Critical care units

1. Critical Care Nutrition
Dr Alfred YF Chan
ICU, PYNEH
23/6/2006

2. Outlines
 Introduction remarks
 Nutritional requirement at baseline
 Metabolic response to stress and
alteration of nutritional requirement
 Pitfalls in critical illness nutrition support
 Special consideration (1) enteral vs. PN
 Special consideration (2) Glutamine

3. Problems in critical care nutrition
 Baseline malnutrition is common
 Poor tolerance to feeding is the rule
 Catabolic state resulting into protein loss
 Poor wound healing, suppress immune
• Feeding-related complication easily seen
 aspiration, VAP, line sepsis, re-feeding
syndrome, under/ overfeeding, LFT
derangement, electrolytes disturbance

4. What a normal person needs
 Energy (measured in kCal)
 CHO: 30-70% of total calories
 Fats: 15-30% of total calories
 Proteins: 1g/kg of body weight
 Minerals: specific need for different metals
 Vitamins
 Water

5.  25-30 kCal per kg weight per day
 Men: 66 + (13.7 × W) + (5 × H) − (6.8 ×
A)
 women: 655 + (9.6 × W) + (1.8 × H) −
(4.7 × A)
 W = body weight in kg
 H = body height in cm
 A = age in years
Harris-Benedict equations (basal
metabolic rate in kcal/day):

6. Amount of energy produced for
different substrates
Substrate Calorie content
kCal Kilo-joules
Protein 4 17
Carbohydrate 4* 17
Fat 9 38
*3.4 kcal if in solution form

7. Minerals
State of catabolism
Normal Mildly
catabolic
Severe
catabolic
Sodium 1-4 mEq 2-3 mEq 3-4 mEq
Potassium 0.7-0.9 mEq 2.0 mEq 3-4 mEq
Calcium 0.22 mEq 0.3 mEq 0.4 mEq
Phosphorous 0.3 mEq 0.8 mEq 1.2-2.0 mEq
Magnesium 0.3 mEq 0.3-0.4 mEq 0.6-0.8 mEq
Minerals requirement: per kg BW per day

8. Starvation vs. stress (injury)
 Starvation: peripheral tissue adapted to
uptake free fatty acids and ketone derivatives
mobilized from adipose tissue. Prognosis
depends on availability of fat.
 Stress: early protein breakdown to amino
acids which are used (1) gluconeogenesis;
(2)TCA cycle substrates. Prognosis depends
on cessation of catabolism.

9. Food intake
Fasting

10. Proteolysis
Negative N balance

12. Metabolic response to stress—
three phases
a) Ebb phase (early phase)
 Immediately after injury
 Decreased oxygen consumption, hypothermia,
lethargy
b) Flow phase (36-48 hours after injury)
 Increased oxygen consumption, hyperthermia,
increased nitrogen excretion and catabolism
 Lasts for days, weeks, or months until healing
c) Recovery phase
 Anabolism to replace loss

13. Metabolic
response
Sequence of events
Sepsis/trauma
Tissue trauma
Septicemia
Cell deaths
local
inflammatory
response
wound healing
recovery
hypermetabolism
muscle wasting
immunosuppression
organ failure
mortality
Death
Malnutrition
New sepsis
Immobility
Ebb
phase
Flow
phase
Anabolic
phase

14. Oxygen
consumption
Time
Stress
Ebb
Flow Recovery

15. Ebb phase
Physiology change Clinical Effect
 blood glucose
 lactate
free fatty acids
 catecholamine
 glucagon
 cardiac output
Below normal
core temperature
 oxygen consumption

16. Flow phase
Physiology change Clinical effects
 catecholamine
 glucagon
 cortisol
 insulin
 cardiac output
 temperature
 aldosterone
 ADH
IL1, IL6, TNF
spillage from
wound
 consumption
of glucose, FFA,
amino acid
 O2 consumption
fluid retention
SIRS
N or  glucose
N or  FFA
normal lactate
 CO2 production
 heat production
multi-organ
failure

18. Physiological outcome in
stress
 Diabetogenic
 Ketogenic
 Proteolytic
 Fluid retention
 Sympathetic hypertonia
 Immunosuppression

19. 70 kg patient in stress
Postoperative 25-30 kcal/kg BW/d 1750-2100 kcal/d
Poly-trauma 30-35 kcal/kg BW/d 2100-2450 kcal/d
Sepsis 25-40 kcal/kg BW/d 1750-2800 kcal/d
Burns 30-45 kcal/kg BW/d 2100-3150 kcal/d
Adjust energy supplement in sick person

20. Adjust protein requirement
1. Normal: 0.8 g/kg body weight
2. Moderate stress: 1.0 to 1.5 g/kg
body weight
3. Severe stress: 1.5 to 2.0 g/kg body
weight

26. TPN preparation—why bother?
All-in-one Multi-chamber

27. Instability of lipid-containing TPN
Creaming Aggregation Coalescence Cracking

28. To improve stability
 Maintain final concentration of nutrients:
1. Amino acids  2.5%
2. Dextrose  3.3%
 pH > 5.0
 Mixing of TPN components (D, AA, Lip)
1. Avoid direct mixing of D and Lip }
2. Add Lip the last step }
Multi-chamber

29. Maximum dextrose infusion
 For a 60 kg patient
 Dextrose infusion should not be
greater than 0.36g/kg/hr
 0.36 x 60 kg x 24 hr
= 518 grams per day
 Excessive dextrose be converted to fat
causing fatty liver and LFT derangment

30.  Estimate daily requirement by
calculating non-protein kcal : N
ratio
1. 150:1  unstressed patient
2. 100:1  severely stressed patients
3. 80:1  most severely stressed
 Non-protein kcal = 3.4 kcal x
Dextrose in g + 1.1 kcal x 10% lipid in
volume
Proteins/ amino acids

31. IV Lipids
 Isotonic and calorically dense, i.e. a good
source of calories for catabolic patients, or
patients with volume/ CHO restrictions
 Can provide  60% of non-protein calories
 Should not exceed 2.5g/kg lipids per day
 4% of total caloric intake should be essential
fatty acids (EFA)
 10% lipid contain 1.1 kcal/ml

32. IV lipids may be risky if
Contraindicated if
1. Abnormal lipid metabolism
2. Lipid nephrosis
3. Severe egg allergies
4. Acute pancreatitis with high TG
Cautious if
1. Chronic liver disease
2. Abnormal coagulation
3. Impaired pulmonary function

33. Medium chain triglycerides
 Theoretically better for sick patients
1. Enter mitochondria independent of
carnitine, i.e. more ready for TCA
cycle
2. More ketones produced  utilized by
peripheral tissue as energy source
 Less proinflammatory

34. IV vitamins supplement
 Supplements added into TPN just prior to
administration to prevent loss from light
 Water-soluble vitamins (Soluvit) are given
with amounts greater than the RDA since
urinary losses increase with IV bolus
 Fat-soluble vitamins (Vitalipid) can
accumulate, and are provided in amounts
equal to the RDA

35. Lactic Acidosis Traced to Thiamine Deficiency Related to
Nationwide Shortage of Multivitamins for Total
Parenteral Nutrition -- United States, 1997
Weekly
June 13, 1997 / 46(23);523-528

37. In comparing TPN with EN
 Myth: TPN is beneficial
 Previous studies have flaws in design
1. Parenteral nutrition was compared with late
enteral nutrition
2. Nasogastric feeding was not based on
logical standardized protocol
3. Glycemic control not mentioned
4. Subgroup benefit: severe malnourished?

38. Meta-analysis comparing EN and PN
ICM 2005; 31:12-23
 Nine studies from 465 publication. Included
studies are RCT for critically ill cases with
meaningful clinical outcomes
 Primary analysis
1. Mortality: OR 0.51 (0.27-0.97) for PN
2. Infections: OR 1.66 (1.09-2.51) for PN
 Subgroup: different timing of EN vs. PN
1. Mortality: OR 1.07, NS for PN vs. early EN
OR 0.29 (p=0.006) vs. late EN
2. Infection: OR 1.47, NS for PN vs. early EN
OR for PN vs. late EN not available

39. Prolonged period of fasting

40. Potential risk of late enteral
feed
 GI tract mucosa morphological change
1. Thinning of mucus covering layer
2. Simplification of microvilli
3. Reduced turnover of surface epithelia
4. Prolonged gut transit time
 Possible net result
1. Relative malabsorption
2. Enhance bacterial +/- toxin translocation

41. Mortality

42. LOS

43. Infection

44. What we are sure about TPN
 More expensive
 More infection
 More demanding in nursing care
 No concrete mortality benefit over the enteral
nutrition
 Last resort in conditions with gut failure
 Infection control strategy
 Faster to reach feeding target

45. Glutamine story
 Muscles: will be released to liver (as Alanine)
and kidney during catabolic state
 Liver: raw material for gluconeogenesis;
important for urea cycle
 Kidney: carrier for ammonia which is vital in
urinary acid excretion
 Intestine: principal ‘food’ for epithelial cells
 White cell: essential for differentiation

47. At molecular level!
 Enhanced heat shock protein expression
 Reduced cellular apoptosis, in particular the
GI epithelial cells
 Attenuation of cytokines release
 Elevated Glutathione level at stress state
 Attenuation of inducible nitric oxide synthase
(iNOs) activation during inflammation

48. What literature said about
glutamine clinical benefit
 May reduce mortality
 May reduce infectious complication
 Route: intravenous route had more abundant
evidence
 Dose: >0.5g/kg weight/ day
 Particular benefit groups: Burns
Trauma
Critical sepsis
 In conjunction with PN?

49. Meta-analysis of glutamine
supplementation in critical illness
 Fourteen randomized studies, excluding
immune-modulating diet studies
 Included trauma, burns, elective post-op,
medical/ surgical ICU cases
 In 751 patients, glutamine associated with RR
0.78 (0.58-1.04) for mortality
 In 326 patients, RR for hospital infections
0.80 (0.64-1.00)
 In 541patients, shorter LOS seen (-2.6 days)

50. Meta-analysis of glutamine
supplementation in critical illness
Subgroups analysis
 Elective OT: no effect on mortality
less infection (RR 0.36)
shorten LOS (-3.54 days)
 ICU: trend to reduce mortality (RR 0.77)
trend to reduce infections (RR 0.86)
no effect on LOS

51. Meta-analysis of glutamine
supplementation in critical illness
 Route: fewer death (RR 0.71) in
parenteral route but not enteral route.
LOS was shortened significantly (-2.8
days) for IV
 Dose: high dose (0.2g /kg/ day) was
associated with fewer deaths (RR 0.71);
fewer infections (RR 0.58) and LOS (-
2.67 days); lower doses had no effect
CCM 2002; 30 (9): 2022-2029

52. Glutamine effect on intestinal
permeability
 Measure by calculation of urinary lactulose:
mannitol ratio after oral ingestion. Increased
ratio for higher GI permeability
 “Protective”: supplementation before or
immediately after OT, trauma or burns can
prevent GI permeability increase
 “Therapeutic”: in established case of raised
permeability, glutamine cannot abolish the
disease
CCM 2005; 33: 1125-1135

54. Effects on burn patient
CCM 2003; 31: 2444-2449
 A prospective randomized double-blind
 Randomized within 24 hours burn, with
surface area at least 20% involved
 Exclude age >65, BSA >80%, CRF, CHF
 Enteral supplement with Glutamine 26g/day
or isonitrogenous mixture
 Positive blood cultures were 3x more common
in control (4.3 Vs. 1.2 days/pat)
 Two death in treatment vs. 12 in control

57. Summary
 In stress, modification of nutritional support
is important
 Be careful about TPN
 Supportive measures required to prevent
complication
 Early feeding if possible
 More evidence to be waited: immune
nutrition, glutamine supplement protocol

58. Thank you for not eating
now