Respiratory distress In the full term neonate

1. Respiratory distress In the full term neonate Christy l. Cummings, MD

2. Objectives • Informal case-based learning • Differentiate between cardiac and respiratory causes of cyanosis • Describe the primary parenchymal diseases that can cause respiratory distress in the term neonate • Describe the primary developmental lung abnormalities that can cause respiratory distress in the term (or near-term) neonate

3. Rule out cardiac disease • Pulse Oximetry Test • Determines whether formal hyperoxia test is useful • Cyanosis without marked respiratory distress and O2 sat < 85% in room air and 100% oxygen suggests intracardiac shunt • If O2 sat increases to > 85% on 100% oxygen, a full hyperoxia test should be performed • Hyperoxia Test • Obtain baseline right radial (preductal) arterial blood gas measurement with baby breathing room air and 100% O2 • A PaO2 > 300 mm Hg on 100% O2 is normal, 150-300 mm Hg suggests pulmonary disease, and 50 -150 mm Hg suggests cardiac disease (or severe pulmonary hypertension) • ECHO

4. Hints on chest radiograph • RDS • Mostly premies, but seen in term (rare) and near-term • Reticular granular pattern and air bronchograms • MAS • Patchy areas of atelectasis due to complete airway obstruction, interspersed with areas of air trapping due to partial obstruction and a one-way valve phenomenon • White out, and/or air leak syndrome • Neonatal pneumonia • Classical patchy infiltrates, but the findings also may be indistinguishable from RDS • Pleural effusion supports diagnosis of PNA, seen 67%

5. Hints on chest radiograph • TTN • Diffuse parenchymal infiltrates, a “wet silhouette” around heart, or accumulation of fluid in various intralobar spaces (fissure) • Indicate increased pulmonary interstitial, alveolar, or pleural water content • CHD • Cardiac enlargement, unusual silhouette (snowman, boot) • Congenital lymphangiectasia • Lungs may appear normal, overinflated or exhibit a coarse interstitial infiltrate due to distended, abnormal lymphatics • Effusion (chylous)

6. Possible diagnosis related to Radiographic features

7. Case • 1 hour old FT baby boy with tachypnea (RR 70s) born via C/S, GBS neg • PE: • Moderate retractions • O2 sat 88% on RA • O2 sat 100% on 100%

8. Transient Tachypnea of the Newborn (TTN) • Relatively benign, self-limited disease • 11:1000 births, M>F • Increased risk: • M, C/S, perinatal asphyxia, cord prolapse, IDM, maternal asthma or anesthesia during labor • Tachypnea (>60bpm) shortly after birth, lasts 1-5d • Unclear etiology: • Delayed resorption of fetal lung fluid related to elevated CVP, delayed clearance of pulmonary liquid by lymphatics • Mild asphyxia resulting in mild pulmonary capillary leak and to myocardial dysfunction with elevated filling pressure • Almost never requires mechanical ventilation

9. Resorption of alveolar fluid at birth: Cellular mechanisms

10. Case • 1 hour old FT baby boy born via NSVD who required PPV in DR, increasing WOB, retractions, required intubation

11. RDS in Term infant: SP-B Deficiency • Congenital abnormalities of surfactant proteins • Most common is deficiency of surfactant protein B (SP-B) • Autosomal recessive, frame-shift mutation chromosome 2, • Severe respiratory distress after birth • CXR identical to RDS • Continued distress despite mechanical ventilation, oxygen, repeated surfactant, corticosteroids • Prognosis is poor, most die within 1-6 months • Only effective therapy (although neither available for nor consented to by all) is lung transplantation

12. Case • 1 hour old FT baby girl born via NSVD, meconium, who emerged limp, was suctioned below cords x1 • Now with grunting, retractions, desats, requiring intubation

13. Meconium Aspiration syndrome • Incidence: • 13% of all live births complicated by meconium-stained amniotic fluid, and of these, 4% to 5% develop MAS • Mechanism • Direct toxicity of the meconium  chemical pneumonitis • Inactivation of surfactant • Activation of complement • Vasoconstriction • Partial/complete airway obstruction by thick meconium • Secondary pulmonary hypertension

14. Meconium Aspiration syndrome • Management • NRP guidelines, endotracheal suction below cords if limp • Intubation, mechanical ventilation • Surfactant • RCTs shown that surfactant reduces need for ECMO • iNO • Since the approval of iNO by the US FDA in 2001, there has been a steady decrease in the use of ECMO for neonates with MAS • HFOV +/- • Reduction in complications from air-leak syndromes (PTX)

15. Case • FT baby girl born via NSVD, GBS+, treated with PCN x1 2 hours PTD • Increased WOB, desats • Requires PPV

16. Pneumonia • Early onset <7d, late onset >7d • In utero • Rubella, CMV, HSV, mumps, adenovirus, Toxo, T. pallidum, M. tuberculosis, Listeria monocytogenes, VZV, HIV • During delivery/perinatally • GBS, Escherichia coli, Klebsiella sp, Chlamydia trachomatis • Postnatally • Respiratory viruses (adenovirus, RSV), gram-positive bacteria(groups A, B, and G streptococci or S. aureus), and gram-negative enteric bacteria (Klebsiella sp, Proteus sp, Pseudomonas aeruginosa, flavobacteria, Serratia marcescens, and E coli)

17. Pulmonary causes for respiratory distress Parenchymal conditions: • Transient tachypnea of the newborn • Meconium aspiration syndrome, other aspirations • Respiratory distress syndrome • Pneumonia • Pulmonary edema • Pulmonary hemorrhage • Pulmonary lymphangiectasia

18. case • FT baby boy born via repeat C/S with increased WOB, retractions • Requires intubation • Transillumination neg

19. Congenital lobar emphysema • Accounts for 50% of structural lesions causing respiratory distress in the newborn • M:F 2:1, associated anomalies 14-40% (often CHD) • Air trapping and overdistention of segments and lobes of the lungs • Prenatal diagnosis via high-res U/S, MRI or CT • Clinical signs/sx include respiratory distress, mediastinal shift, wheezing • Upper lobes afftected 90% time • Symptomatic lesions need surgical resection • Asymptomatic lesions may be watched carefully

20. Case • FT baby girl born via repeat C/S • Respiratory distress • Intubated • CXR appears ok, but on close inspection reveals small dense mass LLL • CT with contrast shown

21. Pulmonary sequestration • Abnormal lung tissue with no connection to normal tracheobronchial tree • Receives arterial blood supply from systemic circulation, usually branch of the aorta • Mutation in Homeobox gene Hoxb-5, crucial for normal airway branching/development • Intralobar vs extralobar

22. Pulmonary sequestration • Intralobar – lesion within lobe without separate pleura • 3x more common than extralobar • May be acquired (recurrent infection due to lack of pleura) • Lower lobe (95%), and in 55% of cases is on the left side • M=F • Extralobar - discrete mass of pulmonary parenchyma outside pleural investment of lung • In 66% of the cases, left side, proximal to esophagus and between lower lobe and diaphragm • M:F 3-4:1 • >65% associated with anomalies (CDH, TAPVR, CHD, CCAM) • Resection for both types necessary

23. case • 1 day old FT female born via NSVD, GBS neg, with respiratory distress

24. CCAM/CPAM • Multicystic mass of dilated bronchiolarlike spaces that proliferate at the expense of alveoli • Large lesions may obstruct venous return to heart, causing fetal hydrops • Abnormal signaling/conjugation between developing terminal bronchioles and alveolar mesenchyme • Mesenchymal & plt-derived GF

25. CCAM/CPAM • M=F, usually affects right side one lobe • Solid lesions worse prognosis than large cysts • Type 1 (75%) – small # of large cysts, 2-10cm, mucin • Type 2 - small cysts (<2cm), assoc anomalies, poor outcomes • Type 3 – microscopic cysts, rare, appears solid on gross exam • (Type 4 – acinar epithelium) • Surgical resection for all types • 100% survival with surgery (without hydrops fetalis)

26. Case • FT baby boy delivered via repeat C/S, prenatal L:H ratio 0.8 and + liver • Intubated immediately

27. Congenital Diaphragmatic Hernia (CDH) • Herniation of intestinal contents into thoracic cavity • Results in pulmonary hypoplasia leading to respiratory distress • 95% occur through posterior foramen of Bochdalek (lies posteriorly and lateral to spine); of these, 80% are on left side • 1 : 4,000 births • Signs/symptoms: • Cyanosis, severe respiratory distress, scaphoid abdomen • Usually seen during routine prenatal U/S • L:H ratio, presence of liver or other organs in chest • Post delivery xray reveals intestinal loops in chest cavity • Immediate intubation and gastric decompression is essential to higher survival rates • Intubation should be performed by most experienced team member

28. Congenital Diaphragmatic Hernia

29. Pulmonary causes for respiratory distress Developmental abnormalities: • Lobar emphysema • Pulmonary sequestration • Cystic adenomatoid malformation • Congenital diaphragmatic hernia • Tracheoesophagealfistula • Pulmonary hypoplasia

30. Case • 3 hour old FT baby girl with respiratory distress while eating, improves with crying. CXR WNL. • ENT consulted, CT ordered

31. Choanal atresia • Congenital anomaly, back of the nasal passage (choana) is blocked, usually by abnormal bony or soft tissue formed during fetal development • 0.82 cases per 10,000 individuals, F>>M • Unilateral (R) and 2:1, B/L • CHARGE syndrome • 6% with chromosomal anomalies • Cyanosis • Worse with feeds or pacifier • Improves with crying • Surgical correction, stent, revisions

32. CHOanal Atresia: CHARGE • C – Coloboma of the eye, CNS anomalies • H - Heart defects • A - Atresia of the choanae • R - Retardation of growth and/or development • G - Genital and/or urinary defects (Hypogonadism) • E - Ear anomalies and/or deafness

33. case • FT baby boy with respiratory distress, hoarse cry • Intubated for worsening respiratory status • CXR WNL • ENT consulted

34. Laryngeal web • Incomplete recanalization of the laryngotracheal tube during 3rd month of gestation (atresia – stenosis) • Most commonly at level of vocal folds anteriorly • Sx: Mild dysphonia to significant airway obstruction • 30% associated airway anomalies (subglottic stenosis), 22q11 • Diagnosis – rigid laryngoscopy/bronchoscophy • Management • Ranges from observation to emergent tracheotomy • Lysis endoscopically using cold knife or laser • Endoscopic suturing of the cut edges or placement of a keel may prevent restenosis in these cases • Thicker webs may require laryngofissure approach, with postoperative stenting of the airway

35. Pulmonary causes for respiratory distress Airway abnormalities: • Choanalatresia/stenosis • Laryngeal web • Laryngotracheomalaciaor bronchomalacia • Subglottic stenosis

36. case • f

37. Rib cage abnormalitiesJeune syndrome • Asphyxiated Thoracic Displasia (Jeune syndrome) • Autosomal recessive • Clinical signs/sx: • Bone dysplasia – rhizomelic brachymelia • Thoracic anomalies – bell shaped rib cage, short ribs • Renal and hepatic malformations • Pulmonary hypoplasia • Radiologic changes often seen by 16-18wk gestation • Usually death in the newborn period from severe pulmonary hypoplasia

38. case • FT baby girl born via NSVD, worsening respiratory distress, increasing O2 • Required intubation and intervention

39. Pneumothorax/mediastinum • Air collection: pleura and chest cavity or mediastinum • Neonatal pneumomediastium 2.5:1000 live births • Assoc with mechanical ventilation, PNA, RDS, mec • Often asymptomatic • May require intervention

40. case • 3 day old FT baby boy born via NSVD, worsening respiratory distress

41. chylothorax • Pleural effusion from lymphatic fluid (chyle) • Leakage from thoracic duct or branch • M:F is 2:1and R>L side • 50% occur within 24hr of life, 70% by 1st week of life • Composition: milky, chylomicrons, TGs, lymphs • Treatment: • Thoracentesis, CT to allow drainage • D/c FFAs in diet; formula high in medium chain TGs (Portagen) bypasses lymphatic system via direct absorption into blood stream • Surgical ligation of thoracic duct • Chemical or surgical pleurodesis • Octreotide for several weeks

42. Pulmonary causes for respiratory distress Mechanical abnormalities: • Rib cage anomalies (eg, Jeune syndrome) • Pneumothorax • Pneumomediastinum • Pleural effusion • Chylothorax

44. Questions? References: And many, many google images…