Respiratory Distress in the Newborn

  • John M. Hutson
  • Spencer W. Beasley
Chapter

Abstract

The general clinical features are described and then the causes obvious on external examination. There are sections on respiratory distress relieved by crying (choanal atresia), the frothy baby (oesophageal atresia), severe or progressive respiratory and respiratory distress that occurs suddenly (pneumothorax).

Keywords

Respiratory Distress Diaphragmatic Hernia Congenital Diaphragmatic Hernia Tension Pneumothorax Oesophageal Atresia 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Oxygenation of the fetus is achieved through gas exchange in the placenta. At birth, this connection with the placenta is lost, and the infant becomes dependent on the lungs which, within seconds of birth, fill with air and pulmonary blood flow increases. Respiratory distress in the newborn occurs if (1) the lungs are unable to expand because of obstruction of the upper airways, (2) there is inadequate room within the thoracic cage for lung expansion to occur or (3) the infant cannot produce sufficient negative intrathoracic pressure to inflate the lungs.

In the premature infant, lack of surfactant allows the alveoli to collapse and leads to respiratory distress (hyaline membrane disease); this condition will worsen significantly the respiratory difficulties experienced by the newborn with a coexisting anomaly which interferes with respiration. When respiratory distress is recognized in the newborn, its cause must be established promptly by careful examination and a chest x-ray.

Occasionally, antenatal ultrasound examination detects major congenital anomalies which cause respiratory insufficiency at birth. For example, the presence of bowel in the thorax with mediastinal shift is indicative of congenital diaphragmatic hernia, and, in such a case, the mother should be transported to a major institution for the birth of her child. As soon as the child is born, the diagnosis can be confirmed and immediate resuscitation instituted.

Clinical Features

The first sign of respiratory distress in the neonate is restlessness (Table 20.1) which may be overlooked at first but is soon accompanied by tachypnoea. The relatively horizontal position of the ribs and lack of bucket-handle movement means that the neonate cannot increase the anteroposterior and transverse diameters of the thorax and relies almost entirely on diaphragmatic movement for effective inspiration (Fig. 20.1). Increase in respiratory effort is achieved by increased diaphragmatic effort and is manifested clinically by protrusion of the upper abdomen, grunting on expiration and flaring of the nostrils. The pliability of the ribs supporting the sternum allows the negative intrathoracic pressure during inspiration to cause retraction of the sternum. If the abdomen is distended already from air swallowing or the passage of air through a tracheo-oesophageal fistula, the diaphragm is pushed upwards, and ventilation is compromised further (Fig. 20.2). In severe respiratory distress, oxygenation across the lungs is impeded and cyanosis develops.
Table 20.1

Signs of respiratory distress in the neonate

1. Restlessness

2. Tachypnoea

3. Increased respiratory effort with sternal retraction

4. Cyanosis

Fig. 20.1

The effect of the shape of the rib cage on ventilation in the neonate

Fig. 20.2

The effect of excess air in the stomach on neonatal ventilation

Progression of respiratory distress results in respiratory failure and, subsequently, cardiovascular collapse. The signs of respiratory distress are not specific for the cause. In some situations, the underlying abnormality is immediately apparent, although a chest x-ray may be required to make a diagnosis.

Cause Obvious on External Examination

Examine the face and neck. Look for a small undercut lower jaw (micrognathia). This may be seen in association with a cleft of the secondary palate (Pierre-Robin syndrome), which can be detected by inspecting the roof of the mouth using a torch. Sometimes, the larger defects are palpable by running the little finger across the roof of the mouth, but this technique is less reliable and the diagnosis is made with greater certainty if seen directly. The small jaw confines the tongue to the back of the mouth where it may fill the cleft and cause obstruction of the nasopharynx (Fig. 20.3). The infant is nursed prone because in the supine position, the tongue falls backwards and exacerbates the obstruction. Persistence of respiratory distress in the prone position may necessitate additional manoeuvres, such as the insertion of a nasopharyngeal airway or a tracheostomy.
Fig. 20.3

The cause of respiratory obstruction in Pierre-Robin syndrome

A large lymphatic malformation, or ‘cystic hygroma’, involving the floor of the mouth or the pharynx may cause upper respiratory tract obstruction and demand early tracheostomy. The cystic hygroma may involve much of the neck and extend through the thoracic inlet into the anterior mediastinum, causing tracheal compression or displacement (Fig. 20.4). The swelling is ill-defined, fluctuant and composed of many cysts which transilluminate brilliantly. Haemorrhage or infection may cause the cysts to enlarge rapidly and obstruct the airway further (see  Chap. 11 for further description).
Fig. 20.4

External compression of the airway with a congenital cervical hamartoma, for example, ‘cystic hygroma’

Respiratory Distress Relieved by Crying

The newborn infant is an obligate nose breather with little ability to breathe through the mouth, even where there is complete obstruction of the nasal passage. Choanal atresia is an uncommon anomaly where there is obstruction of the nasal airway and is important in that, if not recognised at birth, a fatal outcome may result. In complete bilateral choanal atresia, respiratory distress develops rapidly and is severe. The child becomes increasingly distressed and cyanotic, but rapidly turns pink when crying, with relief of the obstruction as air is exchanged via the mouth. The diagnosis of choanal atresia is suggested by the sudden improvement in the infant’s condition on crying and the observation that the asphyxia is relieved by an oropharyngeal airway. The diagnosis is confirmed by inability to pass a small but firm nasogastric tube through either nasal passage. The tube should be directed posteriorly from the nostril in a horizontal plane beneath the turbinates (Fig. 20.5) and not upwards along the line of the nose. An alternative method of demonstrating complete nasal obstruction is to drip saline or Agarol into each nostril and note whether drainage occurs into the oropharynx. It is imperative that the oral airway remains in place until surgery has established a patent nasal passage on each side.
Fig. 20.5

The technique for testing the patency of the nasal airway in choanal atresia. The stiff catheter needs to be passed horizontally below the inferior turbinate

Unilateral choanal atresia does not cause respiratory distress in the newborn and is detected in later years because of a persistent discharge from the obstructed nostril. It must be distinguished from a nasal foreign body which usually produces a purulent discharge.

A rare but potentially lethal cause of upper airway obstruction is a pedunculated hamartoma of the nasopharynx. It causes intermittent obstruction according to the posture of the infant and may be seen at the back of the mouth as it prolapses into the oropharynx. Early diagnosis permits surgical removal before asphyxia occurs.

The Frothy Baby in Respiratory Distress

Oesophageal atresia is a relatively common congenital anomaly where there is interruption of the continuity of the oesophagus, associated in 85 % with a fistulous communication between the lower trachea and distal oesophageal segment. The trachea and the oesophagus both form from the foregut tube, and the fistula represents persistence of this embryological connection.

Swallowed saliva fills the proximal oesophagus, but the atresia prevents it from passing into the stomach. As a consequence, saliva accumulates in the pharynx and mouth, giving the appearance of excessive salivation. The babies are often described as being ‘mucousy’ or ‘drooling’, and frothy saliva is seen dribbling from the side of the mouth (Fig. 20.6). The fistula connecting the trachea with the lower oesophagus may interfere with effective ventilation if air passes preferentially down the fistula into the stomach. Accumulation of air in the stomach may cause abdominal distension with elevation of the diaphragm and exacerbate the respiratory difficulty. In severe cases, cyanosis ensues. Frequently, there is a history of prematurity and maternal polyhydramnios.
Fig. 20.6

Excessive neonatal salivation is highly suggestive of oesophageal atresia

The diagnosis of oesophageal atresia is confirmed easily using one simple clinical manoeuvre. A stiff 10-French-gauge catheter is introduced gently through the mouth into the upper oesophagus. In oesophageal atresia, its progress is arrested between 9 and 13 cm from the gums (Fig. 20.7). A narrow catheter should not be used because it is likely to curl up in the dilated upper oesophagus giving a false impression of oesophageal continuity (Fig. 20.8). Once oesophageal atresia has been diagnosed using this test, the presence of abdominal distension and a resonant abdomen on percussion confirms the existence of a distal tracheo-oesophageal fistula.
Fig. 20.7

The diagnosis of oesophageal atresia. (a) A 10-French tube is inserted gently through the mouth. (b) In oesophageal atresia, the catheter stops at about 10 cm from the gums

Fig. 20.8

Pitfalls in the diagnosis of oesophageal atresia. (a) A small, flexible catheter may roll up in the mouth or upper oesophagus. (b) A small tube passed through the nose may enter the trachea

If the diagnosis of oesophageal atresia has not been made at birth, it becomes apparent at the time of the first feed. The child gags and chokes and develops cyanotic respiratory distress with overflow of the milk from the oesophagus into the airway (Fig. 20.9). In oesophageal atresia, the pharynx should be suctioned frequently to remove excessive saliva and avoid aspiration.
Fig. 20.9

Causes of ­respiratory distress in oesophageal atresia

Oesophageal atresia often (50 %) is associated with other congenital anomalies, particularly cardiac, renal, anorectal, vertebral, radial and digital (i.e. ‘VACTERL’ association). The infant must be examined carefully for the presence of these anomalies. Oesophageal atresia is seen also in association with chromosomal trisomies, of which 13, 18 and 21 are the most common.

A chest x-ray should be obtained in every case. This will often show the dilated upper ‘pouch’ of the oesophagus, and presence of air below the diaphragm suggests a distal tracheo-oesophageal fistula. A lateral film may show the lower oesophagus filled with air from the trachea. Absence of gas in the abdomen is indicative of the rare defects of atresia without fistula or of atresia in association with a proximal tracheo-oesophageal fistula. Overflow of saliva, or reflux of gastric juice up the fistula into the trachea, may produce radiological signs of aspiration pneumonia. The vertebral column should be inspected for hemivertebrae or other anomalies. A contrast study is not needed to make the diagnosis of oesophageal atresia and should be avoided because of the high risk of aspiration.

Onset of Severe or Progressive Respiratory Distress

Respiratory insufficiency shortly after birth in the absence of other conditions suggests a diagnosis of congenital diaphragmatic hernia. Development of the transverse septum between the chest and abdomen is defective, leaving a hole in the diaphragm – usually on the left side – through which the abdominal viscera herniate into the chest. This occurs before birth and inhibits pulmonary development by compressing the lung buds, which are hypoplastic. At birth, this produces respiratory distress because of (1) pulmonary hypoplasia and (2) occupation of much of the thoracic volume by abdominal contents. The degree of hypoplasia of the lungs is the ultimate determinant of survival.

Often, there is rapid development of respiratory distress with cyanosis. The rapidity of onset and severity of symptoms vary with the degree of hypoplasia and the extent of interference with ventilation. In the most severe cases, poor peripheral perfusion and cardiovascular collapse occur within minutes of birth. Apgar scores remain low, and, without immediate resuscitation, these infants die quickly. Lesser degrees of lung compression produce a less dramatic clinical picture, and a few children have no symptoms for days or months.

The chest is barrel-shaped and the abdomen is scaphoid because most of the bowel has herniated through the defect in the diaphragm into the pleural cavity, leaving the abdomen empty of contents (Fig. 20.10). However, once air is swallowed, this sign becomes less obvious. The ­presence of bowel and liver in the chest displaces the mediastinum to the contralateral side. Swallowed air makes this worse. In a left-sided hernia, this produces apparent dextrocardia (with the heart sounds most easily audible in the right chest) and poor sounds on the left side (Fig. 20.11). In the uncommon right-sided hernia, the signs are reversed. The classical sign of bowel sounds in one side of the chest on auscultation is not particularly reliable and may be difficult to elicit.
Fig. 20.10

The clinical features of a left-sided congenital diaphragmatic hernia

Fig. 20.11

The intrathoracic anatomy in a left-sided congenital diaphragmatic hernia

Where congenital diaphragmatic hernia is suspected on clinical grounds, an immediate plain chest x-ray must be obtained. The film should include the abdomen so that the distribution of bowel gas can be determined. The main radiological features include:
  1. 1.

    Loops of bowel in the chest on the side of the defect

     
  2. 2.

    Hemidiaphragm not visible

     
  3. 3.

    Mediastinal shift to the contralateral side

     
  4. 4.

    Abnormal distribution of bowel gas within the abdomen

     

There are a number of uncommon conditions which can have a similar radiological appearance to diaphragmatic hernia, for example, cystic lung disease, lobar emphysema, staphylococcal pneumonia with pneumatocele and other diaphragmatic defects, but these conditions are rarely a cause of such severe respiratory symptoms in the first few hours after birth.

Sudden Onset of Respiratory Distress

The sudden onset of severe and progressive symptoms of respiratory distress in an infant who has been asymptomatic or is stable following endotracheal intubation suggests the development of a pneumothorax. The respiratory rate increases with marked sternal retraction, diminished air entry on auscultation and increased resonance on percussion on the side of the pneumothorax. Shift of the mediastinum is difficult to detect in this condition. The diagnosis should always be considered in infants with a pre-existing condition known to predispose to the development of a pneumothorax. The most critical of these is diaphragmatic hernia, but a pneumothorax may also occur following a difficult delivery or in an infant with hyaline membrane disease, lung cyst and lobar emphysema. A plain radiograph of the chest confirms the diagnosis.

The development of a tension pneumothorax is particularly hazardous to the infant and is suggested by continued progression of symptoms as a result of further mediastinal shift, contralateral lung compression and interference of venous return. Cyanosis and cardiovascular collapse are later signs. The diagnosis of tension pneumothorax is confirmed on chest x-ray, but in some cases, needle aspiration or tube thoracostomy are required as life-saving measures before an x-ray can be obtained. The best position in which to insert a chest drain is through the fourth or fifth intercostal spaces in the anterior axillary line.

Golden Rules

  1.  1.

    Prevent excessive swallowed air in respiratory distress as it interferes with diaphragmatic breathing.

     
  2.  2.

    Nasal obstruction is serious in neonates, who have difficulty breathing through the mouth.

     
  3.  3.

    Cyanosis relieved by crying indicates nasal obstruction (e.g. choanal atresia).

     
  4.  4.

    A big tongue or small jaw may cause obstruction of the pharynx.

     
  5.  5.

    Excessive salivation in the neonate suggests inability to swallow saliva because of oesophageal atresia.

     
  6.  6.

    Gas in the stomach in association with oesophageal atresia confirms the presence of a distal tracheo-oesophageal fistula.

     
  7.  7.

    Oesophageal atresia is confirmed by gentle passage of a stiff 10-French catheter through the mouth: The catheter is arrested at about 10 cm from the gums.

     
  8.  8.

    An infant with oesophageal atresia requires careful examination for other anomalies.

     
  9.  9.

    Diaphragmatic hernia or pneumothorax should be suspected where respiratory distress occurs soon after birth.

     
  10. 10.

    Diaphragmatic hernia is the only common cause of respiratory distress where the abdomen is scaphoid (the bowel is in the thorax).

     

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • John M. Hutson
    • 1
  • Spencer W. Beasley
    • 2
  1. 1.Department of UrologyRoyal Children’s HospitalMelbourneAustralia
  2. 2.Paediatric Surgery Department OtagoUniversity Christchurch HospitalChristchurchNew Zealand

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