Fluid, Electrolytes, Feeding, and Nutrition ✅

Question 1

What is the total body fluid in neonates distributed among?

Answer 1

3 major fluid spaces - plasma, interstitial, and cellular space

Question 2

Is the proportion of fluid in each of the compartments the same in infants and adults?

Answer 2

No, very different

Question 3

How does the extra cellular fluid expressed as a percentage of body weight differ at 26 weeks, term, and in the adult?

Answer 3

In 26 weeks, 50% of fluid is extracellular fluid. In term, around 35%, and in adults, around 20%.
Therefore, relatively less dry weight in younger.

Volume of intracellular fluid is the same.

Question 4

What is the result of the differing proportion of fluids in each compartment in the neonate compared to an adult?

Answer 4

A different approach to fluid management is required

Question 5

What % of the total body weight is water in the early fetal period?

Answer 5

95%

Question 6

What % of the total body weight is water at term?

Answer 6

75%

Question 7

What happens to the distribution of fluid throughout the compartments as the foetus grows?

Answer 7

The amount of fluid in the extracellular spaces decreases gradually, and there is a slow increase in intracellular fluid

Question 8

Why is it important to consider the change in fluid distribution throughout the neonatal period?

Answer 8

It affects decision-making about fluid changes, especially in the sick preterm infant

Question 9

What factors affect the neonatal fluid balance?

Answer 9

• GFR
• RDS
• Transepidermal water loss (TEWL)
• Complications of prematurity

Question 10

How does the GFR in an extremely preterm infant compare to that of a term infant?

Answer 10

It is only around 1/4 of that of a term infant

Question 11

What is the result of the GFR being lower in an extremely preterm infant compared to a term infant?

Answer 11

It makes them vulnerable for fluid overload and hyponatraemia, as well as dehydration and hypernatraemia

Question 12

What else can increase the risk of hypernatraemia in an extremely preterm infant?

Answer 12

Their immature renin-angiotensin mechanism increases the risk following rapid correction of sodium

Question 13

What happens to all babies in the immediate post-natal period, regarding their renal function?

Answer 13

They undergo a diuretic phase

Question 14

What regulates the diuretic phase in the immediate post-natal period?

Answer 14

An increase in atrial natriuretic peptide

Question 15

What does the diuretic phase in the immediate post-natal period lead to?

Answer 15

A physiological contraction of the extracellular volume

Question 16

Describe the sodium balance in a neonate?

Answer 16

There is a negative sodium balance early on, followed by sodium retention in the kidney

Question 17

What is a negative sodium balance early on followed by sodium retention in the kidney important for?

Answer 17

Growth

Question 18

At what gestational age are premature infants able to maintain an adequate water balance over a wide range of fluid intake?

Answer 18

> 30 weeks

Question 19

What can affect fluid homeostasis in extremely preterm infants (<30 weeks)?

Answer 19

• Administration of fluid blouses
• Infection
• Hypotension
• Mechanical ventilation

Question 20

How does RDS affect fluid balance?

Answer 20

Infants with RDS have a delayed diuretic phase, and their extracellular volume is not decreased

Question 21

What is the result of the extracellular volume of infants with RDS not being decreased due to the delayed diuretic phase?

Answer 21

It is important not to give extra fluids and sodium before the diuretic phase

Question 22

Why is there a high transepidermal water loss (TEWL) in babies?

Answer 22

Due to their large surface area and thin, permeable, non-keratinised skin

Question 23

How does the TEWL in infants of 25 weeks gestation compare to that of term infants?

Answer 23

It can be up to 15 times higher

Question 24

What can reduce the TEWL in preterm infants?

Answer 24

• Nursing inside an incubator with high humidity
• Humidification of respiratory gases
• Good skin care

Question 25

How high is the humidity in an incubator?

Answer 25

Up to 80%

Question 26

What neonatal complications can lead to hyponatraemia?

Answer 26

- Pneumothorax - Intraventricular haemorrhage - Conditions requiring surgery

Question 27

What might complications of prematurity lead to, regarding sodium?

Answer 27

Hyponatraemia

Question 28

How can complications of prematurity lead to hyponatraemia?

Answer 28

- Diminished capacity to excrete a free water load - Increased sodium loss in the urine - Iatrogenic fluid administration of hypotonic, low sodium solutions

Question 29

Is true SIADH common in neonates?

Answer 29

No, probably rare

Question 30

What are the fluid requirements of a term neonate at day 1?

Answer 30

Around 50ml/kg/day

Question 31

What are the fluid requirements for a term neonate at day 7?

Answer 31

Around 150ml/kg/day

Question 32

What are the fluid requirements of a preterm neonate at day 1?

Answer 32

60-70ml/kg/day

Question 33

What are the fluid requirements of a preterm neonate at day 7?

Answer 33

Up to 175ml/kg/day

Question 34

What are the energy requirements of a term infant?

Answer 34

100kcal/kg/day

Question 35

What are the energy requirements of a preterm infant?

Answer 35

120kcal/kg/day

Question 36

What are the energy requirements of an IUGR infant?

Answer 36

Up to 140kcal/day/kg

Question 37

What fluids are given to infants in the first 2-3 days of life if IV fluids are required?

Answer 37

Solute-free dextrose solution

Question 38

Why is a solute free dextrose solution used in the first 2-3 days of life?

Answer 38

- Na/K-ATPase mechanism is affected during intensive care for sick babies - Infants have a limited ability to handle solute load in administered fluid

Question 39

What is the Na/K-ATPase mechanism responsive for?

Answer 39

Maintaining sodium and potassium balance

Question 40

Why do infants have a limited ability to handle solute load in administered fluid?

Answer 40

Due to renal impairment

Question 41

What does serum sodium levels reflect?

Answer 41

Sodium and water balance

Question 42

What is considered to be hypernatraemia?

Answer 42

>145mmol/L

Question 43

What is happening with regard to sodium and fluid in hypernatraemia?

Answer 43

There is an absolute or relative deficit of body water in relation to body sodium

Question 44

What is considered to be hyponatraemia?

Answer 44

<135mmol/L

Question 45

What is happening with regard to sodium and water in hyponatraemia?

Answer 45

There is a relative or absolute excess of body water

Question 46

What needs to be clinically assessed when determining the cause of hypo or hypernatraemia?

Answer 46

Change in weight and clinical context

Question 47

What does weight gain in the first few postnatal days with normal serum sodium indicate?

Answer 47

Isotonic expansion of extracellular space and a positive sodium and water balance (at a time when it should be negative)

Question 48

What does hyponatraemia with weight loss or inadequate weight gain indicate?

Answer 48

Sodium depletion

Question 49

What is required when sodium depletion is suspected to be the cause of hyponatraemia?

Answer 49

Supplemental sodium

Question 50

How is hyponatraemia caused by fluid excess treated?

Answer 50

- Fluid restriction | - Treatment of underlying cause

Question 51

What does hypernatraemia with weight loss suggest?

Answer 51

Dehydration

Question 52

What does hypernatraemia with weight gain suggest?

Answer 52

Sodium and water overload

Question 53

Where does most of the potassium in the body exist?

Answer 53

In the intracellular compartment

Question 54

Do blood levels of potassium reflect total body potassium?

Answer 54

No, not usually

Question 55

What maintains the high intracellular potassium concentration?

Answer 55

The Na/K-ATPase

Question 56

How does the Na/K-ATPase maintain the high intracellular potassium concentration?

Answer 56

By pumping sodium out and potassium into the cell

Question 57

What is potassium necessary for?

Answer 57

The electrical responsiveness of muscle cells, and the contractile to of cardiac, skeletal, and smooth muscles

Question 58

When must potassium rich fluids be avoided?

Answer 58

If there is oliguria or anuria due to renal compromise

Question 59

What is the daily sodium requirement of a term infant?

Answer 59

2.5-3.5mmol/kg

Question 60

What is the daily potassium requirement of a term infant?

Answer 60

2.5-3.5mmol/kg

Question 61

What is the daily chloride requirement of a term infant?

Answer 61

5mmol/kg

Question 62

What is the daily phosphorus requirement of a term infant?

Answer 62

1.0-1.5mmol/kg

Question 63

What is the daily calcium requirement of a term infant?

Answer 63

1.2-1.5mmol/kg

Question 64

What is the daily magnesium requirement of a term infant?

Answer 64

0.6mmol/kg

Question 65

What is the daily sodium requirement of a preterm infant?

Answer 65

3-4mmol/kg

Question 66

What is the daily potassium requirement of a preterm infant?

Answer 66

2-3mmol/kg

Question 67

What is the daily chloride requirement of a preterm infant?

Answer 67

1.5-4.5

Question 68

What is the daily phosphorus requirement of a preterm infant?

Answer 68

1.9-4.5mmol/kg

Question 69

What is the daily calcium requirement of a preterm infant?

Answer 69

3-5.5mmol/kg

Question 70

What is the daily magnesium requirement of a preterm infant?

Answer 70

0.3-0.6mmol/kg

Question 71

What is the normal weight loss in the first week in a healthy term infant?

Answer 71

About 5-7%

Question 72

Why do term infants normally loose 5-7% of their birth weight?

Answer 72

- Physiologic contraction of extracellular water volume | - Catabolism secondary to low caloric intake

Question 73

When is the weight loss of a term infant most marked?

Answer 73

On day 2-3

Question 74

When should an infant regain their birth weight?

Answer 74

Within 2 weeks

Question 75

When might the initial weight loss in infants be more marked?

Answer 75

In breastfed infants

Question 76

What can weight loss in excess to 10% lead to?

Answer 76

Hypernatraemic dehydration

Question 77

How much weight does a baby gain in the first 6 months?

Answer 77

Average of around 30g/day

Question 78

When should an infant double their birth weight?

Answer 78

Around 4-5 months

Question 79

When should an infant treble their birth wight?

Answer 79

1 year of age

Question 80

What are the benefits of breast feeding to the baby?

Answer 80

- Most suitable source of nutrition - Reduced risk of infection - May be protective in eczema - Beneficial effect on later ‘cardiovascular’ health - May improve later cognitive function - May protect against SIDS

Question 81

What infections does breastfeeding reduce the risk of?

Answer 81

- Gastroenteritis - Otitis media - Probably severe lower respiratory tract infection requiring hospitalisation

Question 82

When might breastfeeding be protective in eczema?

Answer 82

In infants with a positive family history

Question 83

In what ways does breastfeeding have a beneficial effect on later cardiovascular health?

Answer 83

Improves plasma lipid profile, blood pressure, and risk of obesity

Question 84

What confounds the evidence that breastfeeding reduces the risk of SIDS?

Answer 84

May be through maternal education, socio-economic status, and birth weight

Question 85

What are the advantages of breastfeeding in a preterm infant?

Answer 85

- Better gastrointestinal tolerance - Reduced incidence of necrotising enterocolitis (NEC) and systemic infection - Improved cognitive outcome - Lower BP, more favourable plasma lipid profile, and higher bone mass during childhood and adolescence

Question 86

What are the benefits of breastfeeding for the mother?

Answer 86

- Better mother-infant bonding - Sense of personal achievement - More rapid weight loss - Readily available without any preparation - Easy to express and store - Delayed return to menses - Uterine involution through oxytocin - No cost - Some protection against osteoporosis, ovarian and breast cancer

Question 87

Why might a delayed return to menses be beneficial?

Answer 87

Increased time-interval to next child is important when alternative birth control is not available

Question 88

What happens to the breast in pregnancy?

Answer 88

There is a marked increase in the number of breast ducts

Question 89

What causes the increase in the number of breast ducts in pregnancy?

Answer 89

Response to progesterone, oestrogen, and placental lactometer

Question 90

When does secretion of prolactin start?

Answer 90

In the last trimester

Question 91

What triggers the secretion of colostrum?

Answer 91

Prolactin from the anterior pituitary causes glandular tissue to secrete small amounts of colostrum

Question 92

What controls milk flow after birth?

Answer 92

The let down reflex

Question 93

What mediates the let down reflex?

Answer 93

- Afferent impulse from the baby rooting at the nipple | - Oxytocin secretion from the posterior pituitary

Question 94

How does oxytocin stimulate cause milk to be released?

Answer 94

Oxytocin squeezes milk into large ducts through smooth muscle fibre stimulation around alveoli

Question 95

What maintains milk production?

Answer 95

- Prolactin secretion | - Effective suckling and emptying of breast milk

Question 96

What is the energy content of breast milk?

Answer 96

67kcal/100ml

Question 97

What are the main constituents of breast milk?

Answer 97

- Fat (54%) - Carbohydrate (40%) - Protein (6%)

Question 98

Describe the protein content of breast milk, and how it differs from cows milk?

Answer 98

- It has a relatively low amount of protein, but with a high whey:casein ratio of 0.7 - It has twice as much lactalbumin as cows milk, but no lactoglobin - There are high levels of amino acids such as taurine, aspartic acid, glutamic acid, and asparagine

Question 99

What is a large amount of the nitrogen in breast milk derived from?

Answer 99

Non-protein sources

Question 100

How does the absorption of fat in breast milk compare to cows milk?

Answer 100

It is better

Question 101

Why is the absorption of fat better in breast milk compared to cows milk?

Answer 101

Due to smaller size of fat globules and lipase content

Question 102

How does the fat content of breast milk compare to cows milk?

Answer 102

- Higher amount of unsaturated fatty acids - Higher amount of vitamins A, C, E, and nicotinic acid - Less of vitamins B and K

Question 103

Is the renal solute load high or low in cows milk?

Answer 103

Low

Question 104

How do the calcium and phosphate levels in breast milk compare to cows milk?

Answer 104

They are lower, but better absorbed

Question 105

What are the maternal contraindications to breastfeeding?

Answer 105

- Severe acute illness, e.g. sepsis - Breast abscess - Chemotherapy - Some mental health drugs, e.g. lithium - Active TB - HIV

Question 106

What are the neonatal contraindications to breastfeeding?

Answer 106

- Metabolic conditions such as galactosaemia, phenylketonuria - Lactose intolerance

Question 107

In what condition might breastfeeding be difficult to establish?

Answer 107

Severe cleft lip/palate

Question 108

What is the alternative option to breastfeeding?

Answer 108

Artificial, or formula feeding

Question 109

What are the key differences between breastfeeding and formula feeding?

Answer 109

- High casein protein content and relatively low whey:casein ratio - Low lactose content - No immunological benefits - Higher calcium, phosphate, and iron content, but less absorption and bioavailability