Enteral Nutrition

Enteral Nutrition In
Critically Ill
Rasha S.Bondok
Anaesthesia & Intensive Care
Ain-Shams University
Enteral Nutrition
Enteral nutrition = Administration of
nutrients via the existing GIT
EN is confined to tube feeding
exclusively without regards to oral
nutritional supplement
When is EN indicated in ICU
• All patients with functioning gut who are
not expected to be on a full oral diet within
3 days
Rationale for EN…….
• Favours intestinal villous
• Promotes gut motility
• Reduces translocation of
bacteria from gut
• Less costly than PN
Why feed the critically ill
Metabolic changes occur in
response to starvation, trauma
and sepsis
Starvation & Trauma
Skeletal muscle
Protein breakdown
Amino acids
Glucose Synthesis
Lactate from tissues
Adipose tissue
Glycerol & FFA
Skeletal muscle
Protein breakdown
Amino acids
Glucose Synthesis
Lactate from tissues
Adipose tissue
Glycerol & FFA
Nutritional Assessment as the 1st
step of EN
• Goal :-Detection of prior malnutrition
-Prevent/minimize further loss of BW
1. Patient history
• Disease states associated with heightened
risk of malnutrition
(e. g., chronic debilitating disease)
• Recent severe loss of weight (>5% of usual
body weight in 3 weeks or >10% in 6 months)
Nutritional Assessment……..
-Inadequate nutrition intake results from any of
the following factors:
Orders for nothing by mouth (NPO) x 3 days
Clear liquid diet x 5 days
Malabsorptive disorder
Impaired ability to ingest
Nutritional Assessment……..
2. Assessment of present condition
• Diseases associated with hypermetabolism and
prolonged catabolic activity
(Multiple injuries, Burns, persistent Fever, Sepsis,
• Signs of malnutrition on physical examination
(e. g., cachexia, muscle atrophy, edema)
• Body Mass Index (BW in kg/height in m2)
< 20 kg/m2
Clinical Markers of nutritional
• Clinical Markers of nutritional state:
Widely available, sensitive, easily
reproducible, highly specific
Unfortunately---No such marker is
Clinical Markers of nutritional state
Visceral protein parameters include:
3- Prealbumin.
• Somatic protein parameters include:
• Nitrogen balance studies
Clinical Markers of nutritional state
• Normal level 3.5-5g/dL
• 3-3.5g/dL—nutritional decision point
• < 3.5g/dL--- poor surgical outcome
prolonged ICU stay.
• <3g/dL ---severe malnutrition.
• <2.5g/dL---increased Mortality& Morbidity
• Albumin levels are low ----acute phase response
• Low albumin level is an unreliable marker of
malnutrition in the critically ill.
• ½ life is lengthy 21days ------ can’t effectively
monitor acute response to nutrition therapy
Clinical Markers of nutritional state
• Short ½ life---8-9days
• Normal levels 200-400mg/dL
• Levels 150mg/dL—nutritional decision point
• Factors level:
e.g. Nephritic syndrome, burns, inflammation
chronic infection
Clinical Markers of nutritional state
Short ½ life--- 2 days
Normal level 16-35mg/dL
Nutritionally significant level 11mg/dL
<11mg/dL = Malnutrition
Failure to increase above 11mg/dL –
nutritional needs are not met
• Factors level
e.g. stress, inflammation, surgery, cirrhosis
renal failure.
Nitrogen Balance
• Measures UUN and compares it to nitrogen
intake during that same time
• N2 balance = N2 intake – N2 excretion or =
• [24h protein (g)] – [24 h UUN (g) + 3(g)]
[6.25 g nitrogen]
"fudge factor" of 3 = nitrogen losses in the
faeces, skin, body fluids.
Nitrogen Balance
• If calculated nitrogen balance equals:
0 -- Nitrogen balance.
>0 -- Protein anabolism > catabolism = +ve
nitrogen balance
-- Goal in nutritional repletion is +ve N2 balance
of 4-6 grams per day.
<0 -- Protein catabolism > anabolism = -ve
nitrogen balance
Catabolism: starvation, trauma,
surgery, inadequate nutrition
Nutrition risk index
• Nutrition risk index =
[1.519 x serum albumin (g/l) ]+ [0.417 x
(current weight/usual weight x 100)]
Borderline malnourished
83.5 - 97.5 Mildly malnourished
< 83.5
Severely malnourished
• You are asked to see a 70-year-old man
on his admission to ICU with
oesophageal carcinoma . You note that
his serum albumin level is 22g/l , his
current weight is 58kg. On questioning
he remembers that his usual weight was
69kg when he was well.
• Using the nutrition risk index
how would you categorise
his nutritional state?
• Nutrition risk index =
[1.519 x 22] + [0.417 x {(58/69) x 100}]
Severely malnourished
Contraindications of EN
• Intestinal Obstruction
• Anatomic Disruption.
• Intestinal Ischaemia/Perforation
• Inability to access the gut eg. severe burns
• Shock---reduced intestinal perfusion
Unable to splanchnic blood flow in response to
EN-----be cautious
• Severe diarrhea
• Protracted Vomiting
• Intestinal dysmotility
Are Not
How much EN should critically ill
patient receive?
• During acute initial phase of illness—
exogenous energy 20-25 Kcal/Kg/day
• Excess is detrimental
• During recovery phase ---30-40 Kcal/Kg/day
• Protien intake should be 1.2-1.5 g/Kg/day never
exceeding 1.8 g/Kg/day Except ---extreme
losses: burns, digestive losses
ESPEN Guidelines on Enteral Nutrition:Intensive care Clinical Nutrition (2006)
What length of small bowel
is necessary to maintain
adequate Enteral Nutritional
Is early EN (< 24-48hr) superior to
delayed EN in critical ill?
• Critical ill who are haemodynamically stable +
functioning gut SHOULD be fed early if
• Early EN------Reduction of infection.
------Reduction in hospital stay.
• Early EN 12-24 hours post trauma/burn
– Reduced morbidity
– In 5 studies not 1 case of bowel infarct/ischemia in
early enterally fed
Do Not Feed a Necrotic
Bowel !!
To prevent necrotic bowel
• If EN is not tolerated, TPN is needed,
minimal enteral nutrition = Trophic
< 25% of the calories provided by enteral route :
*stimulate or maintain gut function
*decrease the chances of cholestasis.
• Continuous infusion 10-15 ml/h
• Bolus 6 x 50 ml/24
Access For Enteral Nutrition
• Administration Sites
• Routes For Feeding Access
Administration Site
• Gastric
• Normal reservoir for food
• Formula osmolality is less
of a problem
• Gastric dysfunction
paresis/atony precludes
feeding in the stomach :
 Diabetes
 Drugs (Sympathomimetics,
 Hyperglycemia - ICP
 Surgery & Trauma atony
for 1-2 days but small bowel
motility is normal
• Postpyloric
Sensitive to volume
Rates >100ml/hr are not
Use isotonic formula
Recommended in patients
at risk of aspiration:
Impaired gag cough reflex
Mechanically Vent
Neurological injury
Delayed gastric emptying
Route For Feeding Access
• Short Term access (for 4-6wk)---
Use Nasal Access :naso-gastric/jejunal tubes
• Nasogastric tubes:
Allow use of hypertonic feeds
higher feeding rates
bolus/Intermittent feeding
Fine bore 8-10 F NG tubes
Access Techniques…..cont
Nasojejunal NJ tubes
• Indicated—gastric reflux
--delayed gastric emptying
--unconcious patient
• Fine bore 6-10 F
• Insertion same as NG, but once reached stomach,
patient is turned onto the right side advance tube
• To assist postpyloric placement of NJ tube :
• 10mg Metoclopramide iv 10 min
200mg Erythromycin iv 30min prior placement
Access Techniques…..cont
• Check tube position
Access Techniques…..cont
• Long Term access > 4-6wk----Feeding Ostomies
• Percutaneous Endoscopic Enterostomy
• Surgical Enterostomy
Percutaneous Endoscopic
1- Percutaneous Endoscopic Gastrostomy
PEG: Method of choice
Considered in pat. with normal gastric
Percutaneous Endoscopic Gastrostomy
Gastric cancer
Gastric ulcer
Coagulation disorders
(Source: Kudsk KA, Jacobs DO. Nutrition. In: Surgery: Basic Science and Clinical Medicine.
Norton JA, et al., eds. New York: Springer-Verlag, 2001(2) Part 7, Section 91:136)
Feeding Ostomies (Enterostomies)
Percutaneous Endoscopic Jejunostomy
2- PEJ
• New—
• Technically difficult
• Indicated if postpyloric feeding is needed
• Allows concomittent jejunal feeding and
gastric decompression
Administration of EN
Bolus Feedings
Administer 200-400 ml of
enteral formula into the
stomach over 5 to 20
minutes, usually by gravity
with a large-bore syringe
-Recommended for gastric
-Requires intact gag reflex
-Normal gastric function
Initiation of Bolus Feedings
• Initiate with full strength formula
3-8 times per day with increases of
60-120 ml q 8-12 hours as tolerated
up to goal volume; does not require
dilution unless necessary to meet fluid
ASPEN Nutrition Support Practice Manual, 2005
Continuous Feedings
• Administration into the GIT via pump or
gravity, usually over 8 to 24 hours per day
• Promote tolerance
• Compromised gastric function
• Feeding into small bowel
• Intolerance to other feeding techniques
Initiation of Continuous Feedings
• Initiate at full strength at 10-40 ml/hour
and advance to goal rate in increments
of 10 to 20 mL/hour q 8-12 hours as
• ASPEN Nutrition Support Practice Manual, 2005
Intermittent Feedings
• Administration of 200-300 ml over 30-60
minutes q 4-6 hours
• Intolerance to bolus administration
• Initiation of support without pump
Don’t forget to water your enteral
feeding patients!
• Water in Enteral Products
• Calculate free water:
 1kcal/ml = ~85% free water (850mL
per 1,000 mL formula)
 1.2-1.5 kcal/mL = 69% - 82% (690820)
 1.5-2.0 kcal/mL = 69% - 72% (690720)
 Exact water content on label or in
manufact’s info
• Subtract amount of free water from
• Provide additional water via flushes
Meeting Fluid Needs in EnterallyFed Patients
• Water Flushes
– For Continuous feeds-- Irrigate tube q
4 hrs with 20-60 mL water
– For Intermittent / bolus feed--- Irrigate
tubes before and after each feed with
20-60 mL water
– Use smaller vol for fluid-restricted pts
Enteral Feeding Tolerance
Gastric Residuals
• RV--- routinely checked to assess:
-Tube feeding tolerance and
-Signify aspiration risk
• Take into account flow of normal
secretions from mouth to stomach =
≈ 2–3 L/d or 100–150 mL/hr
• Clinically assess patient for abdominal
distension, fullness, bloating, discomfort
If Gastric Residuals Limit Tube
Feeding Delivery ?
1-Place patient on his right side for 15–20
minutes before checking RV to avoid the
cascade effect
2- Seek transpyloric access of feeding tube
3- Try using a prokinetic agent
4- Switch to a calorically dense product to
decrease total volume needed
5- Tighten glucose control to <200mg% to
avoid gastroparesis from hyperglycemia
6- Use narcotic alternatives
Enteral Nutrition Diets
Enteral Nutrition Diets
1-Polymeric Formula
• Nitrogen source: whole protien
• CHO source: oligosaccharides-starch
• Fat source: vegetable oil.
• Minerals,vitamins,trace elements ---RDA
• A Standardized formulation provides
15-20% Pt, 30-40% Fat, 45-60% CHO
• Require some degree of digestion & absorption
• Isotonic ------ Caloric density 1Kcal/ml
Enteral Nutrition Diets
2-Elemental (Monomeric & Oligomeric Formula)
Chemically defined formulation
• Nitrogen source: di/tripeptides, free a.a
Can be absorbed by active transport without
intraluminal hydrolysis
• CHO source: Oligosaccharides-glucose
• Fat source: Medium Chain Triglycerides,
essential FA
• Indicated --- Limited Digestive Capacity:
intestinal fistula, radiation enteritis, short bowel
Enteral Nutrition Diets
Elemental Formula
• Are Fiber Free
• Due to multiple small particles, it is highly
osmotic 500-900 mOsm/L
• Therefore ---Osmotic diarrhea
• No advantage in using elemental diet in pat
with normal GIT
3-Special Formulas
1-Hepatic Failure Formulas:
Decompensated Cirrhosis/Hepatic encephalopathy
Conc of AAA are and BCAA are .
• This imbalance ---- hepatic encephalopathy by
producing false neurotransmitters
• BCAA-enriched and AAA-deficient nutrition
formula ------- 45%-50% protien (BCAA)
• BCAA inhibit AAA from crossing BBB to
act as false neurotransmitters
2-Renal Failure Formulas:
• CRF----- limited ability to excrete urea and
• Essential AA formula– To use urea for
production of nonessential a.a -----reducing urea
• Hyperammonemia is a risk
• Polymeric Renal formula :low in protein (to limit
urea production) – K – Mg - P
• Indicated for CRF who are not receiving
3-Pulmonary Formulas:
• Metabolism of a calorie of CHO produces
more CO2 than the metabolism of a calorie
of fat
• Low CHO --- CO2 load
• Modified CHO:Fat ratio , 40-55% calories
are provided by fat.
• High fat feeds-----Delayed Gastric Emptying-Abd Distention----affect Diaphragmatic
movement & Thoracic expansion
4-Gastrointestinal dysfunction
• Gut recovery may be accelerated by
supplementation of glutamine and soluble
fiber--a precursor SCFA.
• Glutamine and SCFA are metabolic fuels
of enterocytes and colonocytes
5- Metabolic Stress (Critical Care)
• Provides exogenous source of BCAA----Preferred energy source for muscle during
critical illness
• Not equivalent to Hepatic Failure formula
• High protein & not reduced in AAA content
• Not Given For Hepatic Failure
5-Immunomodulatory (immune
enhancing) Formulas
5-Immunomodulatory (immune
enhancing) Formulas:
• Formulas---- Alter Body’s Response To
Critical Illness
• Modify the inflammatory response
• Enhance resistance to infection & wound
• Alteration include:
Enrichment with specific a.a Glutamine/Arginine
Addition of Nucleotides
Manipulation of FA content (n-6 to n-3 FA ratio)
• Conditionally essential a.a.
• Primary Oxidative fuel for rapidly dividing cells
-----Enterocytes- Lymphocytes- Macrophages
• ++ proliferation of T-cells & formation of ILs
• Precursor of Glutathione—Potent Antioxidant
• A substrate for DNA and RNA synthesis
• Maintains normal intestinal integrity
• Content in polymeric formula < 14% of total
• Optimum Provision is 20-30g/day to meet basal
& GIT requirements in Critical Illness.
• Should be added to standard formula in:
Burned & Trauma Patient Grade A recomend
• Contraindicated in Liver Failure/Encephalopathy
ESPEN guidelines on Enteral nutrition 2007
• Conditionally EAA
• Synthesis occurs --- Intestinal-Renal axis
Epith cells of SI-produce Citrulline from Glutamine
• Plays important role:
-Cell division (improves immune cell no. & func)
-Healing of wounds
-Ammonia detoxification
-Important secretagogue for insulin, glucagon, GH
• Nitric Oxide donor to GI tract
– Necessary for normal immune function
– Helps kills bacteria/parasites
• Nitric Oxide can be detrimental
Mediates VDory effects of endotoxins-----Controversy in cases of Septic Shock!!
What are the major
problems associated with
tube feeding?
1- Aspiration----Most Important
• Prevalence range from 2% - 95%
• Several issues should be considered:
1-Tube Size and Position
Large bore vs small bore
Gastric vs Jejunal
2-Body Position Supine vs Semi recumbent
3-Underlying Disease Gastroparesis/ Atony
4-Feeding Regimen
Intermittent or Continuous vs Bolus
To Limit the Risk of Aspiration
• 1- Raise head of bed 30-40 during
feeding and 1 hr after
• 2-Use intermittent / continuous feeding
regimens rather than------ bolus method
• 3-Check gastric residual regularly
• 4-Consider jejunal access--------recurrent tube feeding aspiration
-high risk of gastric motility dysfunction
2-Diarrhea----Most Common
• Incidence 2.3% - 68%
• Critically ill are more prone
• Multiple aetiologies:
• 1-Medications:
Antibiotics-----overgrowth of C.difficile / Candida
Sorbitol base liquids---Theophylline
Meds containing Magnesium
• 2-Altered bacterial flora
H2-blockers/ PPI---permit bacterial overgrowth
Bacteria colonize---Gastric pH exceeds 4
2-Diarrhea----Most Common
• 3-Formula Composition
Osmolality & Rate
incidence of diarrhea in critically ill
mechanically vent patients----receiving
hyperosmolar feeds at high infusion rates
2-Diarrhea----Most Common
• 4-Hypoalbuminemia
---Reduces osmotic pr & causes intestinal
mucosal oedema
Critically ill with s.Alb < 2.6g/dl
with standard EN
• 5-Formula Contamination
Altered Drug absorption & Metabolism
• Phenytoin
Binds to NG tubing at pH of enteral
formulation----less drug delivery
• Warfarin
Resistance 2ndry to Vit K in Enteral feedings
Stop enteral feeding 2 hrs before and 2
hrs after
Metabolic Complications
• Less frequent compared to TPN
• Hyperglycemia: 2ndry to High CHO load in
specific formula esp critically ill / elderly-------insulin resistance
• Electrolyte imbalance:
Use of high osmolar formulation esp: Pat on
fluid restriction/ renal concentrating
difficulties are at risk of
-----Dehydration & Hypernatremia
Mechanical Complications
 Tube clogging
 First line is to instill warm water using
slight manual pressure.
 If fails, Pancreatic enzyme tablet crushed
with Na HCO3 tablet dissolved in 5ml of
water in order to "digest" the clog

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