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

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HMD Pathology

• Restrictive lung disease

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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

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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)

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TTNB Clinical Findings

• C-section infants
• Good Apgars at birth
• Mild hypoxemia within first 24 hours

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TTNB Chest X Ray

• Lymphatic engorgement
• (white strings)
• Hyperinflation
• (diaphragm greater than 10 ribs)

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TTNB
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TTNB Treatment

• Hood O2 within first 24 to 48 hours
• Infant on room air

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Bronchopulmonary Dysplasia

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

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BPD Pathology

• Stage I - same as HMD

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BPD Pathology

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

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BPD Pathology (cont.)

• Stage III
• continued smooth muscle development
• interstitial fibrosis
• emphysematous bullae

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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)

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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

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BPD Treatment

• Supportive
• Steroids

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Meconium Aspiration Syndrome

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

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MAS Pathology

• Check valve, ball valve effect
• (Increased incidence of pneumothorax)
• Chemical (aspiration) pneumonitis

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MAS Clinical Findings

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

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MAS Chest X Ray

• Increased patchy density
• Hyperinflation

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MAS Treatment

• Deep tracheal suctioning at birth
• Supportive
• Chest physiotherapy

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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 gt 100 is lung disease
• PaO2 50 to 100 is either lung or heart disease
• PaO2 lt 50 is fixed right to left shunt

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Differential Diagnosis of PFC (cont.)

• If fixed R to L shunt is suspected
• Obtain pre and post ductal PaO2
• Difference lt 15 torr, no ductal shunting
• Difference gt 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 gt 100 torr, then PFC is present
• If PaO2 lt 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