Neonatal medicine

Published on 09/03/2015 by admin

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16 Neonatal medicine

Care of the normal baby following delivery

Umbilical cord

The umbilical cord should be clamped once the baby has been delivered by replacing the forceps that may have been used at delivery with a sterile clamp.

Temperature control

The newborn infant is at significant risk of hypothermia because of its impaired ability to increase metabolic rate after delivery. There is a natural heat loss, which is exacerbated by a baby’s high surface area to volume ratio. Hypothermia will also worsen hypoxia and acidosis and induce respiratory distress.

Vitamin K

Vitamin K is essential for the coagulation pathways so a deficiency, as may occur in breastfed babies, may result in haemorrhagic disease of the newborn. Vitamin K deficiency may also occur in premature infants, small babies or babies who are unable to feed sufficiently. Maternal liver disease, drug abuse, or mothers on anticonvulsant or antituberculous medication are more likely to lead to babies with this problem.

Vitamin K as a single intramuscular administration at birth will prevent this disease.

Care on the postnatal ward

General care takes place on the postnatal ward. The cord stump should be cleaned daily with soap and water. Vernix, dried blood and meconium can be cleaned soon after birth, but the first bath can be delayed until the following day. Routine observations on the postnatal ward include temperature, heart rate, respiratory rate, bladder and bowel activity, and weight.

Temperature and heart rate

Abnormal temperature (>38 °C or <35.5 °C) or a tachycardia (>160 bpm) that lasts longer than 1 hour is cause for concern and could indicate sepsis.

Respiratory rate

A normal rate is ≤60 breaths per minute. Other than sepsis, the common cause of tachypnoea is transient tachypnoea of the newborn. This is attributed to a build-up of fetal lung fluid, particularly following caesarean section in the absence of labour, and has characteristic chest X-ray appearances. It is diagnosed only after other causes of respiratory distress have been excluded, especially infection. The common causes of respiratory distress in the term baby include:

• Infection – this commonly includes group B β-haemolytic streptococcus, Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Klebsiella, Enterobacter and Streptococcus pneumoniae

• Meconium aspiration

• Spontaneous pneumothorax

• Severe anaemia

• Central nervous system depression, especially after birth asphyxia

• Cardiac failure

• Metabolic disease with acidosis

• Transient tachypnoea of the newborn

• Congenital anomalies, including causes of upper airway obstruction like goitre, tracheo-oesophageal fistula, diaphragmatic hernia and pulmonary agenesis.

Respiratory distress should be treated as neonatal sepsis until proven otherwise – usually group B streptococcal infection.

Other signs of respiratory distress include grunting; central cyanosis; subcostal, intercostal and sternal recession.

Blood sugar levels

Small and premature babies have different nutritional needs from larger babies and are more prone to hypoglycaemia. If feeding poorly, 3-hourly assessment of blood glucose (before a feed) should be performed. Signs of impending hypoglycaemia include lethargy, irritability, apnoea and fitting. Healthy term babies do not routinely need blood glucose assessment.

Bladder and bowel activity

Failure to pass urine is rare and is associated with palpable kidneys or bladder. Poor stream or dribbling in male infants may be associated with posterior urethral valves.

Meconium is the green/black stool passed in the first 2–3 days after delivery. This changes colour depending on the type of feeding: yellow/mustard and soft with breastfeeding and a firmer yellow/brown stool with bottle-feeding. A delay in passing meconium may indicate intestinal obstruction or Hirschsprung’s disease. Pale stools in a jaundiced baby may indicate obstructive jaundice and extrahepatic biliary atresia should be excluded.

Weight

Babies can lose up to 10% of their birth weight in the first few days of life. As feeding becomes established, birth weight should be reached within the first week and thereafter the baby should gain 20–30 grams a day until 6 months of age.

Feeding

Breastfeeding is becoming more popular and is advised as it has been shown to reduce the risk of gastrointestinal and respiratory infections in term babies as well as necrotizing enterocolitis in premature babies. Human milk has the following advantages:

In spite of these advantages, breastfeeding is contraindicated in severe maternal systemic disease, maternal human immunodeficiency virus (HIV) infection, or if the mother is taking drugs that may be secreted in the milk (always check in the drug formulary):

• Anticoagulants

• Antibiotics, e.g. chloramphenicol, metronidazole, isoniazid, tetracyclines, trimethoprim

• Antiarrhythmics, e.g. atenolol, amiodarone

• Anti-inflammatories, e.g. indometacin

• Antidepressants, e.g. lithium, doxepin

• Antimalarials, e.g. dapsone preparations

• Antimigraine, e.g. ergotamine

• Immunosuppressives.

Breastfeeding babies will feed on demand and will self-regulate their intake.

Examination of the newborn

All babies should be thoroughly examined at delivery and also before discharge from hospital. Initial complete inspection of the infant in a cot will provide much information, such as colour (cyanosis or pallor), posture (complete movement and tone), abnormal morphological features and evidence of respiratory distress.

Skin abnormalities

Milia

These are tiny sebaceous retention cysts that look like small white spots and are mainly found over the nose.

Erythema toxicum (neonatorum)

This very common diffuse erythematous rash often occurs in the first week of life, is harmless and is of uncertain cause.

Vascular naevi

These include capillary haemangiomata, which produce pale pink patches on the neck, forehead and eyelids (often referred to as ‘stork marks’) and gradually fade away. In contrast, port-wine stains are larger and darker.

Jaundice

Physiological jaundice often occurs within the first 5 days, occurring 24–48 hours after delivery, peaking at day 4, and is due to:

• Shortened lifespan of fetal erythrocytes, resulting in increased breakdown as well as liver enzyme immaturity

• Hepatic immaturity.

However, jaundice is abnormal if it occurs in the first 24 hours after birth or lasts beyond 14 days. The most common causes for onset within 24 hours of birth include: erythrocyte haemolysis due to incompatibility, e.g. Rhesus, ABO or other blood group; infection; and excessive erythrocyte breakdown because of bleeding, e.g. cephalohaematoma or infection.

This excess haemolysis results in an unconjugated hyperbilirubinaemia in the baby with the potential for kernicterus. Guidelines are available to determine management options depending on level of unconjugated bilirubin, gestational age of baby and weight. Kernicterus has serious implications, including cerebral palsy, deafness and death. Unconjugated hyperbilirubinaemia usually after haemolysis can be treated with either phototherapy or, in more extreme cases, with intravenous immunoglobulin or exchange transfusion.

Routine investigations include:

• Full blood count, reticulocyte count and blood film

• Maternal and baby blood group

• Coombs’ test

• Urine for culture

• Full infection screen, depending on status of the baby, may be considered, including blood and cerebrospinal fluid for culture.

If baby fails to respond, then investigate further for rarer causes.

The most common cause for prolonged jaundice in the newborn (> 14 days) is breastfeeding. However, other more serious causes like biliary atresia must be excluded. Breast milk jaundice is characterized by a raised unconjugated hyperbilirubinaemia, whereas in biliary atresia the conjugated bilirubin levels are raised. Biliary atresia can be corrected with surgery to the biliary obstruction to prevent chronic liver damage. Other causes of prolonged jaundice include:

• Hypothyroidism

• Galactosaemia

• Viral hepatitis

• Glucose-6-phosphate dehydrogenase deficiency.

Head and neck

The head shape can be distorted by birth, and this will resolve within a few days. Caput succedaneum is the oedematous thickening of the scalp caused by prolonged labour or ventouse delivery, which quickly resolves, but must be distinguished from a cephalohaematoma, a more serious condition caused by a collection of blood between the periosteum and the skull bones.

There are usually two fontanelles: the posterior closes within 3–4 months, but the anterior takes up to 18 months to close.

Observe for typical facial appearances that may be syndromic, paying particular attention to eyes, ears, mouth and tongue.

Chest

Carefully inspect the chest for respiratory rate, symmetry and movement. Auscultation will reveal abnormal breath sounds and confirm heart rate and normal heart sounds and exclude murmurs.

Abdomen

Major defects of the abdominal wall, e.g. gastroschisis or omphalocele, will be evident at birth. The liver, spleen and kidneys are often palpable in normal infants, but any unusually large masses should be further investigated. The anus should be inspected for patency and position. The genitalia should be carefully inspected and in particular it is often quite normal for female infants to have some bloody vaginal discharge. Any ambiguity of the genitalia should be investigated further and chromosome analysis performed as a matter of urgency before confirming the sex of the infant with the parents. Ambiguous genitalia is now referred to as a disorder of sexual differentiation and requires specialist assessment.

Vertebral column

The spine should be continuous and smooth to palpation. Any defects, swelling, birthmarks or hair patches should be investigated with ultrasound as they may indicate an underlying spinal abnormality.

Limbs

The limbs should move freely and have normal posture and tone when still. Birth injuries to the limbs may occur and include fractured humerus or clavicle, brachial plexus injury with the characteristic Erb’s palsy and wrist drop as a result of radial nerve injury with fractured humerus. Hands, feet and digits should be carefully inspected. Developmental dysplasia or congenital dislocation of the hips more commonly occurs in female infants, in a breech delivery or in the presence of a family history. It is important that this is discovered early, as intervention at this stage will prevent problems later in life.

Reflexes

A term baby should be able to support its head with minimal lag as the baby is pulled gently to the sitting position. With the baby suspended in the ventral position, again the head should come into line with the axis of the body. The Moro reflex is a useful primitive reflex in the neurological assessment.

Group B streptococcus

This pathogen is the most common cause of serious bacterial infection in the newborn. It can be either early (the first week of life) or late (up to 3 months) in onset and is manifested as pneumonia, septicaemia or meningitis. Early-onset infection is usually acquired from the mother during delivery, and should be suspected if detected in maternal vaginal swabs antenatally, or in cases of maternal pyrexia in labour, prolonged prelabour ruptured membranes and in the premature infant.

Neonatal disease can be prevented by administering antibiotics to the mother in labour, or to the neonate postpartum.

The small baby

Small-for-gestational-age babies are defined as those weighing less than the 10th centile at birth for that gestation. Alternatively, low-birth-weight babies are those weighing less than 2.5 kg at birth. These babies need to be carefully observed in the neonatal period, as they are more prone to hypothermia, hypoglycaemia and hypocalcaemia.

Prematurity is defined as delivery before 37 completed weeks of pregnancy, regardless of the baby’s birth weight. Premature infants are susceptible to all the problems of the small baby outlined above, including feeding difficulties, temperature regulatory difficulties, infection and jaundice. Specific problems encountered by premature infants are outlined below.

Respiratory distress syndrome

This is also known as hyaline membrane disease and is caused by a deficiency of surfactant in premature lungs. Surfactant lowers the surface tension within the alveolar sacs, preventing their collapse during normal expiration.

Intraventricular haemorrhage

This is a common condition of prematurity with complicated aetiology, including vascular friability and clotting dysfunction. The haemorrhage can vary from a minimal cerebral bleed to an extensive haemorrhage with severe neurological sequelae.

Retinopathy of prematurity

Excessive oxygenation during ventilation has been associated with this type of retinopathy, which may cause retinal detachment and blindness.

Neonatal resuscitation

Most babies are born in good condition and do not require any special stimulation or resuscitation. Immediately following delivery, the baby should be gently dried and rapidly assessed. Mucus is only removed from the mouth and then nose if necessary or if meconium is present at delivery. The Apgar score is a system developed for the initial assessment of the newborn at 1 and 5 minutes, and thereafter if indicated. It consists of a score from 0 to 2 for each of five variables, giving a score out of 10 (Table 16.1).

Table 16.1 Apgar score

The umbilical cord should be kept long in infants likely to need special care (for cannulation) and cord blood taken for blood gas analysis and pH.

If the baby is vigorous and pink, then the baby can be wrapped to keep warm and passed immediately to the mother. If a baby fails to breathe by 1 minute despite drying off and stimulation of the feet, then immediate paediatric assistance should be called. If the baby is considered ‘flat’ or limp at delivery – impaired breathing or heart rate below 100 bpm – then resuscitate immediately following the guidelines outlined in Figures 16.1 and 16.2.

Figure 16.1 Neonatal resuscitation, chart 1.

(Reproduced with permission from Working party of the Royal College of Paediatricians and Child Health and the Royal College of Obstetricians and Gynaecologists 1997 Resuscitation of Babies at Birth. London: BMJ, pp. 57 and 58.)

Figure 16.2 Neonatal resuscitation, chart 2. NNU, neonatal unit.

(Reproduced with permission from Working party of the Royal College of Paediatricians and Child Health and the Royal College of Obstetricians and Gynaecologists 1997 Resuscitation of Babies at Birth. London: BMJ, pp. 57 and 58.)

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