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Respiratory System of the Newborn

Respiratory System of the Newborn. Revised by Gillian McRavin-Johnson, RNC MHS-Good Samaritan Hospital Carmelita Rivero, RNC, MSN Madigan Army Medical Center. Objectives. Review anatomy and physiology of the respiratory system.

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Respiratory System of the Newborn

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  1. Respiratory System of the Newborn • Revised by Gillian McRavin-Johnson, RNC • MHS-Good Samaritan Hospital • Carmelita Rivero, RNC, MSN • Madigan Army Medical Center

  2. Objectives • Review anatomy and physiology of the respiratory system. • List symptoms and identify treatments of Transient Tachypnea of the Newborn. • List symptoms and identify treatments of Respiratory Distress Syndrome. • List symptoms and identity treatments of Meconium Aspiration Syndrome. • Define and discuss causes of apnea. • Review current NRP guidelines for immediate resuscitation of Newborn.

  3. Embryology • Embryonic stage: week 1-5 - A single lung bud begins to divide into 3 sections. Pulmonary vein joins lung bud. • Pseudoglandular stage: week 5-17 - Conducting airways are formed. Capillary bed is formed, no connection to lung buds. Diaphragm develops. • Canalicular stage: week 17-24 - Gas-exchanging acini units appear and type II cells appear. Capillaries invade terminal airway walls.

  4. Respiratory Cells • Type I Pneumocytes - 90% of surface area • Serve the function of gas exchange • Type II Pneumocytes - 66% of cells but only 3% of surface area • Most important function is the synthesis and secretion of surfactant • Glucocorticoids and thyroid hormones hasten maturation • Weeks 24-26 - alveolar sacs appear in limited quantity, type II cells are unable to release enough surfactant to maintain air breathing • Terminal sac stage: week 24-37 - Type II cells increase and mature, lung size and surface area increase rapidly. Capillary loops increase • Alveolar stage: week 30-8/10 years - Continued alveolar proliferation and development

  5. Respiratory Assessment • Normalrespiratory rate: 40-60 RPM • Tachypnea : >60 RPM • Temperature, stress • C-Section • Pain • Persistent tachypnea - Lung pathology

  6. Respiratory Assessment • Maternal History • Type and quality of chest movement • Abnormal Breath sounds • NasalFlaring, Gasping, Expiratory grunting • Sighing and Retractions

  7. Cont. Respiratory Assessment • Asymmetrical breathing - • Pneumothorax • Diaphragmatic Hernia • Heart defects with failure • Phrenic nerve damage • Abnormal breath sounds • Obstruction • Inflammation

  8. Fetal Transition • Lung sacs are filled with fluid • Labor and initial breaths force fluid from lungs • Oxygen causes capillaries in lungs to dilate • Pulmonary pressure lowers and blood from right side of heart bypasses PDA to enter lungs • The change in pressure causes the PDA and the foramen ovale to close

  9. General Treatment • Oxygen • Oxyhood • CPAP • Ventilator • Glucose • Blood pressure support • Normal temperature range • Minimal stimulation, Cluster Care

  10. Blood Gases • Why are blood gasses important? • H+ ions and CO2 • Correction vs. Compensation • Respiratory vs. Metabolic

  11. Blood Gases • Values • pH 7.35-7.45 • paCO2 35-45 • paO2 50-70 • HCO3 18-24 • Base -2-+2 • Oxygen Saturation 90-94%

  12. Transient Tachypnea of the Newborn A.K.A. Wet Lung Syndrome Retained Lung Fluid Or RDS Type II

  13. TTNB: Pathophysiology • Excess fluid in the lungs usu. due to lack of thoracic squeeze, failure to clear normal fetal lung fluid, or both • Fluid accumulates in the peribronchial lymphatics and bronchovascular spaces • Fetal lung fluid is normally cleared via two ways: • Expulsion during delivery • Absorption after delivery in pulmonary circulation and lymphatic drainage

  14. TTNB: Risks • Tend to be term or near term with mature lungs • Increased Risk • Cesarean Section • Breech Births • Second Born Twin • Rapid Delivery • Maternal Heavy Sedation • Polycythemia • Hypothermia after deliveryLGA babies

  15. TTNB: Symptoms • Tachypnea (60-140 BPM) rarely lasting longer than 48-96 hours • Possible mild cyanosis • Retractions, nasal flaring, and grunting • Decreased breath sounds, but no rales • Possible barrel-shaped chest

  16. TTNB: Diagnosis • TTNB is a diagnosis of exclusion • A diagnosis of TTNB can only be made after resolution of symptoms in the first 4 days • CXR shows increased lung fluid and prominent vascular markings • CXR can be identical to RDS in the first 3 hours of life • ABG - mild hypoxemia, mild hypercapnia, normal pH

  17. TTNB: Interventions • Assisted ventilation is rarely required • Provide appropriate oxygen therapy to maintain ABG’s within normal limits • CPAP may be useful for the first few hours when severe pulmonary involvement is present • Use Neopuff/T-piece resuscitator to provide Cpap • Provide calories to support increased respiratory work • May require gavage feeds when tachypneic

  18. Respiratory Distress Syndrome

  19. Respiratory Distress Syndrome: The Cause • Pathophysiology: Surfactant Deficiency • The Problem: Surface Tension • The sides of the alveoli are attracted to each other and, when in proximity, stick together • Surfactant lowers surface tension 50-100 times, especially at expiration

  20. RDS: Statistics • 60% of 24-28 weekers and 30% of 28-34 weekers develop RDS • Mortality from RDS decreased from ~100% to < 10% • RDS is the major cause of respiratory distress in newborns and prematurity is the most important risk factor

  21. RDS: Risks • Increased Risk • Prematurity • Males vs females • Whites vs non-whites • Infants of diabetic mothers • Presence of asphyxia • Cesarean section esp. without labor • Second twin • Prenatal maternal hypotension • Rh-factor incompatibility

  22. RDS: Risks • Decreased Risk • Prolonged rupture of membranes • Intrauterine growth restriction • Pregnancy-induced hypertension • Maternal heroin addiction • Prenatal corticosteroids

  23. RDS: Symptoms • Occur within 4-24 hours of delivery, worsen during the first 48 hours, and begin to improve by 72 hours • Symptoms: • retractions • see-saw respirations • expiratory grunting • nasal flaring • tachypnea • decreased/unequal breath sounds • poor air entry/fine rales on auscultation

  24. RDS: Symptoms • Other symptoms • tachycardia • hypothermia • hypoglycemia • Generalized cyanosis • hypotension • hypotonia • apnea

  25. RDS: Diagnosis • L/S ratio or PG presence • Initial CXR • Decreased lung compliance • Increased work of breathing • ABG - hypoxemia and hypercapnia

  26. RDS:Interventions - Respiratory • Respiratory support - O2, CPAP, Vent • Continuous monitoring - saturations, ABGs • Serial evaluations and CXRs • Administration of exogenous surfactant

  27. RDS:Prevention - Respiratory • Improved prenatal care to decrease preterm deliveries, antenatal steroids (28-32 weeks) • Early and effective resuscitation

  28. Surfactant Benefits: A Review • Increases alveolar stability - decreases atalectasis • Increases compliance • Decreases work of breathing • More uniform alveolar recruitment on inspiration • Decreases pulmonary edema

  29. Benefits of Surfactant • Exogenous surfactant has decreased mortality in infants (500-1500 g) by 28% • Decreases air leaks by as much as 50-60% • No change in incidence of PDA, BPD, or IVH

  30. Drawbacks of Surfactant • Non-uniform distribution • Inactivation by proteinaceous edema • Oxygenation and tidal volume breaths continue to cause damage • Permanent lung damage • Inhibitory effect on future lung growth

  31. Meconium Aspiration Syndrome

  32. Meconium Aspiration Syndrome • Meconium stained amniotic fluid is noted in 10-15% of all babies delivered. • Meconium may be aspirated from the trachea in about 56% of infants born with thick meconium. • About 1/3 of infants with meconium below the cords become ill and require intensive care.

  33. MAS: Pathophysiology • Damage is caused by two problems: • The bile salts and enzymes cause a chemical pneumonitis. • Meconium occludes distal airways causing several types of physical lung damage.

  34. Cont. MAS Pathophysiology • Physical lung damage: • -The meconium completely occludes the airway and the distal alveoli remain atalectatic • -The ball-valve effect - air gets in the alveoli but can’t get out. • -Meconium moves lower in airway and traps alveoli with air inside.

  35. MAS: Risks • Tend to be term, post-term, or SGA. • Prolonged labor • Fetal bradycardia and distress • Breech presentation • Presence of meconium-stained fluid • Delivery by cesarean section

  36. MAS: Symptoms • Meconium staining of umbilical cord, nails, and skin • Hyperexpansion of chest - “barrel chest” • Respiratory distress - 50% of cases • grunting, irregular/gasping respirations • retractions, nasal flaring • tachypnea • coarse bronchial breath sounds with rales

  37. MAS: Diagnosis • ABG - hypoxemia, acidosis • CXR - hyperinflated lungs - 20-30% Severity is determined by: • Consistency of meconium • Amount of meconium • Degree of consolidation on the CXR

  38. Worst Case Scenario • PPHN: Persistent Pulmonary Hypertension • Lung capillaries remain constricted • Pulmonary artery pressures remain higher than systemic blood pressure • High lung pressure pushes blood through Foramen ovale and ductus arteriosus • Blood is not oxygenated • Hypoxemia and acidosis lead to further pulmonary vasoconstriction

  39. MAS: Interventions - Secondary Conditions/Infection • Continuous monitoring of vital signs, ABGs, CXRs • Treat hypotension, acidosis, anemia, infection • Hypotension and acidosis worsen respiratory distress • Meconium is an excellent growth medium for bacteria

  40. Apnea in the Newborn

  41. Definition of Apnea • The cessation of respiratory air flow and/or respiratory movement for 20 seconds or longer. • The cessation of respiratory air flow is associated with pallor, bradycardia, cyanosis, oxygen desaturation, or a change in level of consciousness.

  42. Types of Apnea Apnea occurring at delivery: Primary Apnea – Cessation of respiratory movements from asphyxia during the delivery process; exposure to O2 will induce respirations Secondary Apnea – Caused by prolonged asphyxia; infant will require resuscitation Primary and secondary apnea can be indistinguishable at birth

  43. Causes of Apnea • Prematurity • Respiratory disorders • Immature respiratory center • Obstructive airway • Infection • Sleep state • Temperature instability – try to keep temp at low end of normal • Cardiovascular disorders • Drugs - Drugs – narcotics, anticonvulsants, anesthesia's, magnesium sulfate

  44. Causes of Apnea • Reflex stimulation – Gastroesophageal reflux, pharyngeal stimulation • Environmental • Rapid warming, vasodilates your NB • Hypothermia, hyperthermia • Elevated environmental temperature • Feeding • Stooling • Painful stimuli

  45. Apnea: Diagnosis • Physical exam • Documentation of apneic spells • Length • Time in relation to occurrence – feeding, procedure, stooling, sleep • Position • Associated bradycardia or color change • Type of stimulation needed to resolve apneic episode.

  46. Apnea: Diagnosis • Laboratory workup – infection, respiratory alteration, metabolic alteration • CBC with differential, platelets • Blood gas • Blood cultures, spinal tap, urine, CRP

  47. Apnea: Interventions • Treat the specific disease or underlying cause. • Keep temperature normothermic • Avoid triggers: • vigorous suctioning • hot/cold to face • sudden gastric distension

  48. Apnea: Interventions • Prone positioning • Shoulder roll • Prevent hyperoxia • Prevent painful stimuli - loud noises, extremely vigorous tactile stimulation or strong odors • Chart spells completely

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