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Parenteral Nutrition – An Overview for the Practising Clinician

Parenteral Nutrition – An Overview for the Practising Clinician. 63 rd BAMP / UWI CME Conference 16 th May 2008 St. Michael, Barbados. David Armstrong, Division of Gastroenterology McMaster University & Hamilton Health Sciences Hamilton, Ontario, Canada. McMaster University Medical Centre.

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Parenteral Nutrition – An Overview for the Practising Clinician

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  1. Parenteral Nutrition – An Overview for the Practising Clinician 63rd BAMP / UWI CME Conference 16th May 2008 St. Michael, Barbados David Armstrong, Division of GastroenterologyMcMaster University & Hamilton Health SciencesHamilton, Ontario, Canada

  2. McMaster University Medical Centre

  3. McMaster University Medical Centre

  4. Parenteral Nutrition - Overview • Indications, Contraindications and Routes of Administration • Macronutrient and Micronutrient Use in TPN • Importance of a Parenteral Nutrition Team

  5. “Death from starvation is as final as death from cardiac standstill!”

  6. Starvation • Adult volunteers • Fasted for 30-40 days: 25% weight loss • More prolonged fasting: 50% weight loss • Weakness • Apathy • Reduced work capacity; cardiorespiratory failure • Total starvation is fatal in 8 to 12 weeks • IRA Fast (5/91-8/91): death at 45 days (1/10 - with gunshot) and 57-73 days (9/10)

  7. What is Nutritional Support? “The provision of nutrients orally, enterally or parenterally with therapeutic intent. This includes, but is not limited to, provision of total enteral or parenteral nutrition support, and provision of therapeutic nutrients to maintain and /or restore optimal nutrition status and health.” ASPEN, 2002

  8. Who Should Get Nutritional Support? Patients who: • Cannot meet nutrient requirements • Have documented inadequate oral intake • Have unpredictable return of GI function • Need a prolonged period of NPO/bowel rest

  9. Enteral (GI Tract) versus Parenteral (IV) Nutrition • Not a flip of the coin decision • “If the gut works, use it!”

  10. Magic! Parenteral Nutrition • 23-year old female with Crohn’s disease • Obstruction and perforation – ICU post-op • NPO for 3 weeks, sepsis, weight loss 30 lb • “Does she need TPN, Sir?” “Yes, Armstrong!” • How do we give TPN? • What should we give and how much? • What do we need to monitor? • Who can help us with this? • “You’ll have to read it up, I’m afraid; I’ve never done this and I don’t know anyone who has!”

  11. Common Indications for PN • Inability to absorb adequate nutrients via the GI tract : • Massive small-bowel resection / short bowel syndrome • Severe, untreatable steatorrhea / diarrhoea / malabsorption • Complete bowel obstruction, or intestinal pseudo-obstruction • Prolonged acute abdomen or ileus • Severe catabolism & GI tract unusable within 5–7 days • Enteral access not feasible, not adequate or not tolerated • Pancreatitis with intolerance (eg pain) of jejunal nutrition • High output EC fistula (>500 mL) & no distal enteral access

  12. Potential Indications for PN • Enterocutaneous fistula • IBD unresponsive to medical therapy • Hyperemesis gravidarum – persistent for > 5–7 days and enteral nutrition not possible • Partial small bowel obstruction • Intensive chemotherapy / severe mucositis • Major surgery if enteral nutrition unlikely for >7–10 days • Intractable vomiting if jejunal feeding not possible • Chylous ascites or chylothorax when low

  13. Contra-indications to PN • Functioning gastrointestinal tract • Treatment anticipated for < 5 days in patients without severe malnutrition • Inability to obtain venous access • Poor prognosis that does not warrant aggressive nutrition support • When the risks of PN are judged to exceed the potential benefits

  14. Who Needs PN?Assessing Nutritional Status • Focused nutrition history • Assess current weight and weight-loss history • Physical examination • Assess malabsorption • Fecal fat test • Schilling test • Hydrogen breath test • D-xylose • SGA – Subjective Global Assessment Bashir S, et al. Prim Care 2001;28:629-645.

  15. Assessing Nutritional Status:The SGA B. Physical • Loss of subcutaneous fat • Muscle wasting • Ankle edema • Sacral edema • Ascites C. SGA Rating • A = Well nourished • B = Moderately malnourished • C = Severely malnourished A. History • Weight change <5% = “small”5–10% = “potentially significant” >10% = “definitely significant” • Change in dietary intake • Gastrointestinal symptoms(nausea, vomiting, diarrhea, anorexia) • Functional capacity • Disease and its relation to nutritional requirements Detsky AS et al. JPEN 1987;11:8-13.

  16. How Do We Give PN?

  17. Administration of PN • PN solutions are hypertonic • Infusion, therefore, via: • Central venous catheter, or • Peripheral venous catheter with *reduced* osmolarity

  18. Percutaneous CentralVenous Access • Peripherally inserted central catheters: PICC • Placed at bedside or radiologically • Subclavian vein – used to be most common • Can be placed & removed at bedside, but • Generally, placed radiologically • Confirm placement with chest x-ray • Can change over a wire to replace

  19. Implanted Central Venous Catheters (e.g. Hickman, Groshong, Port-A-Cath) • For prolonged TPN: • Also for fluids, chemotherapy, blood draws • Catheter inserted ‘operatively’ • Placed with fluoroscopic guidance • Implanted into a subcutaneous tunnel

  20. O Tip in SVC Peripherally Inserted Central Catheter (P.I.C.C.) Line • More expensive than peripheral lines • More difficult to place • Last up to 6 - 12 months • Restrict arm movement • Allow higher osmolarity “Central” TPN solutions

  21. Tunnelled (“Hickman”) Line

  22. Implanted Venous Access Device

  23. PROS Least expensive Easily placed and removed Lowest risk for CRI Beneficial for short-term support (< 1 week) CONS Need to change often Every 48-72h Phlebitis and vein injury Only one lumen Limits energy delivery Volume Osmolality (600-900 mOsm/l) pH restriction (pH 5-9) Peripheral IV: short-line

  24. PROS May be used for a longer duration than peripheral Ease of placement compared to central lines Allows access to larger vessel CONS Not a central line Must follow guidelines for peripheral lines for concentration, pH and infusion rates Peripheral IV: mid-line

  25. PROS Can infuse solutions> 900 mOsmol/l May be placed by RN Decreased CRI vs other central lines: HPN Can be multi-lumen Usable for CT contrast CONS Shorter life than other central lines (< 12 m) More difficult self care Blood sampling not always possible More frequent flushing and maintenance More painful Central IV: PICC

  26. PROS Can infuse solutions> 900 mOsmol/l Allow full IV nutritional support Can be multi-lumen Longevity: 1 -3 years Easier self-care (than PICC &, possibly, port) CONS Surgical / Radiological procedure More complex More difficult to remove Tube protruding from chest may affect body image More restrictive than a port Central IV: Hickman / Brovac

  27. PROS Can infuse solutions> 900 mOsmol/l Allow full IV nutritional support Greatest longevity Easier self-care (only needed if accessed) Improved body image & activity CONS Surgical / Radiological procedure More complex More difficult to remove Access requires placement of a Huber needle Infection risk during access Central IV: Implantable Port

  28. Complications of PN • Infectious • e.g. Catheter and systemic infections • Mechanical • e.g. Catheter obstruction, Hydrothorax, Venous thrombosis • Metabolic • e.g. Bone disease, Hepatobiliary disease, Renal disease

  29. Complications of PN Catheters • Catheter infections • Catheter occlusion • Catheter injury/leakage • Catheter migration • Venous thrombosis • “Catateher” line – true story!

  30. Venous Access Line Blockage • Check hub / line integrity / phlebotomy • Careful flushing • Doppler study + “Linogram” • Lipid - 70% EtOH • Calcium / mineral - HCl (0.1 N) • Thrombus - (Urokinase - 5000U) or tPa • Prophylaxis - flushing after ‘cap-off’

  31. Catheter-related infections • Skin commensals (S. epidermidis, S. aureus, Candida spp) & Intestinal flora (Ps spp, Candida) • Monitor temp (blood culture if >38.5oC) • Culture - central and peripheral - 5:1 CFU ratio implicates central line (Vanhuynegem, 1988, Surgery) • 2/3 can be cleared by antibiotics and local care (Benezra, 1988, Am J Med) • Antibiotic lock - 4d Rx + 10d 12-h lock (90% clear)

  32. Risk Factors for Infection • Site - Subclavian < Int. jugular < Femoral • Material - Silastic / Polyurethane < PVC • Type - Subclavian (0.9) < PICC (1.4 / 1000d) - Single lumen < Multi-lumen • Care - 2% chlorhexidine (5.9 % catheter colonisation) 70% isopropyl alcohol (15.6%) 10% povidone iodine (19.5%) • Patient - young, poor technique, smoking, Crohn’s, jejunostomy, thrombosis, narcotics

  33. Parenteral Nutrition - Overview • Indications, Contraindications and Routes of Administration • Macronutrient and Micronutrient Use in TPN • Importance of a Parenteral Nutrition Team

  34. Designing Parenteral Regimens • Assess nutritional status and set goals. • Evaluate constraints on nutrient delivery. • Assess fluid, electrolyte, vitamin, trace element requirements • Order nutrients (protein, CHO, fat), fluids/ electrolytes/ trace elements • Determine administration (rate and duration). • Avoid metabolic complications. http://www.globalrph.com/tpn.htm

  35. Parenteral Nutrition • Carbohydrate (10 - 25% Dextrose) • Amino Acids (0.8 to 1.2 g /kg) • Lipid Emulsion, incl E.F.A. (10 - 30%) • Vitamins / Minerals / Trace Elements • Electrolytes • Fluid (2 - 3 litres /day)

  36. How Much Should We Give?

  37. Nutritional Assessment:The Eggs-Benedict Equation (EBE) A:-Asparagus B:- Bacon C:-Cholesterol E.B.E. = 0.43A + 1.56B + 4.57C

  38. Nutritional Assessment • Dietary Intake Assessment (3-day recall) • Weight & Weight loss (v. IBW / UBW) • Harris-Benedict Equation + ‘Stress factor’ • Blood tests: CBC, Albumin, Electrolytes, Vitamins A, B12, D & E, Fe++, Ca++, Mg++ • (Indirect Calorimetry) • (Anthropometry) • (Nitrogen Balance)

  39. Estimate of Requirements • Most hospitalized patients will require 30 kcals/kg/d • CHO – can utilise dextrose up to 5 mg/kg/min • Protein – The average patient requires 0.8 – 2.0 g protein/kg usual body weight

  40. Constraints on Nutrient Delivery • Do not overload body’s disposal systems • renal, hepatic, respiratory • Nutritional regimen should make sense clinically

  41. Constraints on Nutrient Delivery • Protein • Renal failure without dialysis or with ineffective dialysis • Hepatic encephalopathy • Intractable negative nitrogen balance

  42. Constraints on Nutrient Delivery • Carbohydrates • Oxidative limit 7 gm/kg/day • Glucose intolerance • Minimum of 200 gm if large wound present • Lipid • Oxidative limit 2.5 gm/kg/day • Hyperlipidemia

  43. Constraints on Nutrient Delivery • Fluid • Fluid overload • Renal insufficiency/failure • Congestive heart failure • Pulmonary edema • ARDS

  44. Composition of Standard Parenteral Dextrose Solutions • 5% - 70% solution dextrose in water • 3.4 kcal/gm • 500 ml of a 50% solution contains • 50 gm/100 ml x 500 ml = 250 gm dextrose • 250 gm x 3.4 kcal/gm = 850 kcal

  45. Composition of Standard Parenteral Amino Acid Solutions • Synthetic crystalline amino acids • Contain essential and non-essential AA • Variable amounts of electrolytes • Concentrations depend on final volume • Hypertonic solutions

  46. Characteristics ofIntravenous Lipid Emulsions • Concentrations 10% and 20% • Parent oil Soybean or Safflower • Osmolarity 280 - 340 mOsm/l • Caloric content 10% = 1.1 kcal/ml 20% = 2.0 kcal/ml

  47. Electrolytes in Parenteral Nutrition Solutions • Appropriate prescription requires regular monitoring • For maintenance provision • Add directly to the PN solution • Tailor to individual patient needs • Additional replacement for abnormal losses • Deletions for patients with certain diseases

  48. Vitamins/Trace Elements in Parenteral Nutrition Solutions • Meet established guidelines for PN • Water and fat-soluble vitamins provided • Required for zinc, copper, manganese, chromium & selenium • Added daily to the solution • Requirements may be increased for patients with abnormal losses

  49. Administration of Parenteral Nutrition: Rate and Duration • Administer, initially, over 24 hours • Restrict the rate if regimen is not tolerated • If patient is stable and tolerates regimen, a cycling regimen may provide greater freedom, comfort and ease of care

  50. “3-in-1” (T.N.A.) vs “3-in-2” Disadvantages • Solution instability • Incr. bacterial growth • Can’t use 0.22um filter • Obscures precipitates • Potential catheter occlusion Advantages • Cost (fewer supplies) • Convenience • More balanced delivery • Better lipid tolerance • Decreased potential for contamination

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