Update on blood conservation for cardiac surgery

Sodium citrate effectively used in shed mediastinal blood autotransfusion after cardiac surgery

BACKGROUND

We used sodium citrate as an alternative anticoagulation agent to heparin in the procedure of autologous blood transfusion with patients with postoperative haemorrhage after CPB. The aim of study was to evaluate the efficacy and safety of sodium citrate used in shed mediastinal blood autotransfusion after cardiac surgery.

METHODS

Ninety-three patients were divided into two groups in this study. In the control group, 52 patients' shed mediastinal blood was discarded. The reinfusion group consisted of 41 patients receiving a reinfusion of washed autologous red cells from shed mediastinal blood. Each 400 mL shed blood sample was anticoagulated by 140 mL of 1.6% diluted sodium citrate in the washing procedure using a blood recovery machine. Hemoglobin (Hb), hematocrit (Hct), and electrolyte concentrations in both the patients and shed mediastinal blood were measured before and after this procedure.

RESULTS

The mean volume of autotransfused shed blood was 239.5 ± 54.6 mL.The Hct of the washed red cells was 56.8 ± 6.1%. Significantly, fewer units of allogeneic blood were required per patient in the reinfusion group at 24 h postoperatively (2.91 ± 1.34 vs 4.03 ± 0.19 U, p = 0.002). At 24 h postoperatively, Hb and Hct levels were higher in the reinfusion group than in the control group. The calcium ion concentration was very low in the shed mediastinal blood, 0.25 ± 0.08 mmol/L, and was lower after washing, 0.15 ± 0.04 mmol/L.

CONCLUSIONS

Sodium citrate, as an alternative anticoagulant agent, can be used in autologous shed mediastinal blood transfusion after CPB cardiac surgery. This procedure can effectively reduce the amount of allogeneic blood for patients with haemorrhage.

Association Between Adverse Clinical Outcomes After Coronary Artery Bypass Grafting and Perioperative Blood Transfusions

Background

Bleeding is a serious complication of coronary artery bypass grafting that often leads to blood transfusion. Approximately 50% of patients who have the surgery receive blood products, and blood transfusions play a role in adverse outcomes after the surgery.

Objective

To examine the association between perioperative blood transfusion and postoperative adverse outcomes in patients undergoing coronary artery bypass grafting.

Methods

A systematic review of the literature, via the matrix method of quality evaluation, was conducted. PubMed, CINAHL, and Science Direct databases for 2000 through 2016 were searched. Inclusion criteria were articles published in English and original research related to clinical outcomes of blood transfusion after coronary artery bypass grafting. Seventeen articles were included in the review.

Results

Mortality, both short- and long-term, was significantly higher in transfusion patients than in nontransfusion patients. Patients with transfusion of red blood cells had higher resource utilization and more complications, including infection, pneumonia, renal failure, graft occlusion, and atrial fibrillation, than did nontransfusion patients.

Conclusion

An association exists between red blood cell transfusions and adverse clinical outcomes for patients undergoing coronary artery bypass grafting. Transfusion of red blood cells is sometimes unnecessary, may be injurious, and should be used cautiously. Even a single-unit increase in perioperative red blood cell transfusions can have a significant adverse impact on outcomes. Individual benefits and risks should be weighed before transfusion to avoid adverse outcomes. Transfusion guidelines should be reviewed to include the latest evidence to guarantee the most appropriate use of blood products.

Comparative effectiveness of epsilon-aminocaproic acid and tranexamic acid on postoperative bleeding following cardiac surgery during a national medication shortage

STUDY OBJECTIVE

The aim of this study was to compare the effectiveness of epsilon-aminocaproic acid (εACA) and tranexamic acid (TXA) in contemporary clinical practice during a national medication shortage.

DESIGN

A retrospective cohort study.

SETTING

The study was performed in all consecutive cardiac surgery patients (n=128) admitted to the cardiac-surgical intensive care unit after surgery at a single academic center immediately before and during a national medication shortage.

MEASUREMENTS

Demographic, clinical, and outcomes data were compared by descriptive statistics using χ² and t test. Surgical drainage and transfusions were compared by multivariate linear regression for patients receiving εACA before the shortage and TXA during the shortage.

MAIN RESULTS

In multivariate analysis, no statistical difference was found for surgical drain output (OR 1.10, CI 0.97-1.26, P=.460) or red blood cell transfusion requirement (OR 1.79, CI 0.79-2.73, P=.176). Patients receiving εACA were more likely to receive rescue hemostatic medications (OR 1.62, CI 1.02-2.55, P=.041).

CONCLUSIONS

Substitution of εACA with TXA during a national medication shortage produced equivalent postoperative bleeding and red cell transfusions, although patients receiving εACA were more likely to require supplemental hemostatic agents.

Progress in platelet blockers: the target is the P2Y12 receptor

The considerable progress in P2Y12-platelet blockers has important perioperative implications due to a family of novel agents beyond clopidogrel. Although prasugrel is more potent than clopidogrel due to more efficient hepatic metabolism, it is limited clinically by its irreversibility and bleeding risks. Ticagrelor, as the first approved direct and reversible oral P2Y12 blocker, still is limited clinically by its novel side-effect profile. Intravenous reversible P2Y12 blockade is possible now with both cangrelor and elinogrel, although both agents are still in clinical development. Furthermore, elinogrel offers the possibility of both oral and parenteral P2Y12 blockade with a single agent. Future trials likely will continue to evaluate and compare the safety and efficacy of these agents in multiple clinical settings, including the perioperative period.

Cardiac surgery-associated acute kidney injury

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common and serious postoperative complication of cardiac surgery requiring cardiopulmonary bypass (CPB), and it is the second most common cause of AKI in the intensive care unit. Although the complication has been associated with the use of CPB, the etiology is likely multifactorial and related to intraoperative and early postoperative management including pharmacologic therapy. To date, very little evidence from randomized trials supporting specific interventions to protect from or prevent AKI in broad cardiac surgery populations has been found. The definition of AKI employed by investigators influences not only the incidence of CSA-AKI, but also the identification of risk variables. The advent of novel biomarkers of kidney injury has the potential to facilitate the subclinical diagnosis of CSA-AKI, the assessment of its severity and prognosis, and the early institution of interventions to prevent or reduce kidney damage. Further studies are needed to determine how to optimize cardiac surgical procedures, CPB parameters, and intraoperative and early postoperative blood pressure and renal blood flow to reduce the risk of CSA-AKI. No pharmacologic strategy has demonstrated clear efficacy in the prevention of CSA-AKI; however, some agents, such as the natriuretic peptide nesiritide and the dopamine agonist fenoldopam, have shown promising results in renoprotection. It remains unclear whether CSA-AKI patients can benefit from the early institution of such pharmacologic agents or the early initiation of renal replacement therapy.

Blood transfusion and infection after cardiac surgery

Cardiac surgery is the largest consumer of blood products in medicine; although believed life saving, transfusion carries substantial adverse risks. This study characterizes the relationship between transfusion and risk of major infection after cardiac surgery. In all, 5,158 adults were prospectively enrolled to assess infections after cardiac surgery. The most common procedures were isolated coronary artery bypass graft surgery (31%) and isolated valve surgery (30%); 19% were reoperations. Infections were adjudicated by independent infectious disease experts. Multivariable Cox modeling was used to assess the independent effect of blood and platelet transfusions on major infections within 60 ± 5 days of surgery. Red blood cells (RBC) and platelets were transfused in 48% and 31% of patients, respectively. Each RBC unit transfused was associated with a 29% increase in crude risk of major infection (p < 0.001). Among RBC recipients, the most common infections were pneumonia (3.6%) and bloodstream infections (2%). Risk factors for infection included postoperative RBC units transfused, longer duration of surgery, and transplant or ventricular assist device implantation, in addition to chronic obstructive pulmonary disease, heart failure, and elevated preoperative creatinine. Platelet transfusion decreased the risk of infection (p = 0.02). Greater attention to management practices that limit RBC use, including cell salvage, small priming volumes, vacuum-assisted venous return with rapid autologous priming, and ultrafiltration, and preoperative and intraoperative measures to elevate hematocrit could potentially reduce occurrence of major postoperative infections.