Extensive physiologic changes accompany the birth process (see also Neonatal Pulmonary Function), sometimes unmasking conditions that posed no problem during intrauterine life. For that reason, a person with neonatal resuscitation skills must attend each birth. Gestational age and growth parameters 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 of Perinatal Respiratory Disorders
Respiratory distress in neonates and infants has multiple potential causes (see table Causes of Respiratory Distress in Neonates and Infants).
Causes of Respiratory Distress in Neonates and Infants
Category | Causes |
|---|---|
Cardiac* | Right-to-left shunting or mixing lesions with normal or increased pulmonary flow: Transposition of the great vessels, tetralogy of Fallot with minimal pulmonary outflow tract obstruction, total anomalous venous return, truncus arteriosus, hypoplastic left heart syndrome Right-to-left shunting with decreased pulmonary flow:† Pulmonary atresia, tetralogy of Fallot with significant pulmonary outflow tract obstruction, critical pulmonic stenosis, tricuspid atresia, single ventricle with pulmonic stenosis, Ebstein anomaly, persistent pulmonary hypertension |
Respiratory | Upper tract: Choanal atresia or stenosis, tracheobroncholaryngeal stenosis, compressive obstruction (eg, vascular ring), tracheoesophageal anomalies (eg, cleft, fistula) Lower tract: Respiratory distress syndrome, transient tachypnea of the newborn, meconium aspiration, pneumonia, pneumothorax, congenital diaphragmatic hernia, pulmonary hypoplasia, cystic malformation of the lung, congenital deficiency of surfactant proteins B or C |
Neurologic‡ | Intracranial hemorrhage or hypertension, oversedation (infant or maternal), diaphragmatic paralysis, neuromuscular disease, seizure disorder |
Hematologic | Methemoglobinemia (methemoglobin levels > 40%), polycythemia, severe anemia |
Miscellaneous | Hypoglycemia, metabolic disorders (eg, acid-base disorders, hyperammonemia), hypovolemic shock, sepsis |
* Any cardiac lesion that manifests with poor systemic cardiac output and acidosis is also more likely to have respiratory distress as part of the initial presentation. | |
† Right-to-left shunting with decreased pulmonary flow is less likely than right-to-left shunting or mixing lesions with normal or increased pulmonary flow to manifest with significant respiratory distress. | |
‡ Neurologic issues may manifest with apnea rather than overt respiratory distress. | |
Physiology of Perinatal Respiratory Disorders
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 of Perinatal Respiratory Disorders
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, maternal infection or bleeding, meconium staining of amniotic fluid, oligohydramnios or polyhydramnios, 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. Diffuse crackles, decreased air entry, or grunting suggests poor alveolar expansion as occurs in surfactant deficiency. Asymmetric breath sounds suggest pneumothorax or pneumonia. A displaced left apical impulse, heart murmur, abnormal central or peripheral pulses, or a combination suggests a congenital heart defect. Assessment of blood pressure and femoral pulses may identify shunting (eg, bounding pulses in arteriovenous malformations or patent ductus arteriosus) or left heart dysfunction, 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.
