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Diaphragmatic Conditions

Congenital Diaphragmatic Hernia (CDH)

  • Incidence:
    • Occurs in 1 in 2,000 to 5,000 live births.
    • Diagnosed prenatally in most cases.
    • More common on the left side (84%); bilateral defects are rare (2%).
    • Hernia sac present in 10-15% of cases; must be excised during repair.
    • Overall survival rate: 70-90%, despite advanced treatments.
  • Diagnostic Predictors:
    • Lung area to head circumference ratio (LHR):
      • Sonographic predictor of prognosis.
      • Calculated by multiplying the longest two perpendicular lung measurements (contralateral to CDH) and dividing by head circumference.
      • LHR < 1 and abnormal liver position at 24 weeks gestation indicate poor prognosis.
    • Fetal MRI:
      • Used to determine fetal lung volume.
      • Assesses the ratio of lung to spinal fluid signal intensity.

Pathogenesis

  • Embryology:
    • During 8-10 weeks gestation, the pleuroperitoneal cavities are separated by the developing diaphragm.
    • Persistence of the pleuroperitoneal canal leads to a posterolateral CDH defect.
    • Types of Hernias:
      • Bochdalek hernia: Posterolateral location (most common).
      • Morgagni hernia: Anteromedial location.
  • Effects on Lungs:
    • Abdominal contents herniate into the thoracic cavity, compressing the developing lungs.
    • Results in pulmonary hypoplasia:
      • Smaller bronchi.
      • Less bronchial branching.
      • Reduced alveolar surface area.
    • Both lungs are affected, but the ipsilateral lung is more severely impacted.
  • Pulmonary Vasculature:
    • Increased thickness of arteriolar smooth muscle.
    • Highly sensitive to vasoactive factors.
    • Leads to pulmonary hypertension, significantly affecting morbidity and mortality.

Clinical Presentation

  • Prenatal Diagnosis:
    • Often diagnosed during routine ultrasound as early as 15 weeks gestation.
    • Late-onset CDH (after 25 weeks gestation) has a better prognosis.
    • Poor Prognostic Indicators:
      • Herniation of the stomach and liver.
      • Polyhydramnios.
      • Associated anomalies.
  • Delivery Planning:
    • Should occur at a facility with advanced neonatal care, including ECMO capabilities.
  • Postnatal Symptoms:
    • Immediate respiratory distress after birth.
    • Signs include:
      • Grunting respiration.
      • Chest retractions.
      • Dyspnea and cyanosis.
      • Scaphoid abdomen.
      • Decreased breath sounds; presence of bowel sounds in the chest.
      • Mediastinal shift (heart sounds shifted to the right in left-sided CDH).
      • Preductal and postductal pulse oximetry differential indicating right-to-left shunting due to Persistent Pulmonary Hypertension of the Newborn (PPHN).
  • Diagnostic Imaging:
    • Chest radiograph shows:
      • Multiple bowel loops in the thoracic cavity.
      • Mediastinal shift.
    • Differential Diagnosis:
      • Congenital cystic adenomatoid malformation.
      • Bronchogenic cyst.
      • Diaphragmatic eventration.
      • Cystic teratoma.
  • Delayed Diagnosis:
    • In 10-20% of cases, CDH is diagnosed after the first 24 hours.
    • Symptoms include feeding difficulties, respiratory distress, and pneumonia.
    • Morgagni hernias often diagnosed later in childhood due to asymptomatic infancy.

Management

  • Fetal Interventions:
    • Open fetal surgery was attempted but abandoned due to poor outcomes with liver herniation.
    • Fetal Endoscopic Tracheal Occlusion (FETO):
      • Aims to promote lung growth by preventing egress of pulmonary fluid.
      • Randomized controlled trials have not shown improved survival.
      • TOTAL trial is ongoing to evaluate efficacy.
  • Postnatal Stabilization:
    • Immediate endotracheal intubation to secure airway.
    • Avoid excessive mean airway pressure to prevent barotrauma.
    • Placement of an orogastric tube to decompress the stomach and prevent further lung compression.
    • Gentle ventilatory management with permissive hypercapnia to minimize lung injury.
  • Pharmacologic Support:
    • Inhaled nitric oxide for pulmonary vasodilation.
    • Sildenafil (phosphodiesterase-5 inhibitor) used in some centers for pulmonary hypertension.
    • Use of vasodilators is increasing, though results vary.

Surgical Repair

  • Timing:
    • For infants not requiring ECMO, surgery can proceed soon after birth.
    • Laparoscopic repair is gaining popularity, but long-term benefits are uncertain.
  • ECMO Considerations:
    • Timing of repair in ECMO patients is controversial.
    • Some advocate for repair during ECMO, others after weaning or decannulation.
    • Recent studies suggest better survival when repair is performed after ECMO therapy.
  • Surgical Approach:
    • Subcostal abdominal incision for posterolateral CDH.
    • Reduction of viscera into the abdominal cavity.
    • Diaphragmatic defect repair:
      • Primary repair with interrupted nonabsorbable sutures preferred.
      • Avoid excessive tension to prevent recurrence.
      • Pledgeted sutures may be used.
      • For large defects:
        • Prosthetic materials like Gore-Tex patch commonly used.
        • Regenerative extracellular matrix biomaterials (e.g., Surgisis, AlloDerm) are alternatives.
  • Postoperative Care:
    • Chest tubes are typically not placed.
    • Monitor for mediastinal shift returning to center.
    • Manage abdominal closure carefully due to reduced viscera volume.
      • May require temporary abdominal silo or skin-only closure with delayed fascia closure.
  • Complications on ECMO:
    • Postoperative bleeding is a major risk.
    • Ensure meticulous hemostasis during surgery.

Long-Term Outcomes

  • Chronic Conditions:
    • Persistent PPHN and respiratory dysfunction.
  • Developmental Issues:
    • Developmental delay.
    • Seizures.
    • Hearing loss.
  • Other Morbidities:
    • Chronic lung disease.
    • Scoliosis.
    • Growth retardation.
    • Pectus excavatum deformities.
    • Gastroesophageal reflux disease (GERD).
    • Foregut dysmotility.

Eventration of Diaphragm

  • Definition:
    • Abnormal elevation of the hemidiaphragm affecting respiratory function.
  • Etiology:
    • Congenital or acquired.
  • Congenital Causes:
    • Birth trauma (e.g., Erb palsy).
    • Anatomic abnormalities of the diaphragm.
  • Erb Palsy:
    • Paralysis of the arm due to injury to the brachial plexus (C5-C8).
    • Often includes ipsilateral diaphragmatic paralysis due to phrenic nerve injury.
  • Acquired Causes:
    • Iatrogenic phrenic nerve injury during open cardiac surgery.
  • Diagnosis:
    • Chest radiographs show elevated diaphragm.
    • Confirmed by fluoroscopy or ultrasound demonstrating absent or paradoxical diaphragmatic movement.
  • Symptoms:
    • Respiratory distress.
    • Difficulty weaning from ventilatory support.
  • Treatment:
    • Diaphragmatic plication:
      • Performed via open or laparoscopic approach.
      • Diaphragm is folded taut using multiple interrupted nonabsorbable sutures.

Bronchopulmonary Malformations

Overview

  • Types:
    • Bronchogenic cysts.
    • Intralobar sequestrations (ILS).
    • Extralobar sequestrations (ELS).
    • Congenital pulmonary airway malformations (CPAMs).
    • Congenital lobar emphysema (CLE).
  • Clinical Impact:
    • In perinatal period, can cause:
      • Pleural effusions.
      • Polyhydramnios.
      • Hydrops.
      • Pulmonary hypoplasia.
      • Airway obstruction.
      • Fetal demise in severe cases.
  • Diagnosis:
    • Often identified prenatally via ultrasound.
  • Management:
    • Fetal surgery considered if fetal viability is at risk.
    • Postnatally, some lesions may regress spontaneously.
    • Concern for recurrent pulmonary infections and malignant potential necessitates evaluation.

Bronchogenic Cyst

  • Characteristics:
    • Wall consists of fibroelastic tissue, smooth muscle, and cartilage.
    • Lined with ciliated columnar epithelial cells.
    • May contain mucus-producing cuboidal cells.
  • Locations:
    • Anywhere along the tracheobronchial tree.
    • Commonly near the carina and right hilum.
  • Clinical Presentation:
    • Can enlarge and compress the airway or vital structures.
    • Symptoms include:
      • Dysphagia.
      • Pneumothorax.
      • Cough.
      • Hemoptysis.
      • Risk of infection if presenting later in life.
  • Diagnosis:
    • Suspected on chest radiograph.
    • Confirmed by CT scan showing a spherical non-enhancing cystic mass.
  • Treatment:
    • Surgical resection is recommended regardless of symptoms.
    • Rare cases of malignant transformation reported.

Congenital Pulmonary Airway Malformation (CPAM)

  • Definition:
    • Hamartomatous lesions where a multicystic mass replaces normal lung tissue.
    • Connected to the tracheobronchial tree.
    • Blood supply is pulmonary.
    • Cystic proliferation of the terminal airways, producing cysts lined by mucus-producing respiratory epithelium and elastic tissue in the cyst walls without cartilage formation.
  • Malignant Potential:
    • Risk of malignant transformation (e.g., rhabdomyosarcoma).
  • Classification (Stocker Classification):
    • Type I:
      • ~75% of cases.
      • Few large cysts (2-10 cm).
      • Can compress normal lung tissue.
    • Type II:
      • Numerous small cysts (<1 cm).
    • Type III:
      • Rare.
      • Tiny cysts (a few millimeters).
      • Associated with mediastinal shift, hydrops, and poor prognosis.
  • Common Locations:
    • Left lower lobe is most frequently affected.
    • Can occur in any lobe and, rarely, in more than one lobe or on both sides.
  • Prenatal Management:
    • Fetal MRI distinguishes CPAM from other anomalies.
    • Fetal thoracotomy or thoracoamniotic shunting considered if distress occurs before 32 weeks (rare).
    • Betamethasone may promote regression and resolve hydrops.
  • Postnatal Presentation:
    • May present with life-threatening respiratory distress at birth.
    • Often asymptomatic in infancy.
    • Unrecognized CPAM can present later with chronic cough or recurrent pneumonia.
  • Diagnosis:
    • Chest radiograph shows cystic thoracic mass.
    • Ultrasound and CT scans are routinely used.
  • Treatment:
    • Resection of the involved lobe is recommended.
    • Elective surgery typically performed at 3-6 months of age.

Pulmonary Sequestration

  • Definition:
    • Nonfunctional lung tissue (microcystic) without connection to the tracheobronchial tree.
    • Receives blood supply from an aberrant systemic artery.
  • Types:
    • Intralobar Sequestration (ILS):
      • Contained within normal lung parenchyma.
      • Accounts for 75% of cases.
    • Extralobar Sequestration (ELS):
      • Separate from normal lung, encased by its own pleura.
      • Occurs predominantly in males.
      • Makes up 40% of cases.
  • Associated Anomalies:
    • Posterolateral diaphragmatic hernia.
    • Pectus excavatum and carinatum.
    • Enteric duplication cysts.
  • Clinical Features:
    • No tracheobronchial communication; does not form enlarged cysts or cause spontaneous pneumothoraces.
    • Can infarct, become infected, and cause hemoptysis.
    • May lead to left-to-right shunting and high-output cardiac failure in infants.
  • Diagnosis:
    • Doppler ultrasound may reveal aberrant systemic arterial supply.
    • CT or MRI for detailed vascular anatomy.
  • Prenatal Management:
    • Serial ultrasound monitoring for enlargement and potential complications.
    • BPS may spontaneously regress in utero.
  • Treatment:
    • Elective resection is advocated, especially for ILS.
    • Segmentectomy or lobectomy may be performed.
    • Thoracoscopic resection is increasingly accepted.

Congenital Lobar Emphysema (CLE)

  • Definition:
    • Progressive overdistention of a lobe due to abnormal bronchopulmonary development.
    • Air trapping caused by intrinsic or extrinsic factors.
  • Common Locations:
    • Left upper lobe.
    • Right middle lobe.
  • Epidemiology:
    • Prevalence: 1 in 20,000 to 30,000 deliveries.
    • Symptoms usually manifest within first few days to 6 months after birth.
  • Diagnosis:
    • Appears as an echogenic homogeneous lung mass on ultrasound.
    • Chest radiograph reveals overdistention of the involved lobe.
  • Management:
    • Observation for incidentally discovered lesions, as they may regress.
    • Avoid mistaking for pneumothorax; use positive pressure ventilation cautiously.
    • If causing mediastinal shift and worsening symptoms, perform open lobectomy promptly.

This comprehensive summary includes all key points regarding diaphragmatic conditions and bronchopulmonary malformations, providing detailed explanations and highlighting important concepts for effective revision.