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Neonatal respiratory distress syndrome

Last updated: January 7, 2021

Summary

Neonatal respiratory distress syndrome (NRDS), or surfactant deficiency disorder, is a lung disorder in infants that is caused by a deficiency of pulmonary surfactant. It is most common in preterm infants, with the incidence and severity decreasing with gestational age. Surfactant deficiency causes the alveoli to collapse, resulting in impaired blood gas exchange. Symptoms manifest shortly after birth and include tachypnea, tachycardia, increased breathing effort, and/or cyanosis. The suspected diagnosis is based on clinical features and confirmed by evaluating the extent of atelectasis via chest x-ray. Blood gases show respiratory and metabolic acidosis in addition to hypoxia. Treatment primarily involves emergent resuscitative measures, including nasal continuous positive airway pressure (CPAP) and stabilizing blood sugar levels and electrolytes. In addition, intratracheal surfactant is administered if ventilation alone is unsuccessful. Most cases resolve within 3–5 days of treatment. However, complications such as hypoxemia, tension pneumothorax, bronchopulmonary dysplasia, sepsis, and neonatal death may still occur. NRDS can be prevented by administering antenatal glucocorticoids to the mother if premature delivery is expected.

Epidemiology

References:[1][2]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

References:[1]

Pathophysiology

References:[1][3]

Clinical features

  • History of premature birth
  • Onset of symptoms: usually immediately after birth but can occur within 48–72 hours postpartum
  • Signs of increased breathing effort
    • Tachypnea
    • Nasal flaring and moderate to severe subcostal/intercostal and jugular retractions
  • Typical expiratory “grunting”
  • Auscultation: decreased breath sounds
  • Cyanosis due to pulmonary hypoxic vasoconstriction

References:[1][4][5]

Diagnostics

  • Chest x-ray: diffuse, fine, reticulogranular (ground-glass) densities with low lung volumes and air bronchograms
  • Blood gas analysis
  • Amniocentesis for prenatal testing of NRDS: screening for markers of fetal lung immaturity
    • Lecithin-sphingomyelin ratio < 1.5 (≥ 2 is considered mature)
    • Foam stability index < 0.48
      • A semi-quantitative test used to assess fetal lung maturity
      • Amniotic fluid is mixed with varying concentrations of ethanol and shaken in test tubes
      • Foam forms in the presence of adequate surfactant
      • The index refers to the highest quantity of ethanol that can be added to amniotic fluid with the formation of stable foam.
    • Low surfactant-albumin ratio
  • Pathological findings [6]
    • Hyaline membranes lining the alveoli
      • Composed of fibrin, cellular debris, and red blood cells
      • Appear as eosinophilic, amorphous material lining the alveolar surface
    • Engorged and congested capillary vessels in the interstitium

References:[1][2][4][7][8][9]

Differential diagnoses

Neonatal respiratory distress syndrome

Transient tachypnea of the newborn (wet lung disease) [10] Persistent pulmonary hypertension of the newborn (PPHN) [11] Meconium aspiration syndrome [12][13][14]
Gestation
  • Usually postterm
Etiology
  • Delayed resorption of fetal lung fluid
Risk factors
Onset of symptoms
  • Within the first minutes/hours after birth
  • Immediately after birth and within the next 2 hours
  • Within 24 hours after birth
  • Immediately after birth
Clinical features
  • Low APGAR scores
  • Cyanosis and signs of respiratory distress
  • Heart examination: prominent precordial impulse and a narrowly split and accentuated S2
Imaging
Treatment
  • Supportive care
  • Administration of artificial surfactant
  • Supportive care (e.g., supplemental oxygen, neutral thermal environment, adequate nutrition)
Complications
  • Resolves without complications in the majority of cases
  • Severe PPHN
    • Developmental delay
    • Motor deficit
    • Hearing deficit

The differential diagnoses listed here are not exhaustive.

Treatment

Physiologic O2 saturation in neonates is around 90% instead of 100%. A saturation of 100% is considered toxic for neonates!

References:[1][10][17]

Complications

Bronchopulmonary dysplasia (BPD)

Further complications

Baby oxen have RIBs: Babys receiving too much oxygen get Retinopathy of prematurity, Intraventricular hemorrhage, and Bronchopulmonary dysplasia.

References:[1][4][18][19]

We list the most important complications. The selection is not exhaustive.

Prognosis

  • If left untreated, NRDS has a case fatality rate of 30%.
  • Most cases that are promptly treated resolve within 3–5 days.

Prevention

References:[20]

References

  1. Pramanik AK. Respiratory Distress Syndrome. In: Rosenkrantz T, Respiratory Distress Syndrome. New York, NY: WebMD. http://emedicine.medscape.com/article/976034. Updated: January 16, 2015. Accessed: May 11, 2017.
  2. Besnard AE, Wirjosoekarto SAM, Broeze KA, Opmeer BC, Mol BWJ. Lecithin/sphingomyelin ratio and lamellar body count for fetal lung maturity: a meta-analysis. Eur J Obstet Gynecol Reprod Biol. 2013; 169 (2): p.177-183. doi: 10.1016/j.ejogrb.2013.02.013 . | Open in Read by QxMD
  3. Andreeva AV, Kutuzov MA, Voyno-Yasenetskaya TA. Regulation of surfactant secretion in alveolar type II cells. Am J Physiol Lung Cell Mol Physiol. 2007; 293 (2): p.L259-L271. doi: 10.1152/ajplung.00112.2007 . | Open in Read by QxMD
  4. Le T, Bhushan V, Bagga HS. First Aid for the USMLE Step 2 CK. McGraw-Hill Medical ; 2009
  5. Hermansen CL, Mahajan A. Newborn Respiratory Distress.. Am Fam Physician. 2015; 92 (11): p.994-1002.
  6. Dishop MK. Developmental and Pediatric Lung Disease. Elsevier ; 2018 : p. 99-124.e5
  7. Le T, Bhushan V,‎ Sochat M, Chavda Y, Zureick A. First Aid for the USMLE Step 1 2018. McGraw-Hill Medical ; 2017
  8. Wilmott RW, Kendig EL, Boat TF, Bush A, Chernick V. Kendig and Chernick's Disorders of the Respiratory Tract in Children. Elsevier Health Sciences ; 2012
  9. Sher G, Statland BE, Freer DE. Clinical evaluation of the quantitative foam stability index test. Obstet Gynecol. 1980; 55 (5): p.617-20.
  10. Reuter S, Moser C, Baack M. Respiratory distress in the newborn. Pediatr Rev. 2014; 35 (10): p.417-429. doi: 10.1542/pir.35-10-417 . | Open in Read by QxMD
  11. Abman et al. Guidelines From the American Heart Association and American Thoracic Society: Pediatric Pulmonary Hypertension. Circulation. 2015; 132 (21): p.2037-2099. doi: 10.1161/cir.0000000000000329 . | Open in Read by QxMD
  12. Usta et al.. Risk factors for meconium aspiration syndrome.. Obstet Gynecol. 1995; 86 (2): p.230-4.
  13. Dargaville PA. The Epidemiology of Meconium Aspiration Syndrome: Incidence, Risk Factors, Therapies, and Outcome. Pediatrics. 2006; 117 (5): p.1712-1721. doi: 10.1542/peds.2005-2215 . | Open in Read by QxMD
  14. Committee on Obstetric Practice. Committee Opinion No 689: Delivery of a Newborn With Meconium-Stained Amniotic Fluid. Obstet Gynecol.. 2017; 129 (3): p.e33-e34. doi: 10.1097/aog.0000000000001950 . | Open in Read by QxMD
  15. Townsel CD, Emmer SF, Campbell WA, Hussain N. Gender Differences in Respiratory Morbidity and Mortality of Preterm Neonates. Front Pediatr. 2017; 5 . doi: 10.3389/fped.2017.00006 . | Open in Read by QxMD
  16. Lakshminrusimha S, Keszler M. Persistent Pulmonary Hypertension of the Newborn. NeoReviews. 2015; 16 (12): p.e680-e692. doi: 10.1542/neo.16-12-e680 . | Open in Read by QxMD
  17. Le T, Bhushan V,‎ Sochat M, Chavda Y, Abrams J, Kalani M, Kallianos K, Vaidyanathan V. First Aid for the USMLE Step 1 2019. McGraw-Hill Medical
  18. Kinsella JP, Greenough A, Abman SH. Bronchopulmonary dysplasia. The Lancet. 2006; 367 (9520): p.1421-1431. doi: 10.1016/s0140-6736(06)68615-7 . | Open in Read by QxMD
  19. Rajiah P. Imaging in Bronchopulmonary Dysplasia. In: Lin EC, Imaging in Bronchopulmonary Dysplasia. New York, NY: WebMD. https://emedicine.medscape.com/article/406564-overview. Updated: August 25, 2016. Accessed: January 25, 2018.
  20. Romejko-Wolniewicz E, Teliga-Czajkowska J, Czajkowski K. Antenatal steroids: can we optimize the dose?. Curr Opin Obstet Gynecol. 2014; 26 (2): p.77-82. doi: 10.1097/gco.0000000000000047 . | Open in Read by QxMD
  21. Respiratory Distress Syndrome in Neonates (Hyaline Membrane Disease). http://www.msdmanuals.com/professional/pediatrics/perinatal-problems/respiratory-distress-syndrome-in-neonates#v1089988. Updated: January 1, 2015. Accessed: May 11, 2017.
  22. Kaplan. USMLE Step 2 CK Lecture Notes 2017: Pediatrics. Kaplan ; 2016