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Year 2 HD > 13. Problems of the low birth weight infant > Flashcards

13. Problems of the low birth weight infant Flashcards

1
Q

What is the average birthweight of a full term baby in the UK?

A

Just under 3.5kg

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2
Q

What is meant by ‘full term’ and what is the range?

A

Full term ranges from 37-42 weeks depending on the foetus

Prior to 37 weeks is preterm

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3
Q

What is meant by a low birth weight?

A

This is if the neonate is born below 2.5kg

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4
Q

What is meant by a very low birth rate?

A

This is if the neonate is born below 1.5kg

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5
Q

Define ‘prematurity’

A

If birth of the foetus occurs prior to 37 completed weeks of gestation

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6
Q

What is meant by ‘small for gestational age’ (SGA)?

A

This is if the birth weight of the neonate is below the 10th percentile for their gestational age

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7
Q

What is meant by foetal/intrauterine growth restriction (FGR/IUGR)?

A

This is if there is a failure of the foetus to achieve the normal rate of foetal growth

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8
Q

What is the most common cause of FGR/IUGR?

A

Uteroplacental insufficiency i.e. a lack of blood flow to the foetus
Also commonly due to foetal infections

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9
Q

SO what are the two reasons a neonate might have a low birth weight?

A

SGA

Premature

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10
Q

What are the complications associated with SGA?

A

Greater risk of other growth abnormalities

Links to long term health problems

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11
Q

What are the complications associated with prematurity?

A

Neurodevelopmental issues

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12
Q

What are the different causes for a neonate being SGA?

A

Genetic cause:
Normal small baby
Chromosomal disorders
Inherited disorders

Acquired causes:
Utero-placental insufficiency 
Congenital infection 
Smoking in the mother
Maternal chronic illness e.g. renal, sickle cell anaemia
Multiple pregnancy
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13
Q

What is meant by monochorionic twins?

A

The twins share the placenta

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14
Q

What is meant by dichorionic twins?

A

This is when each twin has their own placental unit

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15
Q

What is twin-twin transfusion?

A

This occurs in monochorionic twins - where one twin may get an increased level of the circulation than the other and so will grow larger than the other

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16
Q

What is Edwards synrome?

A

Trisomy 18
Leads to congenital heart disease, brain abnormalities, limb abnormalities, poor respiratory function and the baby usually does not survive past one year of life

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17
Q

What is the effect of poor placental blood flow on the development of the foetus?

A

The foetus will be rendered to hypoxia
The foetus will attempt to compensate via a reduction in blood flow to the kidneys, gut, liver, skin etc to increase blood flow to the brain and cardiac muscle and adrenals

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18
Q

What is prioritised to receive blood flow during a state of hypoxia?

A

Brain
Heart
Adrenals

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19
Q

Why is temperature regulation an issue in an SGA baby?

A

The smaller baby will have an increased surface area to volume ratio - increased heat loss via increased radiation
The SGA baby will have less adipose tissue for insulation
Will also have a reduced capacity for thermogenesis i.e. reduced capacity to generate heat

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20
Q

What is the nutritional impact on an SGA baby and how can this be treated?

A

The baby is likely to have reduced glycogen reserves either due to preterm or due to inadequate transplacental nutrition and therefore is more likely to be hypoglycaemic

This should be treated via. feeds and if very low via intravenous dextrose

21
Q

What are the clinical presentations and the long term effects of hypoglycaemia in the neonate?

A

Can present as lethargy and fits in the neonate

There is an increased risk of neuro-developmental adverse effects
Increased risk of necrotising enterocolitis

22
Q

What is necrotising enterocolitis?

A

Primarily seen in premature infants

Where portions of the bowel undergo necrosis

23
Q

What is stated by the Barker hypothesis in terms of a low birth weight?

A

States that a low birth weight is associated with increased risks of adult disease e.g. diabetes, hypertension, coronary heart disease, stroke, chronic bronchitis

24
Q

What are the different causes of prematurity?

A

Spontaneous:
May be due to premature rupturing of the amniotic membrane i.e. the waters break too early
Infection of the placenta
Cervical incompetence

Intentional:
Either maternal or foetal complications to preserve the life of the mother or the baby

25
Q

What are the different problems associated with prematurity in the baby?

A

NB. the preterm babies are not just small but their organs are also underdeveloped:
Reduced ability for temperature control
Respiratory problems
Cardiovascular issues
Reduced immune status so increased risk of infection
Neurological impacts

26
Q

How can hypothermia be avoided in a preterm baby (reduced thermal regulation)?

A

Modern incubator to provide humidified warmth

May deliver the baby directly into a polythene bag up to the shoulders to prevent evaporative heat loss

27
Q

Why is it important to keep a premature baby in a warm environment?

A

The lower the environmental temperature, the higher the oxygen consumption in the newborn baby and therefore, there is an increased energy expenditure

28
Q

What is the term for the correct range of temperature to reduce energy expenditure?

A

Neutral thermal environment

This is the range of environmental temperature in which there is the least energy expenditure

29
Q

What is the cause of respiratory problems in premature babies?

A

Preterm babies have immature lungs as the alveoli are still developing - reduced surface area reduces the level of gaseous exchange - limits the ability of the baby to breath on its own

Lungs are deficient in surfactant

There are smaller and weaker intercostal muscles and weaker diaphragm - reduced muscular strength to breath

30
Q

What is surfactant?

A

This is a phospholipid and lipoprotein substance which functions to keep the alveoli open - lines the alveolar surface
This prevents the collapse of the alveoli and hence is essential to lung function

31
Q

What are the short term respiratory problems of a newborn baby?

A

Respiratory distress syndrome
Pneumonia
Apnoea of prematurity

32
Q

What are the long term respiratory problems of a newborn baby?

A

Chronic lung disease of infancy aka. bronchopulmonary dysplasia

33
Q

How can you administer increased surfactant into a newborn and why is this necessary?

A

The preterm baby has not yet produced all of the surfactant that it requires

Can instil surfactant into the lungs via the endotracheal tube to keep the alveoli open

34
Q

What is respiratory distress syndrome and how is this caused?

A

Caused by a lack of surfactant in the premature baby
There are signs of respiratory distress in the infant - tachypnoea, tachycardia, expiratory grunting, nasal flaring, blue discolouration of the skin

35
Q

How can RDS be prevented?

A

Antenatal steroids
Avoidance of intrauterine hypoxia
Prophylactic surfactant treatment
Keep warm, avoid acidosis

36
Q

How can RDS be treated?

A

Instil surfactant

Respiratory support

37
Q

What are the cardiovascular problems associated with prematurity?

A

PPHN - persistent pulmonary hypertension of the newborn
Failure to maintain blood pressure
Patent ductus arteriosus

38
Q

What is the ductus arteriosus?

A

Connection between the aorta and the pulmonary artery

39
Q

What is the problem with a patent ductus arteriosus?

A

This is a failure of the ductus arteriosus to close - mixing of oxygenated and deoxygenated blood and inefficient circulation through the lungs and body

40
Q

What are the nutritional challenges in preterm babies?

A

Immature suckling - has not yet developed and so should be fed via a tube
Poor gut motility
May not tolerate enteral feeds - feeding may result in a metabolic challenge to the intestine and can precipitate necrotising enterocolitis but if not fed then the gut mucosa will atrophy

41
Q

What is necrotising enterocolitis?

What are the risk factors for this?

A

This is an acute bacterial invasion/inflammation/necrosis of the bowel due to gas formation in the bowel wall

Prematurity, hypoxia, infection, enteral feeding

42
Q

What are the clinical presentations for NE?

A

Abdominal distension, tenderness, discolouration, blood in the stools, generalised collapse

43
Q

How is NE treated?

A

Stop feeds
Give antibiotics
May need surgery

44
Q

What is the main issue with sepsis in the newborn?

A

Sepsis can occur as there is an underdeveloped immune system

The main issue is that the baby does not show specific symptoms as there is a poor localisation of the infection
Most often, there will be a generalised collapse

45
Q

Which bacteria most commonly cause infection in the newborn and why?

A

Most commonly group B streptococcus as this is present in the vaginas of 1/3 of women
This can ascend into the vagina during labour
Causes problems in the immunosuppressed neonate

46
Q

Specifically, why is the preterm neonate more prone to contracting infections?

A

Preterm babies lose out on transplacental IgG transfer from the mother as this occurs in the last 12 weeks of pregnancy so lose out on innate immunity
Often cannot be breastfed and lose colostrum and IgA
Does not have a fully formed dermis and so the skin is very susceptible to infection

47
Q

What are the effects on the central nervous system in the preterm baby?

A

Susceptibility to periventricular haemorrhage - if bleeding persists in this region then this can lead to an intraventricular haemorrhage

Intraventricular haemorrhage is bleeding into the ventricular system

48
Q

What are the complications of intracerebral bleeding?

A

Collapse and death
Loss of brain parenchymal tissue with cyst development
Blockage of CSF circulation - can result in hydrocephalus

Year 2 HD (29 decks)

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