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
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
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