CME article
Respiratory Distress of the Term Newborn Infant

https://doi.org/10.1016/j.prrv.2012.02.002Get rights and content

Summary

Respiratory distress is recognised as any signs of breathing difficulties in neonates. In the early neonatal period respiratory distress is common, occurring in up to 7% of newborn infants, resulting in significant numbers of term-born infants being admitted to neonatal units. Many risk factors are involved; the increasing number of term infants delivered by elective caesarean section has also increased the incidence. Additionally the risk decreases with each advancing week of gestation. At 37 weeks, the chances are three times greater than at 39-40 weeks gestation. Multiple conditions can present with features of respiratory distress. Common causes in term newborn infants include transient tachypnoea of the newborn, respiratory distress syndrome, pneumonia, meconium aspiration syndrome, persistent pulmonary hypertension of the neonate and pneumothorax. Early recognition of respiratory distress and initiation of appropriate treatment is important to ensure optimal outcomes. This review will discuss these common causes of respiratory distress in term-born infants.

Introduction

Respiratory distress is common in the early neonatal period and occurs in up to 7% of newborn infants.1 Much of the focus has been on respiratory distress syndrome and chronic lung disease of prematurity in preterm infants (<37 weeks of gestation)2, 3 but every year a significant number of term-born infants are admitted to neonatal units for management of their respiratory distress.4, 5, 6 Multiple conditions can cause respiratory distress in term newborn infants (Table 1). Conditions such as surfactant protein deficiency syndromes or alveolar capillary dysplasia are rare and the reader is referred to recent excellent reviews.7, 8

In Switzerland, Ersch et al. reported an increasing incidence of respiratory distress of all neonates admitted to neonatal units between 1974 and 2004 citing three possible explanations: an increase in extremely low birth weight infants, changes in admission policies and increasing numbers of infants delivered by caesarean section.9 The impact of elective caesarean sections has specifically increased the incidence of respiratory distress in term infants.10 This has been known for many years; in 1995 Morrison et al. estimated that 2,000 cases per year required neonatal admission for pulmonary diseases following caesarean section before onset of labour in the United Kingdom (UK).11

There were 706,248 live births in England and Wales in 2009 and approximately 94% of these were full term deliveries (≥37 weeks of gestation).12, 13 Between 1990 and 2002, the admission rate to a busy neonatal unit in England was 8.6% of all live births.14 The commonest reason for admission was respiratory distress.6, 9 There is a clear inverse relationship between gestational age and incidence of respiratory distress most notably by transient tachypnoea of the newborn (TTN) and respiratory distress syndrome (RDS).4, 10 Gouyon et al. also noted that a major risk factor for severe respiratory distress in term infants was elective caesarean section at 37–38 weeks gestation but with meconium stained liquor being most frequently noted at 39–41 weeks gestation.10 Thus, avoiding routine elective caesarean sections prior to 38 weeks of gestation would markedly decrease the incidence of respiratory problems in the term infant.

Section snippets

Assessment

Respiratory distress is recognised as any signs of breathing difficulties in the neonate (Figure 1). Useful questions to ask are shown in Figure 2. The initial assessment of any infant with respiratory distress should include blood tests (full blood count, C-reactive protein, blood culture and blood gases), pulse oximetry and chest radiography. The initial treatment will aim to reverse the hypoxia, hypercapnia and acidosis that may have developed.

Transient tachypnoea of the newborn

TTN was first coined by Avery in 1966 and is now recognised as the commonest cause of respiratory distress in newborn term infants.15 It is caused by the delay in the absorption of fluid in the lungs after birth (i.e. excessive lung fluid).10 Thus, TTN is frequently seen in babies born following elective caesarean section. It usually presents with grunting and mild signs of respiratory distress, which persist for up to 48 hours and is generally a self-limiting disorder. However, some infants

Respiratory Distress Syndrome

RDS is caused by a deficiency of surfactant and is often also called hyaline membrane disease, which strictly speaking is a histological diagnosis.32 Newborn infants with RDS present during the first 4 to 6 hours of life. It is commonly seen in preterm infants; however, published data have shown that infants with a birth weight of >2500 g account for 9.9%20 to 11.5%9 of infants with RDS and those with gestational age of ≥37 weeks gestation account for 7.8%.20 The Near-Term Respiratory Failure

Pneumonia

A lower respiratory tract infection, particularly bacterial pneumonia can cause severe respiratory distress in the newborn infant. This can be acquired congenitally, through the birth passages especially after prolonged rupture of membranes or postnatally. Pneumonia in newborn infants is often difficult to diagnose and often difficult to distinguish from other causes of respiratory distress including RDS and TTN. Although many investigations including blood white cell counts, blood cultures,

Meconium Aspiration Syndrome

The passage of meconium in utero results in meconium-stained amniotic fluid (MSAF), which may be inhaled by the foetus especially if already compromised. If the infant has symptoms from the inhalation the condition is often referred to as meconium aspiration syndrome (MAS). MAS is essentially a disease of term- and post-term born infants but an infective aetiology especially from Listeria should be suspected in preterm deliveries associated with MSAF. MAS results in respiratory distress of

Persistent Pulmonary hypertension of the neonate

Pulmonary arterial hypertension is relatively common in newborn infants and can be either primary (often termed persistent pulmonary hypertension of the newborn, PPHN) or secondary due to conditions such as RDS, congenital diaphragmatic hernia (CDH), MAS and pneumonia. Pulmonary hypertension needs to be considered in any infants with respiratory distress either as a primary or secondary cause. It is often challenging to manage and usually presents in the first few hours of life but may present

Pneumothorax

Pneumothorax usually develops secondary to an underlying disease process but can occur spontaneously in 1% of newborns around the perinatal period, although only about 10% of these are symptomatic.83 The clinical presentation may vary from mild or severe signs of respiratory distress to a gradual decline in respiratory function.

Congenital thoracic malformations and surgical conditions

There are several congenital thoracic malformations or surgical conditions that can present in the early neonatal period with respiratory distress. These include CDH, congenital cystic adenomatoid malformation, pulmonary hypoplasia, trachea-oesophageal atresia, congenital emphysema, choanal atresia, Pierre Robin syndrome and any cause of mediastinal masses such as a teratoma. These are predominantly managed with surgical intervention and have been reviewed in detail elsewhere.71, 85

Conclusion

We have reviewed common causes of respiratory distress in term infants. TTN and RDS are common especially in infants delivered after elective caesarean sections but generally have excellent prognosis. Even delivery at 37 weeks gestation, considered term, is associated with increased respiratory morbidity thus should be avoided wherever possible. Conditions such as pulmonary arterial hypertension that may be primary or secondary to RDS, MAS or CDH will respond in most cases to oxygen therapy,

Educational Aims

The reader will be able to:

  • Recognise the importance of respiratory distress in term newborn infants.

  • Discuss the differential diagnosis of respiratory distress in term newborn infants.

  • Describe the more common causes of respiratory distress in term newborn infants.

  • Initiate a management plan for the term newborn infant presenting with respiratory distress.

Practice Points for Respiratory Distress in the Term infant

  • A common presenting feature of newborn infants.

  • Early assessment and management are important to reduce complications.

  • There are multiple risk factors, which may contribute to the development of respiratory distress and many of these are difficult to minimise.

  • Often there is difficulty in differentiating between the various diseases that cause respiratory distress.

  • Advances in medical treatment of infants with respiratory distress have improved the morbidity and mortality.

Conflict of interest statement

No conflict of interest of any of the authors.

CME Section

This article has been accredited for CME learning by the European Board for Accreditation in Pneumology (EBAP). You can receive 1 CME credit by successfully answering these questions online. (A) Visit the journal CME site at http://www.prrjournal.com/ (B) Complete the answers online, and receive your final score upon completion of the test. (C) Should you successfully complete the test, you may download your accreditation certificate (subject to an administrative charge).

  • 1.

    Which of the following

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