Intravenous Nutrition, Fluid, and Electrolyte Therapy Flashcards
What is malnutrition associated with?
- Increased infection rates
- Longer hospital length of stay
- Increased hospital costs
- Mortality
Should be assessed throughout hospitalization
How is nutrition status assessed?
- BMI
- Unintentional weight change
- Changes in oral intake
- Severity of illness
- IBW
Assessing purely based on weight may miss some patients
What is the diagnostic criteria for malnutrition according to the AND and ASPEN?
2 or more of the following 6 characteristics:
* Insufficient caloric intake
* Weight loss
* Loss of muscle mass (temporal/interosseous muscle wastingl clavicular prominence)
* Loss of subcutaneous fat (cheeks/orbital area, or space between thumb and forefinger)
* Localized or generalized fluid accumulation, that may mask weight loss (pitting edema)
* Diminished functional status (assessed by handgrip strength with a dynamometer)
What are risks of overfeeding?
- Excess carbs: hyperglycemia, excess carbon dioxide production, concerning in lung disease
- Long-term overfeeding: hepatic steatosis, ureagenesis, immunosuppression (especially overfeeding of lipids)
What is used to determine nutrition requirements?
Harris Benedict Equation
Mifflin-St Jeor Equation
What is the general rule for protein requirements in hospitalized patients?
- 1.2-1.5 g/kg/d
- Burn patients: 2.0 g/kg/d
- Critically ill obese patients: 2.5 g/kg/d (IBW)
Quick rule of thumb for most hospitalized patients caloric and protein needs (IBW)
- 25-30 calories/kg/d
- 1.2 protein g/kg/d
What is the preferred route of feeding?
- Oral if meets needs
- May add supplemental shakes for calories/protein
- Boost shakes have 10 g protein and 240 calories per shake and come in variety of flavors, may order with meal or in between meals
What can be considered when patients cannot safely or adequately meet their nutrient requirements through oral diet alone?
Specialized nutritional support
Enteral or parenteral nutrition reserved for those who cannot take in orally
When should enteral or parenteral nutrition be initiated?
- After 7-10 days with no oral intake
- ONly if going to be using for at least 5-10 days due to costs and risks
What is enteral nutrition?
Tubes enter GI system directly at stomach or small intestine
If gut works, should be used
What are relative and absolute contraindications to enteral feeding?
- Major GI hemorrhage
- Peritonitis
- Severe ileus
- Bowel obstruction or fistulae distal to enteral access site
- Intestinal ischemia
- Malabsorptive disorders with high volume diarrhea
What are types of enteral formulas?
- Elemental or semi-elemental (MC)
- Polymeric
- Immune enhancing diets
What are indications for polymeric enteral formulas?
- To meet daily requirements; for most patients 1-1.5 L/d
- Concentrated feeding best if patient is volume restricted
What are side effects of polymeric and elemental or semi-elemental enteral formula?
Diarrhea and polymeric may require free water supplementation
What is indication for elemental or semi-elemental enteral formula?
maximizes absorption in patients with malabsorptive disorders
What is indication for immune enhancing diets?
May reduce infection risk in surgical patients
How is enteral feeding initiated?
- Start at low rate, and gradually advance to infusion goal over period of 24-48 hours
What should patient sbe evaluated for with enteral nutrition?
- Nausea
- Vomiting
- Diarrhea
- Abdominal Pain
- Bloating
- If develop, feedings held until resolution
- Persistent intolerance –> alternative plan
When would you consider parenteral nutrition?
Patient who cannot tolerate enteral nutrition
What is parenteral nutrition associated with?
- Higher rates of infectious and metabolic complications
- Volume overload
- Hyperglycemia
- Electrolyte abnormalities
What do parenteral solutions contain?
- Carbohydrate in form of dextrose
- Protein as crystalline amino acids
- Lipids from polyunsaturated long-chain triglycerides such as soybean oil or a safflower/soybean oil mixture
- Vitamins, electrolytes, and trace elements added to formulation as needed
What should patients be monitored for with parenteral nutrition?
- Metabolic changes such as hyperglycemia or refeeding syndrome
- Hyperglycemia may increase infectious complications, hospital length of stay, and cost
What is refeeding syndrome characterized by?
- Electrolyte abnormalities that occur during the reinstitution of carbohydrate calories to a starved patient
- Serum phosphate, magnesium, and potassium depletion may develop
How should parenteral nutrition be initiated?
- Start low - 1 L for 1st day, monitoring glucose every few hours and BMP every 8-12 hours
- Carbs make up 50-60%
- Protein 15-25%
- Lipids 20-25%
- Central venous access requires for administration of TPN becasue TPN hyperosmolar
Why would you order IV fluids?
- NPO
- SIgnificant volume deficit
- Ongoing losses
- Specific goal to fluid therapy
- Make sure to assess appropriateness of IVF daily
If the gut works use it!
What are potential complications of using IV fluids?
- Fluid overload
- Dangerous electrolyte derangements
- Line infections
What is total body water?
- Wt (kg) x .6 (m) .5 (f) = TBW in liters
2/3,1/3 rule
2/3 ICF 1/3 ECF
How much ECF is intravascular vs interstitial?
- 1/4 intravascular
- 3/4 interstitial
How much water are normal adults considered to need as a minimum per day?
1600 mL/day 500mL ingested water, 800 mL in food, 300 mL from oxidation
What increases water intake requirement?
- Fever
- Sweating
- Burns
- Tachypnea
- Surgical drains
- Polyuria
- Ongoing significant GI losses
- Water requirements increase by 100 to 150 mL/day for each degree of body temperature elevation over 37 C
What are sources of obligatory water output in normal adults?
- 500 mL urine
- 500 mL skin
- 400 mL respiratory tract
- 200 mL stool
How much fluid is required daily?
35 mL/kg/d
Weight based water requirements
- 0-10 kg = 100 mL/kg
- 10-20 kg = 1000 mL +50 mL per each kg above 10 kg
- 20-70 kg = 1500 mL + 20 mL per each kg above 20 kg
- Over 70 = 2500 (adult requirement)
How much sodium is required per day?
1-3 meq/kg/day
Ex: 70 kg male requires 70-210 meq NaCl, 2500 cc fluid per day
.45% saline contains 77 meq NaCl per liter, 2.5 x 77 =192 meq
Thus .45% saline can be used as MIVF assuming no other volume or electrolyte issues
How much potassium is required per day?
- 1 meq/kg/day
- Can be added to IV fluids but increases osm load
- 20 meq/L is common IVF additione, will supply basal needs for pts who are NPO
Osmotically as active as sodium, addign 40 mEq to liter of .45% saline will create solution similar to 3/4 isotonic saline containing less free water
If a patient is significantly hypokalemia what should be done?
Order separate K+ supplementation, oral potassium preferred
What can Potassium do to a solution?
Limit infusion rate
A plasma K+ 1 mmol/L below normal corresponds to a total body potassium deficit of approximately what?
200-400 mmol, and a drop in plasma K+ to 2 mmol below normal requires 400 -800 mmol for repletion
Typically K+ daily repletion is significantly ….. than the total body deficit as the time required for redistribution is prolonged
less
How is potassium deficit calculated?
Kdeficit (in mmol) = (Knormal lower limit-K measured) x kg body weight x .4
1 mmol = 1 mEq
Every 10 mEq of KCl raises serum K+ by .13 mEq/L
If no immediate threat to life what should be used for hypokalemia?
Oral potassium, most commonly potassium chloride
Typical dose with normal renal function is 40-100 mmol (40-100 mEq) per day in 2 to 3 divided doses
What are glucose requirements?
- 100-200 g/d
- During starvation supplied by fat and protein
- Protein-sparing effect goals of basic IV therapy
- Administration of at least 100 g/d of glucose reduces protein loss by more than one half
Types of fluids used in clinical practice?
- Colloids
- Crystalloids
- blood products
Qualities of colloid solutions?
- Large molecules that don’t pass through cell membranes
- When infused remain in intravascular compartment and expand intravascular volume and draw fluid from extravascular spaces via higher oncotic pressure
Qualities of crystalloid solutions
- Contain small molecules that flow easily acorss cell membranes, allowing for transfer from the bloodstream into the cells and body tissues
- Increases fluid volume in both interstitial and intravascular spaces
- Subdivided into isotonic/hypotonic/hypertonic
What are isotonic fluid types?
- .9% sodium chloride
- LR
- 5% dextrose in water (D5W)
- Ringer’s acetate
What is composition of .9% NaCL
154 meq of Na and 154 meq of Cl
Composition of ringers lactate
Na 130 meq
K 4 meq
Ca 3 meq
Cl 109 meq
HCO3 28 meq
Most physiologically adaptable fluid because electrolyte content most closely related to composition of body’s blood serum and plasma
Choice for first-line fluid resuscitation in burn injuries
When should ringers lactate or hartmann solution be used?
- To replace GI tract fluid losses
- Fistula drainage
- Fluid losses due to burns and truama
- Patients experiencing acute blood loss or hypovolemia due to third-space fluid shifts
How is ringers lactate metabolized?
In liver, converting lactate to bicarb
Which patients should not receive ringers lactate or hartmann solution
- Liver disease
- Lactic acidosis
- Severe renal impairment because contains potassium
- pH greater than 7.5
Characteristics of D5W
- Dextrose 50 g/L
- Isotonic solution
- Becomes hypotonic and causes fluid to shift into cells when metabolized
- Provides free water that pass through membrane pores to both intracellular and extracellular spaces
- Smaller size allows molecules to pass freely between compartments
- Provides 170 calories per liter, but doesn’t replace electrolyte
How do you decide on fluid?
- Goal for therapy: maintenance, rehydration, or volume resuscitation?
- Any baseline electrolyte abnormalities?
- Always look at chemistry before ordering fluids
What would you order in hypovolemia?
Primary goal volume expansion
NS or LR because will put most volume in intravascular space
What would you order in dehydration?
Primary goal is free water replacement (not synonymous with hypovolemia)
Use hypotonic fluid usually .45% saline or D5W
What fluids are best for post-operative patients?
- Pain and narcotics can be stimulants of inappropriate ADH secretion
- Giving hypotonic fluids can cause dangerous hyponatremia
- .9% saline safer fluid but will also deliver free water in setting of SIADH
Why NS for volume expansion?
- Free water is distributed evenly throughout TBW compartment
- Essentially 100% if sodium is confined to extracellular space
- Normal saline contains essentially no free water
Fluid requirements for pediatrics
- First 10 kg = 4 cc/kg/hr
- Second 10 kg = 2 cc/kg/hr
- 1 cc/kg/hr thereafter
4,2,1 rule
In adults fluid requirements
wt (kg) + 40
Ex: 70 kg+ 40 = 110 cc/hr
What does the 4,2,1 rule need to be adjusted for?
- This is maintenance rate so needs to be adjusted for dehydration or ongoing fluid loss
- If taking some PO
- Daily electrolytes, BUN, Cr, I/O and weight should be monitored
