Blood-conservation techniques for coronary-artery bypass surgery at a private hospital

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Haematological effects of reinfused mediastinal blood after cardiac surgery

OBJECTIVE

To explore the risk of inducing a coagulation defect in cardiac surgery patients by the reinfusion of mediastinal blood.

DESIGN

Ten patients who underwent coronary artery surgery were prospectively studied for the haematological effects of reinfusion of blood drained from the chest drain tubes after the operation by a Sorenson autologous transfusion system.

SETTING

Surgery was performed at a private hospital and patient selection was made at the time of reinfusion.

PATIENTS

Nine patients had primary coronary artery surgery and one had a reoperation.

MAIN OUTCOME MEASURES

Blood samples were taken from the patients before reinfusion, one hour after reinfusion, and 24 hours later as well as from the collected blood. Measurements were made of the haemoglobin content, white cell and platelet counts, fibrinogen and fibrinogen degradation products, D-dimer, antithrombin III and plasma haemoglobin content. Estimations were also made of the prothrombin time, the thrombin clotting time and the activated partial thromboplastin time. The hypothesis to be tested by this study was that the reinfusion of mediastinal blood after the operation did not cause any significant disturbance of the patient's blood clotting profile.

RESULTS

An average of 535 mL (range, 400-950 mL) was reinfused after a period of three hours drainage (range, 45 minutes to 5 hours). While the initial patient samples contained a raised plasma haemoglobin level (0.19 g/L) significantly related to the cardiopulmonary bypass time (P less than 0.001), these were free of fibrinogen degradation products except for a sample from one patient who had a reoperation. The blood drained by the Sorenson system was lower in haemoglobin content (7.7 g/dL), and had a significant content of fibrinogen degradation products (147 mg/L) and D-dimer (6.4 mg/L) together with reduced clotting factors when compared with the patients' blood. After reinfusion, the patient sample showed evidence of altered coagulation with mildly increased clotting times (activated partial thromboplastin time 57 s, thrombin clotting time 123 s), the extent of which was related to the volume reinfused (P less than 0.001), but 24 hours later, these effects had all disappeared. All samples were sterile in aerobic and anaerobic culture media.

CONCLUSION

We conclude that the Sorenson system of retrieval of mediastinal blood after cardiac surgery provides a safe and simple method of blood conservation provided that the volume of reinfusion is not excessive.