Extensive physiologic changes in the neonate accompany the birth process (see also Neonatal Pulmonary Function), sometimes unmasking conditions that posed no problem during intrauterine life. For that reason, a clinician with neonatal resuscitation skills should attend each birth. Gestational age, growth parameters, and prenatal testing help predict the risk of neonatal pathology.
Respiratory disorders are the most common reasons for admission to neonatal intensive care units or special care nurseries and affect about 7% of all neonates (1).
Respiratory problems in neonates include the following:
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
Other signs that may be accompany respiratory distress include cyanosis, pallor, mottling or delayed capillary refill, and hypotension.
In neonates, symptoms and signs may be apparent immediately on delivery or develop minutes or hours afterward.
General reference
1. Gould AJ, Ding JJ, Recabo O, et al. Risk factors for respiratory distress syndrome among high-risk early-term and full-term deliveries. J Matern Fetal Neonatal Med. 2022;35(26):10401-10405. doi:10.1080/14767058.2022.2128657
Etiology of Perinatal Respiratory Distress
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 lesions 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 Left-sided obstructive lesions: Critical aortic stenosis, aortic coarctation, or hypoplastic left heart syndrome |
Respiratory | Upper respiratory tract: Choanal atresia or stenosis, tracheobroncholaryngeal stenosis, compressive obstruction (eg, vascular ring, absent pulmonary valve syndrome), tracheoesophageal anomalies (eg, cleft, fistula), Pierre Robin sequence Lower respiratory 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 protein 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. | |
Pletcher BA, Turcios NL. Pulmonary Manifestations of Genetic Disorders in Children. Pediatr Clin North Am. 2021;68(1):1-24. doi:10.1016/j.pcl.2020.09.010 | |
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. Atelectasis also occurs in infants with surfactant deficiency of prematurity and in term and preterm infants with congenital deficiencies of surfactant protein B or C. 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 is focused on maternal and prenatal history, particularly gestational age, maternal infection or bleeding, the presence of meconium staining in 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 is focused 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 may indicate a tension pneumothorax or, if the neonate has other findings such as heart murmur, abnormal central or peripheral pulses, or a combination, it may suggest congenital heart disease. 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 anomalies. 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 gas analysis. Chest radiograph also is recommended.
