Outline how the respiratory system of a neonate differs from that of an adult.
This question required an outline of the anatomical, mechanical and functional differences. It was expected that factors leading to an increased work of breathing and oxygen cost would be mentioned. The mechanics of expiration were not often included in candidates’ answers. Immaturity of the alveoli and peripheral chemoreceptors were common omissions. Inaccuracies regarding upper airway anatomy and compliance of the chest wall cost some candidates marks. The question did not call for an explanation of the relative difficulty of intubation. Discussion of pathophysiology due to airway obstruction, causes of central apnoea or sensitivity to drugs was not required. Many answers included inaccurate information. Points which were often missed were difference in bronchial angles, number of alveoli, number of type 1 fibres in diaphragm, ciliary function and peripheral chemoreceptors.
Domain | Differences in the neonate | In the adult |
Airway |
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Airway resistance |
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Lung volumes and spirometry variables |
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Compliance |
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Gas exchange |
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Control of respiration |
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Respiratory enegetics |
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Davis, Ryan P., and George B. Mychaliska. "Neonatal pulmonary physiology." Seminars in pediatric surgery. Vol. 22. No. 4. WB Saunders, 2013.
Neumann, Roland P., and Britta S. von Ungern‐Sternberg. "The neonatal lung–physiology and ventilation." Pediatric Anesthesia 24.1 (2014): 10-21.
LoMauro, Antonella, and Andrea Aliverti. "Physiology masterclass: extremes of age: newborn and infancy." Breathe 12.1 (2016): 65-68.