Extensive physiologic changes Perinatal Physiology The transition from life in utero to life outside the womb involves multiple changes in physiology and function. See also Perinatal Problems. (See also Liver Structure and Function and Neonatal... read more accompany the birth process (see also Neonatal Pulmonary Function Neonatal Pulmonary Function The transition from life in utero to life outside the womb involves multiple changes in physiology and function. See also Perinatal Problems. (See also Liver Structure and Function and Neonatal... read more ), sometimes unmasking conditions that posed no problem during intrauterine life. For that reason, a person with neonatal resuscitation Neonatal Resuscitation Extensive physiologic changes accompany the birth process, sometimes unmasking conditions that posed no problem during intrauterine life. For that reason, a person with neonatal resuscitation... read more skills must attend each birth. Gestational age Gestational Age Gestational age and growth parameters help identify the risk of neonatal pathology. Gestational age is the primary determinant of organ maturity. Gestational age is usually defined as the number... read more and growth parameters Growth Parameters in Neonates Growth parameters and gestational age help identify the risk of neonatal pathology. Growth is influenced by genetic and nutritional factors as well as intrauterine conditions. Growth parameters... read more help identify the risk of neonatal pathology.
Respiratory problems in neonates include
Symptoms and signs of respiratory distress vary and include the following:
Grunting
Nasal flaring
Intercostal, subcostal, and suprasternal retractions
Weak breathing, irregular breathing, or a combination
Tachypnea and apneic spells
Cyanosis, pallor, mottling, delayed capillary refill, or a combination
Hypotension
In neonates, symptoms and signs may be apparent immediately on delivery or develop minutes or hours afterward.
Etiology
Respiratory distress in neonates and infants has multiple causes ( see Table: Causes of Respiratory Distress in Neonates and Infants Causes of Respiratory Distress in Neonates and Infants 
).
Physiology
There are several significant differences in the physiology of the respiratory system in neonates and infants compared with that of older children and adults. These differences include
A more compliant collapsible chest wall
Decreased lung compliance (in infants with surfactant deficiency due to prematurity or genetic mutations)
More reliance on diaphragmatic excursions over intercostal muscles
Collapsible extrathoracic airways
Also, infants’ smaller airway caliber gives increased airway resistance, and absence of collateral ventilation increases tendency toward atelectasis. Yet, other principles of respiration are similar in adults and children.
Evaluation
Evaluation of neonatal respiratory distress starts with a thorough history and physical examination.
History in the neonate focuses on maternal and prenatal history, particularly gestational age Gestational Age Gestational age and growth parameters help identify the risk of neonatal pathology. Gestational age is the primary determinant of organ maturity. Gestational age is usually defined as the number... read more , maternal infection Infectious Disease in Pregnancy Most common maternal infections (eg, urinary tract infection [UTIs], skin and respiratory tract infections) are usually not serious problems during pregnancy, although some genital infections... read more or bleeding, meconium staining of amniotic fluid, oligohydramnios Oligohydramnios Oligohydramnios is amniotic fluid volume that is less than expected for gestational age; it is associated with maternal and fetal complications. Diagnosis is by ultrasonographic measurement... read more or polyhydramnios Polyhydramnios Polyhydramnios is excessive amniotic fluid; it is associated with maternal and fetal complications. Diagnosis is by ultrasonographic measurement of amniotic fluid volume. Management is by treating... read more , family history of genetic disorders, and history of siblings or other family members with significant respiratory distress or death in the neonatal period.
Physical examination focuses on the heart and lungs. Chest wall asymmetry or sunken abdomen suggests diaphragmatic hernia Diaphragmatic Hernia Diaphragmatic hernia is protrusion of abdominal contents into the thorax through a defect in the diaphragm. Lung compression may cause persistent pulmonary hypertension. Diagnosis is by chest... read more 
. Diffuse crackles, decreased air entry, or grunting suggests poor alveolar expansion as seen in surfactant deficiency. Asymmetric breath sounds suggest pneumothorax Pneumothorax Pulmonary air-leak syndromes involve dissection of air out of the normal pulmonary airspaces. (See also Overview of Perinatal Respiratory Disorders.) Extensive physiologic changes accompany... read more or pneumonia Neonatal Pneumonia Neonatal pneumonia is lung infection in a neonate. Onset may be within hours of birth and part of a generalized sepsis syndrome or after 7 days and confined to the lungs. Signs may be limited... read more . A displaced left apical impulse, heart murmur, abnormal central or peripheral pulses, or a combination suggests a congenital heart defect Overview of Congenital Cardiovascular Anomalies Congenital heart disease is the most common congenital anomaly, occurring in almost 1% of live births ( 1). Among birth defects, congenital heart disease is the leading cause of infant mortality... read more 
. Assessment of blood pressure and femoral pulses may identify circulatory collapse with or without congenital defects. Poor capillary refill reflects circulatory compromise.
In both neonates and infants, it is important to assess oxygenation and response to oxygen therapy by pulse oximetry or blood gases. Chest x-ray also is recommended.
