Overview
The clinical features of respiratory distress are shown in Fig. 39.1.
Monitoring
• Oxygen saturation (maintain >95% in term infants).
• Respiratory rate, heart rate, BP, temperature.
• Arterial blood gases if needing oxygen >30%.
Investigations
• Chest X‐ray – confirms respiratory disease, look for pneumo- thorax, diaphragmatic hernia, lung malformations.
• Complete blood count, blood cultures, C‐reactive protein, consider lumbar puncture.
Management
• Airway and breathing – oxygen/nasal high‐flow therapy/CPAP/
mechanical ventilation as required.
• Circulatory support if necessary.
• Intravenous fluids or frequent nasogastric feeds.
• Intravenous antibiotics – broad‐spectrum coverage.
Respiratory distress:
Tachypnea (RR >60/min) +
Nasal flaring +
Grunting (prolonged expiration against closed glottis)
+
Chest retraction – suprasternal – intercostal – subcostal +
Cyanosis (if severe)
Fig. 39.1 Clinical features of respiratory distress (see video: Signs of respiratory distress).
Causes (Fig. 39.2)
Surfactant deficiency Diaphragmatic hernia Tracheo-esophageal fistula Pulmonary hypoplasia Pleural effusion (chylothorax) Milk aspiration
Airway obstruction e.g. choanal atresia Lung anomalies – congenital pulmonary airway malformation (CPAM), lobar emphysema, pulmonary sequestration
Neuromuscular disorders Severe anemia
Metabolic acidosis (inborn error of metabolism)
Causes of respiratory distress in term infants
Pneumonia/sepsis Meconium aspiration Pneumothorax
Congenital heart disease/heart failure
Persistent pulmonary hypertension of the newborn (PPHN)
Hypoxic–ischemic encephalopathy Less common Transient tachypnea of the
newborn
Common Rare
Fig. 39.2 Causes of respiratory distress in term infants.
Common causes
Transient tachypnea of the newborn (TTNB)
This is by far the most common cause of respiratory distress in term infants. Caused by delay in the absorption of lung liquid (Figs. 39.3 and 39.4), especially following elective cesarean sec- tion. Absence of pressure on the thorax squeezing lung liquid from
the chest is thought to be a factor. However, clearance of fetal lung fluid is largely dependent on reabsorption of alveolar fluid via sodium channels in the lung epithelium, which is influenced by the level of circulating catecholamines. The lower concentration of circulating catecholamines, particularly following elective delivery, results in reduced absorption of lung liquid. Usually settles within first day or two of life, but may have low oxygen requirement and tachypnea for several days.
Respiratory distress in term infants 91
Less common causes Pneumonia
• Risk factors – prolonged rupture of the membranes (PROM), maternal fever, chorioamnionitis.
• All infants with respiratory distress should be started on broad‐
spectrum antibiotics until the results of the blood culture, C‐ reactive protein (CRP), complete blood count (CBC), lumbar puncture (if performed) are known.
• Group B streptococcus is the most common cause.
Meconium aspiration
The proportion of infants who pass meconium at birth increases with gestational age, affecting 20–25% at 42 weeks. Asphyxiated infants may start gasping and aspirate meconium before delivery.
At birth infants may inhale thick meconium (see Chapter 13) which results in mechanical obstruction, chemical pneumonitis and inactivation of surfactant (Fig. 39.5). There is a high incidence of air leak (pneumothorax). Surfactant therapy may be beneficial.
Mechanical ventilation is often required. Accompanying persistent pulmonary hypertension (PPHN) may require nitric oxide and sometimes ECMO (extracorporeal membrane oxygenation), i.e.
cardiopulmonary bypass. Sildenafil may be considered.
Pneumothorax (see Chapter 29)
May occur spontaneously or more commonly as a complication of mechanical ventilation or CPAP. Diagnosed clinically, with unilat- eral decreased breath sounds or by transillumination of the chest (Fig. 39.6) or on chest X‐ray.
Fig. 39.3 Lung liquid in the mouth of a newborn term infant with transient tachypnea of the newborn receiving nasal CPAP.
(a)
(b)
Fig. 39.4 Chest X‐ray in transient tachypnea of the newborn showing fluid in the horizontal fissure and some streaky infiltrates with hyperinflation and perihilar haziness (a). Some hours later, the perihilar haziness has cleared, but there is still fluid in the horizontal fissure and hyperinflation (b).
Fig. 39.5 Chest X‐ray in meconium aspiration. There is hyperinflation of the lungs, flattened diaphragm and widespread patchy areas of collapse evident in coarse irregular densities with areas of overinflation.
There is a tracheal tube and umbilical artery catheter. (Courtesy of Dr Sheila Berlin.)
Heart failure (see Chapter 49)
Check for evidence of heart failure – including active precordium, enlarged heart, gallop rhythm, heart murmurs and enlarged liver.
and that femoral pulses are palpable (reduced in coarctation of the aorta, hypoplastic left heart syndrome).
Persistent pulmonary hypertension of the newborn (PPHN)
Pulmonary hypertension leads to right‐to‐left shunting of blood (Fig. 39.7):
• across the patent foramen ovale
• across the patent ductus arteriosus
• intrapulmonary.
Causes
Usually secondary to:
• birth asphyxia
• meconium aspiration
• sepsis
• diaphragmatic hernia.
Occasionally it is the primary disorder.
Presentation
• Cyanosis or difficulty in oxygenation.
• Reduction between pre and post ductal saturations.
Specific investigations
• Chest X‐ray – shows underlying cause or may be normal or show pulmonary oligemia (diminished vascularity).
• Echocardiography is needed to exclude congenital heart dis- ease. It can also allow estimation of the magnitude of pulmonary hypertension (see Chapter 82).
Management
• Oxygen.
• Optimize mechanical ventilation.
• Circulatory support as required.
• Consider surfactant therapy.
• Pulmonary vasodilator – inhaled nitric oxide (NO). Oral or i.v.
sildenafil may be considered.
• Consider high‐frequency oscillatory ventilation (HFOV).
• Extracorporeal membrane oxygenation (ECMO) as rescue therapy for severe respiratory failure.
Rare causes Surfactant deficiency
Rare in term infants. May occur in infants of maternal diabetes or with surfactant protein B deficiency, a rare genetic disorder.
Diaphragmatic hernia
Main problems
• Pulmonary hypoplasia, as herniated bowel reduces lung development in the fetus.
• Lung compression by the bowel, which increases in size as air enters it.
• Pulmonary hypertension (PPHN) – pulmonary arterioles reduced in number and size, and smooth muscle is hypertrophied.
• Other anomalies – present in 15–25%.
Incidence 1 in 4000 births.
Most common site
Left‐sided hernia of bowel through the posterolateral foramen of the diaphragm (Bochdalek).
Fig. 39.6 Transillumination of the chest showing the presence of pneumothorax.
Across foramen ovale
Across patent ductus arteriosus Intrapulmonary
Fig. 39.7 Pulmonary hypertension leads to right‐to‐left shunting.
Respiratory distress in term infants 93 Presentation
• Prenatal – on ultrasound screening, polyhydramnios. Most identified antenatally. For antenatal management with fetal endo- scopic tracheal occlusion see Chapter 4.
• Resuscitation – failure to respond; deteriorates with bag and mask ventilation.
• Respiratory distress – but onset may be delayed if underlying lung well developed.
Physical signs
• Respiratory distress.
• Asymmetry of chest.
• Reduced air entry on affected side.
• Apex beat displaced.
• Scaphoid abdomen – from reduced content of bowel.
Diagnosis
X‐ray‐chest and abdomen (Fig. 39.8).
Management
• Intubate and ventilate from birth. Gentle ventilation, allowing permissive hypercapnia, i.e. PaCO2 > 60 mmHg (8kPa) but main- taining pH >7.25. Avoid mask ventilation.
• Pass large nasogastric tube and apply suction.
• Stabilize and support circulation.
• Early PN (parenteral nutrition).
• Surgical repair – delay until stable and PPHN is resolving.
• Nitric oxide for PPHN; sildenafil may be considered.
• Extracorporeal membrane oxygenation (ECMO) – pre‐ and post‐
surgery in selected cases.
Mortality 20–30%.
Milk aspiration
Risk of aspiration if infant has cleft palate, neurologic disorder affecting sucking and swallowing or has respiratory distress.
Infants with bronchopulmonary dysplasia often have gastroesoph- ageal reflux, which predisposes to aspiration.
Fig. 39.8 Chest X‐ray showing diaphragmatic hernia. There is bowel in the left chest and the heart and trachea are displaced to the right. There is a gavage (nasogastric) tube, umbilical artery and venous catheters and a radio-opaque umbilical tie.
Neonatology at a Glance, Third Edition. Edited by Tom Lissauer, Avroy A. Fanaroff, Lawrence Miall and Jonathan Fanaroff.
© 2016 John Wiley & Sons, Ltd. Published 2016 by John Wiley & Sons, Ltd.
Cleft lip and palate Incidence – 1 in 1000 live births.
Inheritance – polygenic, but increased risk if family history.
Varies in severity from a mild unilateral cleft lip to severe bilateral cleft palate (Figs. 40.1 and 40.2).
It is increasingly diagnosed on antenatal ultrasound scanning. This allows counseling of the parents and family before birth. Showing parents photographs is often helpful to minimize the shock at birth as the defect is unsightly; photos after surgery provide reassurance that the defect can be corrected (Fig. 40.3).
A specialist multidisciplinary team from a tertiary center is required to provide:
• a key worker, usually a specialist nurse, for advice and to act as advocate for the child and family. Will visit the parents shortly after birth and also gives advice about feeding.
• craniofacial surgeon, orthodontist, speech and language therapist and audiologist.
• surgical repair of the lip, usually at 3 months of age for best long‐
term results, but some centers perform it immediately after birth.
The palate is usually repaired at 6–12 months of age. Further sur- gery may be required when the child is older.
Long‐term complications include middle ear infection and otitis media with effusion, difficulties with speech and orthodontic problems.
There are active self‐help groups for parents who provide information and practical help. In the US there is Wide Smiles; in the UK it is CLAPA, the Cleft Lip and Palate Association.