RESPIRATORY DISTRESS IN NEWBORN

CAUSES:

1. Perinatal asphyxia and intracranial bleed.
2. Transient tachypnea in newborn (TTN).
3. Respiratory distress syndrome / Hyaline membrane disease (RDS).
4. Meconium aspiration syndrome.
5. Congenital pneumonia / sepsis.
6. Congenital heart disease (CHD).
7. Diaphramatic hernia / evantration of diaphragm.
8. Tracheoesophasial fistula.
9. Pneumothorax.
10. Laryngomalacia.                                                                              

  RESPIRATORY DISTRESS  SYNDROME (RDS)                                INCIDENCE:   <28  wks = 60-80%

                          32-36 wks = 15-30%

                           >37 wks = 5%

                           At term = Rarely.

RISK FACTORS :

1. Factors that affect the state of lung development at birth  -----

                          Prematurity, Maternal DM, Genetic factors (White race, male sex,previous siblings of RDS)

2. Factors that may acutely impair surfactant production, release or function-----  Perinatal asphyxia in premature infant (APH, some second twin ).

Cesarian section without labor (decrease adrenergic and steroid hormone during labor).                                                                                                 
 SURFACTANT:               Phosphatidylcholine (Lecithin)—65%

                                              “””             glycerol

                                           Apoproteins

                                           Cholesterol

It appears in amniotic fluid between 28 and 32 wks .Mature surfactants are usually present after 35 wks.

PATHOLOGY:

Surfactant deficiency is the primary cause of RDS.

Diffuse alveolar atelectasis, edema , cell injury occurs.

Serum proteins that inhibit surfactant function leak into the alveoli.

1.      Increase water content.

2.      Immature mechanism for clearance of lung fluid.

3.      Lack of alveolar- capillary apposition.

4.      Low surface area for gas exchange.                           Typical of the immature lung  also contribute to the disease.                                                                  CLINICAL FEATURES:

Usually appear within minutes of birth .

Tachypnea, prominent grunting , intercostals and subcostal retraction, nasal flaring and duskiness.

Cyanosis is relatively unresponsive to O2 administration.

B/S –nomal / diminished with harsh tubular. Fine rales.

Progressive worsening of cyanosis and dyspnea.

In most cases, the symptoms signs may reach a peak within 3 days.

Death is rare on first day, usually occurs between 2 and 7 days and usuly associated with alveolar leaks and pul. or IVH.

INVESTIGATIONS:

              CXR—Fine reticular granularity. Typical pattern at 6-12 hrs.

             Blood gas analysis.

            Acid- base value.

            Pulse oxymetry.

 Prenatal diagnosis:

  L: S ratio= 2:1 excludes RDS.

                 =<1.5 RDS.

COMPLICATIONS.

1. PDA.
2. IVH.
3. Pulmonary air leaks---- Pneumothorax

                                           “      mediastinum .Pn. peritoneum/ pericardium  Subcutenous emphysema   Pul. interstitial emphysema   Airembolism.

4. Bronchopulmonary dysplasia.
5. Pneumonia ---aspiration / bacterial.
6. Complications  of mechanical ventilation.
7. Necrotising enterocolitis.
8. retinopathy of prematurity.
9. Long term neurological sequelae.                                                                                  TREATMENT:

                               The basic defect requiring treatment is inadequate pul. exchange of O2 and CO2 . Metabolic acidosis and circulatory insuffiency are secondary manifestations.        Therapy requires careful and frequent monitoring of HR, RR,arterial PO2,CO2, Ph, HCO3 , electrolytes, blood glucose, Hct. BP, temp.

1.Maintenance of temperature.

2. Respiratory measures----maintenance of respiration and O2 therapy.

3.  Exogenous surfactant through E-T tube.

4.  Correction of acidosis.

5.  Calorie and fluid maintenance.

6.  Broad sprectum antibiotics.

7.  Tx. Of complications.

8.  Follow up.

              TRANSIENT TACHYPNEA OF NEWBORN (TTN) / TYPE -2 RDS.

It is a disease of nearterm and term infants who have resp. distress shortly after delivery that resolve within 3-5 days.

It is caused by delayed resorption of fetal lung fluid from pul. lymphatic system.

        ETIOLOGY

It is unknown.

Risk factors are:

Premature or operative delivery.

Delayed cord clamping or cord milking.

Male sex.

Exessive maternal sedation.

Prolonged labor.

         CLINICAL FEATURES

Develops tachypnea within 2-6 hrs after delivery.

Mild to moderate tachypnea.

Cyanosis.

Slight  IC and subcostal retraction.

Incresed A-P  diameter of upper thorax.

Intermittent exp. Grunting.

Nasal flaring.

Good air exchange.

No rales or rhonchi.

Symptoms typically persists for 12 to 24 hrs with mild TTN but may persist for longer than 72 hrs with severe TTN.

CXR—Prominent pul. vascular markings.

             Fluid lines in fissure.

              Over aeration.

             Flat diaphragm.

             Occationally pleural fluid.

TREATMENT

Recovers rapidly---assurance.

Minimal O2 (<40%).

MECONIUM ASPIRARION SYNDROME (MAS)

Meconium –stained fluid is found in 5-15% of cases and occurs in term or post term infants.

5% of these children develop MAPn.

30% require mechanical ventilation.

<5-10% expire.

MECONIUM

Compositon—epithelial debris, mucous, fetal hair, bile.

ETIOLOGY

Acute or chronic hypoxia can result in the passage of meconium in utero.

Gasping by fetus or newborn cause aspiration of amniotic fluid contaminated by meconium.

PATHOPHYSIOLOGY

Partial or complete blockage of airway .

Inflammation and chemical pneumonia and continued compromise resulting in atelectasis, air leakage, acidosis, hypoxia,hypercapnea and persistent pul. hypertention.

CLINICAL FEATURES:

Respiratory distress starts within the first hrs.

The condition usually improves within 72 hrs.

Tachypnea may persist for days or even several wks.

A normal CXR in an infant with severe hypoxia and no other malformation suggest the diagnosis of pul. hypertention.

CXR-----Patchy infiltrates

               Coarse irregular streakes of both lung fields

               Increased AP diameter and flattening of diaphragm

               Pneumothorax or pn. Mediastinum may be present.

 

Congenital Heart Disease

     

This is an evolving disease which may present with respiratory distress,       Tachycardia, cyanosis, cardiomegaly, hepatomegaly or heart murmur. If may be      suspected if the baby does not respond to usual therapy for respiratory distress.

Pneumothorax

     

                  This is an uncommon cause of respiratory distress an mostly iatrogenic

Diaphragmatic hernia

The baby may present with respiratory distress and dextorcardia because the hernia is usually on the left. There is an associated scaphoid abdomen.

Oesophageal atresia and tracheo-oesophageal fistula

           

The baby presents with excessive frothing at the mouth and respiratory distress due to aspiration of feeds, Often there is history of polyhydramnios.

Relevant history

Antenatal

                        _[-]             Polyhydramnios

                        _[-]             PROM

                        _[-]          Maternal fever

                        _[-]          Gestational age

            Birth

                        _[-]          Meconium staining

                        _[-]          Duration of labor

                        _[-]          Delayed cry

                        _[-]          Mode of delivery

            Postnatal

           

                        _[-]          Onset of respiratory distress

                        _[-]          Copious secretions

                        _[-]          Feeding difficulty, choking and vomiting

Relevant examination

                        _[-]          Feature of respiratory distress

                        _[-]          Meconium stained liquor

                        _[-]          Fever/hypothermia

                       

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