Neonatal Diseases

1. Neonatal Diseases RC 290

2. Respiratory Distress Syndrome(RDS) Also known as Hyaline Membrane Disease (HMD)

3. Occurrence • 1-2% of all births • 10% of all premature births • Greatest occurrence is in the premature and low birth weight infant

4. Etiology & Predisposing Factors • Prematurity • Immature lung architecture and surfactant deficiency • Fetal asphyxia & hypoxia • Maternal diabetes • Increased chance of premature birth • Possible periods of reflex hypoglycemia in the fetus causing impaired surfactant production

5. Pathophysiology Surfactant deficiency • Decreased FRC • Atelectasis • Increased R-L shunt • Increased W.O.B. • Hypoxemia and eventually hypercapnia because of V/Q mismatch

6. Pathophysiology (cont.) Atelectasis keeps PVR high • Increased PAP • Lung hypoperfusion • R-L shunting may re-occur across the Ductus Arteriosus and the Foramen Ovale

7. Hypoxia/hypoxemia results in anaerobic metabolism and lactic acidosis This damages the alveolar-capillary membrane causing formation of hyaline membranes. Hyaline membranes perpetuate all of the problems in the lung

8. The cycle continues until surfactant levels are adequate to stabilize the lung • Symptoms usually appear 2-6 hours after birth • Why not immediately? • Disease peaks at 48-72 hours • Recovery usually occurs 5-7 days after birth

9. Tachypnea (60 BPM or >) Retractions Nasal flaring Expiratory grunting Helps generate autoPEEP Decreased breath sounds with crackles Cyanosis on room air Hypothermia Hypotension Clinical findings: Physical

10. Clinical Findings: Lab • ABGs: initially respiratory alkalosis and hypoxemia that progresses to profound hypoxemia and combined acidosis • Increased Bilirubin • Hypoglycemia • Possibly decreased hematocrit

11. CXR: Normal

12. RDS CXR: Ground Glass Effect

13. RDS CXR: Air Bronchograms & Hilar Densities

14. Time constant is decreased since elastic resistance is so high Increased elastic resistance means decreased compliance!

15. RDS Treatment: Primarily supportive until lung stabilizes • NTE, maintain perfusion, maintain ventilation and oxygenation • O2 therapy, CPAP or mechanical ventilation • May require inverse I:E ratios if oxygenation can not be achieved with normal I:E ratio • Surfactant instillation!!! • May cause a sudden drop in elastic resistance!

16. Prognosis/Complications Prognosis is good once infant makes it past the peak (48-72 hours) Complications possible are: • Intracranial Bleed • BPD (Bronchopulmonary Dysplasia) • PDA (Patent Ductus Arteriosus)

17. Transient Tachypnea of the Newborn (TTN) Also known as Type II RDS or Retained Lung Fluid

18. Occurrence: Similar to RDS More common in term infants!

19. Etiology & Predisposing Factors • C-section • These infants do not have the fluid expelled from their airways as occurs in vaginal delivery • Maternal Diabetes • Increased chance of C-section due to LGA • Cord Compression • Anesthesia

20. TTN Pathophysiology Primary problem = retained lung fluid • Fluid not expelled from airways because of C-section • Poor absorption of remaining fluid by pulmonary capillaries and lymphatics • If retained fluid is in interstitial spaces, compliance and TC are decreased • If retained fluid is in airways,airway resistance and TC are increased • TTN can be restrictive , obstructive, or both! • Fluid usually clears by itself after 24-48 hours after birth

21. Clinical Signs • Tachypnea (usually rate is greater than seen in RDS) • Minimal (if any) nasal flaring or expiratory grunting • ABG’s: mild hypoxemia. PaCO2 depends on whether problem is restrictive or obstructive

22. TTN CXR • Coarse peri-hilar streaks • Prominent lung vasculature • Flattened diaphragms if fluid is causing obstruction/air-trapping

23. TTN Treatment: Like RDS, it is primarily supportive • Monitoring and O2 therapy • Possibly CPAP or mechanical ventilation

24. Prognosis/Complications • Prognosis is very good • Main complication is pneumonia • Often initial diagnosis

25. Lab Time!

26. Patent Ductus Arteriosus-PDA_ Failure of the D.A. to close at birth or a re-opening of the D.A. after birth. Allows shunting between the pulmonary artery and the aorta

27. Occurrence • 1 per 2000 term babies • 30-50% of RDS babies

28. Etiology & Predisposing Factors • Prematurity • D.A. not as sensitive to increasing PaO2 • Hypoxia • Decreasing PaO2 allows it to re-open for up to three weeks after birth • Thus, a PDA can occur in a premature infant who is NOT hypoxic or in a term baby who is hypoxic • Worst case is a premature infant who is hypoxic!

29. Pathophysiology • D.A. fails to close or it re-opens • Then shunting occurs between the pulmonary artery and the aorta • The direction of the shunt depends on which vessel has the higher pressure • A PDA can cause L-R shunting or R-L shunting! • Clinically, most PDA’s refer to a L-R shunt

30. Clinical Signs • Tachypnea, bounding pulses, hyperactive pre-cordium • Decreased breath sounds and possibly some crackles • Possible murmur over left sternal border • Murmur is loudest when D.A. just starts opening or when it is almost closed

31. Clinical Signs (cont.) • ABGs – hypoxemia with respiratory acidosis • If R-L shunting, the PaO2 in the upper extremities, ie pre-ductal, will be greater than the PaO2 in the umbilical artery, ie post-ductal! • TC – decreased if L-R shunting causes pulmonary edema; increased if fluid spills into airways and increases airway resistance • CXR – if L-R shunt, butterfly pattern of pulmonary edema with possible cardiomegaly

32. PDA Treatment • Basic – NTE, O2, may require CMV if not already on the ventilator • Medical • L-R shunt that fails to close: Indomethacin (Indocin) • R-L shunt: Priscoline (Tolazoline) to decrease PVR; also nitric oxide • Surgical –if medical treatment fails, the PDA may be surgically ligated

33. Prognosis/Complications Good prognosis when baby responds to medical treatment May develop : • Shock • CHF • Necrotizing Enterocolitis (NEC)

34. Meconium Aspiration Syndrome-MAS- Syndrome of respiratory distress that occurs when meconium is aspirated prior to or during birth

35. Occurrence • 10-20% of ALL births show meconium staining • 10-50% of stained babies may be symptomatic • More common in term and post-term babies

36. Etiology & Predisposing Factors • Intra-uterine hypoxic or asphyxic episode • Post-term • Cord compression

37. Pathophysiology: Check Valve Effect Causes gas trapping (obstruction) If complete obstruction, then eventually atelectasis occurs Irritating to airways, so edema and bronchospasm Good culture ground for bacteria, so pneumonia possible

38. Pathophysiology (cont.) • V/Q mismatch leads to hypoxia and acidosis which increases PVR • TC increases because it increases airway resistance • Meconium is usually absorbed in 24-48 hours; there are still many possible complications

39. Respiratory depression or distress at birth Hyperinflation Pallor Meconium stained body Possible cyanosis on room air Moist crackles ABGs – hypoxemia with combined acidosis CXR – coarse, patchy infiltrates with areas of atelectasis and areas of hyperinflation May see flattened diaphragms if obstruction is severe Clinical Signs

40. Amnioinfusion – artificial amniotic fluid infused into uterus to dilute meconium Proper resuscitation at birth(clear meconium from trachea before stimulating respiration) Oro-gastric tube NTE O2 NaHCO3 if severe metabolic acidosis Broad spectrum antibiotics Bronchial hygiene May need mechanical ventilation Slow rates and wide I:E ratios because of increased TC Low level of PEEP may help prevent check valve effect May need HFO M.A.S. Treatment

41. Prognosis & Complications Good prognosis if there are no complications Complications: Pneumonia Pulmonary baro/volutrauma Persistent Pulmonary Hypertension (PPHN)

42. Persistent Pulmonary Hypertension-PPHN- Also known as Persistent Fetal Circulation -PFC-

43. Failure to make the transition from fetal to neonatal circulation or a reversion back to the condition where pulmonary artery pressure exceeds aortic pressure Results in R-L shunting across the D.A. and the Foramen Ovale

44. Occurrence • Usually term and post-term babies • Females more often than males • Symptoms may take 12-24 hours after birth to develop

45. Etiology & Predisposing Factors • M.A.S – most common • Hypoxia and /or acidosis, eg RDS • Any condition that causes PVR to increase

46. Pathophysiology • Primary problem is pulmonary artery hypertension • Infants arterial walls are thicker and they are more prone to vasospasm • If pulmonary artery pressure gets high enough, blood will shunt R-L across the D.A. and Foramen Ovale • Remember, conditions that drive up PAP usually make the D.A. open • Lung is hypoperfused resulting in refractory hypoxemia and hypercapnia

47. Clinical Signs • Refractory hypoxemia and cyanosis • Shock and tachypnea • Murmur possible • Pre-ductal PaO2 > post-ductal PaO2 • Hypoxemia with combined acidosis • CXR usually OK when compared to infants condition

48. PPHN Treatment • NTE and O2 • Nitric Oxide • Often in conjunction with HFO • Priscoline, Indocin may also be used • If completely unresponsive to therapy ECMO may be tried

49. Prognosis & Complications Prognosis depends on how well infant responds to treatment Complications • Shock • Intracranial bleed • Internal bleeding • Especially a problem if Priscoline is used

50. Wilson – Mikity Syndrome-Pulmonary Dysmaturity- Respiratory distress that develops after the first week of life and presents with definite CXR changes