The document discusses parenteral nutrition for critically ill patients. It begins by noting the high prevalence of malnutrition in ICUs and challenges in predicting metabolic needs. It then covers the indications for and types of parenteral nutrition, including total and peripheral parenteral nutrition. Practical considerations for intravenous site selection and formulations are discussed. The requirements and recommendations for energy, fluids, carbohydrates, proteins, fats, electrolytes, trace elements and vitamins are provided. Finally, preparations of single and multi-nutrient parenteral nutrition solutions are described.
2. INTRODUCTIOn
• The prevalence of malnutrition among critically ill
patients has remained largely unchanged over
the last two decades.
• The metabolic response to stress, injury, surgery,
or inflammation cannot be accurately predicted
and these metabolic alterations may change
during the course of illness.
3. Introduction(contd…)
• Both underfeeding and overfeeding are common
in ICUs, resulting in large energy and other
nutritional imbalances.
• Systematic research and clinical trials on various
aspects of nutritional support in the ICU are
limited and make it challenging to compile
evidence-based practice guidelines.
4. Why do we require nutrition?
• Energy production.
• Growth / wound healing.
• Maintain good health.
• Maintain good immunity system.
• Physical and mental development.
• To provide raw materials for synthesis of various
substances. e.g. enzymes, hormones, antibodies etc.
5. In critically ill patients
Consumption > Supply of nutrients.
Break down of body tissues
Negative Nitrogen Balance
Reduced immunity
↑ Infection
↓ Wound healing
Increases morbidity with poor outcome
Prolongs hospital stay of critical patients.
6. Definition & types
Parenteral Nutrition(PN): feeding someone via their
blood stream ‘intravenously’.
Partial or Peripheral Parenteral Nutrition(PPN):
simultaneous intravenous nutrition with enteral
nutrition.
Total Parenteral Nutrition(TPN): feeding a patient
solely via the intravenous route.
12. Peripheral Vein(contd…)
ADVANTAGES:
• Least expensive
• Easily placed and
removed.
• Lowest risk for catheter
related infections
DISADVANTAGES:
• High levels of phlebitis and
vein damage
• Need to change frequently
(48–72 hours)
• Kcals usually limited due to
volume restriction.
• Limited to one lumen.
• Limits infusion osmolality to
600–900 mOsm/L and
infusion pH between 5 & 9
13. Peripheral Vein(contd…)
• Ideally the peripheral veins are suitable for
administration of isotonic fat emulsions and
hypocaloric dextrose solutions (i.e., < 10%
dextrose)
• Hence, they are limited to preventing starvation
adaptation and minimizing nitrogen loss.*
* Isaacs JW, Millikan WJ, Stackhouse J, Hersh T, Rudman D. Parenteral nutrition of adults
with a 900 milliosmolar solution via peripheral veins. Am J Clin Nutr 1977;30:552-9.
14. Peripheral Vein(contd…)
• As a rule of thumb: If peripheral access has been changed
2–3 times within the first 48 hours following admission on
standard IV fluids, PPN should not be attempted.
• Combinations of heparin(1500 U) and hydrocortisone(15
mg) added to the PPN formulation, with or without the use
of a nitroglycerin patch(0.1 mg/hr) placed proximal, and as
close as possible to the catheter site, have been used to
extend the viability of peripheral catheters. *
* Tighe MJ, Wong C, Martin IG, et. al. Do heparin, hydrocortisone, and glyceryl trinitrate
influence thrombophlebitis during full intravenous nutrition via a peripheral vein? J Parent
Enteral Nutr, 1995;19(6):507-509.
15. Central vein
• Central venous catheters provide temporary or
longterm access to large diameter veins with
blood flows in the range of 2–6 L/min.
• This rapid blood flow allows infusion of
formulations with osmolarities > 900 mOsm/L.
• If multiple lumens catheter is used, a single
lumen should be designated for PN use only.
16. Central Vein(contd…)
• The Subclavian Vein is the most suitable vein for
parenteral nutrition.
• This is comfortable to the patient and carries less
risk of dislodgement compared to the IJV and
Femoral venous catheter.
• It has less thrombophlebitis risk compared to the
Femoral vein.
17. Central Vein(contd…)
• A central venous line should be placed with strict
aseptic precautions after cleaning the skin with
chlorhexidine and dressed with sterile dressing
(changed every 48 hours).
• The European Society for Clinical Nutrition and
Metabolism (ESPEN) has issued specific
guidelines on the use of Central Venous Catheters
with regard to access, care, diagnosis and
therapy of complications.
19. ENERGY REQUIREMENTS
• Requirement of energy: 30 kcal/kg/day (± 5kcal)
• Indirect calorimetry is considered as the gold standard
for the measurement of metabolic rate and substrate
utilisation.
• Harris-Benedict equation is a more practical means of
estimating the Basal Energy Expenditure (BEE) in
adults.*
* Harris JA, Benedict FG. Biometric Studies of Basal Metabolism in Man. Publication No. 270.
Washington, DC: Carnegie Institution of Washington; 1919.
20. Energy Requirements(contd…)
• Men : BEE = 66.67 + 13.75W + 5H – 6A*
• Women: BEE = 655.1 + 9.56W + 1.85H – 4.68A*
H = height in cm
W = weight in kg
A = age in years
Stress factors have to be added to this BEE
* Harris JA, Benedict FG. Biometric Studies of Basal Metabolism in Man. Publication No. 270.
Washington, DC: Carnegie Institution of Washington; 1919.
21. Energy Requirements(contd…)
Hunter DC, Jaksic T, Lewis D, Benotti PN, Blackburn GL, Bistrian BR. Resting energy
expenditure in the critically ill: estimations versus measurement. Br J Surg 1998;75:875-8.
22. Energy Requirements(contd…)
Ideal body weight (Hamwi method):
• Men :
106 lb (for first 5 ft) + 6 lb (for each additional inch
past 5 ft) or
48.0 kg + 2.7 kg per inch over 5 ft.
• Women :
100 lb (for first 5 ft) + 5 lb (for each additional inch
past 5 ft) or
45.5 kg + 2.2 kg per inch over 5 ft.
23. Energy Requirements(contd…)
• A much easier method is computation of the IBW
by Broca’s index:
Men : Wt in Kg = (Height in cm) – 100
Women: Wt in Kg = (Height in cm) – 105
• Adjusted Body Weight:
IBW + 0.4(Actual Body Weight – IBW)
24. FLUID REQUIREMENT
• Depends on the hydration status of the patient and the
clinical conditions, such as, renal failure, congestive heart
failure etc.
• Generally TPN orders should be reviewed twice daily on a
12-hour basis, so that changes in electrolytes or acid-base
balance can be addressed appropriately without wastage of
costly TPN solutions.
• Requirement of water = 30 ml/kg/day or 1
ml/kcal
25. CARBOHYDRATE REQUIREMENTS
• Carbohydrate is generally provided in amounts
up to 60% of total kcals/day.
• In the hospitalized patient, initial dextrose in PN
solutions should not exceed 7.2 g/kg/day (5
mg/kg/minute) to minimize the occurrence of fatty
liver and hyperglycemia.
• Diabetic patients are at a greater risk for
development of hyperglycemia, hypertriglyceridemia
and an increased RQ of > 1.0 if carbohydrates are
used in excess.
26. Carbohydrate Requirements(contd…)
• Dextrose monohydrate, in concentrations from
2.5 to 70%, is the most common form in which
carbohydrate is administered parenterally.
• 1 gram of Dextrose provides 3.4 Kcalories.
• Most TPN regimens utilise ≤ 25% dextrose,
while the PPN utilise ≤ 10% dextrose solutions
for safe osmolarity infusion.
27. Carbohydrate Requirements(contd…)
• Fructose, sorbitol, xylitol and glycerol as
carbohydrate sources for parenteral nutrition
have been and are being studied, but none of
them have been seen to have any decisive
advantage over dextrose and do not have the US
Food and Drug Administration(USFDA) approval
for use.*
* Karlstad MD, DeMichele SJ, Bistrian BR, Blackburn GL. Effect of total parenteral nutrition
with xylitol on protein and energy metabolism in thermally injured rats. JPEN J Parenter Enteral
Nutr 1991;15:445-9.
28. Dextrose Solutions
• The carbohydrate source for TPN is dextrose.
• The dextrose solutions must be concentrated to provide
enough calories to satisfy daily requirements.
• The standard solution is 50% dextrose, or D50.
• These solutions are hyperosmolar, and must be infused
through large central veins.
30. PROTEIN REQUIREMENTS
• Healthy adults = 0.8–1.0 g/kg/day
• Parenteral proteins were earlier provided as
casein solutions, which had higher microbicidal
growth rates due to contamination.
• But now they are provided in the form of
crystalline amino acids, which have better
nitrogen balance and do not promote microbial
growth.
31. Protein Requirements(contd…)
• Critically ill patients(without hepatic or renal
dysfunction) = 1.5 g/kg/day.
• Acute Renal Failure : 1.5–1.6 g/kg/day
• Chronic Renal Failure = 0.6–0.8 g/kg/day.
• Renal replacement therapy = 2.5 g/kg/day
• In the past, restricting protein in patients with liver
failure was the standard practice. however, it is now
accepted that this may worsen the underlying liver
disease, and does not aid hepatic encephalopathic
episodes.
32. Amino Acid Solutions
• Utilized for protein synthesis only. Not for energy
production.(4kcal/g)
• Correct / prevent Negative Nitrogen balance.
• Protein is provided as amino acid solutions that
contain varying mixtures of essential
(N=9), semi-essential (N=4), and nonessential
(N=10) amino acids.
34. Amino Acid Solutions(contd…)
• Should be given with energy providing Nutrients.
• Should have EAA, NEAA, BCAA. + Electrolytes
• Hyperosmolar solutions:
Osmolarity : 5% - 10% -
490 mosmol/L 990 mosmol/L
35. Amino Acid Solutions(contd…)
GLUTAMINE:
• Principal metabolic fuel for rapidly dividing cells like
intestinal epithelial cells & vascular endothelial cells.
• Maintains the integrity of the bowel mucosa.
• Recommended as a daily nutritional supplement in ICU patients (0.2–
0.4 g/kg/day).*
* Singer P, Berger MM, Van den Berghe G, et al. ESPEN guidelines on parenteral nutrition: Intensive care.
Clin Nutr 2009; 387–400.
36. FAT REQUIREMENTS
• Lipids are used to provide 30% of daily caloric
requirements, and 4% of the daily calories
should be provided as linoleic acid to prevent
essential fatty acid deficiency(EFAD).
• EFAD may develop within 3 weeks of fat free
parenteral nutrition.
• Soybean / safflower oil, egg yolk phospholipids
in 10%, 20% & 30% concentrations are the
common sources for lipids in TPN.
37. Fat Requirements(contd)
• Propofol and parenteral intralipids must be used
with caution because they are mainly composed
of soybean oil or omega-six fatty acids, which
have been seen to be immunosuppressive.
• Long chain triglycerides (LCT) were the main
source of lipids used in TPN earlier, but
subsequent studies have suggested that the LCTs
impair the immune system, specifically the
reticuloendothelial system.
38. Fat Requirements(contd)
• Structured lipids(combination of long and
medium chain fatty acids) have been found to
improve LFT and maintain LDL and HDL ratio.
• The CDC recommends that intralipid infusions be
given within 12 hours once started, to avoid
gram-negative sepsis.*
*Brown DH, Simkover RA. Maximum hang times for i.v. fat emulsions. Am J Hosp Pharm
1987;44:282,284.
39. Lipid Emulsions
• Lipids are provided as emulsions composed of
submicron droplets of cholesterol, phospholipids, and
triglycerides.
• The triglycerides are derived from vegetable oils
(safflower or soybean oils) and are rich in linoleic
acid, an essential fatty acid
• lipid emulsions are available in 10% and 20%
strengths.
• The 10% emulsions provide approximately 1 kcal/mL,
and the 20% emulsions provide 2 kcal/mL.
40. Lipid Emulsions(contd…)
• The lipid emulsions are available in unit volumes
of 50 to 500 mL, and can be infused separately (at
a maximum rate of 50 mL/hour) or added to the
dextrose–amino acid mixtures.
• The triglycerides introduced into the bloodstream
are not cleared for 8 to 10 hours, and lipid
infusions often produce a transient, lipemic
appearing plasma.
44. Micronutrient Requirements(contd…)
• calcium is provided as a gluconate and
magnesium is provided as a sulphate, due to
improved solubility and compatibility.
• Renal failure, cardiac problems, intestinal losses,
hydration status of the patient along with clinical
judgement should be factors in considering
altering these normal recommendations for
electrolytes.
46. Micronutrient Requirements(contd…)
• Copper, zinc, selenium and chromium are the
common trace elements that are supplemented in
PN.
• Many of these trace elements are monitored
monthly in case of patients on prolonged PN, and
subsequent action is taken in the forthcoming
month.
47. Micronutrient Requirements(contd…)
• Manganese and copper may be withheld in
patients with hepatic dysfunction.
• Selenium and chromium intake is restricted in
cases of renal failure.
• Iron is incompatible with lipid containing
formulations of PN and is usually administered as
iron dextran in solution containing dextrose.
48. Micronutrient Requirements(contd…)
• Iodine is often omitted from PN, given that an
adequate amount of iodine is absorbed into the
skin, due to use of iodine containing
disinfectants/ detergents during hospital stay.
• Molybdenum supplementation is required in
neonates / infants on prolonged PN.
50. Micronutrient Requirements(contd…)
• Multivitamin preparations that are commercially
available can be added to PN solutions.
• Many of these lack vitamin K, which needs to be
added separately into the PN bag once a week.
• Thiamine is excessively lost in patients on dialysis
and merits individual supplementation in such
patients.
51. Micronutrient Requirements(contd…)
• It is common for intensivists to err on the side of
over provision of large amounts of vitamin C,
thiamine and perhaps zinc; considering their role
in wound healing and improvement in the general
condition;
• But this at times may be deleterious, as
excessive amounts of these, especially vitamin C,
may lead to increased oxidative stress.
54. Two-in-one Solution
Two chambered bag
1. Amino Acid Solution + (Electrolytes)
2. Dextrose solution.
Contents of both chambers are mixed
together just before infusion.
Volume = 1.5 – 2L
Cal = 1500 - 2000 kcal
Requires fat to be infused.
55. Three-in-one solution
Three chambered bag-
•All three components –
Dextrose, Fat, Amino Acids
and electrolytes are supplied in a
single three chambered pack.
•Mixed together just before I.V.
infusion with many advantages.
•Volume – 2L
•Calorie – 2000kcal
58. Creating a TPN Regimen(contd…)
STEP 1:
• Determine the daily requirement for calories and
protein.
• The daily requirement for calories is 25 kcal/kg.
• The daily protein requirement is 1.2–1.6 g/kg.
59. Creating a TPN Regimen(contd…)
• For the 70 kg patient,
We will use actual body weight, and a daily
protein requirement of 1.4 g/kg.
Therefore, the daily requirement for calories and
protein will be:
Calories: 25 X 70 = 1,750 Kcal/day
Protein: 1.4 X 70 = 98 grams/day
60. Creating a TPN Regimen(contd…)
STEP 2:
• Take a standard mixture of 10% amino acids
(500 mL) and 50% dextrose (500 mL) and
determine the volume of this mixture that is
needed to deliver the estimated daily protein
requirement.
61. Creating a TPN Regimen(contd…)
• The volume of the A10-D50 mixture that will
provide the daily protein requirement is:
98/50 = 1.9 L
• If this mixture is infused over 24 hours, the
infusion rate will be:
1900 ml /24 hr = 81 ml/hr
62. Creating a TPN Regimen(contd…)
STEP 3:
• Now, determine how many nonprotein calories will be
provided by 1.9 liters of A10-D50.
• Dextrose in 1.9 liters of A10-D50:
250 g/L X 1.9 L = 475 gms D
• Now, using an energy yield of 3.4 kcal/g for dextrose,
calculate the calories provided by 475 grams of
dextrose:
475 X 3.4 = 1,615 kcal/day
63. Creating a TPN Regimen(contd…)
STEP 4:
• Daily requirement = 1750 kcal
• Daily dextrose calories = 1615 kcal
• Deficit = 1750 – 1615 = 135 kcal
• The remaining 135 Kcalories will be provided
by lipids.
64. Creating a TPN Regimen(contd…)
• If a 10% lipid emulsion (1 kcal/mL)
is used, the volume will be 135 mL/day.
• Lipid emulsions are available in unit volumes
of 50 mL, so the volume can be adjusted to
150 mL to avoid wastage.
• The maximum infusion rate is 50 mL/hr.
65. Creating a TPN Regimen(contd…)
STEP 5:
• The TPN orders for this example can be written as
follows:
1. A10-D50 to run at 80 mL/hour.
2. 10% Intralipid, 150 mL, to infuse over 3 hours.
3. Add standard electrolytes, multivitamins, and
trace elements.
67. • It would be prudent to start it as soon as one
appreciates that the patient is in requirement of
TPN, that is, nutritionally compromised.
• Strict aseptic precautions should be followed
during introduction of the central line; the
external dressing should be changed every 48
hours using sterile precautions. The external
tubing should be changed every 24 hours starting
with the first feed of the day.
68. • The lumen being used for TPN should be
exclusively reserved for it and no drugs /
infusions (except insulin infusion) should be
allowed in that lumen.
• An interdisciplinary nutrition team, comprising of
the treating physician, intensivist, nutritional
therapist and critical care nurse should monitor
the patient’s nutritional status regularly on a day-
to-day basis.
69. Mirtallo JM. Introduction to parenteral nutrition. In: Gottschlich MM, Ed. The Science and
Practice of Nutrition Support: A Case-Based Core Curriculum. Dubuque, IA: Kendall/Hunt
Publishing Co.;2001: 211–223
70. • Blood lipid levels may be monitored twice weekly.
• Liver function tests must be monitored weekly.
• Patients on long-term TPN need monthly
monitoring of vitamin, mineral and trace element
status.
• Monitoring should be highly individualised to the
existing needs and co-morbidities of the patient.
72. • Catheter-Related Complications
• Carbohydrate Related Complications
• Lipid Related Complications
• Hepatobiliary Complications
• Bowel Sepsis
73. Catheter-Related Complications
A) Due to insertion - Injury to Nerves, blood
vessels, pneumothorax, infusion of PN
solution into plueral cavity.
B) Infection – sepsis, septicaemia, septic shock.
C) Thrombophlebitis – peripheral vein
D) Air Embolism.
74. Carbohydrate Related Complications
• HYPERGLYCEMIA & hypoglycaemia.
• Tight glycemic control is not recommended in
critically ill patients.
• The target range of blood glucose = 140–180
mg/dl.
75. Carbohydrate Related Complications(contd…)
INSULIN THERAPY:
• A continuous infusion of regular insulin is preferred for
critically ill patients who are unstable or have T1DM to
prevent wide swings in glucose levels.
• This can be accomplished by adding insulin to the TPN
solutions.
• Subcutaneous insulin can be used for patients who are
stable.
• Regimens will vary in each patient, but the combination of
an intermediate or long-acting insulin with a rapid-acting
insulin, when needed, is a popular for hospitalized patients.
76. Carbohydrate Related Complications(contd…)
HYPOPHOSPHATEMIA:
• The movement of glucose into cells is associated with a
similar movement of phosphate into cells, and this provides
phosphate for co-factors (e.g., thiamine pyrophosphate)
that participate in glucose metabolism.
• This intracellular shift of phosphate can result in
hypophosphatemia if extracellular phosphate levels are
marginal.
77. Carbohydrate Related Complications(contd…)
RE-FEEDING SYNDROME:
• The potentially fatal shifts in fluids and
electrolytes in malnourished patients receiving
artificial refeeding (whether enterally or
parenterally).
• These shifts result from hormonal and metabolic
changes caused by rapid refeeding and may
cause serious clinical complications.
78. • Observed in patients kept NPO for >7–10 days,
chronic alcoholics and those with severe systemic
derangements on initiation of TPN.
• Hallmark is hypophosphataemia.
• Abnormal Na+ and fluid balance; changes in
glucose, protein, and fat metabolism; thiamine
deficiency; decrease serum K+ & Mg2+.
80. PREVENTION(NICE guidelines):-
• Refeeding should be started at a low level of
energy replacement(<50 %).
• Vitamin supplementation should also be started
with refeeding and continued for at least 10 days.
• Correction of electrolyte and fluid imbalances
before feeding is not necessary; it should be
done alongside feeding.
81. Carbohydrate Related Complications(contd…)
HYPERCAPNIA:
• Excess carbohydrate intake promotes CO2
retention in patients with respiratory
insufficiency.
• However, CO2 retention is a consequence of
overfeeding, and not only overfeeding with
carbohydrates.
82. Lipid Related Complications
• Hypertriglyceridemia
• Essential fatty acid deficiency(EFAD)
• Promote inflammation: Lipid emulsions used in
TPN regimens are rich in oxidizable lipids.
oxidation of infused lipids will trigger an
inflammatory response.
83. Hepatobiliary Complications
HEPATIC STEATOSIS:
• Fat accumulation in the liver is common in patients
receiving longterm TPN.
• It is believed to be the result of chronic overfeeding
with carbohydrates and lipids.
84. • CHOLESTASIS :
• The absence of lipids in the proximal small bowel
prevents cholecystokinin-mediated contraction of
the gallbladder.
• Bile stasis and the accumulation of sludge in the
gallbladder can lead to acalculous cholecystitis.
85. Bowel Sepsis
Lose of functional and structural integrity of gut:
The absence of nutritional bulk in the GI tract leads
to atrophic changes in the bowel mucosa, and
impairs bowel-associated immunity, and these
changes can lead to the systemic spread of enteric
pathogens.
89. Summary
• Critically sick patients are in catabolic phase, require more
energy and nutrients.
• PN is a valuable and necessary medical treatment for
providing both nutritional sustenance and life extension at a
time when it is not possible to sustain them any other way.
• By focusing on the essential elements of PN management,
this form of nutrition support can be applied successfully
with minimal complications.