilation

Diffuse or focal mucosal edema , necrosis/ulceration occur

Earliest changes from light microscopyloss of cilia in columnar epithelium , dysplasia/necrosis of the cells

Page 25: Broncho pulmonary dysplasia(bpd)

AirwayAirway

Neutrophils , lymphocyte infiltrate & goblet cell hyperplasiaincreased mucus production

Granulation tissue & upper airway scarring from deep suctioning & repeated ET intubation results in laryngotracheomalacia , subglottic stenosis & vocal cord paralysis

Page 26: Broncho pulmonary dysplasia(bpd)

AirwayAirway

Necrotizing bronchiolitis – results from edema , inflammatory exudate & necrosis of epithelial cells .

Inflammatory cells , exudates & cellular debris obstruct terminal airways

Activation & proliferation of fibroblastsperibronchial fibrosis & obliterative fibroproliferative bronchiolitis

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Page 28: Broncho pulmonary dysplasia(bpd)

Radiologic FindingsRadiologic Findings

Decreased lung volumes Areas of atelectasis Hyperinflation Lung haziness PIE

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Histologic FindingsHistologic Findings

In 1996 Cherukupalli & colleagues described 4 pathologic stages

Acute lung injury Exudative bronchiolitis Proliferative bronchiolitis Obliterative fibroproliferative bronchiolitis

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Medical care in BPDMedical care in BPD

Prevention Mechanical ventilation O2 therapy Nutritional support Medications

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Mechanical VentilationMechanical Ventilation

O2 & PPV life saving Aggressive weaning to NCPAP eliminate need of

PPV Intubation primarily for surfactant therapy &

quickly extubation to NCPAP decrease need for prolong PPV

If infant needs O2 & PPV gentle modes of ventilation employed to maintain pH 7.28 – 7.40 , pCo2 45 – 65 , pO2 50- 70

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Mechanical VentilationMechanical Ventilation

Pulse oximetry & transcutaneous Co2 mesurements – provide information of oxygenation & ventilation with minimal patient discomfort

SIMV – provide information on TV & minute volumes which minimize O2 toxicity & barotrauma/volumetrauma

SIMV – allow infant to set own IT & rate

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Mechanical VentilationMechanical Ventilation

When weaning from vent & O2 difficult – when adequate TV & low FiO2 achievedtrial of extubation & NCPAP

Commonly extubation failuresecondary to atrophy & fatigue of respiratory muscles

Optimization of nutrition & diuretics – contribute to successful weaning from vent

Meticulous nursing care – essential to ensure airway patency & facilitate extubation

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O2 TherapyO2 Therapy

Chronic hypoxia & airway remodelingpulmonary HT & cor pulmanale

O2stimulate production of NOsmooth muscle relaxationvasodilatation

Page 38: Broncho pulmonary dysplasia(bpd)

O2 TherapyO2 Therapy

Repeated desats secondary to hypoxia results from- decreased respiratory drive

- altered pulmonary mechanics

- excessive stimulation

- bronchospasm Hyperoxiaworsen BPD as preterms have

a relative deficiency of AO

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O2 TherapyO2 Therapy

O2 requirement increase during stressful procedures & feedingstherefore wean O2 slowly

Keep sats 88% - 92% High altitudesmay require O2 many

months PRBC transfusionincrease O2 carrying

capacity in anemic(hct<30%) preterms

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O2 TherapyO2 Therapy

Study in 1988 found increased O2 content & systemic O2 transport , decreased O2 consumption & requirement after blood Tx

Need for multiple Tx & donor exposures decreased byerythropoetin , iron supplements & decreased phlebotomy requirements

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Nutritional SupportNutritional Support

Infant with BPD- increased energy requirements

Early TPN – compensate for catabolic state of preterm

Avoid excessive non N calories increase CO2 & complicate weaning

Early insertion of central linesmaximize calories in TPN

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Nutritional SupportNutritional Support

Rapid & early administration of increased lipidsworsen hyperbillirubinemia & BPD through billirubin displacement from albumin & pulmonary vascular lipid deposition respectively .

Excessive glucose loadincrease O2 consumption , respiratory drive & glucoseuria.

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Nutritional SupportNutritional Support

Cu , Mn , & Zn essential cofactors in AO defenses

Early initiation of small enteral feeds with EBM , slow & steady increase in volumefacilitate tolerance of feeds

Needs 120 – 150 Kcal/kg/day to gain weight

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Medical TherapyMedical Therapy

Diuretics Systemic bronchodilators

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DiureticsDiuretics

Furesemide (Lasix) Rx of choice Decrease PIE & pulmonary vascular

resistance Facilitate weaning from PPV , O2 /both Adverse effects – hyponatremia ,

hypokalemia , hypercalciuria , cholelithiasis , nephrocalcinosis & ototoxicity

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DiureticsDiuretics

Careful parenteral & enteral supplements compensate adverse effects

Thiazide & spiranolactone for long term Rx

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Systemic BronchodilatorsSystemic Bronchodilators

Methylxanthines – increase respiratory drive , decrease apnea , improve diaphragmatic contractility

Smooth muscle relaxation – decrease pulmonary vascular resistance & increase lung compliance

Exhibit diuretic effects

Page 48: Broncho pulmonary dysplasia(bpd)

Systemic BronchodilatorsSystemic Bronchodilators

Theophyline – metabolized primarily to caffeine in liver

Adverse effects – increase heart rate , GER , agitation & seizures

Page 49: Broncho pulmonary dysplasia(bpd)

PrognosisPrognosis

Pulmonary function slowly improves secondary to continued lung & airway growth & healing

Northway- Airway hyperactivity , abnormal pulmonary functions , hyperinflation in chest x ray persists in to adult hood

A study in 1990 found gradual decrease in symptom frequency in children 6 – 9 yrs