Flashcards in Miscellaneous Deck (43)
Describe typical stress and energy response in the body, as it relates to why TPN is needed during illness:
Increased metabolic needs > increased energy needs > increased calorie and nutrient needs > Gluconeogenesis > 1) Glycogen converted to glucose and urea for energy > 2) Fat stores mobilized for energy > 3) Protein stores mobilized for energy > Release of somatic and visceral proteins from muscle, tissue, etc. to create energy > Catabolic state > Negative nitrogen balance > Starvation
Generation of glucose from certain non-carbohydrate carbon substrates
What does TPN promote?
Anabolism (synthesis of complex molecules for energy) to approximately the same ratio as a regular diet in a healthy person
Describe the neuroendocrine-mediated changes that can increase energy expenditure:
Stressor > NE mediated activation to stimulate tissue healing and preserve normal organ function > Few changes occur in first 24 hours > After, intense catabolic activation occurs > Stress hormones released > Increased energy expenditure, body protein breakdown, weight loss > Nitrogen excretion increases + K+ excretion increases + Glucose levels rise + Na+ and fluid retained + Decreased GI motility > Peak of catabolism > Anabolic recovery begins (stress hormones subside, glucose declines, nitrogen balance restored)
What are contraindications to parenteral nutrition support?
- Catheter-related complications (e.g. occlusion, displacement)
- Local and systemic complications associated with CVC
- Pt noncompliance or refusal to eat
- Pt with GI tracts expected to resume normal functioning within 7-10 days
- Poor prognosis
- Superior vena cava thrombosis
- Terminal illness, comfort care only
How many calories do different types of intake provide?
- Proteins = 4 cal/g
- Carbs = 4 cal/g
- Fats = 9 cal/g
What are some of the roles of protein?
- Form immunoglobins to fight infection and disease
- Form structure of tissues
- Energy production
- Maintain oncotic pressure (e.g. plasma proteins)
- Promote tissue growth and repair
- Synthesize compounds (e.g. thrombin, the clotting protein)
- Synthesize essential bodily fluids and secretions (e.g. enzymes, hormones, neurotransmitters, bile acids, etc.)
- Transportation (e.g. albumin transports free bilirubin, free fatty acids, and drugs)
Why is protein a key component of PN?
- Adjunct in off-setting nitrogen loss or in treatment of negative nitrogen balance
- Promotes anabolism
- Prevents protein catabolism
- Always administered concurrently with dextrose
Why are carbs a key component of PN?
- Provide basic energy source (glucose) that can be stored in almost all body tissues (as glycogen)
- Provides needed calories for energy
- Spares protein and prevents gluconeogenesis
- Needed to completely oxidize fat to prevent it being broken down into ketones
- Dextrose has nitrogen sparing effect
- Dextrose utilized type in TPN
Why are fats a key component of PN?
- Most concentrated source of energy for all body tissue types (except CNS, fueled by glucose)
- Supplies a non-carb and non-protein source of energy, causing an increase in heat production and decrease in respiratory quotient
- Isotonic, can be either PIV or CVC
Why would pH related problems interfere with fat in PN?
The prime destabilizers of lipid emulsions are excessive acidity and inappropriate electrolyte content
Describe infusion rates of fats:
- Initial rate 1 ml/min for first 15-30 minutes of infusion, may increase to 2 ml/min
- No more than 500 cc in the first 24 hour of therapy
- After 24 hours should not exceed 2.5 g/kg/day
What mineral CANNOT be mixed with other drugs and infusates?
What is the difference between minerals and vitamins?
Minerals are inorganic elements, and vitamins are organic substances
What are some hepatic and renal compromise considerations with PN?
- Pt's with liver disease (cirrhosis, encephalopathy, coma) have LOW levels of branched chain amino acids and high levels of aromatic amino acids, which makes them intolerant of crystalline amino acid preparations
= intolerant of crystalline amino acid preparations
- When intolerant of crystalline solutions, require amino acids with HIGH levels of branched chain amino acids (with encephalopathy, will improve mental status and EEG patterns)
- TPN solutions contain both essential and non-essential amino acids, BUT renal restrictions = should have ONLY essential amino acids
- Only minimal quantities of ESSENTIAL amino acids will be beneficial (enhance urea utilization, promote protein synthesis, improve metabolic balance [decrease electrolyte imbalances])
What are some guidelines for TPN administration?
- If next dose not yet available, hang a 10% dextrose infuse with 50% dextrose added to prevent rebound hypoglycemia
- Remove refrigerated mixtures ~1 hour before administering (otherwise cold and uncomfortable)
- Introduce TPN relatively slow to preclude hyperglycemia (50 cc/hr)
- Never "catch up" if fallen behind, only adjusted within a 10% margin
- Pt's need to be weaned off to prevent rebound hypoglycemia (4-48 hours, gradually decreasing and evaluating patient response)
Why is TPN susceptible to microbial growth?
Their high dextrose content is attractive to microbes
What are S&S of metabolic acidosis?
- INCREASED RR and depth
- Warm and flushed skin
- Decreased pH
- Decreased HCO3
- Increased serum chloride
- Increased serum bicarbonate
What are S&S of metabolic alkalosis?
- Muscle hypertonia
- DEPRESSED RR
- Decreased serum chloride
- Increased serum bicarbonate
What are S&S of hypoglycemia?
What are S&S of hyperglycemia?
- Increased serum glucose
- Fruity breath
What are S&S of hypocalcemia?
- CNS irritability **
- Muscle cramping/spasms
- Chvostek's and Trousseau's signs
What are S&S of hypokalemia?
- Slight glucose elevation d/t insulin suppression
- Muscle weakness
- Decreased gastric motility
- EKG changes
What are S&S of hyperkalemia?
- EKG changes
- Ventricular dysrhythmias
- Cardiac arrest
- Muscle weakness
- Flaccid muscular paralysis
What is refeeding syndrome?
- Complication that may occur during initial TPN
- Body, during starvation, has adapted somewhat to being nutritionally deprived
- Aggressive initiation of nutritional support can result in electrolyte shift from plasma to intracellular fluid
- Can be very dangerous and fatal d/t cardiorespiratory complications
- May manifest as edema; hypernatremia; hypokalemia; hypomagesemia; and hypophosphatemia
Why does TPN IV sets have filters?
Filters allow for various particles to be removed before infusion, preventing catheter-related complications such as infection
What is a 3:1 solution?
- Aka. TNA
- Amino acids, dextrose AND fats (fats may be done separate, if not it is a 3:1)
- Caution must be taken to minimize pH related problems that might occur in a 3:1 solution (follow proper combining protocols)
According to the course overview, what advantages does CVC have over peripheral lines?
- Administration of solutions that would be irritating to small veins
- Access to individuals with inaccessible peripheral veins
- Rapid administration of large solutions
- Uninterrupted administration of several solutions at one time
- Drawing of blood samples
- Monitoring central venous pressure
Why is TPN typically separate from fat infusions?
- Conventional TPN administration sets and bags contain PVC (synthetic plastic) and have DEHP as a plasticizer (solvent promoting flexibility and promote elasticity), but lipids extract hese
- Recommended to have separate administration sets, glass containers or special non-PVC bags
- infuse lipids via Y-connector or separate lumen