Neonatal Respiratory Distress Priscilla Joe, MD Children’s Hospital and Research Center at Oakland

Neonatal Respiratory Disease Upper airway disease True parenchymal disease Airleak syndromes Disorders of development Primary pulmonary vascular disease

Upper Airway Disease Choanal atresia Pierre Robin sequence Vascular rings

Choanal Atresia Pierre Robin Syndrome

Choanal Atresia/Upper Airway Obstruction Cyanotic when quiet or at rest, pink with crying Inability to pass suction catheter through nares Stridor

Upper airway obstruction Insert an oral airway Provide oxygen Suction secretions May require intubation

Fetal Lung Characteristics Decreased blood flow caused by compression of the pulmonary capillaries by fetal lung fluid Pulmonary arteries thick muscular layer present, very reactive to hypoxemia Lung fluid secretion fetal lungs secrete fluid, adequate lung volume is necessary for fetal development Fetal breathing contributes to fetal lung development, moves fluid in and out of fetal lung Surfactant necessary amount to support breathing after birth, present after ~ 34 weeks gestation Decreased blood flow: caused by compression of the pulmonary capillaries by fetal lung fluid Pulmonary arteries: thick muscular layer present, very reactive to hypoxemia Lung fluid: fetal lungs secrete fluid, adequate lung volume is necessary for fetal development Fetal breathing: contributes to fetal lung development, moves fluid in and out of fetal lung Surfactant: necessary amount to support breathing after birth, present after ~ 34 weeks gestation

Transition Clearance of fetal lung fluid Increased compliance Increased pulmonary blood flow

Respiratory Distress Syndrome Disease of surfactant defiency Surfactant decreases surface tension and improves lung compliance Surface tension: intrinsic tendency for alveoli to collapse

RDS: Risk Factors Secondary surfactant deficiency: Prematurity: Males Maternal diabetes Asphyxia Pneumonia Pulmonary hemorrhage Meconium aspiration Oxygen toxicity Prematurity: Males Second born twins C-section Caucasian race Develops in ~ 50% of infants born between 28-32 weeks gestation Inversely related to prematurity

RDS: Clinical Findings Non-specific findings of respiratory distress Grunting Flaring Retracting O2 requirement

RDS: Radiography Alveolar disease: Diffuse reticular granular or “ground glass”pattern Air bronchograms Underaeration

RDS: Treatment Maintain FRC (CPAP vs. intubation) Surfactant replacement Exogenous surfactants Survanta 4cc/kg Infasurf 3cc/kg

Surfactant Therapy for RDS Decreases mortality Greatest benefit when used with antenatal steroids Improvement in compliance, functional residual capacity, and oxygenation Reduces incidence of air leaks

Congenital Pneumonia Common organisms: Group B streptococcus E.Coli, Klebsiella Chlamydia, Ureaplasma, mycoplasma Listeria TORCH H. Influenza (nontypeable)

Pneumonia: Risk Factors Maternal chorioamnionitis Prolonged rupture of membanes Prematurity Postnatal exposures: Poor hand washing, open skin lesions, contaminated blood products, infected breast milk

Pneumonia Inflammation and edema Bronchial plugging Surfactant inactivation Alveolar collapse Ventilation/perfusion mismatch Desaturation

Pneumonia: Clinical Findings Presents with non-specific findings of respiratory distress Grunting Flaring Retracting O2 requirement

Pneumonia: Radiography There are no classic x-ray findings, in fact, the X-ray in pneumonia can look like anything Fairly normal Classic RDS Classic for MAS

RDS, H influenza pneumonia

Listeria, MAS

E coli pneumonia

Pneumonia: Treatment Respiratory support as indicated with either O2 or positive pressure Treatment with appropriate antimicrobials Initial ampicillin/gentamicin or ampicillin/cefotaxime Broader spectrum antibiotics for nosocomial bacteria

Meconium Aspiration Syndrome Meconium contains epithelial cells and bile salts Released with intrauterine stress or asphyxia Present in 15% of all newborns. Only 5-10% develop MAS Asphyxia causes anal sphincter to relax, also leads to gasping respiratory efforts Often ill Be very concerned about pulmonary hypertension, as this is also a fetal response to asphyxia

Meconium Aspiration Airway plugging, with air trapping Inflammation, leading to inactivation of surfactant Surfactant inactivation leads to decreased compliance, and alveolar collapse Alveolar collapse = loss of FRC Loss of FRC = V/Q mismatch V/Q mismatch = desaturation

Meconium aspiration: Xray Areas of hyperexpansion mixed with patchy densities and atelectasis

Pneumothorax May occur spontaneously during delivery Most common when receiving positive pressure Space occupying lesion within the chest displacing lung, and if under tension, compromising venous return

Pneumothorax: Clinical Findings Presents with non-specific signs of respiratory distress Grunting Flaring Retracting O2 requirement Unequal, decreased breath sounds

Pneumothorax: Treatment O2 as needed Nitrogen washout (pneumo contains 21% O2, >75% nitrogen, if lung has 100% O2, nitrogen will diffuse out of pneumothorax) Try to avoid positive pressure if able Evacuate as needed by thoracentesis or chest tube

Developmental disturbances Pulmonary hypoplasia Congenital diaphragmatic hernia Skeletal deformities

Pulmonary hypoplasia Cannot be assessed radiographically, pulmonary hypoplasia is a pathologic diagnosis Suspect pulmonary hypoplasia if: Rupture of membranes with anhydramnios Renal anomalies Restriction of the chest wall Congenital diaphragmatic hernia

Diaphragmatic Hernia Scaphoid abdomen Bowel sounds in the chest Other associated anomalies Decreased breath sounds Severe hypoxemia

Diaphragmatic Hernia Wide range in clinical presentation Herniation of bowel leads to altered development of the lungs bilaterally

Left CDH

Persistent Pulmonary Hypertension of the Newborn Primary pulmonary hypertension is a pure vascular disease More often present in a mixed picture as in the setting of meconium aspiration syndrome or asphyxia

PPHN In response to an asphyxia event in utero, the fetus diverts all blood flow possible to vital organs (brain/heart/adrenals) This leads to vasoconstriction of non-vital vascular beds, including the pulmonary bed Remodeling of smooth muscle can occur

PPHN Increased PVR PDA PA Aorta RV outflow Following delivery pulmonary vascular resistance plummets, in order to establish pulmonary blood flow In kids with PPHN, they never drop their resistance, leading in the worst case to a right to left shunt at the ductal level PA Aorta

PPHN: Clinical Findings Respiratory distress with hypotension Hypoxemia out of proportion to degree of distress Difference in pre and post ductal sats Right hand Lower extremities Hyperoxia test

PPHN Increases R L shunt: Decreases R L shunt: Increase PVR Decrease pulmonary blood flow Hypoxia Hypercarbia Acidosis Decreases R L shunt: Decrease PVR Increase pulmonary blood flow Hyperoxia Hypocarbia Lack of acidosis

PPHN: Treatment Improve pulmonary blood flow: Avoid: Keep well saturated Normocarbia Avoid: Hypoxia Hypercarbia Acidosis Supportive care: temperature regulation, fluids and lytes, antibiotics

PPHN: Treatment Conventional ventilation or HFOV Nitric oxide Surfactant replacement ECMO