What are the guidelines for intraoperative blood transfusion protocol?

Intraoperative Blood Transfusion Protocol

For most surgical patients without cardiovascular disease, transfuse red blood cells when hemoglobin falls below 7.0 g/dL, but for patients with cardiovascular disease or at risk of end-organ ischemia, use a higher threshold of 8.0-9.0 g/dL, and always integrate clinical assessment of ongoing bleeding, hemodynamic stability, and signs of organ ischemia into the decision. 1

Hemoglobin-Based Transfusion Triggers

Patients Without Cardiovascular Disease

• Transfusion threshold: Hemoglobin <7.0 g/dL 1
• Red blood cells should usually be administered when hemoglobin is <6.0 g/dL, especially when anemia is acute 1
• Red blood cells are usually unnecessary when hemoglobin is >10.0 g/dL 1

Patients With Cardiovascular Disease

• Transfusion threshold: Hemoglobin <8.0-9.0 g/dL 1
• The Scottish Intercollegiate Guidelines Network recommends 9.0 g/dL for patients with cardiovascular disease, including elderly patients or those with peripheral vascular disease 1
• The French Health Authority recommends 8.0 g/dL for patients with coronary artery disease 1

High-Risk Cardiac Patients

• Transfusion threshold: Hemoglobin <10.0 g/dL for patients with angina, heart failure, or those who are beta-blocked 1
• For patients with symptomatic coronary artery disease, a more liberal threshold (>10.0 g/dL) may be appropriate 2

Cardiopulmonary Bypass Patients

• Transfusion threshold: Hemoglobin <6.0 g/dL for patients on CPB with moderate hypothermia 1
• Transfusion threshold: Hemoglobin <7.0 g/dL for patients on CPB at risk of critical end-organ ischemia 1

Multifactorial Decision-Making Beyond Hemoglobin

The American Society of Anesthesiologists emphasizes that hemoglobin concentration alone should not be the sole trigger for transfusion when levels are between 6.0-10.0 g/dL. 1 The decision must incorporate:

Blood Loss Assessment

• Quantitative measurement: Use standard methods including suction canister volume, surgical sponge weighing, and visual assessment of the surgical field 1
• Transfusion trigger: Blood loss ≥1500 mL is considered significant and warrants consideration for transfusion 1, 2
• Monitor for excessive microvascular bleeding suggesting coagulopathy 1

Hemodynamic Monitoring

• Monitor blood pressure and heart rate continuously 1
• Assess for signs of hemodynamic instability including tachycardia and hypotension 2
• Consider the rate and magnitude of ongoing bleeding 1

End-Organ Perfusion Assessment

• Conventional monitoring: ECG for ST-segment changes, oxygen saturation, urine output 1
• Advanced monitoring when appropriate: Echocardiography, mixed venous oxygen saturation, arterial blood gas analysis, cerebral oximetry, near-infrared spectroscopy 1
• Look for signs of organ ischemia including ECG changes suggesting myocardial ischemia 1, 2

Intravascular Volume Status

• Assess adequacy of volume resuscitation before attributing symptoms solely to anemia 1
• Consider cardiopulmonary reserve and the patient's ability to compensate for anemia 1

Transfusion Strategy and Monitoring

Unit-by-Unit Approach

• Transfuse one unit at a time and reassess before administering additional units 1
• Measure hemoglobin or hematocrit after each unit to guide further transfusion decisions 1

Timing of Hemoglobin Measurement

• Measure hemoglobin when substantial blood loss occurs or any indication of organ ischemia develops 1
• Repeated measurements are recommended during active bleeding, though specific timing intervals are not defined 1
• Intraoperative hemoglobin measurement improves appropriate blood use compared to estimation from blood loss alone 3

Special Circumstances

• Early blood product replacement is recommended for procedures with anticipated massive blood loss, such as placenta accreta 1
• For hepatectomy, the Ottawa Criteria define significant blood loss as ≥1500 mL 1

Common Pitfalls to Avoid

• Do not use a single hemoglobin number as a universal trigger without considering the clinical context, patient comorbidities, and signs of inadequate oxygen delivery 1, 2
• Do not ignore patient symptoms when hemoglobin is above 7.0-8.0 g/dL; symptomatic patients may require transfusion at higher thresholds 2
• Do not transfuse to arbitrary "normal" hemoglobin levels (>10.0 g/dL) in hemodynamically stable patients without cardiovascular disease 1, 2
• Do not rely solely on estimated blood loss to guide transfusion; direct hemoglobin measurement is more accurate 3
• Do not forget that hemoglobin concentration may not accurately reflect red blood cell mass in acute blood loss due to plasma volume changes 2
• Do not fail to reassess after each unit transfused; continued transfusion should be based on ongoing clinical need 1, 2

Blood Conservation Techniques

Acute Normovolemic Hemodilution

• Consider for patients with initial hemoglobin ≥12 g/dL undergoing elective surgery with anticipated blood loss ≥1500 mL 4
• ANH reduces allogeneic red cell transfusion rates by approximately 50% in major hepatic resection 5
• Target hematocrit of 20-25% (7.0-8.0 g/dL hemoglobin) is feasible and safe 4

Intraoperative Blood Salvage

• Effective in reducing allogeneic transfusion requirements in cardiac surgery, liver surgery, and major orthopedic procedures 1
• Particularly valuable for cardiovascular surgical procedures 6