Download FT Respiratory Distress

RESPIRATORY DISTRESS IN
THE FULL TERM NEONATE
CHRISTY L. CUMMINGS, MD
OBJECTIVES
1. Informal case-based learning
2. Differentiate between cardiac and respiratory
causes of cyanosis
3. Describe the primary parenchymal diseases that
can cause respiratory distress in the term neonate
4. Describe the primary developmental lung
abnormalities that can cause respiratory distress in
the term (or near-term) neonate
RULE OUT CARDIAC DISEASE
• Pulse Oximetry Test
• Determines whether formal hyperoxia test is useful
• Cyanosis without marked respiratory distress and O2 sat < 85% in
room air and 100% oxygen suggests intracardiac shunt
• If O2 sat increases to > 85% on 100% oxygen, a full hyperoxia test
should be performed
• Hyperoxia Test
• Obtain baseline right radial (preductal) arterial blood gas
measurement with baby breathing room air and 100% O2
• A PaO2 > 300 mm Hg on 100% O2 is normal, 150-300 mm Hg
suggests pulmonary disease, and 50 -150 mm Hg suggests
cardiac disease (or severe pulmonary hypertension)
• ECHO
HINTS ON CHEST RADIOGRAPH
• RDS
• Mostly premies, but seen in term (rare) and near-term
• Reticular granular pattern and air bronchograms
• MAS
• Patchy areas of atelectasis due to complete airway
obstruction, interspersed with areas of air trapping due to
partial obstruction and a one-way valve phenomenon
• White out, and/or air leak syndrome
• Neonatal pneumonia
• Classical patchy infiltrates, but the findings also may be
indistinguishable from RDS
• Pleural effusion supports diagnosis of PNA, seen 67%
HINTS ON CHEST RADIOGRAPH
• TTN
• Diffuse parenchymal infiltrates, a “wet silhouette” around
heart, or accumulation of fluid in various intralobar spaces
(fissure)
• Indicate increased pulmonary interstitial, alveolar, or pleural
water content
• CHD
• Cardiac enlargement, unusual silhouette (snowman, boot)
• Congenital lymphangiectasia
• Lungs may appear normal, overinflated or exhibit a coarse
interstitial infiltrate due to distended, abnormal lymphatics
• Effusion (chylous)
POSSIBLE DIAGNOSIS RELATED TO
RADIOGRAPHIC FEATURES
CASE
• 1 hour old FT baby boy with tachypnea (RR 70s)
born via C/S, GBS neg
• PE:
• Moderate retractions
• O2 sat 88% on RA
• O2 sat 100% on 100%
TRANSIENT TACHYPNEA OF THE
NEWBORN (TTN)
• Relatively benign, self-limited disease
• 11:1000 births, M>F
• Increased risk:
• M, C/S, perinatal asphyxia, cord prolapse, IDM, maternal
asthma or anesthesia during labor
• Tachypnea (>60bpm) shortly after birth, lasts 1-5d
• Unclear etiology:
• Delayed resorption of fetal lung fluid related to elevated CVP,
delayed clearance of pulmonary liquid by lymphatics
• Mild asphyxia resulting in mild pulmonary capillary leak and to
myocardial dysfunction with elevated filling pressure
• Almost never requires mechanical ventilation
RESORPTION OF ALVEOLAR FLUID AT
BIRTH: CELLULAR MECHANISMS
CASE
• 1 hour old FT baby boy born via NSVD who required
PPV in DR, increasing WOB, retractions, required
intubation
RDS IN TERM INFANT: SP-B DEFICIENCY
• Congenital abnormalities of surfactant proteins
• Most common is deficiency of surfactant protein B (SP-B)
• Autosomal recessive, frame-shift mutation chromosome 2,
• Severe respiratory distress after birth
• CXR identical to RDS
• Continued distress despite mechanical ventilation,
oxygen, repeated surfactant, corticosteroids
• Prognosis is poor, most die within 1-6 months
• Only effective therapy (although neither available
for nor consented to by all) is lung transplantation
CASE
• 1 hour old FT baby girl born via NSVD, meconium,
who emerged limp, was suctioned below cords x1
• Now with grunting, retractions, desats, requiring
intubation
MECONIUM ASPIRATION SYNDROME
• Incidence:
• 13% of all live births complicated by meconium-stained
amniotic fluid, and of these, 4% to 5% develop MAS
• Mechanism
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Direct toxicity of the meconium  chemical pneumonitis
Inactivation of surfactant
Activation of complement
Vasoconstriction
Partial/complete airway obstruction by thick meconium
Secondary pulmonary hypertension
MECONIUM ASPIRATION SYNDROME
• Management
• NRP guidelines, endotracheal suction below cords if limp
• Intubation, mechanical ventilation
• Surfactant
• RCTs shown that surfactant reduces need for ECMO
• iNO
• Since the approval of iNO by the US FDA in 2001, there has been
a steady decrease in the use of ECMO for neonates with MAS
• HFOV +/• Reduction in complications from air-leak syndromes (PTX)
CASE
• FT baby girl born via NSVD, GBS+, treated with PCN
x1 2 hours PTD
• Increased WOB, desats
• Requires PPV
PNEUMONIA
• Early onset <7d, late onset >7d
• In utero
• Rubella, CMV, HSV, mumps, adenovirus, Toxo, T. pallidum,
M. tuberculosis, Listeria monocytogenes, VZV, HIV
• During delivery/perinatally
• GBS, Escherichia coli, Klebsiella sp, Chlamydia trachomatis
• Postnatally
• Respiratory viruses (adenovirus, RSV), gram-positive
bacteria(groups A, B, and G streptococci or S. aureus), and
gram-negative enteric bacteria (Klebsiella sp, Proteus sp,
Pseudomonas aeruginosa, flavobacteria, Serratia
marcescens, and E coli)
PULMONARY CAUSES FOR
RESPIRATORY DISTRESS
Parenchymal conditions:
• Transient tachypnea of the newborn
• Meconium aspiration syndrome, other aspirations
• Respiratory distress syndrome
• Pneumonia
• Pulmonary edema
• Pulmonary hemorrhage
• Pulmonary lymphangiectasia
CASE
• FT baby boy born via repeat C/S with increased
WOB, retractions
• Requires intubation
• Transillumination neg
CONGENITAL LOBAR EMPHYSEMA
• Accounts for 50% of structural lesions causing
respiratory distress in the newborn
• M:F 2:1, associated anomalies 14-40% (often CHD)
• Air trapping and overdistention of segments and
lobes of the lungs
• Prenatal diagnosis via high-res U/S, MRI or CT
• Clinical signs/sx include respiratory distress,
mediastinal shift, wheezing
• Upper lobes afftected 90% time
• Symptomatic lesions need surgical resection
• Asymptomatic lesions may be watched carefully
CASE
• FT baby girl born via repeat
C/S
• Respiratory distress
• Intubated
• CXR appears ok, but on
close inspection reveals
small dense mass LLL
• CT with contrast shown
PULMONARY SEQUESTRATION
• Abnormal lung tissue with no connection to normal
tracheobronchial tree
• Receives arterial blood supply from systemic circulation,
usually branch of the aorta
• Mutation in Homeobox gene Hoxb-5, crucial for normal
airway branching/development
• Intralobar vs extralobar
PULMONARY SEQUESTRATION
• Intralobar – lesion within lobe without separate pleura
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3x more common than extralobar
May be acquired (recurrent infection due to lack of pleura)
Lower lobe (95%), and in 55% of cases is on the left side
M=F
• Extralobar - discrete mass of pulmonary parenchyma
outside pleural investment of lung
• In 66% of the cases, left side, proximal to esophagus and
between lower lobe and diaphragm
• M:F 3-4:1
• >65% associated with anomalies (CDH, TAPVR, CHD, CCAM)
• Resection for both types necessary
CASE
• 1 day old FT female born via NSVD, GBS neg, with
respiratory distress
CCAM/CPAM
• Multicystic mass of dilated bronchiolarlike spaces that
proliferate at the expense of alveoli
• Large lesions may obstruct venous return to heart,
causing fetal hydrops
• Abnormal signaling/conjugation between developing
terminal bronchioles and alveolar mesenchyme
• Mesenchymal & plt-derived GF
CCAM/CPAM
• M=F, usually affects right side one lobe
• Solid lesions worse prognosis than large cysts
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Type 1 (75%) – small # of large cysts, 2-10cm, mucin
Type 2 - small cysts (<2cm), assoc anomalies, poor outcomes
Type 3 – microscopic cysts, rare, appears solid on gross exam
(Type 4 – acinar epithelium)
• Surgical resection for all types
• 100% survival with surgery (without hydrops fetalis)
CASE
• FT baby boy delivered via repeat C/S, prenatal L:H
ratio 0.8 and + liver
• Intubated immediately
CONGENITAL DIAPHRAGMATIC HERNIA
(CDH)
 Herniation of intestinal contents into thoracic cavity
 Results in pulmonary hypoplasia leading to respiratory distress
• 95% occur through posterior foramen of Bochdalek (lies
posteriorly and lateral to spine); of these, 80% are on left side
 1 : 4,000 births
 Signs/symptoms:
 Cyanosis, severe respiratory distress, scaphoid abdomen
 Usually seen during routine prenatal U/S
 L:H ratio, presence of liver or other organs in chest
 Post delivery xray reveals intestinal loops in chest cavity
 Immediate intubation and gastric decompression is essential
to higher survival rates
 Intubation should be performed by most experienced team member
CONGENITAL DIAPHRAGMATIC HERNIA
PULMONARY CAUSES FOR
RESPIRATORY DISTRESS
Developmental abnormalities:
• Lobar emphysema
• Pulmonary sequestration
• Cystic adenomatoid malformation
• Congenital diaphragmatic hernia
• Tracheoesophageal fistula
• Pulmonary hypoplasia
CASE
• 3 hour old FT baby girl with respiratory distress while
eating, improves with crying. CXR WNL.
• ENT consulted, CT ordered
CHOANAL ATRESIA
• Congenital anomaly, back of the nasal passage
(choana) is blocked, usually by abnormal bony or
soft tissue formed during fetal development
• 0.82 cases per 10,000 individuals, F>>M
• Unilateral (R) and 2:1, B/L
• CHARGE syndrome
• 6% with chromosomal anomalies
• Cyanosis
• Worse with feeds or pacifier
• Improves with crying
• Surgical correction, stent, revisions
CHOANAL ATRESIA: CHARGE
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C – Coloboma of the eye, CNS anomalies
H - Heart defects
A - Atresia of the choanae
R - Retardation of growth and/or development
G - Genital and/or urinary defects (Hypogonadism)
E - Ear anomalies and/or deafness
CASE
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FT baby boy with respiratory distress, hoarse cry
Intubated for worsening respiratory status
CXR WNL
ENT consulted
LARYNGEAL WEB
• Incomplete recanalization of the laryngotracheal tube
during 3rd month of gestation (atresia – stenosis)
• Most commonly at level of vocal folds anteriorly
• Sx: Mild dysphonia to significant airway obstruction
• 30% associated airway anomalies (subglottic stenosis), 22q11
• Diagnosis – rigid laryngoscopy/bronchoscophy
• Management
• Ranges from observation to emergent tracheotomy
• Lysis endoscopically using cold knife or laser
• Endoscopic suturing of the cut edges or placement of a keel
may prevent restenosis in these cases
• Thicker webs may require laryngofissure approach, with
postoperative stenting of the airway
PULMONARY CAUSES FOR
RESPIRATORY DISTRESS
Airway abnormalities:
• Choanal atresia/stenosis
• Laryngeal web
• Laryngotracheomalacia or bronchomalacia
• Subglottic stenosis
CASE
•f
RIB CAGE ABNORMALITIES
JEUNE SYNDROME
• Asphyxiated Thoracic Displasia (Jeune syndrome)
• Autosomal recessive
• Clinical signs/sx:
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Bone dysplasia – rhizomelic brachymelia
Thoracic anomalies – bell shaped rib cage, short ribs
Renal and hepatic malformations
Pulmonary hypoplasia
• Radiologic changes often seen by 16-18wk gestation
• Usually death in the newborn period from severe
pulmonary hypoplasia
CASE
• FT baby girl born via NSVD, worsening respiratory
distress, increasing O2
• Required intubation and
intervention
PNEUMOTHORAX/MEDIASTINUM
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Air collection: pleura and chest cavity or mediastinum
Neonatal pneumomediastium 2.5:1000 live births
Assoc with mechanical ventilation, PNA, RDS, mec
Often asymptomatic
May require intervention
CASE
• 3 day old FT baby boy born via NSVD, worsening
respiratory distress
CHYLOTHORAX
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Pleural effusion from lymphatic fluid (chyle)
Leakage from thoracic duct or branch
M:F is 2:1and R>L side
50% occur within 24hr of life, 70% by 1st week of life
Composition: milky, chylomicrons, TGs, lymphs
Treatment:
• Thoracentesis, CT to allow drainage
• D/c FFAs in diet; formula high in medium
chain TGs (Portagen) bypasses lymphatic
system via direct absorption into blood stream
• Surgical ligation of thoracic duct
• Chemical or surgical pleurodesis
• Octreotide for several weeks
PULMONARY CAUSES FOR
RESPIRATORY DISTRESS
Mechanical abnormalities:
• Rib cage anomalies (eg, Jeune syndrome)
• Pneumothorax
• Pneumomediastinum
• Pleural effusion
• Chylothorax
QUESTIONS?
References:
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