Caloric Composition and Nutritional Dosing

IV Nutrients

Substance	kcal/g	Common IV Concentration
Dextrose	3.6	70%
Protein	4	3.5-15%
Lipids	10	10%, 20%, and 30% (1, 2, and 3 kcal/mL)

Micronutrient	Quantity QD	Notes
Na	1-2 mEq/kg	Add as Cl, Acetate, or Phos
K	1-2 mEq/kg	Add as Cl, Acetate, or Phos
Phos	20-40 mmol	1 mmol Phos supplies 1.33 mEq Na or 1.47 mEq K, Add as far from Ca as possible
Ca	10-15 mEq	Use Ca Gluconate, put in TPN 1st or Last
Mg	8-20 mEq	Needed in Catabolic / Malnourished Pts
Vitamins	RDA	All vitamins (ADEK, C, and B complexes)
Trace Elements	RDA	Zn, Cu, Mn, Cr, Se

Energy Needs

Harris-Benedict Equations

$$\text{Male BMR} = 66 + 13.7\; \text{Wt} + 5\; \text{Ht} - 6.8\; \text{Age}\\ \text{Female BMR} = 655 + 9.6\; \text{Wt} + 1.7\; \text{Ht} - 4.7\; \text{Age}\\ \text{Wt}\; (kg), \; \text{Ht}\; (cm)$$

TEE

Condition	Goal kcal/kg/d
Non-Stressed, Non-Depleted	20-25
Trauma / Stress / Surgery / Critically Ill	25-30
Major Burn	35-40
Obesity	22-25 (IBW)

$$\frac{\text{Wt}}{\text{IBW}} < 1.3 \implies \text{Wt}\\ \frac{\text{Wt}}{\text{IBW}} > 1.3 \implies \text{NWB}\\ \frac{\text{Wt}}{\text{IBW}} > 1.5 \implies \text{IBW}\\ \text{NBW} = \text{IBW} + 0.25\left(\text{Wt} - \text{IBW}\right)$$

Daily Protein Needs

Condition	Goal g/kg/d
Maintenance	0.8-1
Repletion / Medical Floor	1-1.5
Trauma / Surgery / ICU	1.5-2
Burn	2-2.5
Obesity	2 (IBW)

Nitrogen Balance

Determinant of protein status (negative balance indicates protein breakdown, positive indicates healing / protein synthesis). $\text{Nitrogen Balance} = \frac{\text{24h Protein Intake (g)}}{6.25} + \left( \text{24h UUN (g)} + 4\;\text{(g)} \right)$ Goal Nitrogen Balance: 0 for maintenance, (+)3-5 for repletion

Building a TPN

1. Determine Total Daily Calories and Total Daily Protein
2. Calculate Total Daily Non-Protein Calories
3. Determine an appropriate Carb / Fat Ratio
   • Typically 70%/30%, but can vary from 60-85%/15-40%
4. Add Micronutrients PRN

Respiratory Quotient

$$\text{RQ} = \frac{\text{vCO}_2}{\text{vO}_2}$$

RQ	Predominately Oxidized Substance
0.7	Fat
0.8	Protein
1	Carbs

• Goal RQ: 0.85-0.95
• RQ > 1: Overfeeding and lipogenesis

Enteral Nutrition

Pre-made enteral nutrition solutions exist at 1 and 2 kcal/mL concentrations. 2 kcal/mL should be used in fluid restricted patients.

Administration Methods

• Continuous: Utilizes a pump, lower distention (and therefore aspiration) risk
• Intermittent: Several gravity based feeds of > 200mL over 20-30min
• Bolus: > 200mL over 5-10min (high aspiration risk)
• Cyclic: Administered over 8-20hr QD

Medication Administration Through Feeding Tubes

ISMP Do Not Crush List

If a medication can be crushed:

1. Crush
2. Administer w/ 5-30mL flush
3. Repeat for each medication
4. Give final flush

Monitoring

Test	Initial	QD	PRN
Chemsticks			X
I/Os	X	X
Wt	X	X
Feeding Tube Placement	X		X
Gastric Residual Volume	X		X
Abdominal Distention		X
# and Consistency of Stool		X

Contraindications

• Need less than 5-10d
• Severe pancreatitis
• High-output fistulas
• Inability to gain access
• Intractable V/D
• GI Ischemia
• Ileus

Complications

• Mechanical
  • Clogging
  • Aspiration
  • Accidental Intubation and Aspiration
  • Infection from airway / GI injury
• GI
  • Gastroparesis
  • GERD
  • Diarrhea
  • Constipation
• Metabolic
  • Hyperglycemia
  • Electrolyte and Vitamin Abnormalities
  • Refeeding Syndrome
  • Dehydration

Parenteral Nutrition

Peripheral Administration Limitations: NTE 12.5% Dextrose, NTE 900-1100 mOsm/L, NTE 5d per site

Cl vs Acetate

Typically given a 2/3 Cl, 1/3 Acetate. Alter as needed to aid management of Acid-Base balance according to SID.

Additional Additives

• H2 Antagonist (Famotidine)
• Insulin-R
  • 0.1 U per 3.4 kcal dextrose (1g)
  • For hyperglycemia
  • High insulin additions should be switched to a separate insulin infusion
• Albumin should not be added as a protein source

Monitoring

Lab	Initial	QD (Unstable)	1-2x weekly (Stable)	PRN
BUN, SCr, BG	X	X	X
Na, K, Cl, Bicarb, Mg, Ca, Phos	X	X	X
AST, ALT, LDH, Alk Phos, Bilirubin	X		X	X
GGT				X
Albumin	X		X	X
Prealbumin				X
TGs	X		X	X
Blood Panel				X
Vitamins and Trace Elements				X
TIBC, Ferritin				X

Lab	Q8H	QD	PRN
Volume Remaining of Infusion	X
I/Os	X
Wt		X
Temp	X
REE			X
Urine Gluc			X
Urine Lytes			X
UUN			X

Contraindications

• Functional GI Tract w/ Access
• Needed < 7d

Special Nutritional Populations

Pediatric Patients

CDC / WHO Growth Charts

Energy Requirements

Age	kcal/kg/d	Protein g/kg/d
Preterm	100-120+	3.5-4
0-6mo	100-110	2-3
6-12mo	90-100	1.5-2
1-7yr	60-80	1-2
7-12yr	50-60	1-1.2
12-18	30-50	0.8-0.9

*approx 40% of calories should be from fat

• Breastfeeding CIs
  • HIV (+)
  • Infectious TB
  • Untreated Brucellosis
  • Some Drugs
  • Human T-cell Lymphotrophic Virus Infection
• Breast milk is approximately 20kcal/oz (50% fat)
  • Cow’s milk is not an appropriate replacement
• Vitamin Supplementation
  • Preterm Infants
    • Vit D (< 1.5 kg): 200 U QD
    • Vit D (≥ 1.5kg): 200-400 U QD
    • Iron: 2 mg/kg QD (elemental)
  • Term Infants
    • Vit D 400 U QD if partially or fully breastfed
• Solid foods should be added at 4-6mo, 1 new food q4-5d
  • Avoid honey until > 1yo

DM

• Moderate control of BG
  • 110-220 in ill
  • 140-180 in critically ill
• 30% total kcal as fat
• Give erythromycin or other kinetic agents for delayed gastric emptying in T1DM

CVD

• Avoid overfeeding
• Monitor fluid status

Short Bowel Syndrome

• w/ colon give high carb / low fat
• Consider B12 supplement

Renal Disease

• Fluid restriction
• Pre-Dialysis: Low Protein
  • 0.5-0.8 g/kg (0.5-1 post-op)
• Dialysis: Normal Protein
  • Intermittent HD: 1-1.3 g/kg
  • CRRT: 1.5-2 g/kg

Pulmonary Failure

• 20-30 kcal/kg
• 30-50% of total kcal as fat
• Protein 1-2 g/kg
• Limit carbs (to decrease CO₂ production)

Hepatic Disease

• 35 kcal/kg QD
• Standard protein (1-1.2 g/kg) w/o encephalopathy
• Protein restrict w/ encephalopathy (0.6 g/kg)
• Na restriction w/ ascites or edema

Misc

• GERD: Add H2 Antagonist or PPI
• NG Suction: Hyponatremia, hypokalemia, and/or hypochloremia which may need repletion
• N/V: Hypovolemia, Na imbalance, and/or hypokalemia
• Dialysis: Removes 10-20% of a.a.
• Wound Healing: Add Zn and Vit C
• Loop Diuretic Use: Watch electrolytes and correct
• Steroids: Monitor BG and consider insulin

Nutritional Disorders

Vitamin Deficiencies

Lipophilic Vitamins

• Vit A (retinoids and beta-carotene)
  • Involved primarily in vision, but also as hormones
  • Stored in the liver (and Vit A overdose can be hepatotoxic)
  • Dietary sources include dark green vegetables, liver, egg yolk, and fatty dairy products
  • Deficiency is rare, but can lead to night vision blindness
• Vit D (Cholecalciferol and Ergocalciferol)
  • Provitamin D₃ can be produced in the skin from 7-dehydrocholesterol
  • A cis double bond in Pro-D₃ is isomerized into D₃ (cholecalciferol)
  • Cholecalciferol and ergocalciferol (Vit D₂ from plants) are then hydroxylated in the liver to form 25-hydroxy Vit D₃, and again in the kidney to form 1,25-dihydroxy Vit D₃ or calcitriol, the active biologic agent responsible for calcium homeostasis
  • Deficiency is rare, but causes Rickets in children and Osteomalacia in adults
  • Dietary sources include fortified milk, saltwater fish, liver, and egg yolk
• Vit E (Tocopherols and Tocotrienols)
  • Function as potent antioxidants protecting unsaturated fatty acids
  • May prevents LDL oxidation helping to prevent CVD
  • Dietary sources are vegetable oils rich in polyunsaturated fatty acids
  • Deficiency is rare
• Vit K
  • Functions as an enzyme cofactor for the glutamate post-translational modification to carboxyglutamic acid, which is essential for allowing proteins to tightly bind Ca
  • Vit K dependent post-translational modifications are required for bone mineralization (hydroxyapatite production) and coagulation (multiple clotting factors are Vit K dependent)
  • Deficiency is rare
  • Dietary sources include green, leafy vegetables for Vit K₁ and gut bacterial synthesis for Vit K₂

Hydrophilic Vitamins

• Vit B_{1 (Thiamin)}
  • Utilized as an enzyme cofactor in many enzymes via carbanion production, including many enzymes involved in glucose metabolism
  • Severe deficiency is known as beriberi, which is characterized by muscle weakness
  • Deficiency is most commonly seen in alcoholics, and administration of dextrose containing fluids in thiamin deficient patients can result in Wernicke’s Encephalopathy
    • Pretreat w/ 100mg IM or slow IVPB in suspected deficiency
    • May need up to 1000mg in the 1st 24hrs
  • Chronic deficiency can also lead to Korsakoff’s psychosis, which is irreversible and responds poorly to antipsychotics (but they should still be used)
• Vit B₂ (Riboflavin)
  • Used as an enzyme cofactor (FAD and FMN)
  • Deficiency is rare, but SSx include Cheilitis, Glossitis, and Scaly dermatitis, and is most commonly seen in alcoholics
  • Dietary sources include milk, meat, eggs, and cereal products
• Vit B₃ (Niacin)
  • Converted to NAD and NADP
  • Deficiency (pellagra) is common in pts with malabsorption diseases or alcoholics
  • Pellagra presents with “The 3 D’s”: Dermatitis, Dementia, and Diarrhea
  • Dietary sources include meats, peanuts, and enriched cereals
• Vit B₆ (Pyridoxine)
  • Pyridoxal phosphate is a cofactor for neurotransmitter and sphingolipid synthesis as well as amino acid metabolism
  • Severe deficiency is uncommon, with SSx including irritability, nervousness, and depression in mild cases and peripheral neuropathy and Szs in severe deficiency
  • Dietary sources include meats, vegetables, and whole-grain cereals
• Vit B₇ (Biotin)
  • Cofactor for the conversion of carboxylates to CO₂
  • Deficiency is somewhat rare, and most common in pregnant women
  • Biotin binds incredibly tightly to avidin in egg whites (used throughout biochemical studies and assays, as well as a potential cause of deficiency)
• Vit B₉ (Folate)
  • Converted to tetrahydrofolate which is essential for one-carbon metabolism in a.a. and nucleotide synthesis
  • Deficiency is most common in alcoholics, with notable SSx of macrocytic anemia and neural tube defects in children born to pregnant women with the deficiency
• Vit B₁₂ (Cobalamin)
  • Co containing “heme” group
  • Required for two human biochemical reactions: methionine synthase (homocysteine into methionine) and methylmalonyl-CoA mutase (methylmalonyl-CoA into succinyl-CoA)
  • Deficiency leads to homocysteine and methylmalonate accumulation causing macrocytic anemia and neurologic damage
  • Deficiency can be dietary or “pernicious anemia” in which the absorptive cofactor (intrinsic factor) is absent or non-functioning
  • Deficiency is most commonly seen in long-term vegetarians or malabsorption diseases
• Vit C (Ascorbic Acid)
  • Cofactor for lysine hydroxylation (essential for collagen production)
  • Reducing agent promoting iron absorption and protection of oxidation prone vitamins (A, E, and some B)
  • Deficiency (Scurvy) marked by slow wound healing, decreased immunocompetency, osteoporosis, leading from mucosal membranes (especially the gums), and ulcerations across the body

Refeeding Syndrome

SSx

• Szs
• Coma
• Arrhythmias
• Lactic Acidosis
• Pulmonary Edema
• Fluid Overload

Monitoring

• SSx
• Mg
• K
• Phos

Prevention

• Correct electrolyte abnormalities first
• Start all patients at 50% goal caloric intake, high risk at 25% goal caloric intake
  • Titrate to goal over 3-5d
• If SSx emerge decrease calories and correct emergent electrolyte problems

Kwashiorkor

Protein based malnutrition characterized by hypoalbuminemia, anemia, edema / ascites, muscle atrophy, impaired immune function, and delayed wound healing. Treat w/ slow introduction of food to avoid referring syndrome.

Marasmus

Caloric malnutrition characterized by wt loss, reduction of basal metabolic rate, depletion of fatty stores, bradycardia, and hypothermia. Treat w/ slow introduction of food to avoid referring syndrome.

Essential Fatty Acid Deficiency

SSx

• Dry Skin
• Immune Complications
• Thrombocytopenia
• Alopecia
• Peds
  • Mental Development Delays

Treatment

4-10% of QD calories as Linoleic and Linolenic Acid

References

• ASPEN / SCCM Guidelines for Nutritional Support in Critically Ill Patients