CONGENITAL AND ACQUIRED RESPIRATORY DISORDERS IN INFANTS

OBJECTIVES n Review of Cardio-Pulmonary Development. n Define changes that occur during transition to extra-uterine life with emphasis on breathing mechanics. n Identify infants at risk for and who have respiratory distress n Review of common neonatal disease states.

STAGES OF NORMAL LUNG GROWTH Embryonic - first 5 weeks; formation of proximal airways Pseudoglandular weeks; formation of conducting airways Canalicular weeks; formation of acini Saccular weeks; development of gas- exchange units Alveolar - 36 weeks and up; expansion of surface area

Pseudoglandular 6-16 weeks

Canalicular Phase weeks

Saccular Phase weeks

PHYSIOLOGIC MATURATION (Surfactant Production) n Type 2 pneumocytes appear at weeks n Responsible for reduction of alveolar surface tension. u LaPlace’s Law n Lipid profile as indicator of lung maturity u L/S Ratio u Flourescence Polarization - FLM n Many other factors influence lung maturation

Maturational Factors n Stimulation u Glucorticoids, ACTH u Thyroid Hormones, TRF u EGF u Heroin u Aminophyline,cAMP u Interferon u Estrogens n Inhibition u Diabetes (insulin, hyperglycemia, butyric acid) u Testosterone u TGF-B u Barbiturates u Prolactin

FETAL CIRCULATION

TRANSITION TO EXTRA-UTERINE LIFE n Fetal Breathing n Instantaneous; liquid filled to air filled lungs n Maintenance of FRC n Placental blood flow termination n Decreased PVR n Closure of fetal shunts

MECHANICS OF BREATHING n Respiratory Control Center...CNS u Metabolic Needs n Negative pressure breathing n Compliance and Resistance u Inspiratory Muscles u Rib Cage F “Compliability becomes a liability”

Signs of Respiratory Distress n Tachypnea n Intercostal retractions n Nasal Flaring n Grunting n Cyanosis

When is it abnormal to show signs of respiratory distress? n When tachypnea, retractions, flaring, or grunting persist beyond one hour after birth. n When there is worsening tachypnea, retractions, flaring or grunting at any time. n Any time there is cyanosis

Causes of Neonatal Respiratory Distress n Obstructive/restrictive - mucous, choanal atresia, pneumothorax, diaphragmatic hernia. n Primary lung problem - Respiratory Distress Syndrome (RDS), meconium aspiration, bacterial pneumonia, transient (TTN). n Non -pulmonary - hypovolemia/hypotension, congenital heart disease, hypoxia, acidosis, cold stress, anemia, polycythemia

Infants at Risk for Developing Respiratory Distress n Preterm Infants n Infants with birth asphyxia n Infants of Diabetic Mothers n Infants born by Cesarean Section n Infants born to mothers with fever, Prolonged ROM, foul-smelling amniotic fluid. n Meconium in amniotic fluid. n Other problems

Evaluation of Respiratory Distress n Administer Oxygen and other necessary emergency treatment n Vital sign assessment n Determine cause-- physical exam, Chest x-ray, ABG, Screening tests: Hematocrit, blood glucose, CBC n Sepsis work-up

Principles of Therapy n Improve oxygen delivery to lungs-- supplemental oxygen, CPAP, assisted ventilation, surfactant n Improve blood flow to lungs-- volume expanders, blood transfusion, partial exchange transfusion for high hematocrit, correct acidosis (metabolic/respiratory) n Minimize oxygen consumption-- neutral thermal environment, warming/humidifying oxygen, withhold oral feedings, minimal handling

DISEASE STATES n Respiratory Distress Syndrome n Transient Tachypnea of the Newborn n Meconium Aspiration Syndrome n Persistent Hypertension of the Newborn n Congenital Pneumonia n Congenital Malformations n Acquired Processes

RESPIRATORY DISTRESS SYNDROME Surfactant Deficiency Tidal Volume Ventilation Pulmonary Injury Sequence

CLINICAL FEATURES OF RDS n Tachypnea/Apnea n Dyspnea n Grunting/Flaring n Hypoxemia n Radiographic Features n Pulmonary Function Abnormalities

Early RDS

Progressive RDS

Late RDS

Hyaline Membrane Disease

THERAPY FOR RDS n Oxygen - maintain PaO2 > 50 torr n Nasal CPAP n Intermittent Mandatory Ventilation n Surfactant Replacement n High Frequency Ventilation n Intercurrent Therapies

PIE

PIE Pathology

PIE Histology

Pneumothorax/PIE

Pneumothorax

Pneumopericardium

TRANSIENT TACHYPNEA OF THE NEWBORN n Delayed Fluid Resorption n Hard to differentiate early on from RDS both clinicaly and radiographicaly especially in the premature infant n Initial therapy similar to RDS, but hospital course is quite different

Wet Lung

MECONIUM ASPIRATION SYNDROME n Chemical Pneumonitis n Surfactant Inactivation n Potential for Infection n Potential for Pulmonary Hypertension n Management varies on severity

Meconium Aspiration

PERSISTENT PULMONARY HYPERTENSION n Usually secondary to primary pulmonary disease state n Pulmonary Vascular Lability n Treat the underlying problem n Maintain normo-oxygenation n Selective Pulmonary Vasodilators n Pray for good luck

PPHN

CONGENITAL PNEUMONIA n Infectious; primarily GBS n Amniotic Fluid aspiration n Viral etiology n Surfactant inactivation

GBS Pneumonia

CONGENITAL MALFORMATIONS n Choanal Atresia n Tracheal Atresia/stenosis n Chest Mass u Diaphragmatic hernia u CCAM u Sequestration u Lobar emphysema

CCAM

Lobar Emphysema

Diaphragmatic Hernia

Chylothorax

Phrenic Nerve Paralysis

ACQUIRED DISEASES n Infections n Bronchopulmonary Dysplasia n Sub-glottic stenosis n Apnea of Prematurity

Early BPD

Progressive BPD

Late BPD

APNEA Definition: cessation of breathing for longer than a 15 second period or for a shorter time if there is bradycardia or cyanosis

Babies at Risk for Apnea n Preterm n Respiratory Distress n Metabolic Disorders n Infections n Cold-stressed babies who are being warmed n CNS disorders n Low Blood volume or low Hematocrit n Perinatal Compromise n Maternal drugs in labor

Anticipation and Detection n Place at-risk infants on cardio- respiratory monitor n Low heart rate limit (80-100) n Respiratory alarm (15-20 seconds)

Treatment n Determine cause: n x-ray n blood sugar n body and environmental temperature n hematocrit n sepsis work up n electrolytes n cardiac work up n r/o seizure

Treatment n CPAP n Theophylline/Caffeine therapy n Mechanical ventilation n Apnea monitor