Transcript Parenteral Nutrition (Definition)

Parenteral Nutrition Formula
Calculations and Monitoring Protocols
Macronutrient Concentrations in PN
Solutions
 Macronutrient concentrations (%) = the
grams of solute/100 ml of fluid
 D70 has 70 grams of dextrose per 100 ml.
 10% amino acid solution has 10 grams
amino acids/100 ml of solution
 20% lipids has 20 grams of lipid/100 ml of
solution
Protein Content Calculations
 To calculate the grams
of protein supplied by
a TPN solution,
multiply the total
volume of amino acid
solution (in ml*)
supplied in a day by
the amino acid
concentration.
Example Protein
Calculation
 1000 ml of 8% amino
acids:
 1000 ml x 8 g/100 ml
= 80g
 Or 1000 x .08 = 80 g
Calculation of Dextrose Calories
 Calculate grams of dextrose:
– Multiply the total volume of dextrose soln (in
ml) supplied in a day by the dextrose
concentration. This gives you grams of dextrose
supplied in a day.
 Multiply the grams of dextrose by 3.4 (there
are 3.4 kcal/g dextrose) to determine
kcalories supplied by dextrose in a day.
Sample Dextrose Calculation
 1000 ml of D50W (50% dextrose)
– 1000 ml x 50g / 100 ml = 500g dextrose
– OR 1000 ml x .50 = 500g dextrose
 500g dextrose x 3.4 kcal/g = 1700 kcal
Calculation of Lipid Content
 To determine kcalories supplied by lipid*,
multiply the volume of 10% lipid (in ml) by 1.1;
multiply the volume of 20% lipid (in ml) by 2.0.
 If lipids are not given daily, divide total kcalories
supplied by fat in one week by 7 to get an estimate
of the average fat kcalories per day.
*|Lipid emulsions contain glycerol, so lipid emulsion does not
have 9 kcal per gram as it would if it were pure fat. Some
use 10 kcal/gm for lipid emulsions.
Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html
Example Lipid Calculation for
2-in-1
 500 ml of 10% lipid
– 500 ml x 1.1 kcal/ml = 550 kcal
 500 ml 20% lipid
– 500 ml x 2.0 kcal/ml = 1000 kcal
 Or, alternatively, 500 ml of 10% lipid = 50
grams lipid x 10 kcal/g or 500 kcal
Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html
Calculation of Dextrose/AA with
Piggyback Lipids (2-in-1)
 Determine patient's kcalorie, protein, and fluid
needs.
 Determine lipid volume and rate for "piggy back"
administration.
– Determine kcals to be supplied from lipid. (Usually
30% of total kcals).
– Divide lipid kcals by 1.1 kcal/cc if you are using 10%
lipids; divide lipid kcals by 2 kcal/cc if you are using
20% lipids. This is the total volume.
– Divide total volume of lipid by 24 hr to determine rate
in cc/hr.
Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html
Determine protein concentration
 Subtract volume of lipid from total fluid
requirement to determine remaining fluid
needs.
 Divide protein requirement (in grams) by
remaining fluid requirement and multiply
by 100. This gives you the amino acid
concentration in %.
 Multiply protein requirement in grams x 4
to determine calories from protein
Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html
Determine dextrose concentration.
 Subtract kcals of lipid + calories from protein
from total kcals to determine remaining kcal
needs.
 Divide "remaining kcals" by 3.4 kcal/g to
determine grams of dextrose.
 Divide dextrose grams by remaining fluid needs
(in protein calculations) and multiply by 100 to
determine dextrose concentration.
 Determine rate of AA/dex solution by dividing
"remaining fluid needs” by 24 hr.
Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html
Example Calculation
Nutrient Needs:
Kcals: 1800. Protein: 88 g. Fluid: 2000 cc
1800 kcal x 30% = 540 kcal from lipid
Lipid (10%):
– 540 kcal/1.1 (kcal/cc) = 491 cc/24 hr =
20 cc/hr 10% lipid (round to 480 ml)
 Remaining fluid needs: 2000cc - 480cc =
1520cc
Protein Calculations
Protein: 88 g / 1520 cc x 100 =
5.8% amino acid solution
88 g. x 4 kcal/gm =352 kcals from
protein
 Remaining kcal needs: 1800 – (528 + 352)
= 920 kcal
Dextrose Concentration
 920 kcal/3.4 kcal/g = 270 g dextrose
 270 g / 1520 cc x 100 = 17.7%
dextrose solution
 Rate of Amino Acid / Dextrose: 1520
cc / 24hr = 63 cc/hr
TPN recommendation: Suggest two-in-one
PN 17.7% dextrose, 5.8% a.a. @ 63 cc/hr
with 10% lipids piggyback @ 20 cc/hr
Re-check calculations
TPN recommendation: Suggest two-in-one
PN 17.7% dextrose, 5.8% a.a. @ 63 cc/hr
with 10% lipids piggyback @ 20 cc/hr
63 cc/hr x 24 = 1512 ml
1512 * (.177) = 268 g D X 3.4 kcals= 911
kcals
1512 * (.058) = 88 g a.a. x 4 kcals = 352
20 cc/hr lipids*24 = 480*1.1 kcals/cc = 528
1791
3 in 1 TNA Solutions |
 Determine patient's kcalorie, protein, and fluid
needs.
 Divide daily fluid need by 24 to determine rate of
administration.
 Determine lipid concentration.
– Determine kcals to be supplied from lipid. (Usually
30% of total kcals).
– Determine grams of lipid by dividing kcal lipid by 10. *
– Divide lipid grams by total daily volume (= fluid needs
or final rate x 24) and multiply by 100 to determine %
lipid.
3-in-1 TNA Solutions
 Determine protein concentration by dividing protein needs





(grams) by total daily volume and multiply by 100.
Multiply protein needs in grams x 4 kcal/gm = kcals from
protein
Determine dextrose grams.
Subtract kcals of lipid and kcals from protein from total
kcals to determine remaining kcal needs.
Divide "remaining kcals" by 3.4 kcal/g to determine grams
of dextrose.
Determine dextrose concentration by dividing dextrose
grams by total daily volume and multiply by 100
Sample Calculation 3-in-1
 Nutrient Needs:
– Kcals: 1800 Protein: 88 g Fluid: 2000 cc
 Lipid : 1800 kcal x 30% = 540 kcal
– 540 kcal / 10 kcal per gram = 54 g
– 54 g / 2000 cc x 100 = 2.7% lipid
 Protein: 88 g / 2000 cc x 100 =
4.4% amino acids
 88 g x 4 = 352 kcals from protein
Sample Calculation 3-in-1(cont)
Dextrose: 908 kcal (1800 – 540 - 352)
– 908/3.4 kcal/g = 267 g dextrose
– 267 g / 2000 cc x 100 =
13.4% dextrose solution
– Rate of Amino Acid / Dextrose/Lipid: 2000 cc /
24hr = 83 cc/hr
– TPN prescription: Suggest TNA 13.4%
dextrose, 4.4% amino acids, 2.7% lipids at 83
cc/hour provides 88 g. protein, 1800 kcals,
2000 ml. fluid
Evaluation of a TNA Order
 PN 15% dextrose, 4.5% a.a., 3% lipid @
100 cc/hour
Evaluation of a PN Order
PN 15% dextrose, 4.5% a.a., 3% lipid @ 100
cc/hour
 Total volume = 2400
 Dextrose: 15g/100 ml * 2400 ml = 360 g
 360 g x 3.4 kcal/gram = 1224 kcals
 Lipids 3 g/100 ml x 2400 ml = 72 g lipids
 72 x 10 kcals/gram = 720 kcals
Evaluation of a PN Order
 Amino acids: 4.5 grams/100 ml * 2400 ml =
108 grams protein
 108 x 4 = 432 kcals
 1224 + 720 + 432 = 2376 total kcals
 Lipid is 30% of total calories
 Dextrose is 51.5% of total calories
 Protein is 18% of total calories
Calculation of Nonprotein
Calories
 Some clinicians discriminate between
protein and nonprotein calories although
this is falling out of favor
 This is more commonly used in critically ill
patients
Calculation of Non-Protein Calories
 To determine the nonprotein kcalories (NPC) in a
TPN prescription, add the dextrose calories to the
lipid calories
 In the last example, 1224 kcals (dextrose) + 720
kcals (lipid) = 1944 non-protein kcals
 Dextrose is 63% of nonprotein kcals (1224/1944)
 Lipid is 37% of nonprotein calories
 In critically ill patients, some clinicians restrict
lipid to 30% of nonprotein kcals
Calculation of NPC:N Ratio |
 Calculate grams of nitrogen supplied per
day (1 g N = 6.25g protein)
 Divide total nonprotein calories by grams of
nitrogen
 Desirable NPC:N Ratios:
– 80:1 the most severely stressed patients
– 100:1 severely stressed patients
– 150:1 unstressed patient
Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html
Example NPC:N Calculation
80 grams protein
2250 nonprotein kcalories per day
80g protein/ 6.25 = 12.8
2250/12.8 = 176
NPC:N = 176:1
Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html
Example %NPC Fat Calculation*
2250 nonprotein kcal
550 lipid kcal
550/2250 x 100 = 24% fat kcals
*Limit is 60% NPC
Osmolarity in PPN
 When a hypertonic
solution is introduced
into a small vein with
a low blood flow, fluid
from the surrounding
tissue moves into the
vein due to osmosis.
The area can become
inflamed, and
thrombosis can occur.
IV-Related Phlebitis
Calculating the Osmolarity of a
Parenteral Nutrition Solution
1.
2.
3.
4.
5.
Multiply the grams of dextrose per liter by 5.
Example: 100 g of dextrose x 5 = 500 mOsm/L
Multiply the grams of protein per liter by 10.
Example: 30 g of protein x 10 = 300 mOsm/L
Multiply the grams of lipid per liter by 1.5.
Example: 40 g lipid x 1.5 = 60.
Multiply the (mEq per L sodium + potassium +
calcium + magnesium) X 2
Example: 80 X 2 = 160
Total osmolarity = 500 + 300 + 60 + 160 = 1020
mOsm/L
Source: K&M and PN Nutrition in ADA, Nutrition in Clinical Practice. P 626
Osmolarity Quick Calculation
To calculate solution osmolarity:
 multiply grams of dextrose per liter by 5
 multiply grams of protein per liter by 10
 add a & b
 add 300 to 400 to the answer from "c".
(Vitamins and minerals contribute about
300 to 400 mOsm/L.)
Source: http://www.csun.edu/~cjh78264/parenteral/calculation/calc07.html
Is the solution compoundable?
 TPN is compounded using 10% or 15%
amino acids, 70% dextrose, and 20% lipids
 The TPN prescription must be
compoundable using standard base
solutions
 This becomes an issue if the patient is on a
fluid restriction
Is the Solution Compoundable?
What is the minimum volume to compound the PN
prescription?
Example: 75 g AA
350 g dextrose
50 g lipid
2000 ml fluid restriction
AA: 10 g = 75 g = 750 ml using 10% AA
100 ml X ml
OR divide 75 grams by the % base solution, 75 g/ .10
Is the solution compoundable?
Dextrose: 70 g = 350 g
100 ml X ml
x = 500 ml
Lipid:
X = 250 ml
20 g = 50g
100 ml
x ml
Total volume = 750 ml AA + 500 ml D + 250 ml lipid + 100
ml (for electrolytes/trace) = 1600 ml (minimum volume to
compound solution)
Tip: Substrates should easily fit in 1 kcal/ml solutions
Is this solution compoundable?
PN prescription:
AA 125 g
D 350 g
Lipid 50 g
Fluid restriction 1800 ml/day
Is this solution compoundable?
AA:
10 g = 125 g = 1250 ml 10% AA
100 ml
X ml
Dextrose: 70 g = 350 g x = 500 ml (350/.70)
100 ml X ml
Lipid:
20 g = 50g
100 ml
x ml
X = 250 ml (50/.20)
Total volume = 1250 ml AA + 500 ml D + 250 ml lipid + 100
ml (for electrolytes/trace) = 2100 ml (minimum volume to
compound solution)
Verdict: not compoundable in 1800 ml.
Action: reduce dextrose content or use 15% AA base solution
if available (could deliver protein in 833 ml of 15%)
Parenteral Nutrition
Monitoring
Monitoring for Complications
 Malnourished patients at risk for refeeding
syndrome should have serum phosphorus,
magnesium, potassium, and glucose levels
monitored closely at initiation of SNS. (B)
 In patients with diabetes or risk factors for glucose
intolerance, SNS should be initiated with a low
dextrose infusion rate and blood and urine glucose
monitored closely. (C)
 Blood glucose should be monitored frequently
upon initiation of SNS, upon any change in insulin
dose, and until measurements are stable. (B)
ASPEN BOD. Guidelines for the use of enteral and parenteral nutrition in adult and pediatric
patients. JPEN 26;41SA, 2002
Monitoring for Complications
 Serum electrolytes (sodium, potassium, chloride,
and bicarbonate) should be monitored frequently
upon initiation of SNS until measurements are
stable. (B)
 Patients receiving intravenous fat emulsions
should have serum triglyceride levels monitored
until stable and when changes are made in the
amount of fat administered. (C)
 Liver function tests should be monitored
periodically in patients receiving PN. (A)
ASPEN BOD. Guidelines for the use of enteral and parenteral nutrition in adult and
pediatric patients. JPEN 26;41SA, 2002
Acute Inpatient PN Monitoring
Daily
Frequency
3x/week
Glucose
Initially
√
Electrolytes
Phos, Mg,
BUN, Cr, Ca
Initially
√
Initially
Parameter
Weekly
√
√
TG
Fluid/Is & Os
Temperature
T. Bili, LFTs
√
√
Adapted from K&M, p. 549
Initially
√
Inpatient Monitoring PN
Parameter
Body Weight
Daily
Frequency
Weekly
Initially
√
Nitrogen Balance
HGB, HCT
Initially
√
Catheter Site
√
Lymphocyte Count
Clinical Status
√
PRN
√
√
Monitor—cont’d
 Urine:
Glucose and ketones (4-6/day)
Specific gravity or osmolarity (2-4/day)
Urinary urea nitrogen (weekly)
 Other:
Volume infusate (daily)
Oral intake (daily) if applicable
Urinary output (daily)
Activity, temperature, respiration (daily)
WBC and differential (as needed)
Cultures (as needed)
Monitoring: Nutrition
Serum Hepatic Proteins
Parameter
t½
Albumin
19 days
Transferrin
9 days
Prealbumin
2 – 3 days
Retinol Binding Protein
~12 hours
Complications of PN
 Refeeding syndrome
 Hyperglycemia
 Acid-base disorders
 Hypertriglyceridemia
 Hepatobiliary complications (fatty liver,
cholestasis)
 Metabolic bone disease
 Vascular access sepsis
Refeeding Syndrome
 Patients at risk are malnourished,
particularly marasmic patients
 Can occur with enteral or parenteral
nutrition
 Results from intracellular electrolyte shift
Refeeding Syndrome Symptoms
 Reduced serum levels of magnesium,
potassium, and phosphorus
 Hyperglycemia and hyperinsulinemia
 Interstitial fluid retention
 Cardiac decompensation and arrest
Refeeding Syndrome
Prevention/Treatment
 Monitor and supplement electrolytes,
vitamins and minerals prior to and during
infusion of PN until levels remain stable
 Initiate feedings with 15-20 kcal/kg or 1000
kcals/day and 1.2-1.5 g protein/kg/day
 Limit fluid to 800 ml + insensible losses
(adjust per patient fluid tolerance and
status)
Fuhrman MP. Defensive strategies for avoiding and managing parenteral nutrition
complications. P. 102. In Sharpening your skills as a nutrition support dietitian. DNS,
2003.
Glycemic Control in Critical
Care
 Until recently, BG<200 mg/dl was tolerated
in critically ill patients.
 Now greater attention is given to glycemic
control due to evidence that glucose is
associated with morbidity/mortality and
risk of infection
 New recommendation is to keep BG<150
mg/dl or as close to normal as possible
Van den Berghe et al. NEJM, 2001
Glycemic Control in PN
 In critically ill patients, recommendation is
to keep dextrose infusion <5 mg/kg/minute
or <60% of total kcals.
ASPEN Nutrition Support Practice Manual, 2005, p. 267
Glycemic Control in PN
For Patients Not Previously on Insulin
 Monitor blood glucose levels prior to
initiating PN
 When therapy is initiated, monitor BG q 4-6
hours and use sliding scale or insulin drip as
needed
 Add a portion of the previous day’s insulin
to TPN to maintain blood glucose levels
Charney P. A Spoonful of Sugar: Glycemic Control in the ICU. In Sharpening
your skills as a nutrition support dietitian. DNS, 2003.
Glycemic Control in PN
For Patients Previously on Insulin
 Determine amount of insulin needed prior
to illness
 Determine amount of feedings to be given
 Provide a portion of daily insulin needs in
first PN along with sliding scale or insulin
drip to maintain glucose levels (generally
insulin needs will increase while on PN)
Charney P. A Spoonful of Sugar: Glycemic Control in the ICU. In Sharpening your
skills as a nutrition support dietitian. DNS, 2003.
Regular Insulin in PN
 Availability in TPN : 53 – 100%
 Short half-life
 Delivery coincides with nutrient
infusion
Fluid Excess
 Critically ill pts and those with cardiac, renal,
hepatic failure may require fluid restriction
 May need to restrict total calories to reduce total
volume
 Use most concentrated source of PN components
(70% dextrose = 2.38 kcal/ml; 20% lipid = 2
kcal/ml)
 PPN may be contraindicated due to fluid volume
of 2-4 liters
Fluid Deficit
 Patients with excessive losses may require
sterile water added to the PN
 Provide consistently required fluid volume
in PN
 Monitor I/O, weight, serum sodium, BUN,
HCT, skin turgor, pulse rate, BP, urine
specific gravity
Electrolytes
 Electrolytes in PN should be given at a stable dose
with intermittent requirements for
supplementation given outside the PN
 Sodium levels often reflect fluid distribution
versus sodium status
 Hypokalemia may be due to excessive GI losses,
metabolic alkalosis, and refeeding
 Hyperkalemia may be due to renal failure,
metabolic acidosis, potassium administration, or
hyperglycemia
Acid-Base Balance
 Balance chloride and acetate to
maintain/achieve equilibrium
 The standard acetate/chloride ratio is 1:1
 Increase proportion of chloride with
metabolic alkalosis; increase proportion of
acetate with metabolic acidosis
 Consider chloride and acetate content of
amino acids
Metabolic Acidosis Etiology
 Increased renal or GI loss of bicarbonate
 Addition of strong acid or underexcretion of
H+ ion
 Ketoacidosis
 Renal failure
 Lactic acidosis
 Excessive Cl- administration
Metabolic Acidosis Treatment
 Determine and treat underlying cause
 Prove acetate forms of electrolytes with
HCO3- losses
 Decrease chloride concentration in TNA
 Consider chloride concentration in other IV
fluids
Metabolic Alkalosis Etiology
 loss of H+ ion from increased gastric losses
 Excessive base administration
 Contraction alkalosis
Metabolic Alkalosis Treatment
 Determine and treat underlying cause
 Increase Cl- when alkalosis is due to
diuretics or NG losses
Transitional Feeding
 Maintain full PN support until pt is tolerating 1/3
of needs via enteral route
 Decrease TPN by 50% and continue to taper as the
enteral feeding is advanced to total
 TPN can reduce appetite if >25% of calorie needs
are met via PN
 TPN can be tapered when pt is consuming greater
than 500 calories/d and d-c’d when meeting 60%
of goal
 TPN can be rapidly d-c’d if pt is receiving enteral
feeding in amount great enough to maintain blood
glucose levels
Cessation of TPN
 Rebound hypoglycemia is a potential
complication
 Decrease the volume by 50% for 1-2 hours
before discontinuing the solution to
minimize risk
 PPN can be stopped without concern for
hypoglycemia
Defense Against PN
Complications
 Select appropriate patients to receive PN
 Aseptic technique for insertion and site care of IV
catheters
 Do not overfeed
– Maintain glycemic control <150-170 mg/dl
– Limit lipids to 1 gm/kg and monitor TG levels
– Adjust protein based on metabolic demand and organ
function
 Monitor fluid/electrolyte/mineral status
 Provide standard vitamin and trace element preps
daily