"Conditions that affect the respiratory system are the most frequent cause of morbidity and mortality in the infant. The primary response of hypoxemia in the neonate is backyard. As the physiological status of the child matures, the response to hypoxemia is tachycardia. The age at which this change occurs can vary from 6 months to 2 years; in some children older than 2 years, bradycardia may be the response to hypoxemia.
Infants are prone to respiratory compromise because of physiological characteristics that decrease vital capacity and increase the potential for respiratory distress. Cartilaginous ribs and sternum and intercostal muscles that are not fully developed cause the infant's chest wall to be unstable. The airway is soft, small, and more reactive than the airway of an adult. The diaphragm of the infant lies horizontally; therefore, when the diaphragm contracts during inspiration, the lower ribs are drawn inward. Because of this pattern of breathing, any air or gastric content that causes the stomach to expand inappropriately will cause upward displacement of the diaphragm, limiting available space for lung expansion.
Ventilation and perfusion imbalance in the small patient can cause respiratory distress. Some of the conditions that must be considered when assessing a patient with suspected ventilation and perfusion imbalance include airway obstruction, atelectasis, inadequate inspiratory effort, pulmonary edema, and pneumothorax."(Rushton)
Oxygenation in the infant can be easily ascertained by auscultation of breath sounds. Additional assessments must be performed of the rate and symmetry of respirations, and assessment of the respiratory pattern and color of the patient.
