Neonatal Respiratory Pathology

1. Neonatal Respiratory Pathology • Signs and Symptoms • Common (Major) Neonatal Diseases

2. Normal Neonatal Vital Signs • Smaller = faster • Normal heart rate 120-160/minute • Normal respiratory rate 40-60/minute • Normal blood pressure • pre term 50/30 mm Hg • increases with size

3. Signs & Symptoms of Respiratory Distress • Tachypnea • Nasal flaring • Expiratory grunting • Retractions • See saw breathing • Central cyanosis (as opposed to acrocyanosis) • Apnea

4. Periodic Breathing vs Apnea • Periodic breathing • normal in preterm • seen in 25 to 50% of all preterms • cessation of breathing for 10 seconds with no changes • Apnea • cessation of breathing for 20 seconds with changes • deteriorating color, SaO2, bradycardia

5. Common Neonatal Respiratory Diseases • Hyaline Membrane Disease • Transient Tachypnea of the Newborn • Bronchopulmonary Dysplasia • Meconium Aspiration Syndrome • Persistent Fetal Circulation • Retinopathy of Prematurity

6. Hyaline Membrane Disease • Abbreviated HMD • Also known as RDS type I • Seen in premature infants • Caused by immature surfactant system

7. HMD Pathology • Restrictive lung disease

8. HMD Pathology • Restrictive lung disease • Decreased lung compliance • increased elastic recoil • increased surface tension • increased work of breathing

9. HMD Pathology (cont.) • Atelectasis • decreased diffusion due to surface area • Increased AaDO2 (aA ratio) • increased intrapulmonary shunting (Qs/Qt)

10. HMD Pathology (cont.) • Atelectasis • decreased diffusion due to surface area • Increased AaDO2 (aA ratio) • increased intrapulmonary shunting (Qs/Qt) • Formation of hyaline membrane • decreased diffusion secondary to thickness

11. HMD Histology • Surfactant helps keep lung dry • HMD, alveolar leakage • Fluid rich in protein, fibrin, dying epithelial cells • Forms a hyaline membrane • Membrane forms within first 24 to 48 hours • Around 72 hours, phagocytosis begins

12. HMD Clinical Findings • Premature infant • Grunting and retractions • “Crash” within first 24 to 48 hours

13. HMD Chest X Ray • Hypoinflated (diaphragm less than 8 ribs) • Reticulogranular pattern (Ground glass, frosted glass) • Air Bronchograms

14. HMD Treatment • Artificial Surfactants • “Textbook Management” • Increasing Severity - Hood O2 to CPAP to Vent • Weaning - Vent to CPAP to Hood • Disease runs course 5 to 7 days

15. Transient Tachypnea of the Newborn • Also known as RDS type II • Also known as Wet Lung Syndrome • Abbreviated as TTN, TTNB • Seen in infants delivered via C sections • A disease of retained Fetal Lung Liquid

16. TTNB Pathology • Interstitial edema • Increased Raw (until fluid absorbed)

17. TTNB Clinical Findings • C-section infants • Good Apgars at birth • Mild hypoxemia within first 24 hours

18. TTNB Chest X Ray • Lymphatic engorgement (white strings) • Hyperinflation (diaphragm greater than 10 ribs)

19. TTNB

20. TTNB Treatment • Hood O2 within first 24 to 48 hours • Infant on room air

21. Bronchopulmonary Dysplasia • Abbreviated as BPD • Obstructive disease • Definition - O2 useage, 28 days post partum • Causitive factors: • O2 • Airway Pressure • Time of exposure

22. BPD Pathology • Stage I - same as HMD

23. BPD Pathology • Stage I - same as HMD • Stage II • occurs at 3 to 4 days • alveolar necrosis, development of smooth muscle

24. BPD Pathology (cont.) • Stage III • continued smooth muscle development • interstitial fibrosis • emphysematous bullae

25. BPD Pathology (cont.) • Stage III • continued smooth muscle development • interstitial fibrosis • emphysematous bullae • Stage IV • around one month • emphysema, interstitial fibrosis, pulmonary hypertension

26. Summary BPD Pathology • Increased Raw • Areas of increased and decreased Clt • Hyperinflated • Interstitial edema • many have PDA (L to R)

27. BPD Chest X Ray Stages • Stage I - HMD like • Stage II - increased ‘white out’ • Stage III - ‘sponge like’, bullae and white out • Stage IV - ‘honeycomb’

28. BPD Treatment • Supportive • Steroids

29. Meconium Aspiration Syndrome • Abreviated as MA, MAS • Meconium is infant stool • Presence indicates delivery stress • Found in approx. 10% of all deliveries

30. MAS Pathology • Check valve, ball valve effect (Increased incidence of pneumothorax) • Chemical (aspiration) pneumonitis

31. MAS Clinical Findings • Commonly post mature • larger infants • long fingernails, peeling skin • Delivered through stained amniotic fluid • Yellow or greenish nails, chord

32. MAS Chest X Ray • Increased patchy density • Hyperinflation

33. MAS Treatment • Deep tracheal suctioning at birth • Supportive • Chest physiotherapy

34. Persistent Fetal Circulation • Also known as Persistent Pulmonary Hypertension of the Newborn • Abbreviated as PFC, PPH, PPHNB • Page 81, Whitaker ******Comprehensive Perinatal & Pediatric Respiratory Care*****

35. PFC Pathology • Continuance of Fetal Circulation post partum • R to L shunting through PDA • R to L shunting through FO • Severe hypoxemia

36. PFC Clinical Findings • Infants tend to be term • Non responsive hypoxemia • Right sided PaO2 (preductal) 15 torr higher than left

37. Differential Diagnosis of PFC • Hyperoxia test (100% hood) • PaO2 > 100 is lung disease • PaO2 = 50 to 100 is either lung or heart disease • PaO2 < 50 is fixed right to left shunt

38. Differential Diagnosis of PFC (cont.) • If fixed R to L shunt is suspected • Obtain pre and post ductal PaO2 • Difference < 15 torr, no ductal shunting • Difference > 15 torr, ductal shunting present

39. Differential Diagnosis of PFC (cont.) • Perform Hyperoxic - Hyperventilation Test • Hyperventilate with 100% O2 until PaCO2 20 to 25 torr • If PaO2 > 100 torr, then PFC is present • If PaO2 < 100 torr, then congenital heart disease

40. PFC Treatment • High vent settings (shoot for PaCO2 20-25 torr) • ? Paralysis • Allow PaO2 to be 80 to 100 torr • Use vasodilator Priscolene (Tolazoline) • Nitric Oxide • Use of ECMO

41. Retinopathy of Prematurity • Also known by older name of Retrolental Fibroplasia (RLF) • Page 303, Whitaker ******Comprehensive Perinatal & Pediatric Respiratory Care • Abbreviated as ROP • Visual disturbances secondary to O2 use

42. ROP Pathology • Stage I - vascoconstrictive response of immature retinal vessels when PaO2 is increased • Stage II - (proliferative stage), new vessels form to oxygenate retina, retinal hemorrhage

43. Causative Factors of ROP • PaO2 • Retinal Maturity • Duration of Hyperoxia

44. ROP Treatment • Closely monitor PaO2 or SaO2 • Closely monitor FiO2 • ‘Cryo’ therapy • Ophthalmic examination at discharge