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.

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.

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.

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).

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.