john p. grant, md, cnsp director nutrition support service professor of surgery
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Nutrition Support in Critically Ill Later Nutritional Needs and Metabolic Aberrations in Ventilated Patients. John P. Grant, MD, CNSP Director Nutrition Support Service Professor of Surgery Duke University Medical Center Durham, NC. Optimal Metabolic Care of the Critically Ill Patient. - PowerPoint PPT PresentationTRANSCRIPT
Nutrition Support in Critically Ill
Later Nutritional Needs and Metabolic Aberrations in Ventilated
PatientsJohn P. Grant, MD, CNSPDirector Nutrition Support Service
Professor of SurgeryDuke University Medical Center
Durham, NC
Optimal Metabolic Care of the Critically Ill Patient
Provide Optimal Metabolic Milieu
Maintain oxygenation
Adjust pH
Ensure perfusion
Control waste (dialysis - vol,lytes,prot)
Optimal Metabolic Care of the Critically Ill Patient
Minimize Metabolic Stress Response Control pain
Debridement of necrotic/infected tissue Drain abscesses Dress or cover wounds
Optimal Metabolic Care of the Critically Ill Patient
Optimize milieu for cell metabolism
Minimize stress response
Provide adequate and appropriate nutritional support
Importance of Adequate Nutrition
in the Critically Ill Patient
Nutrient balance and mortality in ICU patients
4/15 with positive nitrogen balance died (27%)
11/28 with 0 to -10,000 Kcal balance died (39%)
12/14 with > -10,000 Kcal balance died (86%)
Bartlett et al., Surgery 92:771, 1982
Caloric Balance and Outcome in ICU
A = positive caloric balance
B = 0 to -10,000 kcal balance
C = > -10,000 kcal balance
2739
86
0102030405060708090
A B C
Caloric Balance vs % Mortality
Bartlett et al., Surgery 92:771, 1982
Days = { [(UBW X 2430) x K] - [(UBW - BW) x 2430]}
AEE - Ei
Where:
Days of Survival Without Nutrition
UBW = usual body weight in kgBW = current body weight in kg K = 0.35 with stress; 0.4 with simple starvation AEE = actual energy expenditure (kcal/d)Ei = energy intake (kcal/d)
Importance of Adequate Nutrition
in Respirator Dependent Patients
Arora and Rochester evaluated the effects of malnutrition on diaphragmatic muscle dimensions at necropsy and in vivo function in patients after prolonged illness (75% UBW) as compared with well nourished patients.
Diaphragmatic muscle mass
43% less
Max Inspiratory Vacuum 35% normal
Max Expiratory Pressure 59% normal
Max Ventilatory Volume 41% normalArora, N.S., and Rochester, D.F.: Am. Rev. Respir. Dis., 126:5-8, 1982.
Adequate Nutritional Support of Respirator Dependent Patients Excessive calories, especially excess glucose calories, can result in excessive CO2 production and increased ventilatory demand in the already compromised patient. May delay weaning.
In ventilatory dependent patients, a high caloric load (2 X REE) has been shown to result in significantly higher O2 consumption and CO2 production than a moderate load (1.5 X REE) in patients otherwise receiving an identical diet.
Van den Berg, B., and Stam, H.: Intensive Care Medicine, 14:206-211, 1988.
Adequate Nutritional Support of Respirator Dependent Patients
Formulas for estimating caloric needs:
Ireton-Jones formula was designed specificallyfor patients with burns or trauma who simultaneously had pulmonary failure. The Ireton-Jones formula is:
BEE = 1925 - 10(A) + 5(W) + 281(S) 292(T) + 851(B)
where A = age in years, W = weight in kilograms,S = sex (male = 1, female = 0), and T = trauma and B = burn (present = 1, absent = 0)
Adequate Nutritional Support of Respirator Dependent Patients
Formulas for estimating caloric needs: Cal Long
AEE (men) = (66.47 + 13.75 W + 5.0 H - 6.76 A) x (activity factor) x (injury factor)
AEE (women) = (655.10 + 9.56 W + 1.85 H - 4.68 A) x (activity factor) x (injury factor)
Activity Factor Use Injury Factor Use
Confined to bed 1.2 Minor OR 1.2
Out of Bed 1.3 Skeletal Trauma 1.3
Major Sepsis 1.6
Severe Burn 2.1
Caloric Support of the ICU PatientOrgan Specific Substrate Support
Carbohydrate Long-chain fatty acids Medium-chain fatty acids (Structured Lipids) Branched-chain amino acids Glutamine
Organ Specific Substrate SupportGlucose
Glucose is required by the brain, renal
medulla, red blood cells, and fibroblasts
Recommended daily consumption: Minimum of 200 and up to 700 grams/day (700 to 2400 kcal/day)
As increasing amounts of glucose are infused, a maximal rate of glucose oxidation and whole body protein synthesis is obtained at 5.0 to 6.0 mg/kg/min (~630 g/d for 80 kg patient)
Burke et al., Ann Surg, 190:274, 1979
Use of Insulin to Stimulate Glucose
UtilizationDoes lower blood sugar in most cases
Drives glucose mainly into muscle
No documented increase in glucose oxidation or nitrogen sparingVary et al., JPEN 10:351, 1986
Use of Insulin in Glucose Utilization
Anaerobic Glycolysis
Pyruvate
Pyruvate Dehydrogenase
Insulin
Krebs cycle Fat Synthesis
Organ Specific Substrate Support
Long-Chain Fatty Acids
Used as a fuel by many organs in the body
Must provide essential fatty acids (Linoleic, Arachidonic, Linolenic) = 15 grams/day
Organ Specific Substrate Support
Long-Chain Fatty Acids
Increased fat clearance from bloodstream during stress
Yet only about 8% is oxidized immediately
Goodenough et al., JPEN 8:357, 1984
Organ Specific Substrate Support
Long-Chain Fatty Acids
In severe stress, fat clearance is minimalCerra et al., Surgery 86:409, 1979Lundholm et al., Crit Care Med 10:740, 1982
May depress RES (>1 kcal/kg/h)Hamaway et al., JPEN 9:559, 1985
Organ Specific Substrate Support
Long-Chain Fatty AcidsSubstituted glucose isocalorically with fat in an experimental animal burn modelDemonstrated a linear decrease in nitrogen balance as glucose was reduced
N loss = 17.44 - 1.997 log e (glucose intake Kcal/sq m/d) + 0.0752 RME (kcal/sq m/d)
Long et al., Ann Surg 185:417, 1977
Long-Chain Fatty Acids
Require carnitine for transport through the inner mitochondrial membrane for beta oxidation
Organ Specific Substrate Support
Long-Chain Fatty Acids
Average recommended dose = 40 - 60 grams/day (360 to 540 kcal/day)
Adequate Nutritional Support of Respirator Dependent Patients
Lipid Support - Intravenous lipid emulsions can be harmful
There is a nonlinier relationship between triglyceride concentration and rate of lipoprotein lipase-mediated triglyceride hydrolysis. When infusion of triglyceride exceeds hydrolysis, serum triglyceride concentrations rise. If triglyceride concentrations exceed a certain level, triglyceride-rich lipoproteins can be removed via nonenzymatic pathways, particularly by the reticuloendothelial system and the lung.
Adequate Nutritional Support of Respirator Dependent Patients
Lipid Support - Intravenous lipid emulsions can be harmful
Higher infection rate, prolonged pulmonary failure, and delayed recovery was observed in a group of trauma patients given TPN with lipid infusions compared to a second group given TPN without lipids.
Battistella, F.D., et al.: J. Trauma, 43:52-58, 1997.
Adequate Nutritional Support of Respirator Dependent Patients
Lipid Support –
A minimum of 1 to 2 percent of total caloric intake should be in the form of essential fatty acids to meet nutritional requirements
Give a mixture of glucose and long-chain fatty acids
in a ratio of 60 to 80 percent glucose to 20 to 40 percent fat
Organ Specific Substrate Support
Structured Lipids
Contain both long-chain (40-50%) and medium-chain (50-60%) fatty acids (MCFA)
MCFA are used as a fuel by most tissues
Organ Specific Substrate Support
Structured Lipids
MCFA do not require carnitine for entry into mitochondria
Provide adequate essential fatty acids
Organ Specific Substrate Support
Structured Lipids
Improved N2 balance in burned ratsMaiz et al., Metabolism 33:901, 1984
Improved N2 balance in stressed patients Dennison et al., JPEN 12:15, 1988
Less interference with the RESHamaway et al., JPEN 9:559, 1985
Adequate Nutritional Support of Respirator Dependent Patients
Protein Support – adjusted for positive nitrogen balance, reduced for renal and hepatic dysfunction
No stress 0.7 to 0.8 g/kg/day
Mild Stress 0.8 to 1.0 g/kg/day
Moderate Stress 1.0 to 1.5 g/kg/day
Severe Stress 1.5 to 2.0 g/kg/day
Organ Specific Substrate Support
Branched-Chain Amino Acids
Alanine
Leucine
Isoleucine
Organ Specific Substrate Support
Branched-Chain Amino Acids
Main energy source for skeletal muscle during stress and sepsis
Not metabolized by the liver: safe to give during liver failure
Give 30 - 40 grams/day: 100 -160 kcal/day (45% BCAA Solution)
Protein
BCAA can enhance nitrogen balance during periods of maximal stress
Cerra et al., Crit Care Med, 11:775, 1983
Organ Specific Substrate Support Glutamine
Necessary precursor for protein and nucleotide synthesis
Regulates acid-base balance through production of urinary ammonia
Major transporter of nitrogen (along with alanine)
Importance of Glutamine in Cell Nutrition
EnterocytesLymphocytesFibroblastsBone Marrow
PancreasLungTumor CellsRenal Tubular CellsVascular Epithelial Cells
Glutamine Metabolism
Metabolized similarly whether it enters enterocyte across the brush border from intestinal lumen or across the basolateral cell membrane from the arterial blood
Oxidation via Krebs cycle yields 30 mole ATP per mole glutamine (glucose = 36)
Glutamine MetabolismGut normally extracts 20 to 30% of glutamine from blood
During stress, muscle releases amino acids with glutamine and alanine making up 60% of total
Muscle glutamine concentration decreases by up to 50% with prolonged stress
Glutamine Metabolism
Uptake of glutamine by the gut is greatly increased in stress, exceeding muscle release
Serum glutamine concentrations fall leading to a relative deficiency state
Provide 6 - 50 grams/day (24 - 200 kcal)
Appropriate Nutritional Support of Respirator Dependent
PatientsEnteral vs Parenteral Support
Postburn Hypermetabolism and Early Enteral Feeding
30% BSA burn in guinea pigsEnteral feeding via g-tube at 2 or 72 hours following burnMucosal weight and thickness were similar
100
120
140
150
160
0 2 4 6 8 10 12
RME % Initial
Postburn day
175 Kcal - 72 h
200 Kcal - 72 h
175 Kcal - 2 h
Alexander, Ann Surg 200:297, 1984
130
110
Denham, Gastroenterology, 113:1741, 1997
Suppression of CytokinesAntagonizing IL-1 and/or TNF activity or blocking receptors – antibody and receptor antagonists
Dramatic improvement in severity and mortality of experimental acute pancreatitis
Norman, Ann Surg, 221;625, 1995Tanaka, Crit Care Med, 23:901, 1995
Suppression of CytokinesPreventing IL-1 and/or TNF production
Generic macrophage pacification
IL-10 regulation of IL-1 and TNF
Inhibiting post-transcriptional modification of pro-IL-1
Norman, J. Interfer Cytokine Res, 17:113, 1997
VanLaethem, Gastroenterology, 108:1917, 1995
Suppression of Cytokines
Gene therapy to inhibit systemic hyperinflammatory response of pancreatitis
Denham, J Gastrointest Surg, 2:95, 1998
Norman, Gastroenterology, 112:A467, 1997
GALT SystemGut-associated lymphoid tissue
Intraepithelial lymphocytes
Lamina propria lymphoid tissue
Peyer’s patches
Mesenteric lymph nodes
GALT SystemIntraepithelial lymphocytes
First to recognize foreign antigens
Lamina propria lymphoid tissue
Source of IgA
Peyer’s patches
Process antigens from intestinal lumen
GALT System
Responsible for reacting to harmful foreign antigens (e.g. bacterial or viral pathogens)
Must not react to non-threatening antigens to avoid chronic inflammatory condition
GALT System
Intravenous feeding with bowel rest and starvation result in significant suppression of the mass and function of GALT, with reduction in IgA secretion and increased gut permeability.
Oral and enteral feedings preserve GALT mass and function
Li, J Trauma, 39:44, 1995
GALT SystemBowel rest (or an elemental diet) reduces intraluminal nutrients that bacteria need
Induces an adaptive response of bacteria to increase their adherence to the intestinal wall as a source of nutrients.
Bacterial adherence causes cellular injury, or even bacterial penetration (translocation), with an adverse host response.
Optimal Metabolic Care of the Critically Ill Patient
If 2% L-glutamine is added to TPN in experimental animal models
Mass and function of GALT is better preserved
Reduces mortality in experimental sepsis model
Not as effective as enteral nutrition
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Caloric Support of the Critically Ill Patient
Kcal/kg/day for stress = 25 (mild), 30 (moderate), 35 (severe)
Long modification of Harris-Benedict Formula
Indirect calorimetry
Nutrition Support in Critically Ill Patients
Conclusions–Optimize milieu for cell metabolism
–Minimize stress response
–± Early dialysis (volume, protein, lytes)
Nutrition Support in Critically Ill Patients
Conclusions
–Begin nutrition support early (24-48 hrs)
–If the gut works, use it….
–If the gut doesn’t work, make it work
–Use insulin sparingly