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Complications of Critical Illness

Complications of Critical Illness. Division of Critical Care Medicine University of Alberta. First, do no harm. Outline. Nutritional support in the ICU Abdominal compartment syndrome DVT/PE in the ICU Ventilator associated pneumonia Gastric stress ulceration. Nutritional Support.

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Complications of Critical Illness

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  1. Complications of Critical Illness Division of Critical Care Medicine University of Alberta

  2. First, do no harm.

  3. Outline • Nutritional support in the ICU • Abdominal compartment syndrome • DVT/PE in the ICU • Ventilator associated pneumonia • Gastric stress ulceration

  4. Nutritional Support

  5. Reasons for Support • Limit catabolism • Substrate for healing • Increase survival

  6. Calculating Metabolic Needs • Formula: Harris-Benedict Equation • Nitrogen Balance • Resting Energy Expenditure

  7. Harris-Benedict Equation • Estimates Basal Metabolic Rate (BMR): • Male BMR kcal/day = 66.47 + 13.7 (kg) + 5 (cm) - 6.76 (yrs) • Female BMR kcal/day = 66.51 + 9.56 (kg) + 1.85 (cm) - 4.68 (yrs) • Total Caloric Requirements equal the B.E.E. multiplied by the sum of the stress and activity factors. • Stress plus activity factors range from 1.2 to over 2. • Factors to add to the BMR: • 25% (mild peritonitis, long bone fracture or mild/moderate trauma) • 50% (severe infection, MSOD, severe trauma) • 100% (burn of 40 to 100% TBSA)

  8. Nitrogen Balance • Measure/estimate all sources of nitrogen output. • stool, urine, skin, fistulae, wounds, etc. • Measure all sources of nitrogen input. • enteral or parenteral nutrition

  9. Greenfield 1997

  10. Calculating Nitrogen Balance

  11. Problems with Nutritional Parameters • UUN will be invalid if creatinine clearance is less than 50. • UUN and prealbumin are not helpful if the patient has not received goal volumes of feeding consistently for three to four days prior to the test.

  12. Metabolic CartIndirect Calorimetry: Theory • Measures O2 absorbed in lungs • Assumptions of Fick equation, at steady state O2 absorbed equals O2 consumed. • Metabolic rate in cc of O2 per minute. • Conversion 5kcal/liter O2. • 24 hour steady state measurement recommended. • Theory - start with a formula, tune it up long-term with the metabolic cart!

  13. Metabolic Cart - Indirect Calorimetry: Results • RQ or respiratory quotient(CO2 expired/O2 inspired). • 0.6 - 0.7 starvation/underfeeding • 0.84 - 0.86 desired range/mixed fuel utilization • 0.9 - 1.0 carbohydrate metabolism • 1.0 + overfeeding/lipogenesis

  14. Wound healing Measured proteins Albumin (t½ = weeks) Prealbumin (t½ = days) Non-water weight gain Other Clinical Parameters

  15. Enteral vs. Parenteral? • Use the GI tract whenever possible. • Contraindications to GI feeds: • large output fistula • SBO • severe pancreatitis • short gut, severe diarrhea, enteritis • non-functional GI tract

  16. Starting Estimates • Determine number of calories needed. • Determine normal or increased protein needs. • Determine if contraindication to fats. • Determine fluid restrictions. • USE THE GI TRACT IF POSSIBLE!!

  17. Nutrients • Fat- essential linolenic, linoleic, arachidonic acids • 9 kcal/gm • Protein- essential and branched chain AA in TPN • 4 kcal/gm - not to be included in calorie estimates • no glutamine in TPN due to instability • Carbohydrates- converted to glucose • 3.4 kcal/gm (4.0 kcal from endogenous source) • Trace Minerals • Chromium, copper, zinc, manganese, selenium, iron • Vitamins • Thiamine • Folate • Vitamin C

  18. Rules of Thumb: TPN • Want 25 - 35% solution of dextrose. • Want 4.25 - 6% AA solution. • normal 0.8 gm/kg/day up to 2.0 gm/kg/day • Kcal/nitrogen ratio • normal 300:1 • post-op 150:1 • trauma/sepsis 100:1 • Lipids 10 - 20% at least twice per week.

  19. TPN vs. Enteral: Advantages? • Many prospective, randomized studies. • TPN group had much higher infection rates. • pneumonia, intraabdominal abscess, line sepsis • Potential Reasons for TPN Failure: • TPN increases blood glucose if not strictly controlled. • numerous studies now show hyperglycemia increases mortality and infectious complications. • Does not contain glutamine.

  20. Why Enteral? • Preservation of villous architecture • may prevent translocation • role of translocation unclear in humans • good study in BMT patients • Ability to give glutamine • major fuel of enterocytes • major nitrogen transfer agent to viscera • in catabolic stress may be an essential AA

  21. Gastric vs. Post-pyloric Feeds • Route probably not important if patient tolerating feeds. • If gastric ileus, recent surgery, or need for frequent procedures where feeds would be stopped if gastric, post-pyloric may be better.

  22. Refeeding Syndrome • In severely malnourished. • Development of severe electrolyte abnormalities: • phosphorous, potassium, magnesium • As muscle mass, cell mass, and ATP repleted: • may reach critically low values, cardiac arrest

  23. Theoretical Advantages of Early Enteral Nutrition 1. Ameliorate the stress response, hypermetabolism, and hypercatabolism. 2. Provide gut stimulation to prevent atrophy and the loss of immunologic and barrier functions of the gut. 3. Minimize rapid onset of acute malnutrition. 4. Decrease LOS and complication rates.

  24. Energy Requirement in Critical Illness: Different Conditions

  25. Total Kcal Goals • 25 - 35 kcal/kg is suitable for most hospitalized patients and is a good rule of thumb. • 21 kcal/kg is appropriate for obese patients. • 30 - 40 kcal/kg may be necessary for highly stressed patients.

  26. Total Protein Goals • 1.0 g/kg for healthy individuals. • 1.2 - 1.5 g/kg for mildly stressed. • 1.5 - 2.0 severely stressed/multiple trauma/head injury/burns.

  27. Lipid Goals • High calorie, low volume. • Suggested max calories - no more than 50% of non-protein Kcal, or < 1 cal/Kg/hr. • Minimum to prevent essential fatty acid deficiency is 2 x 500 cc bottles/week. • Diprivan (propofol) = 1calorie/ml

  28. Consequences of Overfeeding 1. Azotemia - patients > 65 years and patients given > 2g/kg protein are at risk. 2. Fat-overload syndrome - recommended maximum is 1g lipid/kg/d. Infuse IV lipid slowly over 16 - 24 hours. 3. Hepatic steatosis - patients receiving high carbohydrate, very low fat TPN are at risk. 4. Hypercapnia-makes weaning difficult. 5. Hyperglycemia - increases risk of infection. Glucose should not exceed 5 mg/kg/min (4 mg/kg/min for diabetics).

  29. Consequences of Overfeeding 6. Hypertonic dehydration - can be caused by high-protein formula with inadequate fluid provision. 7. Hypertriglyceridemia - propofol, high TPN lipid loads, and sepsis increase the risk. If the patient is hypertriglyceridemic, decrease lipid to an amount to prevent EFAD (500 cc 10% lipid twice weekly) and monitor.

  30. Consequences of Overfeeding 8. Metabolic acidosis - patients receiving low ratios of energy to nitrogen are at risk. Acidosis can cause muscle catabolism and negative nitrogen balance. 9. Refeeding syndrome - common in malnourished patients or those held NPO prior to initiation of feeding. Start feedings conservatively, advance gradually, and monitor Mg, Ph, and K closely.

  31. Nutritional Goals • Feed as soon as hemodynamically stable, after adequate resuscitation. • No disease state improves with starvation. • Poor gut perfusion may contraindicate enteral feeds, but enteral feeds are always preferred when possible.

  32. Abdominal Compartment Syndrome

  33. Abdominal Compartment Syndrome • Acute increase in intra-abdominal pressure • Affects renal, pulmonary, and cardiovascular systems • Decreases ventilation, causes hypoxia, decreased blood flow to lower extremities, and kidney failure.

  34. Abdominal Compartment Syndrome • Caused by intra-abdominal swelling or hemorrhage. • Increase in volume of retroperitoneum such as with pancreatitis also seen. • Even reports of retroperitoneal hemorrhage such as with pelvic fracture or from anticoagulation.

  35. Abdominal Compartment Syndrome • Early recognition and diagnosis vital to prevent complications. • Distended, tense abdomen first sign • Bladder pressure confirms elevated pressure and is easy to perform. • Bladder is direct transmitter of pressure at volumes of less than 100 cc.

  36. Bladder Pressure Measurement • Bladder filled with 50 cc. of sterile saline via foley and pressure monitor connected to side port with 18 ga. needle. • Normal pressure up to 10 cm H2O • Grade I = 10-15 • Grade II = 15-25 • Grade III = 25-35 • Grade IV = >35

  37. Abdominal Compartment Syndrome • Grade I-II can be treated with muscle relaxants as long as clinical situation improves. • Indication for laparotomy with open abdomen: • Grade III and over • Failure of improvement with conservative measures

  38. Venous Thromboembolism in ICU

  39. DVT Recurrence PE Post-phlebitic syndrome Importance of DVT Prophylaxis • Acute DVT/PE prevention • Valvular Damage • Symptomatic proximal DVT can be an extension of distal DVT that was previously asymptomatic. • Significant number of fatal PE’s NOT preceded by symptomatic DVT. • Most preventable cause of hospital associated death in medical patientsPE.

  40. Asymptomatic DVT Upon ICU Admission

  41. Natural History of DVT 132 Surgical patients no prophylaxis 70% No DVT (92) 30% DVT (40) 35% Calf with spontaneous lysis (14) 42% Calf only (17) 23% propagation Popliteal/femoral (9) 56% No PE (5) 44% PE (4)

  42. Incidence of VTEin Major Trauma Without Prophylaxis • Lower leg DVT 58%, proximal DVT 18% • Vast majority clinically not apparent.

  43. Autopsy Studies for PE in Critically Ill Patients

  44. Thromboembolism Riskin Surgical Patients - No Prophylaxis

  45. Trauma and Venous Thromboembolism • Patients recovering from major trauma have highest risk for developing VTE amongst all hospitalized patients. • Without prophylaxis, multisystem or major trauma have a DVT risk exceeding 50%. • PE is the third leading cause of death in trauma patients that survive beyond the first day.

  46. Significant Risk Factors and Odds Ratios for Venous Thromboembolism

  47. VTE Prophylaxis Pharmacologic Unfractionated heparin Low molecular weight heparin Vit K Antagonists Mechanical Graduated Compression Stockings Intermittent Pneumatic Compression Devices IVC filters

  48. INJURED PATIENT High Risk Factors (Odds ratio for VTE = 2 – 3) • Age ³ 40 • Pelvic fx • Lower extremity fx • Shock • Spinal cord injury • Head Injury (AIS ³ 3) Very High Risk Factors (Odds ratio for VTE = 4 - 10) • Major operative procedure • Venous injury • Ventilator days > 3 • 2 or more high risk factors Does the patient have contraindication for Heparin? Does the patient have contraindication for Heparin? No Yes Yes No LMWH* and Mechanical Compression Mechanical Compression and serial CFDI OR Temporary IVC filter Mechanical Compression LMWH* * Prophylactic dose

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