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Intensive Care > Nutrition in Critical Care > Flashcards

Nutrition in Critical Care Flashcards

1
Q

What are the 3 key principles of nutrition in the ICU

A
  1. Optimize enteral nutrition within 48 hours ICU admission
  2. Avoid forced starvation
  3. Judicious use of supplemental parenteral nutrition
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2
Q

How is nutritional assessment conducted in the ICU

A
  1. Malnutrition Universal Screening Tool (MUST) (not validated for ICU pts)
  2. Nutrition Risk in the Critically Ill (NUTRIC) (not validated for ICU pts)
  3. Clinical assessment
    - pre-ICU weight loss
    - decline of physical performance prior to ICU admission
    - Examine muscle mass/ body composition / strength

Patients admitted to ICU > 48 hrs are considered high risk for malnutrition

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3
Q

What is the aim of nutrition in acute illness

A

Meet energy expenditure (EE) to decrease negative energy balance

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4
Q

How should energy expenditure ideally be determined

A

Indirect calorimetry (IC) using: (BEST)
1. VO2 (PAWC)
2. VCO2 (Ventilator)

Feeding equations (less accurate than above)
1. Harris-Benedict
2. Schofield

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5
Q

How much energy per ml do ‘low energy formulations’ provide

A

<0.9 kcal/ml

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6
Q

How much energy per ml do ‘normal energy formulations’ provide

A

0.9 - 1.2 kcal/ml

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7
Q

How much energy per ml do ‘high energy formulations’ provide?

A

> 1.2 kcal/ml

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8
Q

How much protein do high protein formulations provide

A

These formulas contain 20% or more of total energy from protein.

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9
Q

What are high lipid formulas

A

These formulas contain more than 40% of total energy from lipids

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10
Q

Which patient groups should not receive standard formulation enteral nutrition?

A
  1. Volume restriction - require concentrated enteral nutrition
  2. Renal failure ± volume overload ± electrolyte abN - require electrolye restricted (renal) enteral nutrition formulations
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11
Q

Is routine supplementation with the following indicated:
1. Omega 3
2. Antioxidants
3. Glutamine
4. Ornithine ketoglutarate
5. Arginine
6. Pre-biotics
7. Beta-hydroxy-beta-methylbutyrate (HMB)
8. Immune modulators

A

No

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12
Q

How should enteral feeding be initiated in critically ill patients

A

Start the standard formulation at 10 to 30 ml/hour increasing over six days and increasing more incrementally to the target rate in more severely critically ill patients.

INFREQUENT pausing of enteral nutrition for issues such as
- high gastric residual volumes
- Diarrhoea
- Vomiting

may be required.

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13
Q

When should gastric residual volumes be measured?

A

If the patient exhibits a clinical change e.g.
1. Abdominal pain
2. Abdominal distension
3. Deterioration in haemodynamics/overall status

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14
Q

When should post pyloric feeding be used

A

When gastric feeding is not tolerated or is contraindicated or it may be considered in those with a high risk of aspiration

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15
Q

Classify feeding formulations

A

Concentrated
- requiring volume restriction

Predigested (no compelling evidence for benefit)
(Previously called semi-elemental, elemental)
- Malabsorptive syndromes unresponsive to pancreatic enzyme supplementation
- Persistent diarrhoea with standard feed
- thoracic duct leak (chylothorax/chylous ascites)
- ?? short gut or marginal gut function ??

Critical illness
- Renal formulae for fluid and electrolyte restriction
- Glycaemic control formulae for patients receiving bolus feeding

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16
Q

Describe the nutritional characteristics of typical standard enteral nutrition

A

Isotonic to plasma
1 kcal/ml
Lactose free
Intact protein content 40g / 1000 kcal
Non-protein calorie : Nitrogen ratio is 130

CHO - Mix of simple and complex
Fat - Mainly long chain
Essential vit, minerals, micronutrients

17
Q

What is the theoretical advantage to low CHO/High fat enteral nutrition

A

Lower CHO means less CO2 production –> smaller Ve necessary to control PaCO2 –> reduced weaning time.

18
Q

How does the protein content in the renal enteral nutrition formulation differ from the standard formulation. Discuss.

A

Standard formulation = 40g / 1000 kcal

Renal formulation = 44g /1000 kcal

Historically, low protein enteral nutrition was developed for patients with renal disease because of the widespread belief that protein restriction delays the progression of renal disease.
—-> multiple trials show that patients with renal failure can tolerate protein intake as high as 2.5g / kg /day during critical illness.

19
Q

What are the characteristics of renal enteral feeding formulations

A
  1. Promote fluid and specific electrolyte restriction (K, PO4)
20
Q

Which electrolyte cannot be effectively restricted by any of the enteral feeding formulations

A

Calcium. All enteral formulae exceed calcium removal capacity in patients on haemodialysis

21
Q

When should standard enteral feeding formulations be used in renal patients

A
  1. Normal volume and electrolyte status
  2. Patients on continuous renal replacement therapy

standard feeds preferred.

22
Q

What is a reasonable calorie goal for a patient of normal weight

A

25 kcal/kg/day

23
Q

When should gastric residual volumes be measured

A

Clini

24
Q

Classify the complications of enteral nutrition

A
  1. Aspiration
  2. Diarrhoea ( 15% vs 6 % with non-enteral) - mechanism unknown
  3. Metabolic (hyperglycaemia, micronutrient deficiency and re-feeding syndrome)
  4. Dehydration - minimal water contained in standard formulations
  5. Constipation
25
Q

Define the re-feeding syndrome

A

The typical clinical complications that occur due to fluid and electrolyte shifts during nutritional rehabilitation of significantly malnourished patients.

26
Q

List the most important and common characteristics of the re-feeding syndrome

A
  1. Hypophosphataemia
  2. Hypokalaemia + hypoMg
  3. Volume overload with peripheral oedema
  4. CCF
  5. Rhabdomyolysis
  6. Seizures
  7. Haemolysis
  8. Respiratory insufficiency
27
Q

Describe the pathophysiology of the re-feeding syndrome

A

PO4 depleted (malnourished).
–> Nutritional replenishment –>
insulin release
1. –> cellular uptake PO4 –> reduced serum PO4
2. –> Increased synthesis of ADP/2,3 DPG –> use up PO4
–> subsequent lack of phosphorylated intermediates –> tissue hypoxia, myocardial dysfunction, respiratory failure (diaphragm), haemolysis, rhabdomyolysis, seizures.

28
Q

How much water is in standard enteral feeding formulations

A

20 ml/kg (for formulations containing 25 kcal/kg with 1 kcal/ml)

not enough. Must supplement and monitor volume status

Intensive Care (22 decks)

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