D/D RESPIRATORY DISTRESS

Respiratory distress (RD) in newborn is a clinical dia­gnosis, defined as tachypnea, i.e. (RR gt;60#8725;min), associated with inspiratory intercostal retractions, expiratory grunt and cyanosis.

Etiology: Intrauterine/postnatal pneumonia, meconium/ milk aspiration, hyaline membrane disease (HMD) and congenital malformations are four major causes of RD in newborns, apart from other respiratory/extra- respiratory problems (Table 12.32).

Diagnostic approach in neonatal RD includes:

I. Assessment of severity, based on

- Signs of RD, e.g. respiratory rate (RR), presence/ severity of cyanosis, chest-wall retractions or grunt and air-entry on auscultation (Table 12.33, Downes' score).

- Signs of hypoxia, e.g. general activity, level of alertness, nature of cry, acceptance of feeds, etc., and

- Laboratory indicators, e.g. blood gas analysis.

TABLE 12.32: Causes of respiratory distress in newborns

Respiratory causes

• Developmental: HMD, TTN

• Anatomical: TOF, diaphragmatic hernia

• Aspiration:

- Intrauterine (e.g. meconium)

- Postnatal (e.g. milk)

• Infections: Intrauterine or postnatal pneumonia

• Iatrogenic: Pneumothorax, BPD

• Others: Wilson-Mikity syndrome

Extra-respiratory causes

• Cardiac: CHDs, myocarditis

• Hematological: Severe anemia, polycythemia

• Neurological: Birth asphyxia, diaphragmatic palsy

• Metabolic: Acidosis, inborn errors of metabolism

HMD: Hyaline membrane disease, TTN: Transient tachypnea of newborn, TOF: Tracheo-esophageal fistula, BPD: Bronchopulmonary dysplasia

TABLE 12.33: Clinical respiratory distress scoring

TABLE 12.34: Causes of respiratory distress and age of onset

At birth or within 24 hours

• Meconium aspiration syndrome

• Transient tachypnea in newborn

• Hyaline membrane disease

• Birth asphyxia

• Intrauterine pneumonia

• Congenital airway obstruction or lung aplasia

• CNS trauma or malformations

Between 1 ^st-7^th day

• Postnatal aspiration

• Neonatal sepsis/pneumonia

• CHDs and CCF

• Iatrogenic—pneumothorax, acidosis

After first week

• Neonatal sepsis/pneumonia

• CHDs and CCF

• Others: Bronchopulmonary dysplasia, Wilson-Mikity syndrome

II. Etiological diagnosis depends on:

- Gestational age: HMD is an exclusive problem of preterms, while meconium aspiration syndrome (MAS) and transient tachypnea of newborn (TTN) are mostly seen in term babies.

- Age of the onset is a useful indicator of probable pathology for RD (Table 12.34).

- History of antenatal problems, e.g. maternal diabetes (HMD), intrauterine infections (CHDs), poly­hydramnios (tracheoesophageal fistula), oligo­hydramnios (lung aplasia), etc.

- History of obstetric complications, e.g. fetal distress (perinatal pneumonia), premature rupture of membranes (sepsis), meconium-stained delivery (MAS), cesarean delivery (TTN) low Apgar score (birth asphyxia) and neonatal resuscitation (pneumothorax), etc.

- History of excessive frothing from mouth on first day (tracheoesophageal fistula), choking/vomiting after feeds (postnatal aspiration).

- Examination findings, e.g. murmurs (CHDs), signs of sepsis (pneumonia), scaphoid abdomen (diaphragmatic hernia), etc.

III. Laboratory investigations depend on suspected cause, though following are necessary in all cases:

- X-ray chest

- Sepsis screen, e.g. CBC, PS and CRP levels

- Arterial blood gas analysis (ABG), in severe cases

- Tests for surfactant maturity (in preterms)

Other investigations, e.g. echocardiography for CHDs and metabolic screening for inborn errors are indicated in selected cases.

Management of RD depends on etiology, though general principles include:

• Respiratory support with humidified O₂ or assisted ventilation, as per clinical severity and ABG reports.

• Supportive care, i.e. adequate warmth, nutrition, fluid / electrolyte maintenance and prophylactic antibiotics. Parenteral nutrition is preferable in severe RD, due to risk of aspiration with oral feeds.

• Continuous monitoring by clinical assessment, non- invasive pulse oximetry and periodic ABGs.

• Treatment of other complications, e.g. hypoglycemia, acidosis, fluid/electrolyte imbalance, infections and anemia. Packed cell transfusion is indicated in babies with hematocrit lt;40, to improve oxygen-carrying capacity.

• Treatment of primary cause.

12.13.2