Common Respiratory Disorders of the Neonate

1. Common Respiratory Disorders of the Neonate

2. Common Pulmonary Causes of Respiratory Distress in Neonates Parenchymal conditions ● Transient tachypnea of the newborn ● Meconium aspiration syndrome and other aspirations ● Respiratory distress syndrome ● Pneumonia ● Pulmonary edema ● Pulmonary hemorrhage ● Pulmonary lymphangiectasia Developmental abnormalities ● Lobar emphysema ● Pulmonary sequestration ● Cystic adenomatoid malformation ● Congenital diaphragmatic hernia ● Tracheoesophageal fistula ● Pulmonary hypoplasia Airway abnormalities ● Choanal atresia/stenosis ● Laryngeal web ● Laryngotracheomalacia or bronchomalacia ● Subglottic stenosis Mechanical abnormalities ● Rib cage anomalies (eg, Jeune syndrome) ● Pneumothorax ● Pneumomediastinum ● Pleural effusion ● Chylothorax

3. The Neonatal Lung is a Work in Progress • Canalicular phase • Saccular phase • Alveolar phase Agrons Radiographics 2005

4. Respiratory Distress Syndrome(Hyaline Membrane Disease) • Definition? • 1960 – clinical definition describing respiratory distress and a hyaline membrane lining dilated terminal airspaces • 2006 – clinical definition describing respiratory distress and x-ray findings • There is no “test” for RDS

5. Surfactant is Amazing A mixture of lipid and protein that lowers surface tension on an air-water interface Jobe NeoReviews 2006

6. A Very Complex Metabolism • Surfactant is made in type II cells, works in the fluid hypophase of the alveoli and is recycled Jobe NeoReviews 2005

7. RDS is Inversely Related to Gestational Age • Incidence in 2006 • 501-1500g (42%) • 501 -750g (71%) • 751-1000g (54%) • 1001-1250g (36%) • 1251-1500g (22%) • More common in males than females Fanaroff and Martin 2006 p1098

8. Surfactant Maturation Can Be Accelerated • Corticosteroids • TRH • Inflammation • Heroin

9. Pathophysiology is Less Complicated Than It Looks Fanaroff and Martin 2006 p 1100

10. Pathophysiology is Less Complicated Than It Looks Fanaroff and Martin 2006 p 1100

11. Clinical Manifestations • Symptoms usually within hours of birth • Non-specific: tachypnea, cyanosis, nasal flaring, grunting, retractions, etc • Progressive worsening over 2-3 days followed by slow recovery • Classic CXR findings • Diffuse reticulogranular pattern • Air bronchograms

12. Classic RDS

13. Management 1960s Style • Supplemental oxygen • High humidity • Antimicrobials • Rocking chair devices • Sternal fixation

14. Management 2007 Style • Supplemental oxygen and respiratory support • Attention to thermoregulation • Antibiotics • IV fluids • Exogenous surfactant

15. Exogenous Surfactant • There is no question that it works • Decreases mortality from RDS • +/- decrease in BPD • Surfactant works best when: • Administered shortly after birth • Given rapidly • Followed by distending pressure

16. Other Surfactant Fun Facts • Components are recycled and “improved” like natural surfactant • May need additional doses • Optimal ventilator strategies following administration are more a matter of opinion than science

17. Respiratory Support • Goals are to: • Survive the acute phase of the disease • Minimize side effects • Minimize chance of chronic lung disease • Lots of opinion, but no consensus • Conventional ventilation • Pressure • volume • nCPAP • HFV

18. First Do As Little Harm As Possible Fanaroff and Martin 2006 p 1100

19. Chronic Lung Disease is Related to Our Treatments Fanaroff and Martin 2006 p 1100

20. Ventilator Strategies • Distending pressure • Lower Peak Inspiratory Pressures • Lower Tidal Volumes • Early extubation • Permissive hypercarbia • Permissive hypoxemia

21. Nasal CPAP? • Some places use it exclusively as their first-line mode of respiratory support • Columbia Univ – 76% success in infants with BW < 1250g and 50% with BW < 750g • Requires everyone to buy into the system • Can’t give surfactant unless also intubated • Most places use nCPAP for less severe symptoms, following extubation or in conjunction with “in-and-out” surfactant

22. High Flow Nasal Cannula • Nasal Cannula at atypical flows (< 1LPM) • Usually 2-8 LPM in our NICU • Used to provide distending pressure in a similar manner as nCPAP • Does not appear to be equal to nCPAP in efficacy • ? Increased respiratory infection rate

23. Complications of RDS and Its Treatment • Air Leak Syndrome

24. More Complications • Airway injury • Subglottic stenosis (1% < 1.5kg) • Infection • PDA • IVH • Long-term outcomes • More related to gestational age and BW • Most with normal exercise tolerance

25. BPD, a Most Troubling Complication • It begins with the definition: • Supplemental oxygen at 28 days of life following oxygen/ventilator therapy in the first week of life • Supplemental oxygen at 36 weeks PMA following oxygen/ventilator therapy in the first week of life • NIH consensus conference 2000

26. Now It All Makes Sense? The bottom line is that you will see all three definitions

27. Pathophysiology of BPD • Lungs are attempting to: • Heal • Grow and develop • Respond to continued insults

28. CLD is Associated With: • Prematurity • Mechanical trauma • Oxygen toxicity • Infection/inflammation • Pulmonary edema • PDA • ? genetics

29. The Old and the New BPD

30. Clinical Features • BPD is a systemic disease • Pulmonary • Respiratory distress • Hypoxemia, hypercarbia • Increased airways resistance • Growth deficiency • Developmental delay • Cardiovascular dysfunction • Systemic hypertension, ventricular hypertrophy • Metabolic derangements • Sodium, calcium, etc

31. Management • Minimize further harm • Permissive hypercapnea. etc. • Aggressive nutritional support • Conservative fluid management • Caution with diuretics • +/- bronchodilators • Steroids with caution • Minimize and aggressively treat infections • Developmental care

32. Perinatal aspiration of meconium Complicates ~4% of deliveries through meconium stained amniotic fluid Meconium Aspiration Syndrome Fanaroff and Martin 2006 p1123

33. MAS • Coarse infiltrates • Widespread consolidation • Hyperinflation • Pneumothorax and pneumomediastinum may be present

34. Management of MAS • Prevention • Supportive respiratory therapy • ? Higher pO2 • Normal pCO2 • Nitric oxide and other PPHN therapies • Antibiotics • surfactant

35. Transient Tachypnea • Described in the 1960s • Later called RDS Type 2 • Delayed clearance of pulmonary fluid • More common in: • Late preterm • C/S birth • Perinatal depression • Maternal diabetes • Diagnosis of exclusion

36. Symptoms of TTN • Mild to moderate respiratory distress shortly after birth • Increased central vascular markings ("star-burst") • Evidence of interstitial and pleural fluid • Spontaneous improvement in hours to a few days

37. Other Aspiration Syndromes • Babies can aspirate blood and amniotic fluid • No specific diagnostic test • May mimic TTN or MAS • Management is the same