Balancing Parenteral Nutrition Components in Critical Care

03

Sep 24

Nutrition is essential for good health and disease resistance. Most patients can meet their nutritional needs by eating a normal, high-quality diet. However, if a regular diet is insufficient, clinical nutrition therapy is necessary. This may involve oral nutritional supplements, enteral tube feeding, and/or parenteral nutrition (Figure 1).

Figure-1: Routes of nutrition therapy

Enteral nutrition is recommended for patients who are unable to receive optimal nutrition by eating. This method is preferred over giving nutrition through the veins as it is natural and costs less. However, enteral nutrition alone may not provide enough energy and protein, which can worsen health outcomes. In critical care situations, it can be challenging to provide enteral nutrition, which increases the risk of not getting enough nutrients.

Enteral nutrition is preferred but challenging in critical care settings as it increases the risk of underfeeding.

Enteral Nutrition in ICU:

Enteral nutrition (EN) can lead to side effects such as diarrhea. A study of 1712 intensive care unit (ICU) patients who were given enteral nutrition observed that feeding intolerance was strongly associated with higher mortality rates. Non-survivors experienced diarrhea, bowel distension, large gastric residual volume, and absent bowel sounds more frequently than survivors. Underfeeding can increase the risk of complications, including infections, prolonged mechanical ventilation, and death.

EN is contraindicated in intestinal obstruction, lack of intestinal function (e.g., due to severe inflammation or post-operative stasis), and high-loss intestinal fistulae and in conditions where there is an inability to access the gut. It is better to avoid it in patients susceptible to opportunistic infections (oncology treatment, maxillofacial surgery), patients with severe vomiting, and intractable diarrhea.

Parenteral nutrition (PN) is recommended when oral or enteral nutrition is not possible, inadequate, or contraindicated. Additionally, when enteral nutrition alone is insufficient, supplemental parenteral nutrition can be given to help achieve nutritional goals. Table-2 explains the guidelines on when to initiate supplemental parenteral nutrition. It is suggested: “If the energy and nutrient requirements cannot be met by oral and enteral intake alone (<50% of caloric requirement) for more than 7 days, a combination of enteral and parenteral nutrition is recommended (GPP).” If indicated, then parenteral nutrition should be administered as soon as possible, particularly if enteral nutrition is contraindicated. Grade of recommendation GPP [Good Practice Point]/A indicates a strong consensus (100% agreement). 1 

Optimal Timing for Parenteral Nutrition

There is some controversy regarding the ideal time for initiating parenteral nutrition. The American Society for Parenteral and Enteral Nutrition (ASPEN) recommends the following:

  • Supplemental PN initiation 7 days after ICU admission of a well-nourished and stable patient who has been unable to receive 50% or more of their required nutrition from oral or enteral nutrients.
  • PN is to be initiated within 3 to 5 days for those who are nutritionally at risk and are unlikely to achieve the desired EN.
  • PN is to be started as soon as possible after ICU admission in severely malnourished patients at high nutritional risk where EN is not feasible.
  • PN is to be avoided in patients with severe metabolic instability until the condition improves. 2

The European Society for Clinical Nutrition and Metabolism (ESPEN) recommends that all critically ill patients staying in the ICU for more than 2 days should be considered at risk for malnutrition and PN should be started.3 

BUN-blood urea nitrogen; BW-body weight; EN-enteral nutrition, GVR-gastric residual volume; PN-parenteral nutrition; SPN-supplemental parenteral nutrition

Table-2: Clinical approach to supplementary parenteral nutrition.

When EN is insufficient, timely supplemental PN can effectively help reach nutritional goals and improve outcomes. Recent studies showed that timely intervention with PN results in fewer hospital-acquired infections, reduced time on mechanical ventilation, and a potential decrease in mortality rates. Controlled trials demonstrated that, following ICU admission, PN enhanced clinical outcomes and lowered costs. It must be noted that timely PN initiation is safe and well tolerated when used as recommended, as long as overfeeding and hyperglycemia are avoided.

Timely supplemental parenteral nutrition lowers the risk of infection and the length of mechanical ventilation.

Optimal Parenteral Nutrition Composition: The composition of parenteral nutrition is just as important as the method of delivery. Amino acids, glucose, and lipids are the three main nutritional components for humans. When given together in the right quality and quantity, these three macronutrients form the core of a balanced nutritional supply. Adequate nutrition is especially crucial for critically ill patients with trauma, major surgery, systemic inflammatory response syndrome (SIRS), or sepsis. Ideally, these patients require nutrition that includes amino acids, glucose, and lipids. Nutritional and energy needs vary for each patient based on their clinical condition, body weight, and nutritional status. Therefore, PN dosage should be adjusted based on any oral and/or enteral intake. Nitrogen requirements for maintaining body protein mass vary depending on the patient’s condition, such as their nutritional state and degree of catabolic stress or anabolism. Similarly, the lipid dose of PN recommended by ESPEN varies according to the patient’s underlying condition. A complete PN regimen, widely used in hospital settings, consists of an optimized combination of amino acids, glucose, and lipids, along with the addition of vitamins, trace elements, and electrolytes.

Right quality and correct proportion of amino acids, glucose, and lipids form the essential components of a balanced PN to supply & meet the specific nutritional needs of patients.

A clinical trial involving 2400 ICU patients compared the safety and tolerability of PN with EN. Both groups had similar caloric intakes, but most patients did not achieve the target intake. The study found no significant differences between the two groups in terms of the average number of treated infectious complications per patient (0.22 vs 0.21, p=0.72), 90-day mortality rates (37.3% vs 39.1%, p=0.40), 14 other secondary outcomes, or rates of adverse events. Table-3 outlines practical measures for improving the safety of PN.

Parenteral Nutrition ProcessPractical Aspects
PrescriptionCalculation of nutrients according to patients’ needs Development of a nutrition care plan
Preparation/ AdministrationVerification of PN orders should adhere to the five “rights”: right patient, right drug, right dose, right route, and right time. Optimal care of vascular access devices Aseptic handling
MonitoringRegular monitoring of PN therapy: outcome parameters/blood tests (e.g. serum electrolytes, glucose, triglycerides, hepatic and renal function) Documentation of therapy course
Table-3: Practical measures to further enhance the safety of parenteral nutrition

Lipid emulsions

Introduction

Lipid emulsions are an important source of energy and essential fatty acids. According to ESPEN guidelines on PN in intensive care, lipids should be a key component of the regimen to provide energy and essential fatty acids for all patients requiring PN. Parenteral lipid emulsions have been used in routine clinical practice for over 50 years. The earliest studies used soybean oil emulsions, such as Intralipid®, the first well-tolerated lipid emulsion.4 The first generation of lipid emulsions was based on soybean oil or soybean/safflower oil and had a high concentration of long-chain triglycerides consisting predominantly of omega-6 polyunsaturated fatty acids (PUFAs), particularly linoleic acid. A second generation and more complex parenteral lipid emulsions were developed in response to the potential disadvantage of the high omega-6 PUFA content of first-generation lipid emulsions since omega-6 PUFAs are ‘pro-inflammatory and immunosuppressive’. As a result, the latest generation of omega-3 fatty-acid-containing lipid emulsions provides a more balanced combination of fatty acids that aim to achieve the ideal omega-3/omega-6 ratio of approximately 1 to 2. 4

Lipid emulsions play a crucial role in a balanced PN regimen as they provide essential fatty acids, which are a high-caloric & non-glucose energy source that also reduces the risk of hyperglycemia.
Lipid EmulsionsCharacteristicsExamples
First generationRich in omega-6 fatty acids, particularly linoleic acidSoybean oil (e.g. Intralipid)Soybean/safflower oil
Second generationReduced concentration of omega-6 fatty acids, particularly linoleic acidPhysical mixture of MCT/LCT Structured MCT/LCT (e.g. Structolipid®: an emulsion containing medium- and long-chain fatty acids bound to the same glycerol backbone)Olive oil/soybean oil lipid emulsions
Third generationLipid emulsions with a specific fatty-acid pattern Reduced omega-6 fatty-acid content and inclusion of omega-3 fatty acids (EPA and DHA, for example from purified fish oil)Soybean oil/MCT/olive oil/omega-3 fatty acids (SMOFlipid) Omegaven® (10% fish-oil emulsion supplement) Combination of soybean oil/MCT/ omega-3 fatty acids

DHA- docosahexaenoic acid; EPA- eicosapentaenoic acid; LCT- long-chain triglyceride; MCT- medium-chain triglyceride.

Table- 4: First, second, and third-generation lipid emulsions used in PN

Critically ill patients often experience an energy deficit, which can lead to malnutrition, infections, longer hospital stays, and higher mortality rates. To address this issue, patients may receive PN with lipids to improve caloric delivery and correct energy deficits. SMOFlipid, a third-generation lipid emulsion, is a component of SmofKabiven and contains four types of oils: soybean oil, medium-chain triglycerides (MCT), olive oil, and fish oil. SMOFlipid offers additional benefits compared to first- and second-generation lipid emulsions.

SMOFlipid, a 3rd and latest-generation lipid emulsion, is combined of soybean oil, MCT, olive oil, and fish oil, which has additional benefits over 1st and 2nd-generation lipid emulsions.

Source of Essential Fatty Acids:

Incorporating lipid emulsions in PN offers several benefits, such as preventing hyperglycemia and essential fatty-acid deficiency. The first well-tolerated parenteral lipid emulsion, Intralipid, was developed in 1961 based on soybean oil. Although popular in Europe, in the USA, high-osmolar glucose solutions were the only intravenous non-protein energy supply for some time, and lipid emulsions were not initially accepted as part of daily PN. However, it was later discovered that prolonged use of PN devoid of lipid emulsions led to complications such as essential fatty-acid deficiency and hyperglycemia. As a result, lipid emulsions are now recognized as an essential component of PN that ensures the provision of essential fatty acids as well as energy.

Most fatty acids can be made by the human body, except for linoleic acid and alpha-linolenic acid. These are the essential fatty acids that need to be obtained from the diet. Typically, ICU patients need 9-12gm/day of linoleic acid and 1-3gm/day of alpha-linolenic acid. Essential fatty acid requirements differ for pediatric patients, in whom 4.5% and 0.5% of total daily calories should come from linoleic acid and alpha-linolenic acid, respectively. Since these essential fatty acids are produced in plants, plant oils like soybean oil (a component of SMOFlipid) are a rich source. Currently available parenteral lipid emulsions, including SMOFlipid, contain enough linoleic acid and alpha-linolenic acid to prevent essential fatty acid deficiency.

Reducing the Risk of High Glucose Loads:  

When lipids are missing from PN, it can lead to an overload of glucose. High glucose loads generate complications such as hyperglycemia, respiratory stress, excessive carbon dioxide production, fever, additional metabolic stress, and liver steatosis.

Using excessive infusions of hypertonic glucose solutions in critical illnesses that are associated with impaired glucose tolerance results in hyperglycemia, which can potentially progress to a non-ketotic hyperglycemic coma. Hyperglycemia can also be associated with an increased incidence of complications in critically ill patients, such as severe infections, multiple organ failure, and increased mortality rates. In comparison with hypertonic glucose infusions, the modern use of lipid emulsions in PN is associated with a reduction in hyperglycemia and related metabolic complications as the glucose load is reduced. 5

Compared with hypertonic glucose solutions, lipid emulsions in PN are associated with a reduction in hyperglycemia and associated metabolic complications.

The administration of high glucose loads during PN seems to cause metabolic stress, as indicated by increased metabolic rate and catecholamine excretion. These metabolic changes can be reduced by substituting a major portion of glucose calories with intravenous lipid emulsions. Additionally, lipid supplements, due to their ideal respiratory quotient, can reduce nitrogen loss without causing an increase in carbon dioxide production, thus reducing stress on the body. It is known that high glucose intake during PN can lead to increased carbon dioxide production, which can cause respiratory distress, especially in patients with compromised pulmonary function. Experiments have demonstrated that replacing a portion of the glucose with an equal amount of lipids in PN regimens can lead to lower carbon dioxide production and a reduced ventilation rate.

Replacing a portion of the glucose with lipids in PN reduces CO2 and lowers the ventilation rate. This benefits the respiratory and metabolic management of critically ill patients.

Favorable immune and Inflammatory Response with Omega-3 fatty-acid-containing Lipid Emulsions:

SMOFlipid contains fish oil, which has anti-inflammatory and immunomodulatory effects. These effects are most likely due to fish oil’s omega-3 fatty-acid content, consisting of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), as they influence diverse inflammatory processes from signal transduction to protein expression.6

Omega-3 fatty acids exert a beneficial effect on immune deficiency diseases and diseases that ignite hyperinflammation. So, PN that includes fish oil/omega-3 fatty acids will have favorable effects on controlling infection and the length of hospital and ICU stay. Omega-3 and omega-6 fatty acids have opposing actions on inflammation; for example- leukotriene (LT)B4, derived from omega-6 arachidonic acid, is a potent pro-inflammatory mediator, but LTB5 (derived from omega-3 fatty acids) is much weaker in this regard. So, the ideal PN should contain polyunsaturated omega-3 and omega-6 fatty acids in a ratio of 1 to 2.

ESPEN Guidelines on Lipids for Parenteral Nutrition:

The inclusion of lipid emulsions as part of PN offers numerous benefits, and guidelines recommend that they should be an essential component of PN for various patient groups (Table-5). The recommended lipid dose varies among these guidelines, reflecting the diverse lipid requirements of different patient conditions. For instance, while general ICU patients are recommended to receive 0.7—1.5g of lipids per kg of body weight over 12—24 hours, oncology patients may benefit from a higher percentage of lipids in their parenteral nutrition. Specifically, non-surgical oncology PN guidelines highlight the importance of paying special attention to patients with frank cachexia who require PN for several weeks due to abnormalities in energy substrate metabolism. In such cases, using a higher-than-usual percentage of lipids in the admixture (e.g. 50% of non-protein energy) is beneficial. Although recent ESPEN guidelines on clinical nutrition in cancer patients do not recommend a specific lipid dose, they do suggest increasing the ratio of energy from lipids over energy from carbohydrates.

Patient GroupDaily Lipid Requirements
ICU patients0.7—1.5g/kg bw/day over 12—24 hours
Severe pancreatitis0.8—1.5g/kg bw/day
Acute liver failure0.8—1.2g/kg bw/day
Chronic renal failure without renal replacement0.8—1.2g/kg bw/day (Max. 1.5g)
Acute renal failure0.8—1.2g/kg bw/day (Max. 1.5g)
Geriatric patientsLipids constitute a maximum of 50% of the daily energy requirements
Short bowelLipids constitute 33% of the non-protein daily energy requirements or a maximum of 1g/kg bw/day
COPDLipids constitute 35—65% of non-protein daily energy requirements
Alcohol steatohepatitisLipids constitute 40—50% of non-protein daily energy requirements
PediatricsLipids constitute 25—40% of non-protein daily energy requirements
Non-surgical oncologyLipids constitute up to 50% of non-protein daily energy requirements
SurgeryLipids constitute 30% of non-protein daily energy requirements

New ESPEN guidelines are available on clinical nutrition in surgery, and cancer patients,  but these do not define specific glucose requirements. Note: a full list of ESPEN guidelines is available from7

bw-body weight; COPD-chronic obstructive pulmonary disease; ICU-intensive care unit.

Table- 5: Lipid requirements according to ESPEN guidelines on parenteral nutrition

ESPEN guidelines on the lipid dose for PN vary, reflecting diverse lipid requirements in different patient conditions.

The use of PN in elderly patients may require PN regimens with a higher lipid content, accounting for up to 50% of total energy requirements. This is necessary due to the high incidence of insulin resistance and diabetes in this population, which leads to lower glucose utilization and hyperglycemia.8

In patients with chronic obstructive pulmonary disease (COPD), guidelines recommend orienting PN towards lipids as the energy source rather than glucose. Glucose-based PN can cause an increase in respiratory carbon dioxide load, which is particularly undesirable in patients with COPD. By selecting lipids as the energy source, the respiratory quotient can be lowered, and the proportion of lipid-derived non-protein calories should probably be at least 35% (but probably not more than 65%).9

Addition of fish oil/omega-3 fatty acids to lipid emulsions in PN has demonstrable effects on cell membranes and inflammatory processes. It is noted that fish oil-enriched lipid emulsions probably decrease the length of stay in critically ill patients. Postoperative parenteral nutrition, including omega-3 fatty acids, should only be considered in patients who cannot be fed enterally and, therefore, require PN.10

Amino acids

Amino acids are the fundamental building blocks of proteins, playing essential roles in nearly all biological processes and structures. Proteins are comprised of a sequence of amino acids, also known as polypeptide chains, which are folded into specific three-dimensional structures. These structures are maintained by disulfide bridges between cysteine residues in the polypeptide chain. 20 different amino acids make up proteins. Some of the main activities that proteins and amino acids are involved in are summarized as follows:

  1. Enzymes are proteins that are ubiquitous biological catalysts that enhance endogenous reaction rates by at least a million-fold and are involved in nearly all biochemical reactions.
  2. Movement: Muscles are mainly proteins (e.g. actin and myosin) that contract and relax, enabling movement.
  3. Immune support, inflammation, and healing: This includes functions by albumin, fibrinogen, C-reactive protein, and antibodies. Antibodies are proteins that recognize and bind to foreign substances (e.g. antigens such as viruses or bacteria from another organism), triggering an immune response to destroy the antigen.
  4. Transport and storage: Hemoglobin is the iron-protein molecule that transports oxygen in erythrocytes. Transferrin and ferritin are the proteins involved in transporting and storing iron, respectively.
  5. Generating and propagating nerve impulses: Nerve impulses are transmitted and propagated by the release of neurotransmitter substances across synapses (junctions between nerve cells). These neurotransmitters are often amino acids (e.g. glutamate) and the post-synaptic neuroreceptors are glycoprotein molecules such as N-methyl-D-aspartate [NMDA] receptors.
  6. Fluid, electrolyte, and acid-base balance: The proteins involved in these processes include albumin, which helps maintain body fluid volume and composition, and plasma and tissue proteins, which act as buffers to control pH. Other examples are the Na+ K+ ATPases, the membrane-bound glycoprotein enzymes that help control intracellular levels of electrolytes and nutrients such as amino acids and glucose.
  7. Hormonal regulation: Hormones secreted by glands are carried in blood to a site of action (target organs or target cells) elsewhere in the body. Many hormones are derived from amino acids (e.g. thyroxine), polypeptides (e.g. oxytocin), or proteins (e.g. insulin).
  8. Mechanical support: The fibrous protein collagen is a key component of skin and bone that provides these tissues high tensile strength.

Role of Amino Acids in Parenteral Nutrition:

Proteins play a crucial role in the body and are continuously produced and broken down. However, during stressful conditions like trauma, burns, or infections, there is a significant impact on protein balance. In such situations, nearly half of all protein production is dedicated to creating proteins involved in the body’s inflammatory response. This leads to an increase in protein turnover and a shift towards protein breakdown at the whole-body level, causing the loss of proteins from organs like muscles, skin, and bones. The amino acids released from this breakdown in response to stress are utilized in the liver, spleen, immune cells, or wounds. This process can result in muscle wasting, glutamine depletion, high blood sugar, and low levels of albumin in the blood.

To address this protein deficiency, it is recommended to include amino acids in parenteral nutrition. Clinical guidelines from ASPEN, ESPEN, and the German Association for Nutritional Medicine suggest a daily dose of amino acids between 1.2 and 1.5g per kilogram of body weight for most adult patients experiencing protein breakdown, provided their kidney and liver functions are normal. This is notably higher than the recommended daily allowance of 0.8g per kilogram of body weight. It is also important to provide non-protein energy sources in the PN alongside amino acids to ensure that amino acids are not solely used as an energy source. Amino acids can provide about 4kcal of energy per gram, which is similar to the energy provided by glucose but less than that provided by lipids (around 9kcal per gram).

Amino acids are classified as essential, non-essential, or conditionally essential. Essential amino acids, such as histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine, cannot be produced in sufficient quantities by the body and must be obtained from the diet. Non-essential amino acids like alanine, asparagine, aspartic acid, glutamic acid, and serine can be produced by the body and are not essential in the diet, but they still contribute to overall nitrogen balance.

Additionally, certain amino acids, including cysteine, tyrosine, taurine, glycine, arginine, glutamine, and proline, are conditionally essential, meaning that under specific physiological or pathological conditions, the body requires an external supply of these amino acids. Taurine is considered conditionally essential in adults but is essential for infants due to limited endogenous production.

In general, the recommended PN amino acid dose range is about 1.2–1.5gm per kilogram of body weight per day for most adult patients experiencing protein breakdown with normal kidney and liver function. In some cases, higher protein intake, up to approximately 2gm per kilogram of body weight per day, is recommended, such as for patients with burns. Table- 6 outlines amino acid requirements for PN according to ESPEN guidelines.

Patient GroupAmino Acid Requirements
ICU patients1.3—1.5g/kg ideal bw/day
SurgeryUp to 1.5g/kg ideal bw/daya
Oncology> 1.0g/kg bw/day, and if possible up to 1.5g/kg bw/day
Acute pancreatitis1.2—1.5g/kg bw/day
Acute renal failureWithout dialysis: 0.6—0.8g (maximum 1.0g)/kg bw/day With dialysis: 1.0—1.5g/kg bw/day
Home parenteral nutrition0.8—1.0g/kg bw/day Amino acids given should not exceed losses, to limit the risk of hypercalciuria
Inflammatory bowel disease (IBD)1.2—1.5g/kg bw/day during active IBD

New ESPEN guidelines are available on clinical nutrition in surgery but these do not define specific amino acid requirements. Note: a full list of ESPEN guidelines is available from7

b.w-body weight; IBD-inflammatory bowel disease; ICU-intensive care unit.

Table-6: Amino Acid requirement guidelines as per ESPEN.

Glucose

Glucose primarily serves as a readily available source of energy for almost all cells in the body, providing about 4kcal/g of energy. It is also involved in various biosynthetic processes, such as protein synthesis and glycosylation, but these processes make up only a small part of its overall metabolism. Glucose is stored as glycogen in the liver and skeletal muscle, and its metabolism is regulated by the anabolic hormone insulin, as well as the catabolic hormones adrenaline, glucagon, and cortisol. According to the ESPEN parenteral nutrition guidelines, Table-7 shows the glucose requirements.

Patient GroupGlucose Requirements
ICU patientsMinimum amount: ~2g/kg bw/day
Surgery50—70% of non-protein requirement; tendency to increase glucose: fat ratio from 50:50 to 70:30 of non-protein calories a
Non-surgical OncologyNo need for a special formulation a  
Acute pancreatitis50—70% of total energy requirements
Acute renal failure3 —5g (maximum 7g)/kg bw/day
Home parenteral nutrition< 7mg/kg bw/minute (to prevent cholestasis). The fat: glucose energy ratio should not exceed 40:60

New ESPEN guidelines are available on clinical nutrition in surgery, and cancer patients,  but these do not define specific glucose requirements. Note: a full list of ESPEN guidelines is available from7

bw-body weight; ICU-intensive care unit

Table-7: Glucose requirement guidelines as per ESPEN

Summary

  • PN is used when oral and/or EN is not possible, contraindicated, or insufficient.
  • In general, it is recommended that patients who can be fed via the enteral route should receive EN. However, relying solely on EN may lead to inadequate energy and protein intake.
  • EN alone often does not meet energy demands because of contraindications, gastrointestinal intolerance, or frequent interruptions of EN, such as for treatment-related procedures or surgery.
  • It can be very difficult to compensate for nutritional deficits, such as those caused by early underfeeding.
  • Where EN alone is insufficient, early supplemental PN can be an effective strategy to achieve nutritional goals and improve outcomes.
  • When the gastrointestinal tract is not functioning, PN is a generally safe and effective alternative to EN.
  • PN can be delivered either centrally or peripherally.
  • Lipids, glucose, and amino acids constitute the three macronutrients for humans. When given together, and in the correct quality and quantity, they are the core of a balanced and adequate nutritional supply.
  • Lipid emulsions have been used in PN for over 50 years and have an excellent safety and tolerability profile.
  • Lipid emulsions have developed from first-generation emulsions based on soybean oil, to the latest third-generation lipid emulsions, such as SMOFlipid, differentiated by a well-balanced pattern of fatty acids and based on a combination of different lipid components including fish oil.

Important Take Away:

  • Fish oil contains omega-3 polyunsaturated fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which have beneficial anti-inflammatory and immunomodulatory effects.
  • Lipid emulsions provide a concentrated source of calories and essential fatty acids.
  • The use of lipid emulsions in PN has allowed for the partial replacement of glucose as a calorie source. This helps prevent glucose overload, which can lead to harmful consequences such as hyperglycemia, respiratory stress, excessive carbon dioxide production, fever, additional metabolic stress, and liver steatosis.
  • During inflammatory stress/states (e.g. trauma, burns or infections) there is an increased requirement for proteins/amino acids. These are the most important nutrients for healing wounds, supporting immune function, and maintaining lean body mass during stress states.
  • The main function of glucose in PN is, it is a source of readily available energy, and it is also involved in various biosynthetic pathways.
  • Guidelines recommend that lipids, glucose, and amino acids should be integral parts of PN, but requirements for these macronutrients vary according to patient type.

Authors of this article

  1. Professor Syed Mahbubul Alam, MBBS (DMC) & FCPS (Surgery), Former Principal Dhaka Medical College & Former Head of the Department (Surgery), Sir Salimullah Medical College Dhaka, & is the Editor-In-Chief of The Coronal.
  2. Kazi Mahmudul Haque, B.Pharm(ADUST), M.Pharm(UODA), Unit Manager, Radiant Pharmaceuticals Limited.

References

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  3. Singer P, Blaser AR, Berger MM, et al. ESPEN practical and partially revised guideline: Clinical nutrition in the intensive care unit. Clin Nutr. 2023;42(9):1671-1689. doi:10.1016/j.clnu.2023.07.011
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