Respiratory distress syndrome

Changed by Joshua Yap, 16 Apr 2023
Disclosures - updated 15 Jul 2022: Nothing to disclose

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Respiratory distress syndrome (RDS(RDS)) is a relatively common condition that occurs in preterm neonates resulting from insufficient production of surfactant. 

Terminology

RDSRespiratory distress syndrome is also known as hyaline membrane disease (not(this term is not favoured as it reflects non-specific histological findings), neonatal respiratory distress syndrome, lung disease of prematurity (both non-specific terms),or surfactant deficiency disorder 2

Epidemiology

The incidence is estimated at 6 perin 1000 births 2. UncommonIt is uncommon after 36 weeks' gestation due to the development of pneumocyte surfactant production around 35 weeks 5.

Risk factors

Risk factors include:

Associations

Associated conditions are those that can occur in prematurity:

Clinical presentation

Respiratory distress syndrome presents in the first few hours of life in a premature baby. Signs include tachypnoea, expiratory grunting, and nasal flaring. The infant may or may not be cyanosed. Substernal and intercostal retractions may be evident

Risk factors include maternal diabetes, greater prematurity, perinatal asphyxia, and multiple gestations.

Associated conditions are those that can occur in prematurity: germinal matrix haemorrhage, necrotising enterocolitis, patent ductus arteriosus, delayed developmental milestones, hypothermia, and hypoglycaemia.

Pathology

Immature type II pneumocytes cannot produce surfactant. The lack of surfactant increases the surface tension in alveoli causing them to collapse. Patients have a decreased lecithin to sphingomyelin ratio. Damaged cells, necrotic cells, and mucus line the alveoli.

Although most cases are related to prematurity alone, rarely patients may rarely have genetic disorders of surfactant production and can present in a similar clinical and radiological manner 6.

As the alveoli are collapsed (microscopically), the lungs are collapsed macroscopically as well. It is a diffuse type of adhesive atelectasis.

Radiographic features

Plain radiograph
  • low lung volumes

  • diffuse, bilateral and symmetrical granular opacities 

  • bell-shaped thorax

  • air bronchograms may be evident

Hyperinflation makes the diagnosis less likely, unless the patient is intubated.

If treated with surfactant therapy, there may be an asymmetric improvement as more surfactant may reach certain parts of the lungs than others.

Ultrasound

On transabdominal ultrasound, retrodiaphragmatic hyperechogenicity can be seen. If this hyperechogenicity does not resolve by day 9-18 on follow up-up ultrasound, it helps in the prediction of the risk of development of bronchopulmonary dysplasia ref.

Treatment and prognosis

Exogenous surfactant administration is an effective treatment, traditionally administered via endotracheal tube, though less invasive methods of surfactant administration such as via laryngeal mask airway are becoming more common 7. Supportive oxygen therapy is typically required for a period of time.

Complications
Acute
Chronic

Differential diagnosis

Consider:

  • -<p><strong>Respiratory distress syndrome</strong> (<strong>RDS</strong>) is a relatively common condition that occurs in preterm neonates resulting from insufficient production of surfactant. </p><h4>Terminology</h4><p>RDS is also known as <strong>hyaline membrane disease</strong> (not favoured as reflects non-specific histological findings), <strong>neonatal</strong> <strong>respiratory distress syndrome</strong>, <strong>lung disease of prematurity </strong>(both non-specific terms),<strong> </strong>or <strong>surfactant deficiency disorder </strong><sup>2</sup>. </p><h4>Epidemiology</h4><p>The incidence is estimated at 6 per 1000 births <sup>2</sup>. Uncommon after 36 weeks' gestation due to development of pneumocyte surfactant production around 35 weeks <sup>5</sup>.</p><h4>Clinical presentation</h4><p>Respiratory distress presents in the first few hours of life in a premature baby. Signs include tachypnoea, expiratory grunting, and nasal flaring. The infant may or may not be cyanosed. Substernal and intercostal retractions may be evident. </p><p>Risk factors include <a href="/articles/fetal-conditions-associated-with-maternal-diabetes">maternal diabetes</a>, greater prematurity, perinatal asphyxia, and multiple gestations.</p><p>Associated conditions are those that can occur in prematurity: <a href="/articles/germinal-matrix-haemorrhage">germinal matrix haemorrhage</a>, <a href="/articles/necrotising-enterocolitis-1">necrotising enterocolitis</a>, <a href="/articles/patent-ductus-arteriosus">patent ductus arteriosus</a>, delayed developmental milestones, hypothermia, and hypoglycaemia.</p><h4>Pathology</h4><p>Immature type II pneumocytes cannot produce <a href="/articles/surfactant">surfactant</a>. The lack of surfactant increases the surface tension in <a href="/articles/alveoli" title="Alveoli">alveoli</a> causing them to collapse. Patients have a decreased lecithin to sphingomyelin ratio. Damaged cells, necrotic cells, and mucus line the alveoli.</p><p>Although most cases are related to prematurity alone, rarely patients may have genetic disorders of surfactant production and can present in a similar clinical and radiological manner <sup>6</sup>.</p><p>As the alveoli are collapsed (microscopically), the lungs are collapsed macroscopically as well. It is a diffuse type of <a href="/articles/adhesive-atelectasis" title="Adhesive atelectasis">adhesive atelectasis</a>.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><ul>
  • +<p><strong>Respiratory distress syndrome</strong> <strong>(RDS)</strong> is a relatively common condition that occurs in preterm neonates resulting from insufficient production of surfactant. </p><h4>Terminology</h4><p>Respiratory distress syndrome is also known as <strong>hyaline membrane disease</strong> (this term is not favoured as it reflects non-specific histological findings), <strong>neonatal</strong> <strong>respiratory distress syndrome</strong>, <strong>lung disease of prematurity </strong>(both non-specific terms),<strong> </strong>or <strong>surfactant deficiency disorder </strong><sup>2</sup>. </p><h4>Epidemiology</h4><p>The incidence is estimated at 6 in 1000 births <sup>2</sup>. It is uncommon after 36 weeks gestation due to the development of pneumocyte surfactant production around 35 weeks <sup>5</sup>.</p><h5>Risk factors</h5><p>Risk factors include: </p><ul>
  • +<li><p><a href="/articles/fetal-conditions-associated-with-maternal-diabetes">maternal diabetes</a></p></li>
  • +<li><p>greater prematurity</p></li>
  • +<li><p>perinatal asphyxia</p></li>
  • +<li><p>multiple gestations</p></li>
  • +</ul><h5>Associations</h5><p>Associated conditions are those that can occur in prematurity: </p><ul>
  • +<li><p><a href="/articles/germinal-matrix-haemorrhage">germinal matrix haemorrhage</a></p></li>
  • +<li><p><a href="/articles/necrotising-enterocolitis-1">necrotising enterocolitis</a></p></li>
  • +<li><p><a href="/articles/patent-ductus-arteriosus">patent ductus arteriosus</a></p></li>
  • +<li><p>delayed developmental milestones</p></li>
  • +<li><p>hypothermia</p></li>
  • +<li><p>hypoglycaemia</p></li>
  • +</ul><h4>Clinical presentation</h4><p>Respiratory distress syndrome presents in the first few hours of life in a premature baby. Signs include tachypnoea, expiratory grunting, and nasal flaring. The infant may or may not be cyanosed. Substernal and intercostal retractions may be evident.</p><h4>Pathology</h4><p>Immature type II pneumocytes cannot produce <a href="/articles/surfactant">surfactant</a>. The lack of surfactant increases the surface tension in <a href="/articles/alveoli" title="Alveoli">alveoli</a> causing them to collapse. Patients have a decreased lecithin to sphingomyelin ratio. Damaged cells, necrotic cells, and mucus line the alveoli.</p><p>Although most cases are related to prematurity alone, patients may rarely have genetic disorders of surfactant production and can present in a similar clinical and radiological manner <sup>6</sup>.</p><p>As the alveoli are collapsed (microscopically), the lungs are collapsed macroscopically as well. It is a diffuse type of <a href="/articles/adhesive-atelectasis" title="Adhesive atelectasis">adhesive atelectasis</a>.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><ul>
  • -</ul><p>Hyperinflation makes the diagnosis less likely, unless the patient is intubated.</p><p>If treated with surfactant therapy, there may be an asymmetric improvement as more surfactant may reach certain parts of the lungs than others.</p><h5>Ultrasound</h5><p>On transabdominal ultrasound, retrodiaphragmatic hyperechogenicity can be seen. If this hyperechogenicity does not resolve by day 9-18 on follow up ultrasound, it helps in the prediction of risk of development of bronchopulmonary dysplasia <sup>ref</sup>.</p><h4>Treatment and prognosis</h4><p>Exogenous surfactant administration is an effective treatment, traditionally administered via endotracheal tube, though less invasive methods of surfactant administration such as via laryngeal mask airway are becoming more common <sup>7</sup>. Supportive oxygen therapy is typically required for a period of time.</p><h5>Complications</h5><h6>Acute</h6><ul>
  • +</ul><p>Hyperinflation makes the diagnosis less likely, unless the patient is intubated.</p><p>If treated with surfactant therapy, there may be an asymmetric improvement as more surfactant may reach certain parts of the lungs than others.</p><h5>Ultrasound</h5><p>On transabdominal ultrasound, retrodiaphragmatic hyperechogenicity can be seen. If this hyperechogenicity does not resolve by day 9-18 on follow-up ultrasound, it helps in the prediction of the risk of development of <a href="/articles/bronchopulmonary-dysplasia" title="Bronchopulmonary dysplasia">bronchopulmonary dysplasia</a> <sup>ref</sup>.</p><h4>Treatment and prognosis</h4><p>Exogenous surfactant administration is an effective treatment, traditionally administered via endotracheal tube, though less invasive methods of surfactant administration such as via laryngeal mask airway are becoming more common <sup>7</sup>. Supportive oxygen therapy is typically required for a period of time.</p><h5>Complications</h5><h6>Acute</h6><ul>
  • -<li><p><a href="/articles/pulmonary-interstitial-emphysema">pulmonary interstitial emphysema</a> or air leak (secondary to requirement for mechanical ventilation)</p></li>
  • +<li><p><a href="/articles/pulmonary-interstitial-emphysema">pulmonary interstitial emphysema</a> or air leak (secondary to mechanical ventilation)</p></li>
  • -<li><p><a href="/articles/transient-tachypnoea-of-the-newborn">transient tachypnoea of the newborn</a>: lung volumes are normal to slightly hyperinflated in TTN and decreased in RDS</p></li>
  • +<li><p><a href="/articles/transient-tachypnoea-of-the-newborn">transient tachypnoea of the newborn (TTN)</a>: lung volumes are normal to slightly hyperinflated in transient tachypnoea of the newborn and decreased in respiratory distress syndrome</p></li>

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