Download File

PARENTERAL NUTRITION
FORMULA CALCULATIONS AND
MONITORING PROTOCOLS
KNH 411 Medical Nutrition Therapy I
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 20% lipid


500 ml x 1.1 kcal/ml = 550 kcal
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

Kcals: 1800 Protein: 88 g Fluid: 2000 cc
 Lipid


Needs:
: 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
100 ml
= 125 g = 1250 ml 10% AA
X ml
Dextrose: 70 g = 350 g
100 ml X ml
x = 500 ml (350/.70)
Lipid:
X = 250 ml (50/.20)
20 g = 50g
100 ml
x ml
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
Albumin
t½
19 days
Transferrin
days
9
Prealbumin
days
2–3
Retinol Binding Protein
hours
~12
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 HCO3losses
 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