Nutritional Support

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,t 1/2 21), 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/mm 3
Anthropometric measures
> 10 % loss of ‘well’ body weight
Body mass index : weight (kg)/ height 2 (m 2 )
<18 kg/m 2 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

Enteral Formula Categories 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

Enteral Formula Categories Polymeric

Enteral Formula Categories 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

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

Enteral Formula Categories 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

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

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

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

Enteral Formula Categories 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

Disease Specific Formulas 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)

Disease Specific Formulas 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

Disease Specific Formulas 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

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

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 Parenteral Nutrition
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
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 ++ , PO 4 2-
Lipid
Other tests when indicated

Steps to Ordering TPN 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

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 o C rise in temperature

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

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
Caloric Requirements Malnutrition - 30% Peritonitis + 15% Soft tissue trauma + 15% Fracture + 20% Fever (per o c 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%
Caloric Requirements

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?

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

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

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

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)
PO 4 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

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

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
Infectious Complications

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

Mechanical Complications 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 Nutritional Assessment 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

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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Nutritional Support

by Deep Deep on May 09, 2009

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