vdocument.in_nutritional-support-55849fd534680.ppt

2022/10/5 Nutrition in Critical illness 1
Nutritional Support in Critical
illness
Tianjin Medical University General Hospital
Emergency Center
Shou songtao

 Nutritional support is the provision of
nutrients to patients who cannot meet
their nutritional requirements by eating
standard diets.
Definition

‘A slender and restricted diet is always dangerous
in chronic and in acute diseases’
Hippocrates 400 B.C.

 Malnutrition occurs in approx.40% of
hospitalized patients
 Can lead to increased morbidity and
mortality
 Impairment of skeletal, cardiac, respiratory
muscle function
 Impairment of immune function
 Atrophy of GIT
 Impaired healing

 1970s: TPN - separate CH, AAs and Lipids
 2500-3000kcals/day: Lactic acidosis, high glucose
loads, fatty livers, high insulin
 Single lumen C/Lines, no pumps
 Urinary urea measured, N calculated
 1980s: Scientific studies of metabolism:
recognition of overfeeding
 1990s: nitrogen limitation: 0.2g/kg/24hr, start
of immunonutrition trials
 2000s: glucose control, specific nutrients

ICU Nutrition through the ages
Overfeeding
1980s

 4 basic questions to be answered:
 Who?
 When?
 How much?
 How?

Organisation of Nutrition Support
3. NICE Guidelines for Nutrition Support in Adults 2006
Screen
Recognise
Treat
Oral Enteral Parenteral
Monitor & Review

Screen
 Various nutritional screening tools
• Low risk: routine clinical care
• Medium risk: observe
• High risk: treat- refer to dietitian/local protocols

Screening in ICU
 Almost all patients require artificial nutrition-
cannot ‘observe’
 Needs adaptation using NICE Guidelines
 Adapted MUST for ICU: Uses BMI/weight
loss/food intake + refeeding risk assessment;
linked to feeding flowchart

Nutritional Assessment
 History – 10% weight loss or more suggests protein
malnutrition
 Exam – Weight/Ideal body weight (<85% predicted),
temporal muscle wasting, anthropometrics
 Nutritional markers
-daily weight – more a measure of fluid status than nutritional status
-24 hour urine urea nitrogen (cannot be used in renal failure)
-albumin (<30mg/dl,t1/221), prealbumin(<12mg/dl, 2), transferrin(<150mmol/L, 7)
-albumin influenced by fluid status, acute phase response

 Immune function – skin testing, anergy,total
lymphocyte count<1800/mm3
 Anthropometric measures
 > 10 % loss of ‘well’ body weight
 Body mass index : weight (kg)/ height 2 (m2)
 <18 kg/m2 assoc. With prolonged ICU, increased post-
operative complications, higher readmission rates
 Mid-arm circumference, skin fold thickness
 Poor accuracy, specificity, reproducibility

Nutritional assessment
 Serum proteins
 Albumin
 Reflects synthesis, degradation, losses, exchange
between intracellular and extracellular compartments
 Half life 21 days – limited ability to reflect acute
changes
 < 3.5 g/dL assoc. increased morbidity

 Serum proteins
 Transferrin (1/2 life 7 days), Pre-albumin (1/2
life 2 days)
 More accurately reflect acute changes
 Limited by erratic responses to stress, sepsis,
cancer

 Nitrogen balance
= N intake – N loss
= (dietary protein x 0.16) – (urea nitrogen (urine) + 4
g (stool/skin) )
 Positive balance indicates anabolic state
 Negative balance indicates catabolic state
 Aim to provide non-protein sources of fuel to
allow protein to be used for anabolic processes

How much to give in ICU?
 Schofield equation/Harris Benedict
e.g. for 65 year old woman: BMR = (9.2x weight in
kg) + 687, = requirement in Kcal/24hr
 Add Activity and Stress factors e.g. 10% for
bedbound + 20-60% for sepsis/burns
 For 65kg ventilated woman with sepsis: 1670 Kcal
= approx 25 Kcal/kg/d
 No dietitian? Rough guide: 25 Kcal/kg/day total
energy. Increase to 30 as patient improves

How much to give?
 0.2g/Kg/day of Nitrogen (1.25g/kg/day protein)
 30 – 35ml fluid/kg/24 hours baseline
 Add 2-2.5ml/kg/day of fluid for each degree of
temperature
 Account for excess fluid losses
 Adequate electrolytes, micronutrients, vitamins
 Avoid overfeeding
 Obesity: feed to BMR, add stress factor only if
severe i.e. burns/trauma

Types of nutrition support
 Routes of nutrition support
 Enteral nutrition
 Parenteral nutrition

Enteral nutrition
 In general, the preferred method of choice

Enteral Nutrition
 Nutrition delivered via the gut
 Includes oral feedings and tube feedings

Indications for Enteral Nutrition
 Malnourished patient expected to be
unable to eat >5-7 days
 Normally nourished patient expected to be
unable to eat >7-9 days
 Adaptive phase of short bowel syndrome
 Increased needs that cannot be met
through oral intake (burns, trauma)
 Inadequate oral intake resulting in
deterioration of nutritional status or delayed
recovery from illness
ASPEN. The science and practice of nutrition
support. A case-Based Core curriculum. 2001; 143

Contraindications for EN
 Severe acute pancreatitis
 High output proximal fistula
 Inability to gain access
 Intractable vomiting or diarrhea
 Aggressive therapy not warranted
ASPEN. The science and practice of nutrition support. A case-based core curriculum. 2001; 143

Contraindications for EN
 Inadequate resuscitation or hypotension;
hemodynamic instability
 Ileus
 Intestinal obstruction
 Severe G.I. Bleed
 Expected need less than 5-7 days if
malnourished or 7-9 days if normally
nourished

 Long-term nutrition
• Gastrostomy
• Jejunostomy
 Short-term nutrition
• Nasogastric feeding
• Nasoduodenal feeding
• Nasojejunal feeding
Enteral nutrition

Diagram of enteral tube placement.

With/without endoscopic
Long time
with endoscopic operation
Gastric tube duodenal tube
gastrostomy Gastrostomy
Duodenum
feeding
Jejunostomy
feeding
Decision of Selecting The Modes
of Administration
Enteral Nutrition
Short time
Tube Percutaneous tube

Enteral Formulas
 Liquid diets intended for oral use or for
tube feeding
 Ready-to-use or powdered form
 Designed to meet variety of medical
and nutrition needs
 Can be used alone or given with foods

Formula Selection
The suitability of a feeding formula should be evaluated based on
 Functional status of GI tract
 Digestion and absorption capability of patient
 Physical characteristics of formula (osmolality, fiber content,
caloric density, viscosity)
 Macronutrient ratios
 Specific metabolic needs
 Contribution of the feeding to fluid and electrolyte needs or
restriction
 Cost effectiveness

Enteral Formulas
 Determine best choice by medical and
nutrition assessment
 Meet specific nutrition needs

Enteral Formula Categories
 Polymeric
 Monomeric
 Fiber-containing
 Disease-specific
 Rehydration
 Modular

Polymeric
 Whole protein nitrogen source
 For use in patients with normal or near
normal GI function
 Protein isolate formulas
 Protein that has been separated from a food
(casein from milk, albumin from egg)
 Blenderized formulas
 May contain pureed meat, vegetables, fruits,
milk, starches with v/m added
 Made at home or purchased commercially

Polymeric

Monomeric
 Elemental/hydrolyzed
 Predigested nutrients
 Free amino acids and/or short peptide
chains
 Has low fat content or high percentage
of MCT, LCT, structured lipids

Monomeric

Monomeric
 Use in patients with compromised
digestive and/or absorptive capacity
 More expensive than standard formulas
 Tend to be more hyperosmolar because
of small particle size

Fiber-Containing
 Fiber-containing: containing a source of
fiber; reportedly beneficial for
prevention/treatment of altered bowel
function in enterally fed patients
 Soy polysaccharide is the most
common fiber additive in enteral
feedings
ASPEN. The science and practice of nutrition support. A case-
based core curriculum. 2001; 148

Fiber-Containing
 Soluble fiber (guar gum, oat fiber, pectin)
may exert trophic effect on colonic mucosa
and be useful in normalizing bowel function
 Patients with impaired gastric emptying
should not be fed fiber-containing formula
into the stomach
ASPEN. The science and practice of nutrition support.
A case-based core curriculum. 2001; 148

Fiber-Containing

Enteral Formulas: Calorie Dense
 May be used in fluid-restricted or
volume-sensitive patients
 Calorie density ranges from 1.3 to 2
kcals/ml
 Monitor fluid/hydration status

Enteral Formulas: Calorie Dense

Disease Specific
 Designed for patients with specific disease
states.
 Available for patients with respiratory
disease, ARDS, diabetes, renal failure,
hepatic failure, and immune compromise.

Disease Specific

Disease Specific Formulas
Diabetic
 Amount and type of CHO modified to reduce
blood glucose response
 Increased fat content (may have increased
monounsaturated fats)
 May be worth trying diabetes formulas in
patients who have failed to achieve good
blood glucose control on standard formulas

Disease Specific Formulas: Diabetic

Hepatic
 Generally have reduced aromatic amino
acids and increased branched chain amino
acids
 More expensive than standard products
 Often lower in protein than standard formulas
(may be too low for most liver patients)

Renal
 Typically are calorie dense (2.0 kcal/cc)
products with relatively low protein levels and
modified electrolytes
 Generally too low in protein for dialyzed
patients and acutely ill patients
 May be useful for short term use as
supplement or calorie source in pre-dialysis
chronic renal failure patients

Disease-Specific Formulas Renal
Novasource Renal

Immune-Enhancing
 Have added “immune-enhancing”
nutrients (arginine, glutamine, omega-3
fatty acids, nucleotides)
 Meta-analysis suggests that they might
be most beneficial in surgical patients

Immune-Enhancing Formulas

Disease-Specific Formula Pulmonary
 Contain higher percentage of total calories
from fat to reduce respiratory quotient and
make it easier to wean from respirator
 High fat gastric feedings may cause delayed
emptying in critically ill patients

Disease-Specific Formulas: Pulmonary

Enteral Formula Nutrient Sources
Carbohydrate
 CHO content ranges from 40-90% of total
calories
 Fiber: soy polysaccharide (most common)
guar gum, oat fiber, pectin

Enteral Formula Nutrient Sources
Lipids
 Fat provides isotonic, concentrated energy
source
 Corn and soybean oil common
 May include MCTs; more easily digested and
absorbed
 Fat content ranges from <10% to >50% of
calories
ASPEN. The science and practice of nutrition support. A case-
based core curriculum. 2001; 148

Enteral Formulas Nutrient Sources
Protein
 Whole protein, hydrolyzed protein, free
amino acids
 Casein, soy protein, lactalbumin, whey, egg
white albumin
 Small peptides absorbed as efficiently as
free amino acids
 Free amino acids are more hyperosmolar

Initiation of Feeds
 Approaches
 Bolus vs continuous feeds
 Full feeds vs graded regimens

Assessment of Clinical Response
 Anthropometric measurements
 Feeding tolerance

Enteral nutrition
 Complications
 Gastrointestinal
 Mechanical
 Metabolic
 Formula related

GI Complications
 Vomiting
 Diarrhea
 Constipation
 Abdominal pain / bloating
 Gastric irritation
 Aspiration

Mechanical Complications
 Tube occlusion
 Nasopharyngeal effects
 Tube fractures
 Leakage
 Obstruction
 Irritation

Metabolic Complications
 Hypovolemia
 Hyperkalemia
 Hypophosphatemia
 Hypertonic dehydration
 Fluid overload

Formula Complications
 Incompatibility with medications
 Hyperosmolality
 Contamination

Application Criterion of EN
“When the gut works, and can
be used safely, use it ”

Parenteral Nutrition

Allows greater caloric intake
BUT
 Is more expensive
 Has more complications
 Needs more technical expertise

Who Will Benefit From
Parenteral Nutrition?
Patients with/who
 Abnormal gut function
 Cannot consume adequate amounts of
nutrients by enteral feeding

Two Main Forms of
 Peripheral Parenteral Nutrition
 Central (Total) Parenteral Nutrition
Both differ in
 composition of feed
 primary caloric source
 potential complications
 method of administration

Peripheral Parenteral Nutrition
Given through peripheral vein
 Short term use
 Mildly stressed patients
 Low caloric requirements
 Contraindications to central TPN

What to Do Before Starting TPN
 Nutritional Assessment
 Venous access evaluation
 Baseline weight
 Baseline lab investigations

Venous Access for TPN
Need venous access to a “large” central
line
with fast flow to avoid thrombophlebitis
Superior
Vena Cava
• Subclavian approach
• Internal jugular approach
• External jugular approach

Baseline Lab Investigations
 Full blood count
 Coagulation screen
 Ca++, Mg++, PO4
2-
 Lipid
 Other tests when indicated

Decide how much fat &
carbohydrate to give
Determine Total Fluid Volume
Determine Non-N Caloric needs
Determine Protein requirements
Determine Electrolyte and Trace
element requirements
Determine need for additives
Steps to Ordering TPN

How Much Volume to Give?
 Cater for maintenance & on going
losses
 Normal maintenance requirements
 By body weight
 alternatively, 30 to 50 ml/kg/day
 Add on going losses based on I/O chart
 Consider insensible fluid losses also
e.g. add 10% for every oC rise in temperature

Determine Caloric needs

Caloric Requirements
Based on Total Energy Expenditure
 Can be estimated using predictive equations
TEE = REE + Stress Factor + Activity Factor
 Can be measured using metabolic cart

Stress Factor
Malnutrition - 30%
Peritonitis + 15%
Soft tissue trauma + 15%
Fracture + 20%
Fever (per oc rise) + 13%
Moderate infection + 20%
Severe infection + 40%
<20% BSA burns + 50%
20-40% BSA burns + 80%
>40% BSA burns + 100%

Activity Factor
 Bed-bound + 20%
 Ambulant + 30%
 Active + 50%

How Much CHO & Fats?
“Too much of a good thing causes problems”
 Not more than 4 mg / kg / min Dextrose
(less than 6 g / kg / day)
 Not more than 0.7 mg / kg / min Lipid
(less than 1 g / kg / day)

 Fats usually form 25 to 30% of calories
 Not more than 40 to 50%
 Increase usually in severe stress
 Aim for serum TG levels < 350 mg/dl or
3.95 mmol/L
 CHO usually form 70-75 % of calories
How Much CHO & Fats?

Determine Caloric needs

How Much Protein to Give?
 Based on calorie : nitrogen ratio
 Based on degree of stress &
body weight
 Based on Nitrogen Balance

Calorie : Nitrogen Ratio
Normal ratio is
150 cal : 1g Nitrogen
Critically ill patients
85 to 100 cal : 1 g Nitrogen in

Based on Stress & BW
Non-stress patients 0.8 g / kg / day
Mild stress 1.0 to 1.2 g / kg / day
Moderate stress 1.3 to 1.75 g / kg / day
Severe stress 2 to 2.5 g / kg / day

Based on Nitrogen Balance
Aim for positive balance of
1.5 to 2g / kg / day

Determine Electrolyte and
Trace element requirements

Electrolyte Requirements
Cater for maintenance + replacement needs
Na+ 1 to 2 mmol/kg/d (or 60-120 meq/d)
K+ 0.5 to 1 mmol/kg/d (or 30 - 60 meq/d)
Mg++ 0.35 to 0.45 meq/kg/d (or 10 to 20 meq /d)
Ca++ 0.2 to 0.3 meq/kg/d (or 10 to 15 meq/d)
PO4
2- 20 to 30 mmol/d

Trace Elements
Total requirements not well established
Commercial preparations exist to provide RDA
Zn 2-4 mg/day
Cr 10-15 ug/day
Cu 0.3 to 0.5 mg/day
Mn 0.4 to 0.8 mg/day

Other Additives
Vitamins
 Give that recommended for oral intake
 1 ampoule MultiVit per bag of TPN
 MultiVit does not include Vit K
 can give 1 mg/day or 5-10 mg/wk

Other Additives
Medications
Insulin
 0.1 u per g dextrose in TPN
 10 u per litre TPN initial dose
Other medications

TPN Monitoring
Clinical Review
Lab investigations
Adjust TPN order accordingly

Clinical Review
 Clinical examination
 Vital signs
 Fluid balance
 Catheter care
 Sepsis review
 Blood sugar profile
 Body weight

Lab investigations
 Full Blood Count
 Renal Panel # 1
 Ca++, Mg++, PO42-
 Liver Function Test
 Iron Panel
 Lipid Panel
 Nitrogen Balance
 weekly, unless indicated
 daily until stable, then 2x/wk
 daily until stable, then 2x/wk
 weekly
 weekly
 1-2x/wk
 weekly

Complications Related to TPN
 Mechanical Complications
 Metabolic Complications
 Infectious Complications

Related to vascular access technique
• pneumothorax
• air embolism
• arterial injury
• bleeding
• brachial plexus injury
• catheter malplacement
• catheter embolism
• thoracic duct injury

Venous thrombosis
Catheter occlusion
Related to catheter in situ

Abnormalities related to excessive
or inadequate administration
 hyper / hypoglycaemia
 electrolyte abnormalities
 acid-base disorders
 hyperlipidaemia

Hepatic complications
 Biochemical abnormalities
 Cholestatic jaundice
 too much calories (carbohydrate intake)
 too much fat
 Acalculous cholecystitis

Infectious Complications
 Insertion site contamination
 Catheter contamination
 improper insertion technique
 use of catheter for non-feeding purposes
 contaminated TPN solution
 contaminated tubing
 Secondary contamination
 septicaemia

Stopping TPN
 Stop TPN when enteral feeding can
restart
 Wean slowly to avoid hypoglycaemia
 Monitor during wean
 Give IV Dextrose 10% solution at previous
infusion rate for at least 4 to 6h
 Alternatively, wean TPN while introducing
enteral feeding and stop when enteral intake
meets TEE

Approach to Nutritional Support
Maintenance Repletion
GI Tract Functional
YES NO
Enteral Nutrition Parenteral Nutrition

Advantages - Enteral vs PN
 Preserves gut integrity
 Possibly decreases bacterial translocation
 Preserves immunological function of gut
 Reduces costs
 Fewer infectious complications in critically ill
patients
 Safer and more cost effective in many
settings
ASPEN. The science and practice of nutrition support. A case-based core curriculum. 2001;
147
ADA EAL, Critical Illness, accessed 8-07

Single nutrient supplementation
 L-glutamine
 Used in purine, pyrimidine, lymphocyte and macrophage
function, gut integrity and gut barrier function
 If given, reduces nitrogen loss
 Reduced length of stay, following colorectal surgery in elective
setting
 Other studies shown reduced risk of pneumonia, bacteraemia,
sepsis following major trauma
 ? Role in short gut syndrome – improving GI absorbtion

Single nutrient supplementation
 Essential fatty acids
 Variety of functions, key role in maintaining membrane
structure and function
 Alter immune function (n-3 FA suppress immune function)
 Preliminary studies using n-3 FA in inflammatory bowel disease
showed improvement in histological appearance, reduction in
disease activity, decreased steroid requirement

Importants:
 Definition of nutritional support
 Routs of nutritional support
 Advantages of EN
 Common complications of TPN

Nutrition in Critical illness 114
2022/10/5
Maintains Stimulates
the environment defences
FEEDING
Provides energy

Thank you !!

Essential Nonessential
Arginine Alanine
Histidine Asparagine
Isoleucine Aspartate
Leucine Cysteine
Lysine Glutamate
Methionine Glutamine
Phenylalanine Glycine
Threonine Proline
Tryptophan Serine
Valine Tyrosine

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