Nutritional Support

23/4/12 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

Overfeeding1980s


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 NutritionEnteral Nutrition

Nutrition delivered via the gut Includes oral feedings and tube feedings

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

Jejunostomyfeeding

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 SelectionThe 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

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 CategoriesPolymeric

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 CategoriesPolymeric


Enteral Formula CategoriesMonomeric

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 CategoriesFiber-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 CategoriesDisease 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 CategoriesDisease Specific


Disease Specific FormulasDiabetic

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 FormulasHepatic

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 FormulasRenal 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 FormulasImmune-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 SourcesCarbohydrate CHO content ranges from 40-90% of total

calories Fiber: soy polysaccharide (most common)

guar gum, oat fiber, pectin


Enteral Formula Nutrient SourcesLipids 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 SourcesProtein 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 NutritionAllows 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

SuperiorSuperiorVena CavaVena Cava

• Subclavian approachSubclavian approach

• Internal jugular approachInternal jugular approach

• External jugular approachExternal jugular approach



Baseline Lab Investigations

Full blood count Coagulation screen Ca++, Mg++, PO4

2-

Lipid Other tests when indicated


Decide how much fat & Decide how much fat & carbohydrate to givecarbohydrate to give

Determine Total Fluid VolumeDetermine Total Fluid Volume

Determine Non-N Caloric needsDetermine Non-N Caloric needs

Determine Protein requirementsDetermine Protein requirements

Determine Electrolyte and Trace Determine Electrolyte and Trace element requirementselement requirements

Determine need for additivesDetermine 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 needsDetermine 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 needsDetermine 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 Determine Electrolyte and Trace element requirementsTrace 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)

PO42- 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

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


weekly

weekly

1-2x/wk

weekly

weekly, unless indicated



weekly

weekly

1-2x/wk

weekly


Complications Related to TPN


Metabolic Complications

Infectious Complications


Mechanical ComplicationsRelated to vascular access technique

• pneumothoraxpneumothorax

• air embolismair embolism

• arterial injuryarterial injury

• bleedingbleeding

• brachial plexus injurybrachial plexus injury

• catheter malplacementcatheter malplacement

• catheter embolismcatheter embolism

• thoracic duct injurythoracic duct injury



Venous thrombosis

Catheter occlusion

Related to catheter in situRelated to catheter in situ


Metabolic ComplicationsAbnormalities related to excessive or inadequate administration

hyper / hypoglycaemia

electrolyte abnormalities

acid-base disorders

hyperlipidaemia


Metabolic ComplicationsHepatic 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


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 illnessNutrition in Critical illness 11411423/4/1223/4/12

MaintainsMaintainsStimulates Stimulates

the environmentthe environmentdefencesdefences

FEEDINGFEEDING

Provides Provides energyenergy


Thank you !!


Essential Nonessential

Arginine Alanine

Histidine Asparagine

Isoleucine Aspartate

Leucine Cysteine

Lysine Glutamate

Methionine Glutamine

Phenylalanine Glycine

Threonine Proline

Tryptophan Serine

Valine Tyrosine

Health & Medicine

Nutritional Support