1. PAL – Distressed Newborn
Brittany Greene

2. Case Stem
A female infant is born in a community hospital by assisted breech delivery at 34 weeks to a 16 year old single primigravida. There had been no antenatal care. Her birth weight is 1.8 kg, and Apgar scores mins later, the baby’s breathing is laboured and there is apparent cyanosis.

3. Objectives
Review the basic principles of newborn care and neonatal resuscitation and discuss use and significance of Apgar scores
Understand the fetal circulation and the changes that occur at birth
Review lung development in utero, the pathophysiology of respiratory distress syndrome and its management
Explore the most common causes of distress in the newborn and its management
Describe 3 commonly measured growth parameters and understand the concepts of low birth weight, prematurity, psychosocial issues, and their implications/significance

4. Fetal Circulation
Ductus arteriosus
Foramen ovale
Ductus venosus

5. Changes at Birth Alveolar fluid clearance Lung expansion
Circulatory changes
Increased O2 tension at birth enhances epithelial resorption of sodium and fluids
Initial breaths generate high transpulmonary pressure which drives fluid from air spaces to interstitium
Thoracic squeeze during delivery
Increasing inspiratory pressure expands alveolar air spaces and establishes FRC + stimulates surfactant release
Clamping of cord removes the low resistance placenta causing a rise in neonatal systemic BP, and lung expansion reduces pulmonary vascular resistance and pulmonary artery pressure
Decreased right-to-left shunt at DA and increased left-to-right shunt
Increased lung perfusion  increased O2 saturation  closure of DA
LA pressure rises and RA pressure falls, until LA pressure exceeds RA  FO closes

6. Lung Development in Utero
Early Embryonic Phase(3-7 weeks)
Pseudoglandular Phase (5-17 weeks)
Canalicular Phase (16-26 weeks)
Saccular Phase (24-36 weeks)
Alveolar Phase (36 weeks to 8 years)
1. Lung buds form
2. Bronchial tree and acinar tubes develop, few terminal buds
3. Completion of branching, terminal airways developing into alveoli, differentiation of Type I and II pneumocytes. May be possible to have limited gas exchange towards end of stage
4. Development of true alveoli, production of surfactant
5. True alveolar ducts and alveoli form

7. Surfactant LaPlace’s Law: P = 2T/R T is surface tension
P is pressure necessary to keep the sphere open
T is surface tension
R is radius of the sphere
With surfactant reducing the surface tension, even at low volumes, less pressure is needed to maintain open alveoli  maintains alveolar volume and stability
Pressure is proportional to surface tension and inversely proportional to radius
Lipoprotein complex
Hydrophilic groups at the air-water interface of alveoli
Hydrophobic tails (DPPC) face the air, reducing surface tension

8. APGAR Score Quick evaluation of newborn at 1 and 5 mins
10 point score with > 7 being normal, 4-6 requiring assistance, and < 4 requiring resuscitation
Apgar Sign 2 1
Appearance (skin colour)
Normal colour all over (hands & feet pink)
Normal colour but hands & feet are bluish
Bluish-gray or pale
Pulse (HR)
Normal (>100 bpm)
< 100 bpm
Absent pulse
Grimace (“reflex irritability”)
Pulls away, sneezes, coughs, or cries with stimulation
Facial movement only (grimaces with stimulation)
Absent (no response to stimulation)
Activity (muscle tone)
Active, spontaneous movement
Arms and legs flexed with little movement
No movement, floppy tone
Respiration (RR and effort)
Normal rate and effort, good cry
Slow or irregular breathing, weak cry
Absent (no breathing)

9. Basic Principles of Newborn Care
Rapid assessment: if “yes” to all 3 questions  dry the baby, place skin-to-skin with mother, covered with dry linen to maintain T
Term gestation?
Crying or breathing?
Good muscle tone?
If “no” to any  baby should receive one or more of the 4 categories of action (in sequence)
Initial stabilization – provide warmth, clear airway if necessary, dry, stimulate
Ventilation
Chest compressions
Administration of epi and/or volume expansion

10. Newborn Resuscitation Algorithm

11. Case 1
Male newborn baby weighing 2.62 kg born to 35 yo mother by c-section at 35+4 weeks GA because of oligohydramnios. APGAR scores at 51 and 95. The baby develops tachypnea soon after birth.

12. Transient Tachypnea of the Newborn
Presentation
Tachypnea within 2 hrs of birth, other signs of respiratory distress. Often no hypoxia or cyanosis
Pathophys
Residual pulmonary fluid in lung after delivery
Risk Factors
Maternal asthma, male, macrosomia, maternal DM, c-section
CXR Findings
“Wet silhouette” around heart, intralobar fluid accumulation, diffuse paranchymal infiltrates
Management
Self-limited, symptoms last up to 2 days, provide supp O2 via hood or nasal cannula to maintain SpO2 > 90%, tube feeding, IV fluids if needed
Prognosis
Excellent
If doesn’t improve after 4-6 hrs or initial CBC abnormal, obtain blood culture, begin antibiotics (amp + gent)

13. Case 2
A baby is born by spontaneous vaginal delivery at 30 weeks to a 25 yo primigravida. Her birth weight is 2.05 kg, and Apgar score is 81. RR 40 and poor air entry bilaterally, no adv. sounds. Within a few mins, she becomes cyanosed and cry is feeble. With suction and supp O2, RR becomes irregular and grunting is heard.

14. Respiratory Distress Syndrome (Hyaline Membrane Disease)
Presentation
Immediately after birth, tachypnea, grunting, retractions, hypoxia, cyanosis
Pathophys
Immature type II alveolar cells  less surfactant, increased alveolar surface tension, decreased compliance  pulmonary vascular constriction, hypoperfusion, lung tissue ischemia  formation of hyaline membranes  bronchopulmonary dysplasia
Risk Factors
Prematurity (1/3 of infants born at wks), male, maternal DM
CXR Findings
Homogenous opaque infiltrates, diffuse atelectasis, air bronchograms
Management
Prevention – give antenatal corticosteroids to pregnant women at <34 wks if high risk of preterm delivery within 7 days.
Nasal CPAP. If respiratory failure, intubate. Indicated if persistent resp. acidosis on CPAP, hypoxemia on CPAP, severe apnea.
Surfactant therapy via ETT– exogenous surfactant replacement most effective if given within first mins of life.
Supportive care – prophylactic abx, maintain temperature, tube feeds
Prognosis
Acute complications – alveolar rupture, infection, IVH, PDA, pulmonary hemorrhage, NEC, GI perforation, apnea of prematurity
Chronic – BPD, retinopathy of prematurity, neurologic impairment
Hyaline membranes = combination of sloughed epithelium, protein, edema
ACS enhances maturational changes in fetal lung architecture and biochem, with increased synthesis and release of surfactant.
Mechanical ventilation is a risk factor for BPD – try to avoid it with CPAP.
Bronchopulmonary dysplasia – chronic lung disease, requiring O2 at corrected GA of 36 weeks. it’s directly related to high volume/pressure from mechanical ventilation. Highest risk at youngest GAs.

15. Case 3
A female baby is delivered at 42+6 wks GA by emergency c-section because of fetal distress and thick MSAF. Birth weight is 3 kg. Apgar is 3 at 1 min. The baby is grunting with moderate retractions.

16. Meconium Aspiration Syndrome
Presentation
Respiratory distress immediately after delivery, with hypoxia. Baby born through meconium stained amniotic fluid, or evidence of meconium staining on exam.
Pathophys
Fetal passage of meconium in utero  aspiration of mec  irritation, obstruction, medium for bacterial culture
Risk Factors
Post-term neonates, small for GA, fetal hypoxia
CXR Findings
Patchy atelectasis or consolidation, hyperinflation
Management
if MSAF – use minimal stimulation and keep baby head down to prevent breathing in meconioum
No evidence for routine amnioinfusion or suctioning (if HR>100, spont. respitation, reasonable tone).
Supportive care, supp. O2. Prophylactic abx until cultures neg.
Prognosis
Pulmonary sequelae – reactive airway disease common
Neurodevelopmental impairment – possibly due to underlying intrauterine hypoxia and chronic infection
Mec composed of desquamated cells, secretions, lanugo, water, bile pigments, pancreatic enzymes, amniotic fluid
Normal – passage of mec occurs early in first trimester, then slows after 16 wks and becomes infrequent by 20 wks, as anal sphincter is innervated. Passage may be caused by increased peristalsis and relaxation of anal sphincter due to increased vagal outflow with cord compression or increased sympathetic inflow during hypoxia.

17. Less Common Causes Infection Pneumothorax
Presents as respiratory distress, temperature instability hours to days after birth
RFs: prolonged rupture of membranes, prematurity, maternal fever
Bilateral infiltrates on CXR ± pleural effusions, serial blood cultures
Pneumothorax
Can occur spontaneously, or secondary to infection, MAS, lung deformity
Persistent pulmonary hypertension of the newborn
Pulmonary vascular resistance fails to decrease after birth
Can occur spontaneously, or secondary to MAS, infection, TTN

18. Differential Diagnosis of Respiratory Distress in the Newborn
Most common (in order of incidence)
Transient tachypnea of the newborn (TTN)
Respiratory distress syndrome (RDS), aka hyaline membrane disease
Meconium aspiration syndrome
Less common, but significant
Delayed transition
Infection (pneumonia, sepsis)
Persistent pulmonary hypertension of the newborn (PPHN)
Pneumothorax
Non-pulmonary causes, e.g. anemia, congenital heart disease, congenital malformation, medications, neurologic or metabolic abnormalities, polycythemia, upper airway obstruction

19. Additional Information

20. Growth Parameters
Growth is a reflection of overall health and nutritional status
Pattern of growth, not just absolute number
Height
Weight
Normal birth weight is 2.5 – 4.5 kg (5.5 to 10 lbs)
Head circumference

21. Prematurity Definitions: any birth occurring before 27 weeks GA
Late preterm = GA weeks
Very preterm = GA < 32 weeks
Extremely preterm = GA < 28 weeks
Associated with 1/3 of all infant deaths, 50% mortality rate if born at or before 25 weeks
Short term complications – respiratory distress, retinopathy, PDA, bronchopulmonary dysplasia, late-onset sepsis, necrotizing enterocolitis, IVH
Long term complications – neurodevelopmental disabilities, e.g. CP, respiratory disorders, gastrointestinal problems, vision and hearing impairment

23. Low Birth Weight Premature infants can be classified by birth weight
Low BW if < 2500 g
Very Low BW if < 1500 g
Extremely BW if < 1000 g
Assess birth weight by percentile for GA
Both low birth weight premature infants and small for gestation age (at term) infants have increased mortality and morbidity