The document provides an overview of nutritional support in critical illness, including definitions, history, assessment, guidelines, and types of nutrition support such as enteral and parenteral nutrition. It discusses screening patients, performing nutritional assessments, determining caloric and protein needs based on stress level and condition, selecting appropriate enteral formulas, initiating and managing enteral feeds, and ordering and administering parenteral nutrition including determining fluid volumes, electrolytes, and other additives.

1. Nutritional Support in Critical illness Tianjin Medical University General Hospital Emergency Center Shou songtao

2. Nutritional support is the provision of nutrients to patients who cannot meet their nutritional requirements by eating standard diets. Definition

3. ‘ A slender and restricted diet is always dangerous in chronic and in acute diseases’ Hippocrates 400 B.C.

4. Malnutrition occurs in approx.40% of hospitalized patients Can lead to increased morbidity and mortality Impairment of skeletal, cardiac, respiratory muscle function Impairment of immune function Atrophy of GIT Impaired healing

5. 1970s: TPN - separate CH, AAs and Lipids 2500-3000kcals/day: Lactic acidosis, high glucose loads, fatty livers, high insulin Single lumen C/Lines, no pumps Urinary urea measured, N calculated 1980s: Scientific studies of metabolism: recognition of overfeeding 1990s: nitrogen limitation: 0.2g/kg/24hr, start of immunonutrition trials 2000s: glucose control, specific nutrients

6. ICU Nutrition through the ages Overfeeding 1980s

7. 4 basic questions to be answered: Who? When? How much? How?

10. Organisation of Nutrition Support 3. NICE Guidelines for Nutrition Support in Adults 2006 Screen Recognise Treat Oral Enteral Parenteral Monitor & Review

11. Screen Various nutritional screening tools Low risk: routine clinical care Medium risk: observe High risk: treat- refer to dietitian/local protocols

12. Screening in ICU Almost all patients require artificial nutrition- cannot ‘observe’ Needs adaptation using NICE Guidelines Adapted MUST for ICU: Uses BMI/weight loss/food intake + refeeding risk assessment; linked to feeding flowchart

13. Nutritional Assessment History – 10% weight loss or more suggests protein malnutrition Exam – Weight/Ideal body weight (<85% predicted), temporal muscle wasting, anthropometrics Nutritional markers - daily weight – more a measure of fluid status than nutritional status -24 hour urine urea nitrogen (cannot be used in renal failure) -albumin (<30mg/dl,t 1/2 21), prealbumin(<12mg/dl, 2), transferrin(<150mmol/L, 7) -albumin influenced by fluid status, acute phase response

14. Nutritional Assessment Immune function – skin testing, anergy,total lymphocyte count<1800/mm 3 Anthropometric measures > 10 % loss of ‘well’ body weight Body mass index : weight (kg)/ height 2 (m 2 ) <18 kg/m 2 assoc. With prolonged ICU, increased post-operative complications, higher readmission rates Mid-arm circumference, skin fold thickness Poor accuracy, specificity, reproducibility

15. Nutritional assessment Serum proteins Albumin Reflects synthesis, degradation, losses, exchange between intracellular and extracellular compartments Half life 21 days – limited ability to reflect acute changes < 3.5 g/dL assoc. increased morbidity

16. Nutritional assessment Serum proteins Transferrin (1/2 life 7 days), Pre-albumin (1/2 life 2 days) More accurately reflect acute changes Limited by erratic responses to stress, sepsis, cancer

17. Nutritional assessment Nitrogen balance = N intake – N loss = (dietary protein x 0.16) – (urea nitrogen (urine) + 4 g (stool/skin) ) Positive balance indicates anabolic state Negative balance indicates catabolic state Aim to provide non-protein sources of fuel to allow protein to be used for anabolic processes

18. How much to give in ICU? Schofield equation/Harris Benedict e.g. for 65 year old woman: BMR = (9.2x weight in kg) + 687, = requirement in Kcal/24hr Add Activity and Stress factors e.g. 10% for bedbound + 20-60% for sepsis/burns For 65kg ventilated woman with sepsis: 1670 Kcal = approx 25 Kcal/kg/d No dietitian? Rough guide: 25 Kcal/kg/day total energy. Increase to 30 as patient improves

19. How much to give? 0.2g/Kg/day of Nitrogen (1.25g/kg/day protein) 30 – 35ml fluid/kg/24 hours baseline Add 2-2.5ml/kg/day of fluid for each degree of temperature Account for excess fluid losses Adequate electrolytes, micronutrients, vitamins Avoid overfeeding Obesity: feed to BMR, add stress factor only if severe i.e. burns/trauma

20. Types of nutrition support Routes of nutrition support Enteral nutrition Parenteral nutrition

21. Enteral nutrition In general, the preferred method of choice

22. Enteral Nutrition Nutrition delivered via the gut Includes oral feedings and tube feedings

23. Indications for Enteral Nutrition Malnourished patient expected to be unable to eat >5-7 days Normally nourished patient expected to be unable to eat >7-9 days Adaptive phase of short bowel syndrome Increased needs that cannot be met through oral intake (burns, trauma) Inadequate oral intake resulting in deterioration of nutritional status or delayed recovery from illness ASPEN. The science and practice of nutrition support. A case-Based Core curriculum. 2001; 143

24. Contraindications for EN Severe acute pancreatitis High output proximal fistula Inability to gain access Intractable vomiting or diarrhea Aggressive therapy not warranted ASPEN. The science and practice of nutrition support. A case-based core curriculum. 2001; 143

25. Contraindications for EN Inadequate resuscitation or hypotension; hemodynamic instability Ileus Intestinal obstruction Severe G.I. Bleed Expected need less than 5-7 days if malnourished or 7-9 days if normally nourished

26. Long-term nutrition Gastrostomy Jejunostomy Short-term nutrition Nasogastric feeding Nasoduodenal feeding Nasojejunal feeding Enteral nutrition

28. Diagram of enteral tube placement.

29. With/without endoscopic Long time with endoscopic operation Gastric tube duodenal tube gastrostomy Gastrostomy Duodenum feeding Jejunostomy feeding Decision of Selecting The Modes of Administration Enteral Nutrition Short time Tube Percutaneous tube

33. Enteral Formulas Liquid diets intended for oral use or for tube feeding Ready-to-use or powdered form Designed to meet variety of medical and nutrition needs Can be used alone or given with foods

34. Formula Selection The suitability of a feeding formula should be evaluated based on Functional status of GI tract Digestion and absorption capability of patient Physical characteristics of formula (osmolality, fiber content, caloric density, viscosity) Macronutrient ratios Specific metabolic needs Contribution of the feeding to fluid and electrolyte needs or restriction Cost effectiveness

35. Enteral Formulas Determine best choice by medical and nutrition assessment Meet specific nutrition needs

36. Enteral Formula Categories Polymeric Monomeric Fiber-containing Disease-specific Rehydration Modular

37. Enteral Formula Categories Polymeric Whole protein nitrogen source For use in patients with normal or near normal GI function Protein isolate formulas Protein that has been separated from a food (casein from milk, albumin from egg) Blenderized formulas May contain pureed meat, vegetables, fruits, milk, starches with v/m added Made at home or purchased commercially

38. Enteral Formula Categories Polymeric

39. Enteral Formula Categories Monomeric Elemental/hydrolyzed Predigested nutrients Free amino acids and/or short peptide chains Has low fat content or high percentage of MCT, LCT, structured lipids

40. Enteral Formula Categories Monomeric

41. Enteral Formula Categories Monomeric Use in patients with compromised digestive and/or absorptive capacity More expensive than standard formulas Tend to be more hyperosmolar because of small particle size

42. Enteral Formula Categories Fiber-Containing Fiber-containing: containing a source of fiber; reportedly beneficial for prevention/treatment of altered bowel function in enterally fed patients Soy polysaccharide is the most common fiber additive in enteral feedings ASPEN. The science and practice of nutrition support. A case-based core curriculum. 2001; 148

43. Enteral Formula Categories Fiber-Containing Soluble fiber (guar gum, oat fiber, pectin) may exert trophic effect on colonic mucosa and be useful in normalizing bowel function Patients with impaired gastric emptying should not be fed fiber-containing formula into the stomach ASPEN. The science and practice of nutrition support. A case-based core curriculum. 2001; 148

44. Enteral Formula Categories Fiber-Containing

45. Enteral Formulas: Calorie Dense May be used in fluid-restricted or volume-sensitive patients Calorie density ranges from 1.3 to 2 kcals/ml Monitor fluid/hydration status

46. Enteral Formulas: Calorie Dense

47. Enteral Formula Categories Disease Specific Designed for patients with specific disease states. Available for patients with respiratory disease, ARDS, diabetes, renal failure, hepatic failure, and immune compromise.

48. Enteral Formula Categories Disease Specific

49. Disease Specific Formulas Diabetic Amount and type of CHO modified to reduce blood glucose response Increased fat content (may have increased monounsaturated fats) May be worth trying diabetes formulas in patients who have failed to achieve good blood glucose control on standard formulas

50. Disease Specific Formulas: Diabetic

51. Disease Specific Formulas Hepatic Generally have reduced aromatic amino acids and increased branched chain amino acids More expensive than standard products Often lower in protein than standard formulas (may be too low for most liver patients)

52. Disease Specific Formulas Renal Typically are calorie dense (2.0 kcal/cc) products with relatively low protein levels and modified electrolytes Generally too low in protein for dialyzed patients and acutely ill patients May be useful for short term use as supplement or calorie source in pre-dialysis chronic renal failure patients

53. Disease-Specific Formulas Renal Novasource Renal

54. Disease Specific Formulas Immune-Enhancing Have added “immune-enhancing” nutrients (arginine, glutamine, omega-3 fatty acids, nucleotides) Meta-analysis suggests that they might be most beneficial in surgical patients

55. Immune-Enhancing Formulas

56. Disease-Specific Formula Pulmonary Contain higher percentage of total calories from fat to reduce respiratory quotient and make it easier to wean from respirator High fat gastric feedings may cause delayed emptying in critically ill patients

57. Disease-Specific Formulas: Pulmonary

58. Enteral Formula Nutrient Sources Carbohydrate CHO content ranges from 40-90% of total calories Fiber: soy polysaccharide (most common) guar gum, oat fiber, pectin

59. Enteral Formula Nutrient Sources Lipids Fat provides isotonic, concentrated energy source Corn and soybean oil common May include MCTs; more easily digested and absorbed Fat content ranges from <10% to >50% of calories ASPEN. The science and practice of nutrition support. A case-based core curriculum. 2001; 148

60. Enteral Formulas Nutrient Sources Protein Whole protein, hydrolyzed protein, free amino acids Casein, soy protein, lactalbumin, whey, egg white albumin Small peptides absorbed as efficiently as free amino acids Free amino acids are more hyperosmolar

61. Initiation of Feeds Approaches Bolus vs continuous feeds Full feeds vs graded regimens

62. Assessment of Clinical Response Anthropometric measurements Feeding tolerance

63. Enteral nutrition Complications Gastrointestinal Mechanical Metabolic Formula related

64. GI Complications Vomiting Diarrhea Constipation Abdominal pain / bloating Gastric irritation Aspiration

65. Mechanical Complications Tube occlusion Nasopharyngeal effects Tube fractures Leakage Obstruction Irritation

66. Metabolic Complications Hypovolemia Hyperkalemia Hypophosphatemia Hypertonic dehydration Fluid overload

67. Formula Complications Incompatibility with medications Hyperosmolality Contamination

68. Application Criterion of EN “ When the gut works, and can be used safely, use it ”

69. Parenteral Nutrition

70. Parenteral Nutrition Allows greater caloric intake BUT Is more expensive Has more complications Needs more technical expertise

71. Who Will Benefit From Parenteral Nutrition? Patients with/who Abnormal gut function Cannot consume adequate amounts of nutrients by enteral feeding

72. Two Main Forms of Parenteral Nutrition Peripheral Parenteral Nutrition Central (Total) Parenteral Nutrition Both differ in composition of feed primary caloric source potential complications method of administration

73. Peripheral Parenteral Nutrition Given through peripheral vein Short term use Mildly stressed patients Low caloric requirements Contraindications to central TPN

74. What to Do Before Starting TPN Nutritional Assessment Venous access evaluation Baseline weight Baseline lab investigations

75. Venous Access for TPN Need venous access to a “large” central line with fast flow to avoid thrombophlebitis Superior Vena Cava Subclavian approach Internal jugular approach External jugular approach

77. Baseline Lab Investigations Full blood count Coagulation screen Ca ++ , Mg ++ , PO 4 2- Lipid Other tests when indicated

78. Steps to Ordering TPN Decide how much fat & carbohydrate to give Determine Total Fluid Volume Determine Non-N Caloric needs Determine Protein requirements Determine Electrolyte and Trace element requirements Determine need for additives

79. Steps to Ordering TPN Decide how much fat & carbohydrate to give Determine Total Fluid Volume Determine Non-N Caloric needs Determine Protein requirements Determine Electrolyte and Trace element requirements Determine need for additives

80. How Much Volume to Give? Cater for maintenance & on going losses Normal maintenance requirements By body weight alternatively, 30 to 50 ml/kg/day Add on going losses based on I/O chart Consider insensible fluid losses also e.g. add 10% for every o C rise in temperature

81. Steps to Ordering TPN Determine Total Fluid Volume Determine Caloric needs Determine Protein requirements Decide how much fat & carbohydrate to give Determine Electrolyte and Trace element requirements Determine need for additives

82. Caloric Requirements Based on Total Energy Expenditure Can be estimated using predictive equations TEE = REE + Stress Factor + Activity Factor Can be measured using metabolic cart

83. Stress Factor Caloric Requirements Malnutrition - 30% Peritonitis + 15% Soft tissue trauma + 15% Fracture + 20% Fever (per o c rise) + 13% Moderate infection + 20% Severe infection + 40% <20% BSA burns + 50% 20-40% BSA burns + 80% >40% BSA burns + 100%

84. Activity Factor Bed-bound + 20% Ambulant + 30% Active + 50% Caloric Requirements

85. How Much CHO & Fats? “ Too much of a good thing causes problems” Not more than 4 mg / kg / min Dextrose (less than 6 g / kg / day) Not more than 0.7 mg / kg / min Lipid (less than 1 g / kg / day)

86. Fats usually form 25 to 30% of calories Not more than 40 to 50% Increase usually in severe stress Aim for serum TG levels < 350 mg/dl or 3.95 mmol/L CHO usually form 70-75 % of calories How Much CHO & Fats?

87. Steps to Ordering TPN Determine Total Fluid Volume Determine Caloric needs Determine Protein requirements Decide how much fat & carbohydrate to give Determine Electrolyte and Trace element requirements Determine need for additives

88. How Much Protein to Give? Based on calorie : nitrogen ratio Based on degree of stress & body weight Based on Nitrogen Balance

89. Calorie : Nitrogen Ratio Normal ratio is 150 cal : 1g Nitrogen Critically ill patients 85 to 100 cal : 1 g Nitrogen in

90. Based on Stress & BW Non-stress patients 0.8 g / kg / day Mild stress 1.0 to 1.2 g / kg / day Moderate stress 1.3 to 1.75 g / kg / day Severe stress 2 to 2.5 g / kg / day

91. Based on Nitrogen Balance Aim for positive balance of 1.5 to 2g / kg / day

92. Steps to Ordering TPN Decide how much fat & carbohydrate to give Determine Total Fluid Volume Determine Protein requirements Determine Non-N Caloric needs Determine Electrolyte and Trace element requirements Determine need for additives

93. Electrolyte Requirements Cater for maintenance + replacement needs Na + 1 to 2 mmol/kg/d (or 60-120 meq/d) K + 0.5 to 1 mmol/kg/d (or 30 - 60 meq/d) Mg ++ 0.35 to 0.45 meq/kg/d (or 10 to 20 meq /d) Ca ++ 0.2 to 0.3 meq/kg/d (or 10 to 15 meq/d) PO 4 2- 20 to 30 mmol/d

94. Trace Elements Total requirements not well established Commercial preparations exist to provide RDA Zn 2-4 mg/day Cr 10-15 ug/day Cu 0.3 to 0.5 mg/day Mn 0.4 to 0.8 mg/day

95. Steps to Ordering TPN Decide how much fat & carbohydrate to give Determine Total Fluid Volume Determine Protein requirements Determine Non-N Caloric needs Determine Electrolyte and Trace element requirements Determine need for additives

96. Other Additives Vitamins Give that recommended for oral intake 1 ampoule MultiVit per bag of TPN MultiVit does not include Vit K can give 1 mg/day or 5-10 mg/wk

97. Other Additives Medications Insulin 0.1 u per g dextrose in TPN 10 u per litre TPN initial dose Other medications

98. TPN Monitoring Clinical Review Lab investigations Adjust TPN order accordingly

99. Clinical Review Clinical examination Vital signs Fluid balance Catheter care Sepsis review Blood sugar profile Body weight

100. Lab investigations Full Blood Count Renal Panel # 1 Ca++, Mg++, PO42- Liver Function Test Iron Panel Lipid Panel Nitrogen Balance weekly, unless indicated daily until stable, then 2x/wk daily until stable, then 2x/wk weekly weekly 1-2x/wk weekly

101. Complications Related to TPN Mechanical Complications Metabolic Complications Infectious Complications

102. Mechanical Complications Related to vascular access technique pneumothorax air embolism arterial injury bleeding brachial plexus injury catheter malplacement catheter embolism thoracic duct injury

103. Mechanical Complications Venous thrombosis Catheter occlusion Related to catheter in situ

104. Metabolic Complications Abnormalities related to excessive or inadequate administration hyper / hypoglycaemia electrolyte abnormalities acid-base disorders hyperlipidaemia

105. Metabolic Complications Hepatic complications Biochemical abnormalities Cholestatic jaundice too much calories (carbohydrate intake) too much fat Acalculous cholecystitis

106. Infectious Complications Insertion site contamination Catheter contamination improper insertion technique use of catheter for non-feeding purposes contaminated TPN solution contaminated tubing Secondary contamination septicaemia

107. Stopping TPN Stop TPN when enteral feeding can restart Wean slowly to avoid hypoglycaemia Monitor during wean Give IV Dextrose 10% solution at previous infusion rate for at least 4 to 6h Alternatively, wean TPN while introducing enteral feeding and stop when enteral intake meets TEE

108. Approach to Nutritional Support Nutritional Assessment Maintenance Repletion GI Tract Functional YES NO Enteral Nutrition Parenteral Nutrition

109. Advantages - Enteral vs PN Preserves gut integrity Possibly decreases bacterial translocation Preserves immunological function of gut Reduces costs Fewer infectious complications in critically ill patients Safer and more cost effective in many settings ASPEN. The science and practice of nutrition support. A case-based core curriculum. 2001; 147 ADA EAL, Critical Illness, accessed 8-07

110. Single nutrient supplementation L-glutamine Used in purine, pyrimidine, lymphocyte and macrophage function, gut integrity and gut barrier function If given, reduces nitrogen loss Reduced length of stay, following colorectal surgery in elective setting Other studies shown reduced risk of pneumonia, bacteraemia, sepsis following major trauma ? Role in short gut syndrome – improving GI absorbtion

111. Single nutrient supplementation Essential fatty acids Variety of functions, key role in maintaining membrane structure and function Alter immune function (n-3 FA suppress immune function) Preliminary studies using n-3 FA in inflammatory bowel disease showed improvement in histological appearance, reduction in disease activity, decreased steroid requirement

113. Importants: Definition of nutritional support Routs of nutritional support Advantages of EN Common complications of TPN

114. Maintains Stimulates the environment defences FEEDING Provides energy

115. Thank you !!

116. Essential Nonessential Arginine Alanine Histidine Asparagine Isoleucine Aspartate Leucine Cysteine Lysine Glutamate Methionine Glutamine Phenylalanine Glycine Threonine Proline Tryptophan Serine Valine Tyrosine