Full information on Nutrition in ICU patients with different disease and system involvement.

1. NUTRITION IN ICU
Dr. Nisheeth M. Patel
M. D (Medicine), FCCCM
Consultant Physician & Intensivist

2. Introduction:
• Malnutrition is a disorder in body composition in
which inadequate macronutrient (protein,
carbohydrate, and fat) or micronutrient (vitamins,
minerals, and trace elements) intake results in
decreased body mass, reduced organ mass, and most
important, decreased organ function.
• Malnutrition is most frequently associated with a
risk for immune dysfunction-related infection,
wound healing/fascial dehiscence, and breakdown
of surgical anastomoses, it can affect virtually all
organ systems when severe.

3. Effects of Malnutrition
• Skeletal muscle wasting
• Decreased myocardial mass
• Diastolic cardiac dysfunction
• Decreased sensitivity to inotropic agent
• Respiratory insufficiency
• Need for prolonged mechanical ventilation
• Renal cortical atrophy
• loss of gastrointestinal absorptive/barrier
functions.

4. • Malnutrition becomes particularly important in
critically ill patients, in whom the combination
of bed rest and catabolic illnesses
▫ Sepsis
▫ Multiple trauma
▫ Burns, pancreatitis
▫ Acute respiratory distress syndrome (ARDS)
• Hasten the malnutrition, loss of lean body mass,
and organ system dysfunction.

5. Starvation versus Stress Metabolism
• Starvation is a clinical situation that develops
whenever nutrient supply is inadequate to meet
nutrient demand.
• Stress metabolism is a generalized response
whereby energy and substrate are mobilized to
support inflammation, immune function, and
tissue repair. It occurs in response to a variety of
stimuli such as sepsis, multiple trauma, burns,
pancreatitis, bone marrow transplantation, and
major surgery.

6. Characteristic Starvation Hypermetabolism
Energy expenditure Decreased Increased
Respiratory quotient Low (0.7) High (0.85)
Response to feeding +++ +
Mediator activation + +++
Primary fuels Fat Mixed
Gluconeogenesis + +++
Proteolysis + +++
Protein synthesis + ++
Ureagenesis/urinary urea
nitrogen
+ +++
Ketone formation ++++ +

7. Carbohydrate Metabolism in Critical
Illness:
• Carbohydrate metabolism in critical illness is
characterized clinically by hyperglycemia, often
described as being due to “insulin resistance”
based on increased blood glucose levels in the
presence of high circulating levels of insulin.
• Cellular glucose uptake and oxidation in the
critically ill are increased
• Hyperglycemia is associated with increased
glucose production, decreased insulin-mediated
glucose uptake, and increased non–insulin-
mediated glucose uptake.

8. Fat Metabolism in Critical Illness
• Marked increase in lipolytic activity in adipose
tissue as a result of catecholamine-mediated
stimulation of β2-receptors; cytokines may also
participate in this process
• Increased oxidation of fatty acids of all chain lengths
and decreased plasma levels of medium- and long-
chain essential fatty acids relative to the quantities
of oleic acid
• Hypertriglyceridemia is common in critically ill
patients results from the combination of increased
hepatic triglyceride production and decreased
clearance
• Ketonemia is common in starvation, whereas
ketogenesis is decreased in stress metabolism.

9. Protein Metabolism in Critical Illness:
• Protein synthesis is increased in the stressed state
relative to that seen in starvation.
• Protein breakdown is markedly increased in
comparison to the synthetic rate, thereby resulting
in net protein catabolism and a rapid decrease in
lean body mass
• Amino acids mobilized from skeletal muscle are
redistributed to other areas of the body to support
immune function, wound healing, and tissue repair,
as well as for the hepatic synthesis of acute-phase
proteins, presumably in an attempt to enhance
survival.

10. Indications for Nutrition Support
• Nutrition support should be considered once
hemorrhage has been controlled, devitalized tissue
débrided, fractures stabilized, and the patient
resuscitated from shock.
• There are suggestions in the literature that early
enteral feeding, within 24 to 72 hours of admission,
may help decrease post burn and post injury hyper
metabolism and reduce infectious complications.
• Initiated in any patient who is malnourished on
admission to the intensive care unit (ICU), for any
patient who is likely to become malnourished during
a long and complicated ICU stay, and for any patient
who has not eaten for 5 to 7 days.

11. Goals of Nutrition Support
• The goals of nutrition support in a critically ill
patient are to minimize the effects of starvation to
provide appropriate doses of macronutrients and
micronutrients, to minimize complications of
nutrition support, and to improve outcomes.
• To provide sufficient calories to meet the energy
requirements of the hyper metabolic state while
avoiding the complications associated with
overfeeding.
• Provide sufficient protein to attain nitrogen balance
or minimize the nitrogen deficit, provide electrolytes
to maintain normal levels while taking into account
excessive losses or impaired excretion, and provide
appropriate vitamins and trace elements with
consideration of disease-specific requirements.

12. BEE, basal energy expenditure; IDC, indirect calorimetry; RDA, recommended
dietary allowance; REE, resting energy expenditure.
Nutrient General Recommendation
Total calories
25-30 kcal/kg/day
OR
BEE × 1.2-2.0
OR
REE by IDC
Glucose
5 g/kg/day
OR
20 kcal/kg/day
OR
60-70% of calories
Fat
15-40% of calories
OR
Less than 1 g/kg/day
Amino acids or protein 1.2-2.0 g/kg/day
Trace elements and vitamins RDA
Electrolytes Maintain normal levels

13. Route and Timing of Administration
• Nutrition support can be delivered
▫ Enterally (via the gastrointestinal tract)
▫ Parenterally (via the intravenous route)

14. Total Parental Nutrition
Advantages Disadvantages
• Does not require an intact or
functioning gastrointestinal
tract
• Convenient to use
• Prescribed nutrients will be
administered
• These nutrients will appear in
the bloodstream.
• Cost
• Procedure (central venous
catheter)-related
complications
• Increased likelihood of
metabolic complications,
including hyperglycemia
• Increased risk of infectious
complications.

15. Enteral Nutrition:
Advantages Disadvantages
• Less expensive
• More physiologic
• Less metabolic complications
such as electrolyte
abnormalities and
hyperglycemia
• Stimulates gut function
• Preserves mucosal integrity
and barrier function
• Requirement for an intact and
functioning gastrointestinal
tract
• Procedure (feeding tube
placement)-related
complications
• Pulmonary aspiration
• Malabsorption
• Feeding intolerance (pain,
vomiting, bloating, diarrhea)
• Inability to deliver the entire
nutrient prescription.

16. • Less costly and associated with fewer metabolic
complications and a lower incidence of infection,
the enteral route continues to be the
recommended route for nutrition support.
• Some percentage of critically ill patients, enteral
nutrition is either contraindicated or not
tolerated, and parental nutrition remains a
viable option
• In TPN overfeeding should be avoided and
hyperglycemia should be controlled.

17. Timing for Initiating feeding
• Enteral nutrition started early (within 24 to 72
hours of admission ) is associated with less gut
permeability, release of inflammatory cytokines, and
reduced systemic endotoxemia.
• In patients who are hemodynamically stable, it is
recommended that enteral nutrition be started
within 48 hours of admission
• In a recent RCT, it had been observed that Early
parenteral nutrition, even when used to supplement
enteral nutrition, may be harmful and should be
avoided unless the patient is chronically
malnourished.

18. Types of nutrition formulas
• Parenteral nutrition is most commonly
administered as a three-in-one solution of dextrose,
lipid, and amino acids.
• TPN order forms typically allow the physician to
order “standard” or custom solutions, fluid-
restricted solutions, and in some cases, disease-
specific solutions such as renal failure or hepatic
failure solutions.
• Enteral formulas are usually premixed with a fixed
nonprotein calorie-to-nitrogen ratio, and the needs
of a specific patient are generally met by changing
the formula.
• Protein and carbohydrate supplements can be added
at the bedside to alter premixed formulas.

19. • High-protein formulas contain more than 45 g
protein per 1000 kcal and are designed for
patients with increased protein needs, such as
patients with catabolic illness.
• Calorie-dense formulas are designed for patients
in whom fluid restriction is required. They are
generally relatively low in protein and not ideal
for a stressed patient.

20. Organ-Specific Enteral Formulas
• Pulmonary failure formulas:
• acute respiratory failure associated with chronic
lung disease.
• At least 50% of calories as fat:
▫ Reduce CO2 production
▫ Decrease the work of breathing relative to high-
carbohydrate formulas.
• Avoiding overfeeding is more important in
reducing ventilatory demand.

21. Hepatic failure formulas
• Contain high concentrations of branched-chain
amino acids and reduced concentrations of
aromatic amino acids.
• Although these solutions have been shown to
correct the abnormal amino acid profile
characteristic of patients with liver failure.
• Hepatic failure formulas should be reserved for
the rare encephalopathic patient who is
refractory to lactulose and luminal antibiotics.

22. Renal Failure Formulas
• Renal failure formulas have reduced
concentrations of electrolytes and decreased
protein content to minimize nitrogenous waste
in patients with renal failure.
• Patients with acute renal failure frequently have
associated catabolic illness and as a result need
more protein rather than less.
• Although these formulas may be useful in
patients with electrolyte abnormalities not yet
being dialyzed.
• Inappropriate for patients with catabolic illness
who are undergoing dialysis and particularly
CRRT.

23. • Immunomodulating enteral formulas are
supplemented with various combinations of specific
nutrients, arginine, ω-3 polyunsaturated fatty acids,
nucleotides, glutamine, and antioxidants aimed at
improving immune function and reducing
inflammation in critically ill patients.
• Guidelines for the PANST in the Adult Critically Ill
Patient, published jointly by the SSCCM and ASPEN
recommend the use of an immunomodulating
enteral formula supplemented with fish oil and
antioxidants for patients with acute lung
injury/ARDS.
• Further, these guidelines recommend enteral
formulas supplemented with arginine for patients
with major surgery, burns, and trauma, but
emphasize that such formulas may be harmful in
severe sepsis.

24. Nutrition Assessment
• Anthropometric measurements such as triceps
skinfold thickness (SFT), midarm circumference
(MAC), and arm muscle area, which is derived from
SFT and MAC, can be used to estimate fat mass and
lean body mass.
• These measurements are not practical for
nutritional monitoring in a recumbent, critically ill
patient.
• Visceral protein levels have long been used in
nutritional assessment and monitoring and can be
useful in the appropriate clinical setting.

25. • Albumin, Transferrin, retinol binding protein,
transthyretin can be used for assessment for
nutritional status.
• However, visceral protein levels are affected by a
variety of non-nutritional factors, they are not
recommended for the monitoring of nutritional
status in critically ill patients.
• Nitrogen balance is the nutritional parameter
most consistently associated with improved
outcomes, and nitrogen balance studies are used
routinely to monitor nutrition support. Ideally,
positive nitrogen balance is the goal.

26. • Numerous techniques for assessment and
monitoring of energy balance
▫ Continuous whole-body calorimetry
▫ Doubly labeled water technique
▫ Nuclear magnetic resonance spectroscopy
using 31P
• No method is ideal.
• Though potentially useful, these methods are
either cumbersome, expensive, or impractical for
use in critically ill patients.
• Overall, assessing the nutrition in critically ill
patients is challenging and for accurate
methods, trials are still going on.

27. Complications of Enteral Nutrition
Support
• Mechanical and technical complications of
enteral nutrition include:
▫ Feeding tube misplacement
▫ Gastrointestinal perforation
▫ Sinusitis
▫ Otitis media
▫ Ulceration of the nasal septum
▫ Obstruction of the feeding tube

28. • Aspiration pneumonia is the major infectious
complication of enteral nutrition.
• Bolus feeding carries a higher risk of aspiration
than continuous feeding does.
• Gastrointestinal complications:
▫ Abdominal distention
▫ Nausea
▫ Vomiting
▫ Diarrhea
▫ Constipation

29. Complications of Parenteral Nutrition
Support
• Mechanical and technical complications are related
to central venous catheter placement and include
pneumothorax, arterial injury, hemothorax,
hydrothorax, cardiac arrhythmia, and cardiac
perforation with tamponade.
• Catheter infection and catheter-associated
bloodstream infection are the major infectious
complications of parenteral nutrition.
• Most common infecting organisms are coagulase-
negative staphylococci, Staphylococcus aureus,
and Candida species

30. Metabolic Complications
• Common metabolic complications of nutrition
support include
▫ Hyperglycemia
▫ Hepatobiliary complications
▫ Disturbances in water and electrolyte balance
▫ Acid-base abnormalities.
• Though more common in patients receiving
parenteral nutrition, metabolic complications
can occur with either form of nutrition support.

31. Hyperglycemia
• Frequently in critically ill patients receiving
nutrition support
• Most common in diabetic patients and those with
catabolic illness.
• Complications related to hyperglycemia include:
▫ Infection
▫ Hyperosmolarity
▫ Osmotic diuresis.
• The first step in the control of blood sugar is
avoidance of overfeeding
• Currently, most practitioners aim for blood glucose
levels below 150 to 180 mg/dL.

32. Hepatobiliary complications
• Hepatic steatosis (Intrahepatic and extrahepatic
cholestasis)
• Hepatic steatosis may develop after 7 to 21 days of
parenteral nutrition and is characterized initially by
elevated transaminases.
• Usually asymptomatic, fatty infiltration can, in severe
cases, be accompanied by hepatomegaly and right upper
quadrant abdominal pain.
• Cholestasis occurs later in the course of parenteral
nutrition and is characterized by elevations in bilirubin
and alkaline phosphatase.
• Cholelithiasis has been linked to long-term TPN use.
• Management of hepatobiliary complications is aimed at
prevention. Overfeeding should be avoided.

33. Electrolyte disturbance & Acid Base
disorder
• Hypernatremia or hyponatremia can be managed by
increasing or decreasing free water.
• Refeeding syndrome, serum levels of these
intracellular electrolytes fall precipitously, with
hypophosphatemia resulting in hemolysis,
rhabdomyolysis, and heart failure with hypokalemia and
hypomagnesemia leading to cardiac arrhythmias.
• Serum levels of intracellular electrolytes should be
corrected before and, in particular, 24 hours after the
institution of nutrition support.
• Hyperkalemia and hypomagnesemia may lead to
weakness and cardiac arrhythmia

34. • Hyperphosphatemia may result in hypotension,
hypocalcemia, and metastatic calcification.
• Hyperphosphatemia is often treated with oral
phosphate binders such as calcium carbonate.
• Metabolic acidosis related to nutrition support is
most commonly due to excess chloride
administration and resultant renal bicarbonate
losses.
• Also occur as a result of thiamine deficiency with
resultant lactic acidosis.

35. Thank
you