Diaphragmatic Hernias

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Diaphragmatic Hernias

• Sanjay Munireddy
• Sinai Hospital of Baltimore
• Feb 5, 2008

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Diaphragmatic Hernias

• Congenital
• Traumatic

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Congenital Diaphragmatic Hernias (CDH)

• One of the most common congenital abnormalities
• Incidence 1 in 2000 to 5000 births
• One third of infants with CDH are stillborn,
  usually due to associated fatal anomalies like
  neural tube defects and cardiac defects
• Defects are common on left side (80) compared to
  right (20)

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Congenital Diaphragmatic Hernias (CDH)

• Bilateral CDH defects are rare
• Sporadic developmental anomaly, although familial
  cases have been reported
• Expected risk in a 1st degree relative is 1 in 45
• One third have associated major defects
• Combination of CDH and abnormal karyotype is
  associated with poor outcome

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Congenital Diaphragmatic Hernias (CDH)

• Cause is unknown
• Presumed combination of intrinsic predisposition
  (genetic) and environmental insult (teratogen or
  deficiency)
• Pharmacological agents like quinine, thalidomide,
  nitrofen, phenmetrazine
• Vitamin A deficiency ?? (alterations in
  retinoid-regulated target genes)

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Congenital Diaphragmatic Hernias (CDH)

• During early development, midgut is largely
  extracoelomic.
• If closure of pleuroperitoneal canal does not
  occur by the time the midgut returns to abdomen
  during 9th 10th week of gestation, viscera
  herniate into thoracic cavity
• In addition to SB, organs such as spleen,
  stomach, colon liver may herniate through the
  defect

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Congenital Diaphragmatic Hernias (CDH)

• Types of Congenital Diaphragmatic Hernias (CDH)
• Bochdalek
• Morgagni
• Diaphragmatic eventration
• Central tendon defects

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Bochdalek Hernia

• Postero-lateral diaphragmatic hernia
• Most common manifestation of CDH, accounting for
  more than 95 of cases
• Majority of Bochdalek hernias (80-85) occur on
  the left side of the diaphragm
• A failure of the diaphragm to completely close
  during development.
• Herniation of the abdominal contents into the
  chest
• Pulmonary hypoplasia

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Morgagni Hernia

• anterior defect of the diaphragm
• referred to as Morgagnis, retrosternal, or
  parasternal hernia
• accounts for approximately 2 of all CDH cases
• characterized by herniation through the foramina
  of Morgagni which are located immediately
  adjacent to the xyphoid process of the sternum
• majority occur on the right side of the body and
  are generally asymptomatic

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Diaphragmatic eventration

• abnormal displacement (i.e. elevation) of part or
  all of an otherwise intact diaphragm into the
  chest cavity
• diaphragm is thinner in the region of
  eventration, allowing the abdominal viscera to
  protrude upwards
• thinning is thought to occur because of
  incomplete muscularisation of the diaphragm
• Minor forms of diaphragm eventration are
  asymptomatic

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Congenital Diaphragmatic Hernias (CDH)

• Left sided CDH is a 2 - 4 cm postero-lateral
  defect
• Right lobe of liver can occupy most of hemithorax
  in rt side defect
• Hepatic veins may drain ectopically into right
  atrium
• Lung and liver may be fused

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Pathophysiology

• Pulmonary parenchymal compression by herniated
  organs and its effect on growth and maturation of
  lung
• Unilateral hernia is associated with bilateral
  abnormal pulmonary development (severe on
  ipsilateral side)
• Lung is smaller, pulmonary vascular bed is
  abnormal on affected side in pts with CDH

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Pathophysiology

• Inappropriate and significant medial muscular
  hyperplasia in arterioles, leading to increased
  susceptibility to development of pulmonary
  hypertension
• Factors contributing to Pulm HTN are
• Hypoxia
• Stress
• Acidosis
• hypothermia

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Diagnosis

• Often made on prenatal ultrasound exam
• Prenatal MRI when obstetric US has detected a
  complex fetal anomaly
• After birth, spectrum of respiratory symptoms
  depend on degree of pulmonary hypoplasia and pulm
  HTN
• Respiratory distress at birth within first 24
  hours of life

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Diagnosis

• Affected infants have a scaphoid abdomen
• Chest x-ray demonstrates loops of intestines in
  the chest
• Location of stomach is confirmed by placement of
  a NGT
• CXR shows shifting of cardiac silhouette into
  contralateral thorax
• CXR is unreliable for estimating degree of
  pulmonary hypoplasia

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Diagnosis

• Additional radiographic and ultrasonographic exam
  needed to search for associated anomalies
• Echocardiography
• 10 - 20 of infants are diagnosed after the 1st
  day of life

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Treatment

• CDH is a physiologic emergency and not a surgical
  emergency
• Pregnant mother should be referred to appropriate
  tertiary perinatal center where full array of
  respiratory care strategies (NO, Oscillating
  ventilators, ECMO) are available
• Endotracheal intubation and NGT insertion

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Treatment

• Bag-mask ventilation is contraindicated to avoid
  distension of stomach and intestines in thoracic
  cavity
• Proper temperature regulation, glucose
  homeostasis, and volume status
• Most infants can be successfully managed with
  pressure-cycled ventilator
• Goals of respiratory support are PaO2 gt 60 and
  PaCO2 lt 60

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Treatment

• Extremes of hyperventilation (high rates and high
  pressures) should be avoided
• High frequency technologies like jet ventilator
  or oscillating ventilator may be required
• Antihypertensives to decrease pulmonary HTN like
  NO, Viagra
• ECMO if everything fails

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Treatment

• During last 25 years greater emphasis has been
  placed on the physiologic behavior of lungs, and
  thus better survival
• Lung function is the most important determinant
  of survival in CDH
• Surgery may be delayed almost indefinitely, if
  necessary
• Pulm HTN is treated aggressively by whatever
  means necessary
• Surgical repair is performed when labile pulm HTN
  has resolved

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Surgery

• Delayed surgical repair is now widely placed
• Most institutions perform surgery in NICU
• Laparotomy, thoracotomy, laparoscopy and
  thoracoscopy
• When diaphragmatic tissue is adequate, primary
  repair with nonabsorbable suture can be done

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Surgery

• If the defect is too large, prosthetic material
  can be used for a tension-free repair
• Major drawback of using prosthetic material is
  risk of infection and risk of dislodgement and
  subsequent re-herniation
• Post-op management should continue the goals
  established before surgery

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Outcome

• Survival rates for isolated CDH have improved
  dramatically (gt90)
• Major predictor of survival is resolution of
  pulmonary HTN
• In the survivors, long term problems include
  chronic lung disease, developmental delay,
  nutritional and growth related problems

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Evolving Therapies

• In utero repair
• Liquid ventilation
• Pulmonary transplantation
• Pharmacology
• Prostacyclin derivatives
• Calcium channel blockers
• Phosphodiesterase inhibitors