The Preterm Infant Flashcards
What are the medical problems encountered by preterm infants?
- Respiratory:
- RDS
- Apnoea
- Pneumothorax - CVS:
- Hypotension
- PDA - Metabolic:
- Electrolyte imbalance - Neurological:
- IVH - GI:
- Necrotising Enterocolitis
- Hernias
- Reflux - Infection
- Jaundice
- Retinopathy of Prematurity
- Temperature control
- Nutrition
What is the cause of RDS in a preterm infant?
Deficiency in surfactant leading to increased alveolar surface tension
Which infants are more at risk of RDS?
Those born at less than 28wks gestation and male infants
What term infants are at risk of RDS?
- Infants of diabetic mothers
2. Infants with genetic mutations in surfactant genes
How can we prevent RDS in preterm infants?
Antenatal corticosteroids (glucocorticoids) can be given to stimulate surfactant production
What are the clinical signs of RDS in a neonate?
- Tachypnoea >60bpm
- Chest wall recession and nasal flaring
- Expiratory grunting
- Cyanosis
What is the management of RDS in a preterm infant?
Surfactant therapy, via tracheal tube or catheter, and respiratory support
What types of respiratory support can be offered to a neonate?
- Non-invasive:
- CPAP
- High flow nasal cannula - Invasive:
- Mechanical ventilation
How is the mechanical ventilation adjusted?
It is adjusted according to oxygenation, chest wall movements and bloods gas analysis
What is pulmonary interstitial emphysema?
When air from overdistended alveoli escapes into the interstitium
What is a pneumothorax?
A pneumothorax is when air leaks into the pleural cavity
What are the clinical signs of a pneumothorax in a neonate?
- Increased oxygen requirement
- Decreased breath sounds on affected side
- Decreased chest movements on affected side
How do we diagnose a pneumothorax in a neonate?
It can be diagnosed with transillumination or CXR
Define a tension pneumothorax
A tension pneumothorax is the progressive build up of air within the pleural space, usually due to a large lung laceration, which allows air to enter the pleural space but not to leave it (one way valve)
What is the management of a tension pneumothorax?
URGENT decompression with a chest drain
How can we prevent a pneumothorax in a neonate?
Ventilate with the lowest pressures possible
What infants are at risk of apnoea?
Very low birthweight infants until they reach about 32wks of gestation
What is the mechanism behind the apnoea?
Bradycardia occurs and either:
a) Infant stops breathing for over 20-30secs or
b) Breathing continues against a closed glottis
What underlying causes of apnoea should be excluded?
- Hypoxia
- Infection
- Anaemia
- Electrolyte disturbance
- Hypoglycaemia
- Seizures
- Heart failure
- Aspiration due to reflux
What is the usual cause of apnoea in preterm infants?
Immaturity of respiratory control
What is the treatment of apnoea in preterm infants?
- Gentle physical stimulation
- Caffeine (central respiratory stimulant)
- CPAP or mechanical ventilation if frequent episodes
Why are preterm infants at greater risk of hypothermia?
- Large surface area relative to mass so greater heat loss than heat generation
- Higher transepidermal water loss than term infants
- Little subcutaneous fat
- Cannot conserve heat
What are the consequences of hypothermia in a neonate?
- Increased energy consumption
- Hypoxia and hypoglycaemia
- Failure to gain weight
How can we maintain temperature in a neonate?
Incubators - increase ambient humidity so decrease transepidermal water loss
Overhead radiant heaters used initially
What are the consequences of a PDA?
- Shunting of blood from left to right
- Apnoea and bradycardia
- Increased oxygen requirement
- Difficulty weaning from artificial ventilation
What are the clinical signs of PDA?
- Bounding pulses
- Prominent precordial impulse
- Systolic murmur
What investigations are performed for PDA?
Echocardiogram
What is the pharmacological management of PDA?
- Prostaglandin synthetase inhibitor
- Indomethacin
- Ibuprofen
What are the surgical options for treatment of PDA?
Surgical ligation - only done if pharmacological methods fail and patient is symptomatic
What are the fluid requirements of a preterm infant?
Requirements vary with chronological and gestational age
1st day of life - 60-90ml/kg
Increase by 20-30ml/kg per day to 150-180ml/kg on day 5
How are fluid requirements adjusted?
Adjusted according to:
- Clinical condition
- Plasma electrolytes
- Urine output
- Weight change
Why are the nutritional requirements of a preterm infant higher?
Their requirements are higher due to rapid growth
What mode do we use to feed preterm infants?
Mode of nutrition depends on gestational age
35-36wks = mature enough to suck and swallow milk
Less mature = orogastric or nasogastric tube
How can we meet the nutritional requirements of a very preterm infant?
Introduce enteral feeds ASAP
Supplement breast milk with phosphate
Can also supplement with protein, calories and calcium
What are the advantages and disadvantages of special infant formulas?
They can meet the increased nutritional requirements of preterm infants but they provide no protection against infection, unlike breast milk
How do we meet the nutritional requirements of the extremely preterm or sick neonate?
Parenteral nutrition via a PIC line or an umbilical venous catheter
Why are preterm infants more predisposed to iron deficiency and how do we prevent it?
As most of the iron transfer from the mother is in the third trimester.
Combat this by starting supplements at several weeks of age.
Why are preterm infants at greater risk of infection?
- IgG mainly transferred in 3rd trimester
- No IgA or IgM transfer
- Infection of mother’s cervix can be a cause of preterm labour
When do most infections occur?
Most occur at several days of age
What increases risk of infection for these infants?
- Indwelling catheters
2. Mechanical ventilation
Define Necrotising Enterocolitis (NEC)
NEC is damage to vulnerable bowel via ischaemic injury or bacterial invasion which occurs in the first few weeks of life
What are the clinical signs of NEC?
- Feed intolerance
- Bile stained vomit
- Distended abdomen
- Fresh blood in stool
What are the features of NEC on x-ray?
- Distended loops of bowel
- Thickening of the bowel wall
- Intramural gas
- May have gas in portal venous tract
What is the management of NEC?
- Stop oral feed
- Broad spectrum antibiotics (cover aerobes and anaerobes)
- TPN
- Mechanical ventilation
- Circulatory support
- Surgery if perforation
What are the complications of NEC?
- Bowel perforation
- Strictures
- Malabsorption
- Increased risk of poor neurodevelopmental outcome
What are the risk factors for IVH?
- Very low birth weight infant
- Perinatal asphyxia
- Severe RDS
- Pneumothorax
What are the complications of a large IVH?
Impaired drainage leading to hydrocephalus - treated with a ventriculo-peritoneal shunt
What are the complications of sever IVH?
Hemiplegia
Define Retinopathy of Prematurity
Retinopathy of Prematurity is abnormal replacement of sensory retina by fibrous tissue and blood vessels
What are the complications of retinopathy of prematurity?
- Retinal detachment
- Fibrosis
- Blindness
What are the risk factors for developing retinopathy of prematurity?
- Very low birth weight infants
2. Uncontrolled use of high concentrations of oxygen
How is retinopathy of prematurity managed?
- Laser therapy can decrease visual impairment
2. Intravitreal anti-VEGF is being investigated but is not routine
Define Hyponatraemia
Na+ <130mmol/L
What are the causes of hyponatraemia in a neonate?
- Water overload
- Maternal fluid overload
- Iatrogenic
- Sick infant
- Excess renal loss
- GI loss
- Drainage of ascites/CSF
- Hypoadrenalism
What are the symptoms of hyponatraemia in a neonate?
- Irritability
- Apnoeas
- Seizures
How is hyponatraemia managed?
Management depends on the underlying cause
Too rapid correction can cause neurological damage
Define Hypernatraemia
Na+ >150mmol/L
What are the causes of hypernatraemia in a neonate?
- Water depletion
2. Excess Na+ administration
What infants are at increased risk of hypernatraemia?
- Extremely preterm infants in first days of life
2. Breastfed infants with poor intake
How do we manage hypernatraemia in a neonate?
Increase fluid intake
Be cautious with rapid correction
Define Hypokalemia
K+ <2.5mmol/L
What are the causes of hypokalemia in a neonate?
- Excess losses
2. Inadequate intake
How do we manage hypokalemia in a neonate?
Correct with supplementation (either IV or enteral)
Be aware with IV infusion as risk of arrhythmias
Define Hyperkalemia
K+ >7.5mmol/L OR >6.5mmol/L + ECG changes
What are the causes of hyperkalemia in a neonate?
Failure of K+ excretion (renal failure)
How do we manage hyperkalemia in a neonate?
- Administer calcium gluconate for myocardial stabilisation
- Eliminate the excess K+ with calcium resonium and dialysis
- Redistribute the K+ using Salbutamol and Insulin (SE of these is hypokalemia)
