Drugs to Minimize Perioperative Blood Loss in Cardiac Surgery

A meta-analysis of the effectiveness of cell salvage to minimize perioperative allogeneic blood transfusion in cardiac and orthopedic surgery. International Study of Perioperative Transfusion (ISPOT) Investigators

Concern about risks of allogeneic transfusion has led to an interest in methods for decreasing perioperative transfusion. To determine whether cell salvage reduces patient exposure to allogeneic blood, we performed meta-analyses of randomized trials, evaluating the effectiveness and safety of cell salvage in cardiac or orthopedic elective surgery. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Twenty-seven studies were included in the meta-analyses. Cell salvage devices that do not wash salvaged blood were marginally effective in cardiac surgery patients when used postoperatively (relative risk [RR] = 0.85, 95% confidence interval [CI] = 0.79-0.92). Devices that wash or do not wash salvaged blood considerably decreased the proportion of orthopedic surgery patients who received allogeneic transfusion (RR = 0.39, 95% CI = 0.30-0.51 and RR = 0.35, 95% CI 0.26-0.46, respectively). No studies of cell savers that wash salvaged blood during cardiac surgery were included. Cell salvage did not appear to increase the frequency of adverse events. We conclude that cell salvage in orthopedic surgery decreases the risk of patients' exposure to allogeneic blood transfusion perioperatively. Postoperative cell salvage in cardiac surgery, with devices that do not wash the salvaged blood, is only marginally effective.

IMPLICATIONS

This meta-analysis of all published randomized trials provides the best current estimate of the effectiveness of cell salvage and is useful in guiding clinical practice. We conclude that cell salvage in orthopedic surgery decreases the proportion of patients requiring allogeneic blood transfusion perioperatively, but postoperative cell salvage is only marginally effective in cardiac surgery.

Assessing the quality of randomized trials: reliability of the Jadad scale

An instrument was developed and validated by Jadad, et al. to assess the quality of clinical trials using studies from the pain literature. Our study determined the reliability of the Jadad scale and the effect of blinding on interrater agreement in another group of primary studies. Four raters independently assessed blinded and unblinded versions of 76 randomized trials. Interrater agreement was calculated among combinations of four raters for blinded and unblinded versions of the studies. A 4 x 2 x 2 repeated measures design was employed to evaluate the effect of blinding. The interrater agreement for the Jadad scale was poor (kappa 0.37 to 0.39), but agreement improved substantially (kappa 0.53 to 0.59) with removal of the third item (an explanation of withdrawals). Blinding did not significantly affect the Jadad scale scores. A more precise description of how to score the withdrawal item and careful conduct of a practice set of articles might improve interrater agreement. In contrast with the conclusions reached by Jadad, we were unable to demonstrate a significant effect of blinding on the quality scores.

A meta-analysis of the effectiveness of cell salvage to minimize perioperative allogeneic blood transfusion in cardiac and orthopedic surgery. International Study of Perioperative Transfusion (ISPOT) Investigators

Concern about risks of allogeneic transfusion has led to an interest in methods for decreasing perioperative transfusion. To determine whether cell salvage reduces patient exposure to allogeneic blood, we performed meta-analyses of randomized trials, evaluating the effectiveness and safety of cell salvage in cardiac or orthopedic elective surgery. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Twenty-seven studies were included in the meta-analyses. Cell salvage devices that do not wash salvaged blood were marginally effective in cardiac surgery patients when used postoperatively (relative risk [RR] = 0.85, 95% confidence interval [CI] = 0.79-0.92). Devices that wash or do not wash salvaged blood considerably decreased the proportion of orthopedic surgery patients who received allogeneic transfusion (RR = 0.39, 95% CI = 0.30-0.51 and RR = 0.35, 95% CI 0.26-0.46, respectively). No studies of cell savers that wash salvaged blood during cardiac surgery were included. Cell salvage did not appear to increase the frequency of adverse events. We conclude that cell salvage in orthopedic surgery decreases the risk of patients' exposure to allogeneic blood transfusion perioperatively. Postoperative cell salvage in cardiac surgery, with devices that do not wash the salvaged blood, is only marginally effective.

IMPLICATIONS

This meta-analysis of all published randomized trials provides the best current estimate of the effectiveness of cell salvage and is useful in guiding clinical practice. We conclude that cell salvage in orthopedic surgery decreases the proportion of patients requiring allogeneic blood transfusion perioperatively, but postoperative cell salvage is only marginally effective in cardiac surgery.

[Changes in homeostasis during surgical liver resection]

OBJECTIVES

To assess changes in haemostasis during liver resection and to discuss the indications for antifibrinolytic therapy.

STUDY DESIGN

Open prospective study.

PATIENTS

The study included 39 consecutive non-cirrhotic patients presenting for liver resection under portal triad clamping.

METHOD

General anaesthesia was obtained with thiopentone, fentanyl, vecuronium and isoflurane. Transfusion scheme was standardized. Aprotinin (5,000 kIU.kg-1 BW) was administered in case of unexplained bleeding in the operative field. Coagulation pattern was assessed by routine tests and thrombelastrography before surgery, before portal triad clamping, 5 min after reperfusion and at completion of surgery. Patients requiring aprotinin intraoperatively were compared to others.

RESULTS

In 32 patients no significant bleeding occurred. Their coagulation pattern was moderately changed and remained within the normal range. In seven patients severe bleeding occurred which was treated with aprotinin. Their coagulation tests were significantly modified, especially after reperfusion, associating an increase in aPTT, TT, FDP, DDim, r + k and a decreased platelet count.

CONCLUSION

These changes were more in favour of a dilution coagulopathy or a DIC than hyperfibrinolysis. Therefore substitutive therapy with coagulation factors should be preferred to an antifibrinolytic agent. A systematic administration of the latter for liver resection in non-cirrhotic patients is debatable, considering the allergic risk (reoperation for cancer recurrence), thrombosis facilitation (pedicle clamping) and high cost.

Use of point-of-care test in identification of patients who can benefit from desmopressin during cardiac surgery: a randomised controlled trial

BACKGROUND

Platelet dysfunction is a major cause of excessive microvascular bleeding after cardiac surgery. A new point-of-care test (hemoSTATUS) can identify patients at risk of excessive bleeding. We aimed to find out whether patients who can benefit from desmopressin during cardiac surgery can be identified by this test.

METHODS

We enrolled 203 patients scheduled for elective cardiac surgery in a prospective, double-blind, placebo-controlled trial. Patients with abnormal hemoSTATUS clot-ratio results (<60% of maximum in channel 5) after discontinuation of cardiopulmonary bypass were randomly assigned desmopressin (n=50) or placebo (n=51). Patients with normal clot ratios were included in an untreated control group (n=72).

FINDINGS

Intraoperative platelet counts and clot ratios were significantly higher in the untreated control group than in the study-drug groups. In intensive care, clot ratios in patients who received desmopressin were similar to those in the untreated control group, despite significantly lower platelet counts, but were lower in the placebo group than in the other two groups (p=0.0001). Compared with the placebo group, patients who received desmopressin had less blood loss in 24 h (mean 624 [SD 209] vs 1028 mL [682] p=0.0004) and required less transfusion of red blood cells (1.1 [022] vs 2.2 U [0.32] p=0.009), platelets (0.1 [0.04] vs 1.9 U [4.5] p=0.0001), and fresh-frozen plasma (0.1 [0.07] vs 0.75 U [0.21] p=0.0008), and had less total blood-donor exposures (1.56 [0.31] vs 5.2 [0.8] p=0.0001). Placebo patients also had substantially higher blood loss and transfusion requirements than untreated control patients.

INTERPRETATION

Patients identified with hemoSTATUS as being at increased risk of excessive bleeding after cardiac surgery can benefit from administration of desmopressin. Further studies are, however, needed to confirm these findings as well as to identify the mechanism of action and safety of desmopressin in the clinical setting.

Effects of nonsteroidal anti-inflammatory therapy on platelets

Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) can produce a mild, systemic hemostatic defect by inhibiting normal platelet function. Aspirin acetylates and permanently inactivates cyclooxygenase (COX), while nonaspirin NSAIDs reversibly block COX; thus, all of these drugs cause platelet dysfunction by inhibiting the formation of thromboxane A2, a platelet-activating and vasoconstricting eicosanoid. However, spontaneous bleeding complications outside the gastrointestinal tract very rarely result from the use of aspirin and other NSAIDs in individuals who are otherwise hemostatically normal. Most types of surgery are not usually associated with clinically significant bleeding in patients taking these drugs, making it typically unnecessary to discontinue them and thus delay surgery for the purpose of restoring normal hemostasis. Exceptions may include operations at sites where optimal hemostasis is critical, surgical manipulation of the genitourinary tract and oral cavity, and possibly cardiac surgery. Factors that increase the risk of bleeding with aspirin and other NSAIDs include coexisting coagulation abnormalities and the simultaneous use of alcohol or anticoagulants.

Early and late outcome after elective cardiac surgery in patients with cirrhosis

BACKGROUND

A prospective study was performed to evaluate the early and late outcome after elective cardiac surgery in patients with cirrhosis.

METHODS

All patients who underwent elective cardiac surgery between 1995 and 1997, and were suspected of having a history of cirrhosis, were followed in the intensive care unit (ICU), during hospitalization and after hospital discharge. All patients received high doses of aprotinin during surgery.

RESULTS

Ten patients of Child-Pugh class A and 2 patients of Child-Pugh class B were studied. All patients had signs of portal hypertension, and 11 of 12 patients had thrombocytopenia. In the first 24 h after operation, the median chest tube output was 810 mL (range 350 to 1,500 mL). Median ICU and hospital stays were 3 and 15 days, respectively (range 2 to 10 and 7 to 36 days, respectively). Seven patients experienced postoperative morbidity and 7 patients had significant complications after their hospital discharge. One death occurred in the ICU. Two deaths occurred after hospital discharge and were related to further hepatic damage.

CONCLUSIONS

These results suggest that, in patients with mild or moderate cirrhosis, the incidence of significant complications was high after elective cardiac surgery, increasing the length of stay in ICU and overall hospitalization time and compromising the health status, even well after the operation.

Is epsilon-aminocaproic acid as effective as aprotinin in reducing bleeding with cardiac surgery?: a meta-analysis

BACKGROUND

Although aprotinin is known to be effective in reducing postoperative hemorrhage after cardiac surgery, epsilon-aminocaproic acid, an alternative antifibrinolytic, is considerably less expensive. Because the results of 3 small randomized clinical trials comparing these 2 agents directly were inconclusive, we performed a meta-analysis to compare the relative effectiveness and adverse-effect profile of these 2 agents against placebo.

METHODS AND RESULTS

Data from 52 randomized clinical trials published between 1985 and 1998 involving the use of epsilon-aminocaproic acid (n=9) or aprotinin (n=46) in patients undergoing cardiac surgery were abstracted. Our primary outcomes were total blood loss, red blood cell transfusion rates and amounts, reexploration, stroke, myocardial infarction, and mortality. The meta-analysis revealed substantial reductions in total blood loss with epsilon-aminocaproic acid and low-dose aprotinin (each with a 35% reduction versus placebo, P<0.001) and high-dose aprotinin (53% reduction, P<0.001). There were identical reductions in total postoperative transfusions with epsilon-aminocaproic acid (61% reduction versus placebo, P<0. 010) and high-dose aprotinin (62% reduction, P<0.001). The proportion of patients transfused was similarly reduced with epsilon-aminocaproic acid (OR, 0.32; 95% CI, 0.15 to 0.69) and high-dose aprotinin (OR, 0.28; 0.22 to 0.37). Although both drugs reduced rates of reexploration to similar degrees, this effect was statistically significant only with high-dose aprotinin (OR, 0.39; 0. 24 to 0.61). epsilon-Aminocaproic acid and aprotinin had no effect on risks of postoperative myocardial infarction or overall mortality.

CONCLUSIONS

Because the 2 antifibrinolytic agents appear to have similar efficacies, the considerably less-expensive epsilon-aminocaproic acid may be preferred over aprotinin for reducing hemorrhage with cardiac surgery.

Erythropoietin to minimize perioperative blood transfusion: a systematic review of randomized trials. The International Study of Peri-operative Transfusion (ISPOT) Investigators

Our aim was to perform a systematic review to determine the efficacy and side-effects of erythropoietin, given with or without autologous predonation, to patients undergoing orthopaedic or cardiac surgery. A number of studies have been done to determine whether erythropoietin minimizes exposure to perioperative allogeneic red cell transfusion. A systematic review of all randomized trials will provide the best estimate of the efficacy and side-effects of erythropoietin therapy. All randomized trials of erythropoietin in cardiac or orthopaedic surgery that reported the proportion of patients receiving perioperative allogeneic transfusion were included. The efficacy of erythropoietin was evaluated in subgroups of patients depending upon the route of administration, dose of erythropoietin, the type of control and the methodological quality of the study report. The odds ratio for the proportion of patients transfused with allogeneic blood in studies of erythropoietin to augment autologous donation was 0.42 (95% confidence limits 0.28-0.62; P < 0.0001) for orthopaedic surgery and 0.25 (95% CI 0.08-0.82; P = 0.02) for cardiac surgery. The odds ratio for erythropoietin alone was 0.36 (95% CI 0.24-0.56; P = 0.0001) in orthopaedic surgery and 0.25 (95% CI 0.06-1.04; P < 0.06) in cardiac surgery. The route of administration, dose of erythropoietin, type of control and methodological quality of the study report had no statistically significant effect upon the odds ratios. Although there was no convincing evidence that erythropoietin used alone increased the frequency of thrombotic complications, some studies found an excess of events in erythropoietin-treated patients, and the number of patients studied was relatively small. Erythropoietin, when given alone or to augment autologous donation, decreased exposure to perioperative allogeneic transfusion in orthopaedic and cardiac surgery. Further studies are required to definitively establish the safety of erythropoietin alone, to determine the optimal dose of perioperative erythropoietin, and to compare its efficacy and cost-effectiveness with other methods of minimizing perioperative transfusion.

Perioperative red cell transfusion: evidence, guidelines and practice

Although we still do not know enough about the influence of anaemia and transfusion on outcomes for the surgical patient, it is possible to develop a general consensus about many aspects of management. A quality programme to improve consistency of practice in these consensus areas is feasible. (Table 6) This should be linked with further randomised trials to evaluate the clinical effectiveness of alternative regimes.

Tranexamic acid and aprotinin reduce postoperative bleeding and transfusions during primary coronary revascularization

We evaluated the blood conservation effects of tranexamic acid (TA) or aprotinin administered before and during cardiopulmonary bypass (CPB) in a prospective, randomized, double-blind study of 150 adult patients undergoing primary coronary artery bypass grafting surgery. Patients received either TA (2 g) or large-dose aprotinin (7 million KIU). Thirty additional untreated patients otherwise managed in a similar fashion were included from a recently completed study for comparison of outcomes. Demographic, medical, surgical, laboratory, mediastinal chest tube drainage (MCTD), transfusion, and outcome data were collected. Allogeneic blood product administration was tightly controlled. The demographic, medical, and surgical characteristics did not significantly differ between the two therapy groups. The median postoperative MCTD loss in the TA group did not significantly differ from that in the aprotinin-treated group (708 vs 600 mL). The percentage of patients that received no allogeneic blood products was 25% for the TA group and 27% for the aprotinin group (P = not significant). The median number of allogeneic blood products administered to the TA group (0 U) did not significantly differ from that administered to the aprotinin group (0 U). The percentage of patients with excessive MCTD (>1000 mL/24 h) did not significantly differ between groups (19% and 17%, respectively). In comparison, the control group had a significantly greater (P < 0.05) median MCTD (1020 mL), median allogeneic blood product exposure (4.5 U), and incidence of excessive MCTD (66%) and transfusion therapy (66%). These data help to support the use of pharmacologic methods to improve clinically relevant indicators of blood conservation for primary CPB procedures. Furthermore, the data show that TA is equivalent to aprotinin for blood conservation in patients at risk of excessive post-CPB bleeding and transfusion therapy.

IMPLICATIONS

In a randomized, blind trial, we evaluated the effects of tranexamic acid or aprotinin on blood conservation after primary cardiopulmonary bypass surgery. Both drugs were equally effective in reducing blood loss, the incidence of transfusion, and the amount of blood products transfused compared with placebon.

The effectiveness of low dose tranexamic acid in primary cardiac surgery

PURPOSE

This randomized controlled clinical trial compared three doses of tranexamic acid (TA) in primary cardiac surgery in terms of blood loss and transfusion requirements.

METHODS

Patients presenting for primary coronary artery bypass grafting (CABG) and/or valve replacement were randomly assigned to one of three TA regimens: 20 mg.kg-1 (LD), 50 mg.kg-1 (MD), and 100 mg.kg-1 (HD). All participants and staff were blinded to the allocation. Haemoglobin (Hgb), haematocrit and platelet count were determined preoperatively, after bypass, at CCA arrival, and 12 and 24 hr after surgery. Coagulation parameters were measured before and after surgery. Blood loss was measured intraoperatively and for 24 hr postoperatively following a standardized protocol. Blood products were administered in a standardized fashion.

RESULTS

Two hundred twenty patients completed the trial over 10 months: 74 in LD, 75 in MD and 72 in HD dose groups. All patients groups were comparable; similar procedures were performed in each group. No differences were identified for blood loss intra-operatively (490 +/- 232 ml, 523 +/- 413 ml, 488 +/- 357 ml, respectively), 24 hr post-operatively (543 +/- 223 ml, 544 +/- 231, 458 +/- 210 ml, respectively), and overall (1032 +/- 358 ml, 1067 +/- 502 ml, 946 +/- 459 ml, respectively). Blood product administration was similar in the three groups. No differences in postoperative complications were found.

CONCLUSIONS

This study demonstrates the equivalency of the three doses of TA in primary cardiac surgical procedures. The use of low dose (20 mg.kg-1) TA results in comparable outcomes, without additional complications.