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Enteral and parenteral

nutrition

Nutrition and Surgery

Malnutrition may compound the severity of

complications related to a surgical

procedure

A well-nourished patient usually tolerates

major surgery better than a severely

malnourished patient

Malnutrition is associated with a high

incidence of operative complications and

death.

Nutrition

Carbohydrates

Limited strorage capacity, needed for

CNS (glucose) function

Recommended 45-65% total daily

calories.

Nutrition

Fats

Major endogenous fuel source in healthy

adults

Too little can lead to essential fatty acid

(linoleic acid) deficiency and increased

risk of infections

Recommended 20-30% of total caloric

intake

Nutrition

Protein

Needed to maintain anabolic state (match

catabolism)

Must adjust in patients with renal and

hepatic failure

Recommended 10-35% of total caloric

intake.

Normal Nutrition

Requirements

HEALTHLY male/female

(weight maintenance)

• Caloric intake=25-30 kcal/kg/day

• Protein intake=0.8-1gm/kg/day

(max=150gm/day)

• Fluid intake=~ 30 ml/kg/day

Nutrition

Requirements? SURGICAL PATIENT ?

Stress

Injury or disease

Surgery

Pre-hospital/pre-

surgical nutrition

Nutrition history

Special considerations

The surgical patient . . . .

Increased risk of malnutrition due to:

Inadequate nutritional intake

surgical stress

subsequent increase in metabolic rate.

Extraordinary stressors (hypovolemia, bacteremia,

medications)

Wound healing

Anabolic state, appropriate vitamins

Poor nutrition=poor outcomes

For every gm deficit of untreated hypoalbuminemia

there is ~ 30% increase in mortality

Nutrition

SURGERY PATIENT

Caloric intake

*Mild stress, inpatient

25-30 kcal/kg/day

*Moderate stress, ICU patient

30-35 kcal/kg/day

*Severe stress, burn patient

30-40 kcal/kg/day

Protein intake

1-2 gm/kg/day

Fluid intake

INDIVIDUALIZED

HEALTHLY 70 kg MALE

Caloric intake

25-30 kcal/kg/day

Protein intake

0.8-1gm/kg/day

(max=150gm/day)

Fluid intake

30 ml/kg/day

Measures of success:

serum markers Albumin

Synthesized in and catabolized by the liver

Pro: often ranked as the strongest predictor of

surgical outcomes- inverse relationship between

postoperative morbidity and mortality compared

with preoperative serum albumin levels

Con: lack of specificity due to long half-life

(approximately 20 days).

Normal range: 3.5-5 g/dL.

-strongest predictor of postoperative mortality

Postoperative Nutritional Care

Traditional Method: Diet advancement

Introduction of solid food depends on the

condition of the GI tract. Wait for return of

bowel sounds or passage of flatus.

Start clear liquids when signs of bowel

function returns

Oral feeding as soon as after surgery- FAST

TRACK SURGERY

Basic Concept

Early recovery of organ function

for better outcomes

Goals of FAST TRACK SURGERY

Lower risk, better outcome

Accelerate recovery

Reduce morbidity, complications

(pulmonary, cardiac, thromboembolic,

infectious)

Shorten convalescence

Limited Fasting

Solids until 6 hours before surgery

Clear fluids until 2 hours before surgery

Safe

Beneficial

Carbohydrate-loaded liquid pre-op

post-op catabolism

insulin resistance, hyperglycemia

muscle loss

Early Feeding

Start clear fluids 2h post-op

Aim > 800mL fluids on day of surgery

Routine nutritional supplements

IV appropriately, avoid fluid overload,

Nutrition Support

Length of time a patient can remain NPO

after surgery without complications is

uknown, however depends on:

Severity of operative stress

Patient’s preexisting nutritional status

Nature and severity of illness

Two types of nutritional support

Enteral

Parenteral

What is enteral nutrition?

Enteral Nutrition

Also called "tube feeding," enteral nutrition is

a liquid mixture of all the needed nutrients.

It is given through a tube in the stomach or

small intestine.

If oral feeding is not possible, or an extended

NPO period is anticipated, an access devise

for enteral feeding should be inserted at the

time of surgery.

Indications for Enteral

Nutrition

Malnourished patient expected to be

unable to eat adequately for > 5-7 days

Adequately nourished patient expected to

be unable to eat > 7-9 days

Adaptive phase of short bowel syndrome

Following severe trauma or burns

Contraindications to Enteral

Nutrition Support

Malnourished patient expected to eat within 5-7

days

High output enteric fistula distal to feeding tube

Inability to gain access

Intractable vomiting or diarrhea

Aggressive therapy not warranted

Expected need less than 5-7 days if

malnourished or 7-9 days if normally nourished

Enteral Access Devices

Nasogastric

Nasoenteric

Gastrostomy PEG (percutaneous endoscopic gastrostomy)

Surgical or open gastrostomy

Jejunostomy PEJ (percutaneous endoscopic jejunostomy)

Surgical or open jejunostomy

Transgastric Jejunostomy PEG (percutaneous endoscopic gastrostomy)

Surgical or open gastro-jejunostomy

Feeding Tube Selection

Can the patient be fed into the stomach, or

is small bowel access required?

How long will the patient need tube

feedings?

Gastric vs. Small Bowel

Access

“If the stomach empties, use it.”

Indications to consider small bowel access: Gastroparesis / gastric ileus

Recent abdominal surgery

Sepsis

Significant gastroesophageal reflux

Pancreatitis

Aspiration

Ileus

Proximal enteric fistula or obstruction

Choosing Appropriate

Formulas

Categories of enteral formulas:

Polymeric

Whole protein nitrogen source, for use in patients with normal

or near normal GI function, for GS

Monomeric or elemental

Predigested nutrients; most have a low fat content or high %

of MCT; for use in patients with severely impaired GI

function, for JS

Disease specific

Formulas designed for feeding patients with specific disease

states

Formulas are available for respiratory disease, diabetes,

renal failure, hepatic failure, and immune compromise

Enteral Nutrition Prescription

Guidelines

Gastric feeding Continuous feeding:

Start at rate ...5..10..20..40..80 ml/hour

Bolus feeding: Start with 120 mL bolus

Increase by 60 mL q bolus to goal volume

Typical bolus frequency every 3-8 hours

Small bowel feeding Continuous feeding only; do not bolus due to risk of

dumping syndrome

Complications of Enteral

Nutrition Support

Issues with access, administration, GI

complications, metabolic complications.

These include:

Nausea, vomitting, diarrhea, delayed gastric

emptying, malabsorption, refeeding

syndrome, hyponatremia, microbial

contamination, tube obstruction, leakage from

ostomy/stoma site,

What is parenteral nutrition?

Parenteral Nutrition

also called "total parenteral nutrition," "TPN,"

or "hyperalimentation."

It is a special liquid mixture given into the

blood via a catheter in a vein.

The mixture contains all the protein,

carbohydrates, fat, vitamins, minerals, and

other nutrients needed.

Indications for Parenteral

Nutrition Support

Malnourished patient expected to be

unable to eat > 5-7 days AND enteral

nutrition is contraindicated

Patient failed enteral nutrition trial with

appropriate tube placement (post-pyloric)

Enteral nutrition is contraindicated or

severe GI dysfunction is present

Paralytic ileus, mesenteric ischemia, small

bowel obstruction, enteric fistula distal to

enteral access sites

PPN vs. TPN

TPN (total parenteral nutrition) High glucose concentration (15%-25% final dextrose

concentration)

Provides a hyperosmolar formulation (1300-1800 mOsm/L)

Must be delivered into a large-diameter vein-central vein

PPN (peripheral parenteral nutrition) Similar nutrient components as TPN, but lower

concentration (5%-10% final dextrose concentration)

Osmolarity < 900 mOsm/L (maximum tolerated by a peripheral vein)

May be delivered into a peripheral vein

Because of lower concentration, large fluid volumes are needed to provide a comparable calorie and protein dose as TPN

Parenteral Access Devices

Peripheral venous access

Catheter placed percutaneously into a

peripheral vessel

Central venous access (catheter tip in SVC)

Percutaneous jugular, femoral, or subclavian

catheter

Implanted ports (surgically placed)

PICC (peripherally inserted central catheter)

Writing TPN prescriptions

1. Determine total volume of formulation based on individual patient fluid needs

2. Determine amino acid (protein) contentAdequate to meet patient’s estimated needs

3. Determine dextrose (carbohydrate) content~70-80% of non-protein calories

4. Determine lipid (fat) content~20-30% non-protein calories

5. Determine electrolyte needs

6. Determine acid/base status

7. Check to make sure desired formulation will fit in the total volume indicated

Complications of Parenteral

Nutrition

Hepatic steatosis

May occur within 1-2 weeks after starting PN

May be associated with fatty liver infiltration

Usually is benign, transient, and reversible in

patients on short-term PN and typically

resolves in 10-15 days

Limiting fat content of PN and cycling PN over

12 hours is needed to control steatosis in

long-term PN patients

Complications of Parenteral

Nutrition Support (continued)

Cholestasis May occur 2-6 weeks after starting PN

Indicated by progressive increase in TBili and an elevated serum alkaline phosphatase

Occurs because there are no intestinal nutrients to stimulate hepatic bile flow

Trophic enteral feeding to stimulate the gallbladder can be helpful in reducing/preventing cholestasis

Gastrointestinal atrophy Lack of enteral stimulation is associated with villus hypoplasia,

colonic mucosal atrophy, decreased gastric function, impaired GI immunity, bacterial overgrowth, and bacterial translocation

Trophic enteral feeding to minimize/prevent GI atrophy

Transitional Feedings

Parenteral to enteral feedings

Introduce a minimal amount of enteral feeding at a low rate (30-

40 ml/hr) to establish tolerance.

Decrease PN level slowly to keep nutrient levels at same

prescribed amount

As enteral rate is increased by 25-30 ml/hr increments every 8-24

hrs, parenteral can be reduced

Discontinue PN solution if 75% of nutrient needs met by enteral

route.

Parenteral/Enteral to oral feedings

Ideally accomplished by monitoring oral intake and concomitantly

decreasing rate of nutrition support until 75% of needs are met.

Oral supplements are useful if needs not met 100% by diet.

Refeeding Syndrome

“the metabolic and physiologic consequences of depletion, repletion, compartmental shifts, and interrelationships of phosphorus, potassium, and magnesium…”

Severe drop in serum electrolyte levels resulting from intracellular electrolyte movement when energy is provided after a period of starvation (usually > 7-10 days)

Physiologic and metabolic sequelae may include: EKG changes, hypotension, arrhythmia, cardiac arrest

Weakness, paralysis

Respiratory depression

Ketoacidosis / metabolic acidosis

Refeeding Syndrome(continued)

Prevention and Therapy

Correct electrolyte abnormalities before starting

nutrition support

Continue to monitor serum electrolytes after

nutrition support begins and replete

aggressively

Initiate nutrition support at low

rate/concentration (~ 50% of estimated needs)

and advance to goal slowly in patients who are

at high risk

Consequences of Over-feeding

Risks associated with over-feeding: Hyperglycemia

Hepatic dysfunction from fatty infiltration

Respiratory acidosis from increased CO2 production

Difficulty weaning from the ventilator

Risks associated with under-feeding: Depressed ventilatory drive

Decreased respiratory muscle function

Impaired immune function

Increased infection