RESPIRATORY SYSTEM CHANGES IN NEONATE AND ADULT

Anatomical differences in the airway and the differences in respiratory physiology between a neonate and an adult

Neonate

Adult

Anatomical Changes: They have a larger head and tongue Narrow nasal passages Cephalad Larynx Large Epiglottis Short Trachea and Neck Narrowest part of airways is the cricoid cartilage Ribs are pliable and horinzontal,diaphragmatic muscles are weaker and abdomen protuberant so the respiratory rate is increased to compensate for less efficient ventilation. Small airways and limited number of alveoli reduces their lung compliance Alveolar maturation is not complete So the work of breathing is increased and respiratory muscles fatigue easily Tidal volume and dead space are per kilogram of body weight and are constant in all age groups Physiological Changes Chest wall collapse during inspiration and relatively low residual volume at expiration There is reduction in Functional Residual Capacity which limits oxygen reserves during periods of apnoea and predisposes neonates to hypoxemia and atelactasis Relatively higher rate of oxygen consumption Ventilation is not hypoxia and hypercapnia driven on the contrary the reduce ventilation

Anatomical Changes Propotionate smaller head and tongue Broader nasal passages Caudad Larynx Smaller Epiglottis Relatively elongated neck and trachea Narrowest part of the airway is the glottis Ribs are more more curved with stronger muscles making ventilation more efficient Airways better developed Physiological Changes Increased compliance of chest wall and better residual volume increase the functional residual capacity which gives a better oxygen reserve Ventialtion is hypoxia and hypercapnia driven ,partial pressure of oxygen and carbon dioxide is a feedback to respiratory centres in brain