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Red Cell Transfusion in Critical Care Patients

Red Cell Transfusion in Critical Care Patients. Alan Tinmouth, MD MSc University of Ottawa Centre for Transfusion Research, Ottawa Health Research Institute and the Ottawa Hospital November 2009 . Objectives.

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Red Cell Transfusion in Critical Care Patients

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  1. Red Cell Transfusion in Critical Care Patients Alan Tinmouth, MD MSc University of Ottawa Centre for Transfusion Research, Ottawa Health Research Institute and the Ottawa Hospital November 2009

  2. Objectives • Review the seminal observational and randomized clinical trials evaluating red cell transfusions in the critically ill. • Understand the limitations of the current evidence surrounding red cell transfusions. • Understand the limits and benefits of alternatives / strategies to reduce the need for red cell transfusions.

  3. Case 1 Hebert, Crit Care Med 2005; 33; 7.

  4. Anemia in the critically ill is very common • 95% anemic by 3rd day in ICU • 40 – 45% of patients will receive RBCs • Average = 5 units RBC Vincent et al, JAMA 2002; Corwin et al, CCM 2004

  5. RBC Transfusions in Critical Care and Cardiac Surgery in Canada, 1998-2000 Hutton et al. CJA 2005

  6. Purpose of an RBC transfusion Increase hemoglobin levels. Increase O2 delivery and consumption. Decrease morbidity and mortality.

  7. The Role of Hemoglobin in O2 Delivery (1) DO2 = CO x (%sat x 1.39 x Hb) (2) CO = HR x stroke volume DO2 = O2 Delivery (ml/L) CO = Cardiac output(L/min) %Sat = % saturation of Hb Hb = Hemoglobin (g/L) 1.39 = O2 carried in blood (ml/L)

  8. Delivery Dependent Delivery Independent VO2 Critical DO2 DO2 Oxygen Delivery and RBC Transfusion • At least 19 clinical studies evaluating impact RBCs on oxygen kinetics in humans • Uniform increase in DO2 but not VO2 Hebert et al, CMAJ, 1997

  9. Oxygen Delivery and Consumption following RBC transfusion Suttner et al. Anesth Analg 2004; 99: 2-11

  10. Transfusion Requirements in Critical Care (TRICC)Hebert PC, et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. N Engl J Med. 1999;340(6):409-17 Purpose: To determine if a restrictive and liberal red cell transfusion strategy are equivalent in terms of effects on mortality and morbidity in volume resuscitated critically ill patients Hebert et al. NEJM 321: 151-156, 1999

  11. TRICC Study Study design: Multicentre RCT Setting:25 ICUs across Canada Study Population: Included Hb< 9.0 g/dl within 72 hrs and excluded patients with active blood loss (3.0 g/dl decrease or >3 unit transfusion in 12 hrs) Intervention: 7.0 g/dl vs 10.0 g/dl hemoglobin trigger Outcomes: 30 day all-cause mortality and organ failure Hebert et al. NEJM 321: 151-156, 1999

  12. 120 110 100 90 80 70 Hemoglobin (g/L) 60 50 40 30 20 10 0 0 5 10 15 20 25 30 Time (Days) Hemoglobins over time Liberal strategy Restrictive strategy p<0.01 Hebert et al. NEJM 321: 151-156, 1999

  13. 100 Restrictive strategy 90 80 Survival (%) Liberal strategy 70 p=0.10 60 50 0 5 10 15 20 25 30 Time (Days) Survival of all patients over 30 days 18.7% 23.3% Hebert et al. NEJM 321: 151-156, 1999

  14. Survival of patients < 55 years of age Hebert et al. NEJM 321: 151-156, 1999

  15. TRICC – Mortality and MODS Outcomes Liberal Restrictive P-Value (n=420) (n=418) Mortality No.(%) 30-day 98 (23.3) 78 (18.7) 0.11 60-day 111(26.5) 95(22.8) 0.23 ICU 68 (16) 56 (13) 0.29 Hospital 118(28.1) 93(22.3) 0.05 Organ Dysfunction MODS 8.8 ± 4.4 8.3 ± 4.6 0.10 MODS* 11.8 ± 7.7 10.7 ± 7.5 0.03 Change in MODS 1.26 ± 4.30 0.79 ± 4.26 0.15 Hebert et al. NEJM 321: 151-156, 1999

  16. Case 1 Hebert, Crit Care Med 2005; 33; 7.

  17. ICU Responses 1997 and 2003 Hebert, Crit Care Med 2005; 33; 7.

  18. RBC transfusions and risk of death Marik and Corwin, CCM 2008;36:2667

  19. Can we trust these studies? Inferences from these studies are weakened because: • Logic of transfusions always being harmful?? • Retrospective with limited data • Minimal adjustment for confounding factors • Timing of RBCs unknown • Trigger unknown…admission hematocrit/nadir hematocrit • Main culprit: “Confounding by Indication” • higher acuity → more aggressive care

  20. Adverse Effects Associated with Transfusion Hypotension Flushing Anxiety GIT Symptoms Pain Proinflammatory Other adverse effects of leukocytes Kinins Complement Histimine PLASMA Cleavage / activation of Plasma proteins Fever Neutrophilia Flushing Proinflammatory Capillary leak TRALI / ARDS MOF Cytokines Microaggregates BUFFY COAT Thrombosis ? ARDS RES Blockade Microvascular Pathology Procoagulants RED CELLS Thrombosis Haemolysis Billirubin LDH Iron Chemical, Metabolic & Physical Impaired O2 delivery Acidosis K+, Na+, NH4+ Hypothermia Glucose Plasticisers Jaundice • Impaired RBC survival • Reduced efficacy • Adverse effects

  21. Consequences of Biochemical and BioMechanical Changes in Stored RBCs • Left shift of oxygen-hemoglobin dissociation curve • Loss of red blood cell deformability • Increased RBC aggregation • Increased RBC adhesion to endothelial cells • Release of hypercoagulable microvessicles • Increased NO scavenging • Accumulation of cytokines Tinmouth. Transfusion 2006

  22. Case 3 Hebert, Crit Care Med 2005; 33; 7.

  23. APACHE II =< 20 APACHE II > 20 Restrictive strategy 100 100 90 90 Restrictive strategy 80 80 Liberal strategy Survival (%) Survival (%) 70 70 Liberal Strategy p = 0.02 60 60 p=0.54 50 50 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Time (Days) Time (Days) TRICC and acuity of illness Hebert et al. NEJM 321: 151-156, 1999

  24. Goal Directed Therapy in Early Sepsis Rivers et al. NEJM 2004; 345: 1368

  25. Goal Directed Therapy in Early Sepsis Rivers et al. NEJM 2004; 345: 1368

  26. Case 3

  27. ICU Responses 1997 and 2003 Hebert, Crit Care Med 2005; 33; 7.

  28. Case 2 Hebert, Crit Care Med 2005; 33; 7.

  29. TRICC – Cardiovascular Disease Patients with cardiovascular diseases (n=357) Patients with Ischemic Heart Disease (n=257) Hebert et al. NEJM 321: 151-156, 1999

  30. Complications during the ICU Stay Complication Liberal Restrictive P Values (n=420) (n=418) Cardiac No. (%) 88 (21.0) 55 (13.2) <0.01 Myocardial Infarction 12 (2.9) 3 (0.7) 0.02 Pulmonary Edema 45 (10.7) 22 (5.3) <0.01 Angina 9 (2.1) 5 (1.2) 0.28 Cardiac Arrest 33 (7.9) 29 (6.9) 0.6 Pulmonary No. (%) 122 (29.1) 106 (25.4) 0.22 ARDS 48 (11.4) 32 (7.7) 0.06 Pneumonia 86 (20.5) 87 (20.8) 0.92 Hebert et al. NEJM 321: 151-156, 1999

  31. RBC transfusions in acute MI Wu. NEJM 2001; 345: 1230.

  32. RBC transfusion in ACS • Transfused patients were older, had more co-morbidities and higher mortality rates Rao. NEJM 2001; 345: 1230.

  33. RBC transfusion in ACS • Adjusted analysis showed higher mortality rate associated with transfusions • No associated with harm for nadir hct of 0.20-0,25 • Increased mortality for nadir hct > 0.30 Rao. NEJM 2001; 345: 1230.

  34. Case 2 Hebert, Crit Care Med 2005; 33; 7.

  35. ICU Responses 1997 and 2003 Hebert, Crit Care Med 2005; 33; 7.

  36. Case 4 Walsh, Transf 2009; epub.

  37. TRICC and mechanical ventilation Hebert et al. NEJM 321: 151-156, 1999

  38. Case 4 Walsh, Transf 2009; epub.

  39. Case 5 • 28 year old Jehova Witness. Peripartum hemorrage taken to OR and hysterectomy performed. Bleeding now controlled. Admitted to ICU post-op with Hgb 28 g/L. Treatment recommendations ?

  40. Alternatives to Red Cell Transfusions • Erythropoietin • Iron replacement • Folate Other • Factor VIIa for bleeding • Reduce phlebotomy – pediatric tubes

  41. EPO in Critical Care – Part 1 Corwin, JAMA 2002; 288: 2827.

  42. EPO in Critical Care – Part 1 • EPO raised hemoglobin (13.2 g/L vs. 9.4 g/L) • EPO resulted in 19% reduction in number of units RBCs transfused

  43. EPO in Critical Care – part II • EPO raised increased hemoglobin (16 g/L vs. 12 g/L, p < 0.001) and resulted in higher hemoglobin levels. • No difference in transfusion rates with restrictive transfusion policy Corwin, NEJM 2007; 357: 965.

  44. EPO in Critical Care – part II Thrombosis Mortality Corwin, NEJM 2007; 357: 965.

  45. Conclusions • In critical care patients, restrictive RBC transfusion strategy is not worse than liberal transfusion strategy • Patients not likely to benefit from RBC transfusion are only likely to be harmed • Results of TRICC not generalizable to all critically ill patients • e.g. cardiac and bleeding patient • Alternatives to transfusions also have adverse effects • “best transfusion is not simply transfusion not given”

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