Drugs to Minimize Perioperative Blood Loss in Cardiac Surgery

The role of amicar in decreasing perioperative blood loss in idiopathic scoliosis

STUDY DESIGN

Four separate studies on the role of Amicar in decreasing perioperative blood loss in idiopathic scoliosis.

OBJECTIVES

To assess the efficacy and possible mechanisms of action for Amicar.

SUMMARY OF BACKGROUND DATA

Preliminary prospective, randomized double-blind and analysis of same-day anterior spinal fusion (ASF), fibrinogen, and posterior spinal fusion (PSF) studies have demonstrated Amicar to be effective in idiopathic scoliosis surgery. Increased fibrinogen secretion is a possible explanation.

METHODS

Amicar is administered at 100 mg/kg over 15 minutes not to exceed 5 g at anesthesia induction. Maintenance is 10 mg/kg per hour until wound closure.

RESULTS

Preliminary study: Amicar (N = 28) was effective compared with a control group (N = 31). Perioperative blood loss and transfusion following PSF were 1,604 +/- 517 mL and 1.1 +/- 1.0 U in the Amicar group compared with 2,312 +/- 994 mL and 2.1 +/- 1.1 U in the control group (P < 0.003). Prospective, randomized double-blind study confirmed this efficacy, although primarily in postoperative suction drainage: 1,391 +/- 212 mL and 1.1 +/- 1.0 U compared with 1,716 +/- 513 mL and 2.1 +/- 1.3 U (P < 0.002). A fibrinogen study (N = 21) demonstrated steady and excessive increase following PSF: before surgery it was 266 +/- 63 mg/dL and on the fifth postoperative day 699 +/- 94 mg/dL. In same-day anterior and posterior spinal surgery, Amicar was again effective, but primarily in decreasing chest tube drainage and during PSF. Group 1 (N = 15, no Amicar) 3,807 +/- 105 mL and 3.1 +/- 1.5 U; Group 2 (N = 27, Amicar for PSF only) 2,080 +/- 659 mL and 1.9 +/- 0.9 U; and Group 3 (N = 16, both ASF and PSF) 2,183 +/- 851 mL and 1.0 +/- 0.8 U.

CONCLUSIONS

Amicar appears highly effective in decreasing perioperative blood loss. This results in less autologous blood donation, blood transfusion, costs, and complications. Its mechanism of action is uncertain but may be related to increased fibrinogen secretion.

Aprotinin and epsilon aminocaproic acid are effective in reducing blood loss after primary total hip arthroplasty--a prospective randomized double-blind placebo-controlled study

A prospective randomized double-blind placebo-controlled study was undertaken to determine the efficacy and mechanism of action of two antifibrinolytic drugs aprotinin and epsilon aminocaproic acid (EACA) in reducing blood loss in primary unilateral total hip arthroplasty (THA). Aprotinin was administered as a bolus of 2 x 10(6) kallikrein inhibitor units (KIU) followed by 0.5 x 10(6) KIU h(-1) for 3 h, EACA was given as 10 g over 30 min followed by 5 g over 3 h. The median postoperative blood loss 24 h postoperatively was reduced from 450 mL in the placebo group to 180 mL for aprotinin (60% reduction, P < 0.001) and to 210 mL for EACA (53% reduction, P < 0.01). In this population, there was no reduction in the perioperative transfusion requirements. The mechanism of both drugs was independent of platelets as indicated by flow cytometric measurement of change of their expression of P-selectin, platelet-monocyte aggregates, V/Va and CD40 ligand. There were no thrombotic or infective complications and no adverse events were attributable to use of either drug. Infusion of either aprotinin or EACA at the doses described is a safe and effective means of reducing blood loss after THA. These therapies provide a means of reducing blood loss in THA patients.

Evidence-based review of the role of aprotinin in blood conservation during orthopaedic surgery

Aprotinin is a serine protease inhibitor with antifibrinolytic properties that has been approved as a blood-conserving drug in cardiac surgery by the United States Food and Drug Administration. On the basis of the current evidence from Level-I trials, we make a grade-A recommendation for use of the high-dose aprotinin regimen in hip and spine surgery. Because of conflicting data, the low-dose aprotinin therapy as well as the use of aprotinin in patients with cancer cannot be recommended (grade-I recommendation). High-quality randomized trials are necessary to determine the optimal (and minimal) therapeutic dose of aprotinin and the optimal time of aprotinin administration during surgery.

Coagulation Disorders and Blood Product Use in Patients Undergoing Thoracoabdominal Aortic Aneurysm Repair

Repair of thoracoabdominal aortic aneurysms (TAAA) is associated with major blood loss, often exceeding the patient's intravascular volume, and complex intraoperative and postoperative coagulopathies necessitating large-volume transfusion of blood products. Abnormalities sufficient to cause thrombocytopenia or clinically important prolongation of clotting parameters are rarely present before surgery in elective aneurysms but are more common with ruptured aneurysms. The finding of intraoperative and postoperative deficiencies of clotting factors, along with thrombin generation and activation of the thrombolytic system, is reflective of massive blood losses, visceral ischemia, and massive transfusions. An aggressive strategy of transfusion of blood products is critical to the prevention of clinically significant coagulopathy during surgery. Adjuncts to reduce blood losses and blood product use include low-dose aprotinin or epsilon -aminocaproic acid, intraoperative blood salvaging, and acute normovolemic hemodilution. In TAAA repair, an average blood loss of 5000 to 6000 mL and average transfusion of allogeneic blood products of 50 to 60 U are to be anticipated.

Reducing allogeneic transfusion in cardiac surgery: a randomized double-blind placebo-controlled trial of antifibrinolytic therapies used in addition to intra-operative cell salvage

BACKGROUND

The transfusion of allogeneic red blood cells and allogeneic coagulation products is associated with risk to the patient and the depletion of an increasingly scarce resource. This prospective, randomized, double-blind, placebo-controlled trial investigated practices to avoid transfusion in patients undergoing first-time cardiac surgery.

METHODS

Patients were randomized to one of three treatment groups: an aprotinin group, a tranexamic acid group, and a control group receiving normal saline. Intra-operative cell salvage was used for all patients. The primary outcomes were the number of patients exposed to allogeneic red blood cells, allogeneic coagulation products or any allogeneic transfusion (allogeneic red blood cells and/or allogeneic coagulation products).

RESULTS

Patients were 2.5 times more likely to receive any allogeneic transfusion in the tranexamic group than in the aprotinin group (21 patients out of 60 compared with nine out of 60, respectively). The relative risk of any allogeneic transfusion comparing aprotinin with tranexamic acid was 0.43 (95% confidence interval 0.21-0.86; P=0.019). Patients in the control group were four times more likely to receive any allogeneic transfusion when compared with the aprotinin group (37 patients out of 60 compared with nine out of 60, respectively). The relative risk of any allogeneic transfusion comparing aprotinin with control was 0.24 (95% confidence interval 0.13-0.46; P<0.001).

CONCLUSIONS

When used in addition to intra-operative cell salvage, aprotinin is the most efficacious pharmacological therapy for reducing patient exposure to any allogeneic transfusion during first-time cardiac surgery.

Perioperative systemic haemostatic agents

Skilful surgery combined with blood-saving methods and careful management of blood coagulation will all help reduce unnecessary blood loss and transfusion requirements. Excessive surgical bleeding causes hypovolaemia, haemodynamic instability, anaemia and reduced oxygen delivery to tissues, with a subsequent increase in postoperative morbidity and mortality. The role of anaesthetists in managing surgical blood loss has increased greatly in the last decade. Position of the patient during surgery and the provision of a hypotensive anaesthetic regimen were once considered the most important contributions of the anaesthetist to decreasing blood loss. Now, several pharmacological haemostatic agents are being used by anaesthetists as blood-saving agents. After a brief discussion of the physiology of haemostasis, this article will review the evidence for the role of such agents in reducing perioperative blood loss and transfusion requirements.

Can extra protamine eliminate heparin rebound following cardiopulmonary bypass surgery?

OBJECTIVES

Heparin rebound, the reappearance of anticoagulant activity after adequate neutralization with protamine, is thought to contribute to excessive postoperative bleeding after cardiac surgery. We have previously demonstrated that a significant amount of heparin is bound nonspecifically to plasma proteins and is incompletely neutralized by protamine. The aim of this study was to investigate whether clinically important bleeding attributable to heparin rebound can be eliminated by infusion of small amounts of additional protamine for 6 hours postoperatively and whether this treatment can reduce mediastinal blood loss.

METHODS

Three hundred patients undergoing elective cardiac surgery were randomized to receive either a continuous infusion of protamine sulphate (25 mg/h for 6 hours) postoperatively or saline placebo. Serial blood samples were obtained to measure thrombin clotting time and anti-factor Xa activity. Heparin bound nonspecifically to plasma proteins was measured after displacement with a chemically altered heparin with low affinity to antithrombin. Mediastinal blood loss and transfusion requirements were recorded.

RESULTS

Heparin rebound was demonstrated in every patient in the placebo group as reflected by increased thrombin clotting time, anti-factor Xa activity, and protein-bound heparin between 1 and 6 hours after surgery. In contrast, heparin rebound was eliminated in the protamine infusion group. The thrombin clotting time was normalized and both heparin concentration and protein-bound heparin were almost undetectable (P <.001). There was a modest 13% reduction in postoperative bleeding but this did not reduce blood transfusions. No adverse events were attributable to the extra protamine.

CONCLUSIONS

Postoperative protamine infusion was able to almost totally abolish heparin rebound. In the context of this study, protamine infusion resulted in reduced postoperative bleeding but the magnitude was insufficient to alter transfusion requirements.

Tranexamic acid for major spinal surgery

Patients who undergo major spinal surgery often require multiple blood transfusions. The antifibrinolytics are medications that can reduce blood-transfusion requirements in cardiac surgery and total knee arthroplasty. The present role of synthetic antifibrinolytics, especially tranexamic acid, in reducing peri-operative blood-transfusion requirements in spine surgery is still unclear. The majority of studies exploring the role of these drugs in spine surgery have limited patient enrollment and report mixed results. The goal of the present review is to discuss the pharmacology of tranexamic acid briefly. A brief synopsis of the studies using the synthetic antifibrinolytics for spine surgery is presented. Finally, the potential risks and the benefits of antifibrinolytics are discussed.

Guidelines for the use of fresh-frozen plasma, cryoprecipitate and cryosupernatant

The indications for transfusing fresh-frozen plasma (FFP), cryoprecipitate and cryosupernatant plasma are very limited. When transfused they can have unpredictable adverse effects. The risks of transmitting infection are similar to those of other blood components unless a pathogen-reduced plasma (PRP) is used. Of particular concern are allergic reactions and anaphylaxis, transfusion-related acute lung injury, and haemolysis from transfused antibodies to blood group antigens, especially A and B. FFP is not indicated in disseminated intravascular coagulation without bleeding, is only recommended as a plasma exchange medium for thrombotic thrombocytopenic purpura (for which cryosupernatant is a possible alternative), should never be used to reverse warfarin anticoagulation in the absence of severe bleeding, and has only a very limited place in prophylaxis prior to liver biopsy. When used for surgical or traumatic bleeding, FFP and cryoprecipitate doses should be guided by coagulation studies, which may include near-patient testing. FFP is not indicated to reverse vitamin K deficiency for neonates or patients in intensive care units. PRP may be used as an alternative to FFP. In the UK, PRP from countries with a low bovine spongiform encephalopathy incidence is recommended by the Departments of Health for children born after 1 January 1996. Arrangements for limited supplies of single donor PRP of non-UK origin are expected to be completed in 2004. Batched pooled commercially prepared PRP from donors in the USA (Octaplas) is licensed and available in the UK. FFP must be thawed using a technique that avoids risk of bacterial contamination. Plastic packs containing any of these plasma products are brittle in the frozen state and must be handled with care.

Management of Jehovah’s Witness patients with haematological problems

The management of practising Jehovah's Witnesses who have haematological problems presents many different challenges both at the level of treatment strategy and ethics. This article focuses on the beliefs of Jehovah's Witnesses and addresses treatment modalities available for and acceptable to these individuals. Recent advances in the development of novel therapeutic agents have aided the management of Jehovah's Witnesses. Finally, the background to the ethical dilemmas raised by these issues is discussed.

[Pharmacological alternatives to blood transfusion: what is new about?]

Pharmacological approaches to reduce blood transfusion include the protease inhibitor aprotinin, lysine-analogue antifibrinolytics synthetic arginine-vasopressin derivatives (DDAVP) and recombinant factor VII (rfVIIa). These agents are known to prevent the need for blood after major surgery (cardiac, hepatic, and orthopaedic). Among the nonhemostatic agents erythropoietin (EPO) may be effective to reduce blood requirements in medical and surgical patients. Aprotinin is consistently effective in reducing blood transfusion in cardiac and hepatic surgical procedures, but there is little data to support its use in elective orthopaedic surgery. Antifibrinolytics show no evidence of efficacy in cardiac and hepatic surgery and its use is not warranted in orthopaedic surgery. Limited data suggest that DDAVP may be effective when a defect in platelet function is demonstrated. rFVIIa emerges as a promising haemostatic agent with proven benefit to reduce bleeding in haemophiliacs with inhibitors but might also be effective in patients with thrombocytopenia and thrombopathy, as well as in life-threatening hemorrhage in postsurgical patients. Ongoing studies will established its role a possible "universal haemostatic agent". Hematopoietic cytokines, such as EPO, may have a place to avoid blood transfusion in a variety of clinical conditions, including cancer and critically ill patients.

The use of recombinant coagulation factor VIIa in uncontrolled postoperative bleeding in children undergoing cardiac surgery with cardiopulmonary bypass

OBJECTIVE

To assess the hemostatic efficacy of recombinant coagulation factor VIIa (rFVIIa) in the management of uncontrolled bleeding in postcardiac surgery with cardiopulmonary bypass in children.

DESIGN

An open-label study.

SETTING

A postoperative intensive care unit.

PATIENTS

Eight consecutive pediatric patients with excessive bleeding after cardiac surgery with cardiopulmonary bypass that met the criteria for reexploration and did not respond to optimal transfusions of platelets and fresh frozen plasma.

INTERVENTIONS

rFVIIa 30 microg/kg was given as a bolus injection. A higher dose of 60 microg/kg was used if a patient had preoperative coagulopathy, preoperative multiple-organ failure, or indications that required an emergency operation. The same dose was repeated 15 mins after the previous injection if the bleeding had not decreased. If the bleeding had decreased but still exceeded 10 mL/hr for body weight </=5 kg or exceeded 2 mL.kg(-1).hr(-1) for body weight >5 kg, the same dose was repeated 2 hrs after the previous injection. A maximum of four doses could be given before rFVIIa was considered ineffective and a reexploration was needed.

MEASUREMENTS AND MAIN RESULTS

Postoperative blood loss was estimated from the volume of chest tube drainage. rFVIIa successfully controlled bleeding and prevented reexploration in all seven patients who received treatment according to the protocol. One patient who received only one dose of rFVIIa required reexploration because a second dose was not available. No adverse events related to rFVIIa were seen.

CONCLUSIONS

rFVIIa may be useful in preventing reexploration in uncontrolled postoperative bleeding in children undergoing cardiac surgery with cardiopulmonary bypass. Randomized, placebo-controlled studies are needed to confirm the safety and efficacy of rFVIIa in this clinical setting.

Production and use of fibrin glue at blood transfusion service of Bellaria-Maggiore Hospital Bologna

FG is created by combining the two principal clotting factors found in plasma, fibrinogen and thrombin, whose natural function is to halt bleeding and seal tissues. We determined the safety, and efficacy of autologous FG by an automated device CryoSeal FS System. This procedure allows the blood transfusion center to produce a standardized product having similar characteristics of the pharmaceutical products available on the market and to produce a consistent amount of FG components from a single unit of autologous blood. The study involved a retrospective controlled evaluation of urologic patients compared with a control group operated of radical perineal prostatectomy. Blood loss difference is not significant. The hospital stay of the study group is shorter then the control group. The control group received more unit of homologous blood compared to the study group. This acquisition is suggestive for hypothetical blood saving.

Meeting the clinical challenge of care for Jehovah’s Witnesses1 1Editor’s Note: This article represents the current position of the Watch Tower Society on the use of blood components and fractions in the care of patients who are Jehovah’s Witnesses

Quality patient care entails more than simply biomedical interventions. Respect for the wishes, values, and preferences of patients are important elements of quality care. Unique aspects of the beliefs of Jehovah's Witnesses may present physicians with ethical and clinical conflicts. Witnesses believe that allogeneic blood transfusion (ie, whole blood, red blood cells, white cells, platelets, and plasma) and preoperative autologous blood deposit (PAD) are prohibited by several Biblical passages. This article reviews the Witness position on medical care, blood components, and fractions, placing these and related interventions into categories that may help physicians to individualize clinical management plans and meet the challenge of caring for patients who are Jehovah's Witnesses. It includes an overview of cost, safety, efficacy, and medicolegal issues related to patient care using transfusion-alternative strategies.

The effect of amicar on perioperative blood loss in idiopathic scoliosis: the results of a prospective, randomized double-blind study

STUDY DESIGN

A prospective, randomized, double-blind Institutional Review Board-approved study evaluating the efficacy of Amicar (epsilon aminocaproic acid), an antifibrinolytic agent, in decreasing perioperative blood loss in idiopathic scoliosis.

OBJECTIVES

To compare the perioperative (intraoperative and postoperative) blood loss and the need for autologous and homologous blood replacement in two groups of essentially identical patients undergoing a posterior spinal fusion for idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Reducing perioperative blood loss and the need for transfusion in patients undergoing spinal surgery is important to orthopedic surgeons. Recently, there has been interest in pharmacologic agents, particularly Amicar and Aprotinin, to assist in decreasing perioperative blood loss. In 2001, in a preliminary study, we demonstrated that Amicar appeared to be effective in reducing perioperative blood loss in patients with idiopathic scoliosis undergoing a posterior spinal fusion and segmental spinal instrumentation. This was a study of 28 consecutive patients receiving Amicar compared to a historical control group of the 31 previous consecutive patients with the same study criteria. The current study was performed to confirm our preliminary findings.

METHODS

We analyzed the perioperative blood loss of 36 patients with idiopathic scoliosis who were blindly randomized by the operating room pharmacy into an Amicar and control group. The criteria to be included in the study was the same as the preliminary study: diagnosis of idiopathic scoliosis, age at surgery 11 to 18 years, posterior spinal fusion and segmental spinal instrumentation only, autogenous iliac crest bone graft or homologous cancellous bone graft, and a signed agreement to participate in the study. The patients in both groups had the same anesthetic technique, intraoperative procedure, instrumentation, postoperative management, and standardized indications for transfusions.

RESULTS

Before surgery, the patients in both groups were essentially identical. The distribution of patients and their results was not known until the completion of the study. Patients in the Amicar group demonstrated a statistically significant decrease in perioperative blood loss and the need for autologous blood transfusion. Interestingly, this decrease was predominantly in the postoperative suction drainage. This may be due to elevated fibrinogen levels induced by Amicar. The patients taking Amicar had no intraoperative or postoperative thromboembolic complications.

CONCLUSIONS

The results of this study confirmed that the use of intraoperative Amicar is a safe, effective, and inexpensive method to significantly reduce perioperative blood loss in patients with idiopathic scoliosis undergoing posterior spinal fusion and segmental spinal instrumentation. The results have allowed us to reduce our recommendation for perioperative autologous blood donation, thereby further decreasing costs.

Strategies for minimizing blood loss in orthopedic surgery

Several major orthopedic surgical procedures including hip arthroplasty, femoral osteotomy, and spinal fusion may result in significant blood loss and the need for allogeneic blood transfusions. Due to the heightened awareness of the potential deleterious effects of allogeneic blood product administration, several techniques have been evaluated to determine their efficacy in limiting perioperative blood loss. The following article will discuss the options to limit the need for allogeneic blood product administration during orthopedic surgical procedures. These techniques include: general considerations, autologous transfusion therapy, intraoperative and postoperative blood salvage, pharmacologic manipulation of the coagulation cascade, and controlled hypotension. Undoubtedly, many of these techniques are effective alone; however, the goal of performing major orthopedic surgical procedures without the use of allogeneic blood products can only be accomplished by combining several of these techniques.

Avoidance of Bleeding During Surgery in Patients Receiving Anticoagulant and/or Antiplatelet Therapy

Perioperative management of chronically anticoagulated patients and/or patients treated with antiplatelet therapy is a complex medical problem. This review considers the pharmacokinetic and pharmacodynamic properties of commonly used antiplatelet and anticoagulant drugs with special emphasis on loss of effects after discontinuation and possible counteracting (or antidote) strategies. These drugs are aspirin (acetylsalicylic acid), ticlopidine/clopidogrel, abciximab, tirofiban and eptifibatide, heparin (unfractionated and low-molecular-weight), warfarin and direct thrombin inhibitors. Since the pharmacological mechanisms of some of these drugs are based on irreversible or slowly reversible effects, their pharmacokinetic profiles are not necessarily predictive for their pharmacodynamic profiles. A close and direct relationship between plasma concentrations and effects is seen only for the glycoprotein (GP) IIb/IIIa inhibitors tirofiban and eptifibatide with a fast off-rate for dissociation from the GPIIb/IIIa receptor, and for direct thrombin inhibitors (hirudin and argatroban). For other compounds, drug concentrations in plasma and pharmacodynamic effects are not closely correlated because of, for example, irreversible binding to their target (aspirin, clopidogrel and abciximab), inhibition of the generation of a subset of clotting factors with differing regeneration and degradation rates (coumarins) or sustained binding to the vascular wall (heparins). Surgery in patients on anticoagulant and/or antiplatelet therapy may be categorised as: (i) elective versus urgent; and (ii) cardiopulmonary bypass (CPB) versus non-CPB. Monotherapy with clopidogrel or aspirin need not be discontinued in elective non-CPB surgery, and temporary discontinuation of warfarin should be accompanied by preoperative intravenous heparin only in selected high-risk patients. Vitamin K as an antidote for warfarin should only be used subcutaneously and solely in urgent/emergency surgery. In elective surgery requiring CPB (coronary artery bypass grafting), it is recommended to discontinue aspirin 7 days preoperatively in patients with a low risk profile. Patients requiring urgent CPB surgery (e.g. after failure of a percutaneous coronary angioplasty with or without coronary stent deployment) are usually pretreated with several antiplatelet agents (e.g. aspirin and clopidogrel, together with a GPIIb/IIIa inhibitor) together with unfractionated or low-molecular-weight heparin. With judicious planning, urgent/emergency cardiac surgery can be safely performed on these patients. Delaying surgery (e.g. for 12 hours in patients treated with abciximab) should be considered if possible. Standard heparin doses should be given to achieve optimal anticoagulation for CPB. Prophylactic use of aprotinin (intra- and/or postoperatively), aminocaproic acid or tranexamic acid should be considered. Early (in the operating theatre prior to chest closure) and judicious use of replacement blood products (platelets) should be commenced when clinically indicated.

Desmopressin for minimising perioperative allogeneic blood transfusion

BACKGROUND

Public concerns regarding the safety of transfused blood have prompted re-consideration of the use of allogeneic (from an unrelated donor) red blood cell (RBC) transfusion, and of a range of techniques designed to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of desmopressin acetate (1-deamino-8-D-arginine-vasopressin; DDAVP), in reducing perioperative blood loss and the need for red cell transfusion in patients who do not have congenital bleeding disorders.

SEARCH STRATEGY

Articles were identified by: computer searches of MEDLINE, EMBASE, Current Contents (to May 2003), and the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library, Issue 1, 2003). References in the identified trials and review articles were searched and authors contacted to identify additional studies.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to DDAVP, or to a control group, who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed using criteria proposed by Schulz et al. (Schulz 1995) and Jadad et al. (Jadad 1996). Main outcomes measured were: the number of patients exposed to allogeneic red cell transfusion, and the amount of blood transfused. Other outcomes measured were: re-operation for bleeding, blood loss, post-operative complications (thrombosis, infection, non-fatal myocardial infarction), mortality, and length of hospital stay (LOS).

MAIN RESULTS

Eighteen trials of DDAVP (n=1295) reported data on the number of patients transfused with allogeneic RBC transfusion. In subjects treated with DDAVP, the pooled relative risk of exposure to perioperative allogeneic RBC transfusion was 0.95 (95%CI = 0.86 to 1.06). The use of DDAVP did not significantly reduce blood loss; weighted mean difference (WMD) = -114.3ml: 95% confidence interval (95%CI) = -258.8 to 30.2ml per patient) or the volume of RBC transfused (WMD = -0.35 units: 95%CI = -0.70 to 0.01 units). In DDAVP-treated patients the relative risk of requiring re-operation due to bleeding was 0.69 (95%CI = 0.26 to 1.83). There was no statistically significant effect overall for mortality and non-fatal myocardial infarction in DDAVP-treated patients compared with control (RR = 1.72: 95%CI = 0.68 to 4.33) and (RR = 1.38: 95%CI = 0.77 to 2.50) respectively.

REVIEWER'S CONCLUSIONS

There is no convincing evidence that desmopressin minimises perioperative allogeneic RBC transfusion in patients who do not have congenital bleeding disorders. These data suggest that there is no benefit from using DDAVP as a means of minimising perioperative allogeneic RBC transfusion.

Surgery without blood

OBJECTIVE

The principle aim of "bloodless surgery" is to minimize blood loss and to reduce or eliminate exposure to allogeneic blood transfusion. The risks associated with blood transfusions have been well documented, and it is the goal of bloodless surgery centers to avoid complications and unnecessary use of blood. Blood transfusion is a significant adjunct to perioperative resuscitation. However, we aim to elucidate different approaches to minimizing blood loss and avoiding transfusion.

DESIGN

In this document, we review the background and current status of bloodless surgery centers and then the different approaches to achieve the program goals.

FINDINGS

There is no one single universal blood conservation strategy that is applicable to all patients and populations. Factors such as preexisting disease will alter the approach; however, it is the ability of any program to form a comprehensive strategy for blood conservation that is integral to the success of any such program.

CONCLUSION

The success of a bloodless surgery program requires both teamwork and careful cooperation between the blood bank, pharmacy, administration, hematologists, surgeon, and anesthesiologist to ensure that the goals of minimizing blood loss and avoiding transfusion are met.

Current status of antifibrinolytics in cardiopulmonary bypass and elective deep hypothermic circulatory arrest

Cardiopulmonary bypass (CPB) results in many physiologic derangements, including activation of the hemostatic and fibrinolytic pathways. Deep hypothermic circulatory arrest (DHCA) adds a further insult to the coagulation systems because it involves more extreme hypothermia and organ ischemia related to blood stasis. The abnormalities induced by CPB disrupt the checks and balances in the hemostatic and fibrinolytic systems, resulting in a pathologic state that leads to excessive bleeding and other perioperative complications. Prophylactic antifibrinolytic therapy can attenuate the response to this insult by restoring the delicate balance within these systems, potentially reducing the complication rate and improving patient outcomes.

Increased blood product use among coronary artery bypass patients prescribed preoperative aspirin and clopidogrel

BACKGROUND

The administration of antiplatelet drugs before coronary artery bypass graft surgery (CABG) is associated with an increased risk of major hemorrhage and related surgical reexploration. Little is known about the relative effect of combined clopidogrel and aspirin on blood product use around the time of CABG. We evaluated the associated risk between the combined use of aspirin and clopidogrel and the transfusion of blood products perioperatively.

METHODS

We retrospectively studied a cohort of 659 individuals who underwent a first CABG, without concomitant valvular or aortic surgery, at a single large Canadian cardiac surgical centre between January 2000 and April 2002. The four study exposure groups were those prescribed aspirin (n = 105), clopidogrel (n = 11), the combination of both (n = 46), or neither drug (n = 497), within 7 days prior to CABG. The primary study outcome was the excessive transfusion of blood products during CABG and up to the second post-operative day, defined as > or = 2 units of packed red blood cells (PRBC), > or = 2 units of fresh frozen plasma, > or = 5 units of cryoprecipitate or > or = 5 units of platelets. Secondary outcomes included the mean number of transfused units of each type of blood product.

RESULTS

A greater mean number of units of PRBC were transfused among those who received clopidogrel alone (2.9) or in combination with aspirin (2.4), compared to those on aspirin alone (1.9) or neither antiplatelet drug (1.4) (P = 0.001). A similar trend was seen for the respective mean number of transfused units of platelets (3.6, 3.7, 1.3 and 1.0; P < 0.001) and fresh frozen plasma (2.5, 3.1, 2.3, 1.6; P = 0.01). Compared to non-users, the associated risk of excessive blood product transfusion was highest among recipients of aspirin and clopidogrel together (adjusted OR 2.2, 95% CI 1.1-4.3). No significant association was seen among lone users of aspirin (adjusted OR 1.0, 95% CI 0.6-1.6) or clopidogrel (adjusted OR 0.7, 95% CI 0.2-2.5), compared to non-users.

CONCLUSIONS

While combined use of aspirin and clopidogrel shortly before CABG surgery may increase the associated risk of excess transfusion of blood products perioperatively, several study limitations prevent any confident conclusions from being drawn. Beyond challenging these findings, future research might focus on the value of both intraoperative monitoring of platelet function, and the effectiveness of antifibrinolytic agents, at reducing the risk of postoperative bleeding.

Pharmacological strategies to decrease transfusion requirements in patients undergoing surgery

Surgical procedures are inevitably associated with bleeding. The amount of blood loss may vary widely between different surgical procedures and depends on surgical as well as non-surgical factors. Whereas adequate surgical haemostasis may suffice in most patients, pro-haemostatic pharmacological agents may be of additional benefit in patients with (diffuse) surgical bleeding or in patients with a specific underlying haemostatic defect. In general, surgical haemostasis and pharmacological therapies can be complementary in controlling blood loss. The use of pharmacological therapies to reduce blood loss and blood transfusions in surgery has historically been restricted to a few drugs. Antifibrinolytic agents (aprotinin, tranexamic acid and aminocaproic acid) have the best evidence supporting their use, especially in cardiac surgery, liver transplantation and some orthopaedic surgical procedures. Meta-analyses of randomised, controlled trials in cardiac patients have suggested a slight benefit of aprotinin, compared with the other antifibrinolytics. Desmopressin is the treatment of choice in patients with mild haemophilia A and von Willebrand disease. It has also been shown to be effective in patients undergoing cardiac surgery who received aspirin up to the time of operation. However, overall evidence does not support a beneficial effect of desmopressin in patients without pre-existing coagulopathy undergoing elective surgical procedures. Topical agents, such as fibrin sealants have been successfully used in a variety of surgical procedures. However, only very few controlled clinical trials have been performed and scientific evidence supporting their use is still limited. Novel drugs, like recombinant factor VIIa (eptacog alfa), are currently under clinical investigation. Recombinant factor VIIa has been introduced for the treatment of haemophilia patients with inhibitors, either in surgical or non-surgical situations. Preliminary data indicate that it may also be effective in surgical patients without pre-existing coagulation abnormalities. More clinical trials are warranted before definitive conclusions can be drawn about the safety and the exact role of this new drug in surgical patients. Only adequately powered and properly designed randomised, clinical trials will allow us to define the most effective and the safest pharmacological therapies for reducing blood loss and transfusion requirements in surgical patients. Future trials should also consider cost-effectiveness because of considerable differences in the costs of the available pro-haemostatic pharmacological agents.

Single-dose tranexamic acid reduces postoperative bleeding after coronary surgery in patients treated with aspirin until surgery

Tranexamic acid reduces postoperative bleeding after coronary artery bypass grafting. We evaluated the effects of a single dose of tranexamic acid given immediately before cardiopulmonary bypass (CPB) in patients treated with aspirin until the day before surgery. The study was a prospective, randomized, double-blinded, placebo-controlled, parallel-group trial. Eighty patients were included and divided into two groups: one group received tranexamic acid 30 mg/kg, and one group received placebo (0.9% NaCl) as a bolus injection before CPB. Postoperative blood loss was recorded for 16 h. Transfusions of blood products were recorded for the whole hospital stay. Transfusions of packed red cells were given when the hematocrit value was less than 20% during CPB and less than 25% after surgery. The patients in the tranexamic acid group had significantly less postoperative bleeding compared with the patients in the placebo group (mean [SD]) (475 [274] mL versus 713 [243] mL; P < 0.001). An effective inhibition of fibrinolysis was found in patients receiving tranexamic acid. Tranexamic acid reduces postoperative bleeding in coronary artery bypass grafting patients treated with aspirin until the day before surgery.

IMPLICATIONS

Continuation of aspirin medication until the day before coronary artery bypass grafting may increase postoperative bleeding. The administration of a single dose of tranexamic acid (30 mg/kg) immediately before cardiopulmonary bypass significantly reduced postoperative bleeding and inhibited fibrinolysis in these patients.

Factors determining the duration of tracheal intubation in cardiac surgery: a single-centre sequential patient audit

BACKGROUND AND OBJECTIVE

The study was designed to identify those factors associated with early tracheal extubation following cardiac surgery. Previous studies have tended to concentrate on surgery for coronary artery bypass or on other selected cohorts.

METHODS

Sequential cohort analysis of 296 unselected adult cardiac surgery patients was performed over 3 months.

RESULTS

In total, 39% of all patients were extubated within 6 h, 89% within 24 h and 95% within 48 h. Delayed extubation (>6 h after surgery) appeared unrelated to age, gender, body mass index, a previous pattern of angina or myocardial infarction, diabetes, preoperative atrial fibrillation, and preoperative cardiovascular assessment, as well as other factors. Delayed tracheal extubation was associated with poor left ventricular, renal and pulmonary function, a high Euroscore, as well as the type, duration and urgency of surgery. Early extubation (<6 h) was not associated with a reduced length of stay in either the intensive care unit or in hospital compared with patients who were extubated between 6 and 24 h. In these groups, it is presumed that organizational and not clinical factors appear to be responsible for a delay in discharge from intensive care. Patients who were extubated after 24 h had a longer duration of hospital stay and a greater incidence of postoperative complications. Postoperative complications were not adversely affected by early tracheal extubation.

CONCLUSIONS

In an unselected sequential cohort, both patient- and surgery-specific factors may be influential in determining the duration of postoperative ventilation of the lungs following cardiac surgery. In view of the changing nature of the surgical population, regular re-evaluation is useful in reassessing performance.

Injection pain of rocuronium and vecuronium is evoked by direct activation of nociceptive nerve endings

BACKGROUND AND OBJECTIVE

Rocuronium and, to a lesser extent, vecuronium can induce burning sensations associated with withdrawal reactions during administration. Dermal microdialysis in human and electrophysiological recordings of nociceptors in mouse skin were used to elucidate the underlying mechanisms of pain induction.

METHODS

Microdialysis catheters were inserted intradermally into the forearm of 10 volunteers and were perfused with two different concentrations of rocuronium and vecuronium (1 and 10 mg mL(-1)) or a control. Dialysis samples were taken every 15 min and analysed for protein, histamine, tryptase and bradykinin content. Pain intensity was rated on a numerical scale of 0-10. In a parallel design, activation of cutaneous nociceptors was assessed directly in a skin-nerve in vitro preparation of the mouse hind paw. The receptive fields of identified single C-nociceptors (n = 12) were superfused with rocuronium or vecuronium solutions (10 mg mL(-1)) at physiological pH.

RESULTS

In accordance with clinical observations, microdialysis of rocuronium (10 mg mL(-1)) induced sharp burning pain (NRS 4.1 +/- 1.8), whereas vecuronium given in the usual clinical concentration (1 mg mL(-1)) induced only minor pain sensations (NRS 0.6 +/- 1.3). At equimolar concentrations, pain sensation and concomitant mediator release evoked by both drugs were similar. No correlations were found between pain rating and mediator release. In the in vitro preparation, C-fibres showed a consistent excitatory response with rapid onset after stimulation with vecuronium as well as rocuronium (differences not significant).

CONCLUSIONS

The algogenic effect of aminosteroidal neuromuscular blocking drugs can be attributed to a direct activation of C-nociceptors.

Anaesthetic strategies to reduce perioperative blood loss in paediatric surgery

In adults, a number of measures to reduce perioperative blood loss have been established. These techniques serve to reduce patients' exposure to homologous blood. Most adults are concerned with this issue especially since many patients became infected with human immunodeficiency virus (HIV) during the 1980s through exposure to blood components. While blood-saving strategies are widely used in adults, they are mostly neglected in infants. However, it is these young patients with their whole life in front of them who, it could be argued, would benefit especially from any potentially avoidable infection (HIV, hepatitis, etc.) or immunological complications. In infants and small children, these blood-sparing techniques may not be as effective as in adults and technical limitations may prevent their application. However, some of these measures can be used and may serve to prevent or reduce exposure to homologous blood. In the following review, blood-saving techniques established in adults are described and their applicability for paediatric patients discussed.

Effects of propofol on the systolic and diastolic performance of the postischaemic, reperfused myocardium in rabbits

BACKGROUND AND OBJECTIVE

The effect of propofol on myocardial dysfunction during ischaemia and reperfusion is controversial yet important because of its frequent use in cardiac anaesthesia. Although animal studies suggest a free radical-scavenging potential, the cardioprotective properties of propofol have not been demonstrated consistently in vivo. Previous studies focused on systolic function while diastolic function may be a more sensitive marker of ischaemic injury. The main aim was to document the effect of propofol on diastolic function in isolated, blood perfused rabbit hearts subjected to moderate global ischaemia and reperfusion.

METHODS

Propofol 168 micromol L(-1), or the equivalent of its vehicle, Intralipid, was administered to 34 paced parabiotic Langendorff blood-perfused isolated rabbit hearts before and after 30 min of global normothermic ischaemia. Recovery of systolic function was quantified with the maximum rate of rise of left ventricular pressure. Diastolic performance was assessed using the time constant of the decline in left ventricular pressure (tau) and chamber stiffness (VdP/dV at 12 mmHg).

RESULTS

Recovery of systolic function during reperfusion was comparable in the two groups. There was no difference in left ventricular pressure between the two groups at any time during the experiments. Chamber stiffness increased significantly during ischaemia and reperfusion in the control group (from 34 +/- 9 to 54 +/- 8 mmHg during ischaemia, and 43 +/- 5 mmHg after 30 min reperfusion; mean +/-95% confidence interval) but not in the propofol-treated group (29 +/- 5, 36 +/- 8 and 30 +/- 8 at baseline, ischaemia and 30 min reperfusion, respectively).

CONCLUSIONS

Propofol has no protective effect on active relaxation or on systolic function in the present model, but it reduces ischaemic and postischaemic chamber stiffness.

Effects of bupivacaine used with sevoflurane on the rhythm and contractility in the isolated rat heart

BACKGROUND AND OBJECTIVE

The effects of sevoflurane on bupivacaine cardiotoxicity are mainly attributed to systemic effects. The purpose of this study was to investigate the direct myocardial effects of sevoflurane on bupivacaine toxicity.

METHODS

Hearts of 30 Wistar albino rats were isolated and mounted on a Langendorff apparatus perfused by modified Tyrode solution. Experimental groups were: a sevoflurane group (Group S, n = 10)--following baseline and 20 min (Stage 1) recordings, sevoflurane was added in doses of 1.4% (1 MAC) and 2.8% (2 MAC). In the two bupivacaine groups, bupivacaine 5 micromol (Group B5, n = 10) and bupivacaine 10 micromol (Group B10, n = 10) was added to the solution at Stage 1, and sevoflurane was added to the system as in Group S. Haemodynamic variables, i.e. heart rate, PR interval, QRS duration, left ventricular systolic pressure, contractility (+dp/dtmax), relaxation, time to reach peak systolic pressure, change in left ventricular diastolic pressure from baseline, and rate-pressure product were recorded.

RESULTS

In Group S, there was no change in cardiac rhythm. In bupivacaine groups, severe rhythm disturbances occurred and both the PR intervals and QRS complexes were prolonged significantly. All contractility variables deteriorated and the rate-pressure product decreased by 67-90% with the addition of bupivacaine. In all groups, 2 MAC sevoflurane lowered +dp/dtmax further.

CONCLUSIONS

Sevoflurane does not have any untoward effect on bupivacaine-induced cardiotoxicity in clinically relevant doses in the isolated rat heart.

Effect of the neuronal nitric oxide synthase inhibitor 7-nitroindazole on the righting reflex ED50 and minimum alveolar concentration during sevoflurane anaesthesia in rats

BACKGROUND AND OBJECTIVE

The aim was to determine the effect of acute and chronic administration of 7-nitroindazole, a selective neuronal nitric oxide synthase inhibitor, on the righting reflex ED50 and the minimum alveolar concentration during sevoflurane anaesthesia in rats.

METHODS

7-Nitroindazole was acutely (0, 50 and 100 mg kg(-1)) and chronically (0 and 150 mg kg(-1) day(-1), 4 days) administered to rats. After the preparation, the minimum alveolar concentration and the righting reflex ED50 were measured. The concentration of cGMP in the brain, cerebellum and spinal cord was also measured.

RESULTS

Acute administration reduced the minimum alveolar concentration (50 mg kg(-1), 58.8% (95% CI: 50.3-67.3%) of the baseline value, P < 0.01; 100 mg kg(-1), 55.8 (46.9-64.7), P < 0.01) and the righting reflex ED50 (50 mg kg(-1), 27.2 (17.2-37.2), P < 0.01; 100 mg kg(-1), 14.3 (6.6-22.0), P < 0.01). Chronic administration did not reduce the minimum alveolar concentration; however, it reduced the righting reflex ED50 (65.3 (52.9-77.7), P < 0.01). Overall, the reduction in minimum alveolar concentration in the acute and chronic protocol did not correlate with that of the righting reflex ED50. 7-Nitroindazole (100 mg kg(-1), acute) reduced the cGMP concentration within the cerebellum by 55.4%; however, it did not decrease concentrations in the brain or spinal cord.

CONCLUSIONS

Different mechanisms are responsible for the observed alterations to the minimum alveolar concentration and the righting reflex ED50 following treatment with 7-nitroindazole. The nitric oxide-cGMP pathway might play a less important role in the determination of minimum alveolar concentration than the righting reflex ED50.

Suprascapular nerve block or a piroxicam patch for shoulder tip pain after day case laparoscopic surgery

BACKGROUND AND OBJECTIVE

The reported incidence of shoulder tip pain following laparoscopic surgery varies from 35 to 63%. This study evaluated the analgesic efficacy of either performing a prophylactic suprascapular nerve block with bupivacaine or applying a piroxicam patch to the skin over both shoulders for the relief of shoulder tip pain after laparoscopy.

METHODS

Sixty healthy informed female patients were randomly assigned to one of three groups: (a) a control group (n = 20), no treatment; (b) a suprascapular nerve block group (n = 20) in which a bilateral suprascapular nerve block was performed before induction of anaesthesia with 5 mL 0.5% bupivacaine with epinephrine; and (c) a piroxicam patch group (n = 20) in which a 48 mg piroxicam patch on the skin of each shoulder was applied before induction of anaesthesia. All patients received a total intravenous anaesthesia technique with propofol, fentanyl and vecuronium. Shoulder tip and wound pain were recorded on a visual analogue pain scale at five time intervals for 24 h after surgery.

RESULTS

A total of 80% of patients in the control group, 75% in the suprascapular nerve block group and 45% in the piroxicam patch group complained of shoulder tip pain during the recording period (P < 0.05). The scores for shoulder tip pain in the piroxicam patch group were significantly lower compared with the control group at 3, 6 and 12 h, and compared with the suprascapular nerve block group at 6 and 12 h. The need for analgesics was also significantly lower in the piroxicam patch group compared with the other two groups.

CONCLUSIONS

Prophylactic piroxicam patches are effective and safe for the relief of shoulder tip pain after laparoscopy. Bilateral suprascapular nerve block is not effective in this setting.

Treatment of hiccup during general anaesthesia or sedation: a qualitative systematic review

BACKGROUND AND OBJECTIVE

Acute hiccup is a minor complication that can occur during sedation or general anaesthesia. The disorder can disturb the surgical field, might interfere with lung ventilation or could hamper diagnostic procedures. The objective was to perform a systematic search for interventions aimed at treating hiccup occurring during anaesthesia or sedation.

METHODS

A systematic search for reports describing interventions to treat hiccup in conjunction with anaesthesia was carried out (MEDLINE, EMBASE, Cochrane-Library, manual screening of reference lists and review articles, up to December 2001). Search terms were 'hiccup', 'singultus' or 'hiccough'.

RESULTS

Twenty-six reports involving approximately 581 patients focused on hiccup remedies in the anaesthesia setting. Only one report was substantiated by a randomized controlled trial. This investigated methylphenidate 10 mg intravenously in 51 patients, which did not show a beneficial effect compared with placebo. Hiccup was a self-limiting phenomenon. Case series and case reports focused on various systemically applied drugs in 12 reports, stimulating techniques (e.g. pharyngeal stimulation) in seven, topical applied remedies (e.g. intranasal ice-cold water) in four, and ventilation techniques (e.g. continuous positive pressure ventilation) in two.

CONCLUSIONS

A large variety of interventions have been proposed for the treatment of hiccup during anaesthesia and sedation. However, perioperative treatment is still based on empirical findings and no treatment is 'evidence-based'. Thus, no valid recommendations for the treatment of hiccup can be derived. Uncontrolled observations are inadequate to establish treatment efficacy.

Pharmacokinetics and pharmacodynamics of the new propofol prodrug GPI 15715 in rats

BACKGROUND AND OBJECTIVE

We studied the pharmacokinetics and pharmacodynamics of GPI 15715 (Aquavan injection), a new water-soluble prodrug metabolized to propofol by hydrolysis.

METHODS

Nine adult male Sprague-Dawley rats (398 +/- 31 g) received a bolus dose of 40 mg GPI 15715. The plasma concentrations of GPI 15715 and propofol were determined from arterial blood samples, and the pharmacokinetics of both compounds were investigated using compartment models whereby the elimination from the central compartment of GPI 15715 was used as drug input for the central compartment of propofol. Pharmacodynamics were assessed using the median frequency of the EEG power spectrum.

RESULTS

A maximum propofol concentration of 7.1 +/- 1.7 microg mL(-1) was reached 3.7 +/- 0.2 min after bolus administration. Pharmacokinetics were best described by two-compartment models. GPI 15715 showed a short half-life (2.9 +/- 0.2 and 23.9 +/- 9.9 min), an elimination rate constant of 0.18 +/- 0.01 min(-1) and a central volume of distribution of 0.25 +/- 0.02 L kg(-1). For propofol, the half-life was 1.9 +/- 0.1 and 45 +/- 7 min, the elimination rate constant was 0.15 +/- 0.02 min(-1) and the central volume of distribution was 2.3 +/- 0.6 L kg(-1). The maximum effect on the electroencephalogram (EEG)--EEG suppression for >4 s--occurred 6.5 +/- 1.2 min after bolus administration and baseline values of the EEG median frequency were regained 30 min later. The EEG effect could be described by a sigmoid Emax model including an effect compartment (E0 = 16.9 +/- 7.9 Hz, EC50 = 2.6 +/- 0.8 microg mL(-1), ke0 = 0.35 +/- 0.04 min(-1)).

CONCLUSIONS

Compared with known propofol formulations, propofol from GPI 15715 showed a longer half-life, an increased volume of distribution, a delayed onset, a sustained duration of action and a greater potency with respect to concentration.

High-affinity block of voltage-operated rat IIA neuronal sodium channels by 2,6 di-tert-butylphenol, a propofol analogue

BACKGROUND AND OBJECTIVE

Propofol is a phenol derivative (2,6 di-isopropylphenol) with a unique effect profile including activating effects on GABA(A) and blocking effects on voltage-operated sodium channels. If the substituents in the 2- and the 6-positions are replaced by tert-butyl groups, the resulting phenol derivative, 2,6 di-tert-butylphenol, despite being a close structural propofol analogue, completely lacks GABA(A) receptor effects. The aim of this in vitro study was to investigate the effects of 2,6 di-tert-butylphenol on voltage-operated neuronal sodium channels in order to determine whether and, if so, how these structural changes alter the sodium channel-blocking effect seen with propofol.

METHODS

Whole-cell sodium inward currents through heterologously expressed rat type IIA sodium channels were recorded in the absence and presence of definite concentrations of 2,6 di-tert-butylphenol and propofol.

RESULTS

When applied at concentrations > or = 30 micromol, 2,6 di-tert-butylphenol completely and irreversibly blocked sodium inward currents. The blockade equilibrium time was about 2 min. A partial washout was possible only if the application was stopped before the equilibrium of the blockade was achieved.

CONCLUSIONS

2,6 Di-tert-butylphenol exerts a high-affinity block of neuronal sodium channels. Apparently, the slight structural differences of 2,6 di-tert-butylphenol in comparison with propofol--which account for the lack of GABA(A) receptor effects--enhance its voltage-operated sodium channel-blocking effects. As 2,6 di-tert-butylphenol is much more potent than most sodium channel blockers in clinical use, it might be of interest in the development of local anaesthetics.

Effects of rolipram, pimobendan and zaprinast on ischaemia-induced dysrhythmias and on ventricular cyclic nucleotide content in the anaesthetized rat

BACKGROUND AND OBJECTIVE

This study was designed to compare the haemodynamic, electrophysiological and pharmacodynamic effects of three selective inhibitors of the different isoenzyme forms of phosphodiesterase (PDE) on ischaemia-induced dysrhythmias in the anaesthetized rat. The drugs used were pimobendan, a selective PDE III inhibitor, rolipram, a selective PDE IV inhibitor, and zaprinast, a selective PDE V inhibitor.

METHODS

The coronary artery was occluded 15 min after commencing drug administration, and myocardial ischaemia was maintained for 30 min during which the heart rate and mean arterial pressure were recorded. cAMP and cGMP were determined by radioimmunoassay.

RESULTS

Pretreatment with rolipram decreased the duration of ventricular tachycardia without any change in the incidences of dysrhythmias or the mortality rate. This drug did not modify ventricular content of adenosine 3',5'-cyclic monophosphate (cAMP) or guanosine 3',5'-cyclic monophosphate (cGMP). Pimobendan (1 mg kg(-1) + 0.1 mg kg(-1) min) decreased the duration of ventricular tachycardia. This dose of pimobendan and zaprinast (1 mg kg(-1) + 0.1 mg kg(-1) min(-1)) increased the incidence rate of ventricular fibrillation following coronary artery ligation and the mortality rate. Moreover, both drugs increased cGMP in the ventricle.

CONCLUSIONS

The results demonstrated that pimobendan and zaprinast increased the incidence of dysrhythmias and the mortality rate, which was accompanied by an increase in the ventricular content of cGMP. Rolipram decreased the duration of ventricular tachycardia without a change in the cyclic nucleotide content or in the mortality rate.

Factor V Leiden protects against blood loss and transfusion after cardiac surgery

BACKGROUND

The outcome of cardiac surgery is influenced by several factors, but the impact of specific genetic variants has not been systematically explored. Because blood conservation is a pressing issue in cardiac surgery, we tested the hypothesis that factor V Leiden (FVL), a common coagulation factor polymorphism, may protect against blood loss and transfusion in patients undergoing cardiac surgery.

METHODS AND RESULTS

We enrolled 517 patients undergoing cardiac surgery, including 26 heterozygous FVL carriers, and evaluated the impact of FVL on chest tube output and transfusion by using univariate and multivariate techniques. For patients with FVL, blood loss at 6 (238+/-131 mL) and 24 hours (522+/-302 mL) was significantly lower than that for noncarriers (358+/-259 mL and 730+/-452 mL; P<0.001 and P=0.001, respectively). In a multivariate regression analysis, controlling for ethnicity and factors known to affect blood loss, FVL was a significant independent contributor at both time points. Using a similar regression approach, FVL did not have a significant effect on the number of units transfused. However, logistic regression of the risk of receiving any transfusion during hospitalization demonstrated a significant independent protective effect of FVL on overall transfusion risk.

CONCLUSIONS

FVL represents a common genetic trait that may protect against blood loss and transfusion in this population. This study demonstrates that genetic variability can affect the outcome of cardiac surgery.

High-dose aprotinin reduces activation of hemostasis, allogeneic blood requirement, and duration of postoperative ventilation in pediatric cardiac surgery

BACKGROUND

Though multiple studies have affirmed the effectiveness of aprotinin in reducing blood loss in adult cardiac surgery, the possible benefit in pediatric cardiac surgery is controversial.

METHODS

In a double-blind, randomized, and placebo-controlled study, the efficacy of aprotinin in attenuating the hemostatic and inflammatory activation during cardiopulmonary bypass in 60 patients weighing less than 10 kg was investigated. Secondary endpoints were the influence of aprotinin on the reduction of blood loss and allogeneic blood requirement, as well as postoperative oxygenation and length of mechanical ventilation. Aprotinin was administered in a high-dose of 3 x 10(4) KIU/kg plus a bolus of 5 x 10(5) KIU (not weight adjusted) added to the pump prime.

RESULTS

Aprotinin plasma concentration at the end of cardiopulmonary bypass (CPB) was with 184 +/- 45 KIU/mL, within the targeted range of 200 KIU/mL. Coagulation and fibrinolysis were suppressed (F1.2 1 hour after CPB: 5.35 +/- 2.9 nmol/L vs 14.5 +/- 23.1 nmol/L; D-dimer 1 hour after CPB: 0.63 +/- 0.6 ng/mL vs 2.3 +/- 3.1 ng/mL; p < 0.05), inflammatory markers (interleukin [IL]-6, IL-8, IL-10) increased over time without significant differences between the groups, and only complement C3a activation was significantly attenuated at the end of CPB in the aprotinin group. Chest tube drainage was significantly reduced (24 hours: median 13.5 [IQR 12.2] mL/kg vs 19.4 [8.2] mL/kg; p < 0.05). All patients received one unit of packed cells to prime the heart lung machine. A second unit was needed significantly less often in the aprotinin group (13% vs 47%; p < 0.05). Postoperative oxygenation (pO2/FIO2 172 [IQR 128] mm Hg vs 127 [74]; p < 0.05) improved, and the time on ventilator was shorter in the aprotinin group (median 45 hours [IQR 94] vs 101 [IQR 74]; p < 0.05). No side effects were attributable to the use of aprotinin.

CONCLUSIONS

High-dose aprotinin effectively attenuated hemostatic activation and reduced blood loss and transfusion requirement in pediatric cardiac surgery. Postoperative ventilation was also shortened in the aprotinin group.

Platelet-rich-plasmapheresis for minimising peri-operative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have generated considerable enthusiasm for the use of technologies intended to reduce the use of allogeneic blood (blood from an unrelated donor). Platelet-rich plasmapheresis (PRP) offers an alternative approach to blood conservation.

OBJECTIVES

To examine the evidence for the efficacy of PRP in reducing peri-operative allogeneic red blood cell (RBC) transfusion, and the evidence for any effect on clinical outcomes such as mortality and re-operation rates.

SEARCH STRATEGY

Studies were identified by: computer searches of MEDLINE, EMBASE, Current Contents, and the Cochrane Library (to June 2001). These searches were supplemented by checking the reference lists of published articles, reports, and reviews.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to PRP, or to a control group who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Main outcomes measured were: the number of patients receiving an allogeneic RBC transfusion, and the amount of RBC transfused. Trial quality was assessed using criteria proposed by Schulz et al. (Schulz 1995) and Jadad et al. (Jadad 1996).

MAIN RESULTS

Nineteen trials of PRP were identified that reported data for the number of patients exposed to allogeneic RBC transfusion. These trials evaluated a total of 1452 patients. The pooled relative risk (RR) of exposure to allogeneic blood transfusion in those patients randomised to PRP was 0.71 (95%CI: 0.56, 0.90), equating to a relative risk reduction (RRR) of 29%; the average absolute risk reduction (ARR) was 19% (RD = -0.19: 95%CI: -0.29, -0.09). On average, PRP did not significantly reduce the total volume of RBC transfused (weighted mean difference [WMD] = -0.69: 95%CI: -1.93, 0.56 units). Substantial statistical heterogeneity was observed (p < 0.001). Trials provided inadequate data regarding the impact of PRP on morbidity, mortality, and hospital length of stay. The majority of trials were small and of poor methodological quality.

REVIEWER'S CONCLUSIONS

Although the results suggest that PRP is effective in reducing allogeneic RBC transfusion in adult patients undergoing elective surgery, there was considerable heterogeneity in treatment effects and the trials were of poor methodological quality. As the majority of trials were unblinded, transfusion practices may have been influenced by knowledge of the patient's allocation status, potentially exaggerating the true magnitude of the beneficial effect of PRP. The available studies provided inadequate data for firm conclusions to be drawn regarding the impact of PRP on clinically important endpoints.

Cell salvage for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood, have prompted reconsideration of the use of allogeneic (blood from an unrelated donor) red blood cell (RBC) transfusion, and a range of techniques to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of cell salvage in reducing allogeneic blood transfusion and the evidence for any effect on clinical outcomes.

SEARCH STRATEGY

Articles were identified by: computer searches of MEDLINE, EMBASE, Current Contents (to July 2002), the Cochrane Controlled Trials Register (Issue 2, 2002) and websites of international health technology assessment agencies. References in the identified trials and review articles were searched and authors contacted to identify additional studies.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to cell salvage, or to a control group, who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed using criteria proposed by Schulz et al. (Schulz 1995) and Jadad et al. (Jadad 1996). Main outcomes measured were: the number of patients exposed to allogeneic red cell transfusion, and the amount of blood transfused. Other outcomes measured were: re-operation for bleeding, blood loss, post-operative complications (thrombosis, infection, non-fatal myocardial infarction, renal failure), mortality, and length of hospital stay (LOS).

MAIN RESULTS

Overall, the use of cell salvage reduced the rate of exposure to allogeneic RBC transfusion by a relative 40% (relative risk [RR] = 0.60: 95% confidence interval [CI] = 0.51 to 0.70). The absolute reduction in risk (ARR) of receiving an allogeneic RBC transfusion was 23% (95%CI = 16% to 30%). In orthopaedic procedures the relative risk (RR) of exposure to RBC transfusion was 0.42 (95%CI = 0.32 to 0.54) compared to 0.78 (95%CI = 0.68 to 0.88) for cardiac procedures. The use of cell salvage resulted in an average saving of 0.64 units of allogeneic RBC per patient (weighted mean difference [WMD] = -0.64: 95%CI = -0.86 to -0.46). Cell salvage did not appear to impact adversely on clinical outcomes.

REVIEWER'S CONCLUSIONS

The results suggest cell salvage is efficacious in reducing the need for allogeneic red cell transfusion in adult elective surgery. However, the methodological quality of trials was poor. As the trials were unblinded and lacked adequate concealment of treatment allocation, transfusion practices may have been influenced by knowledge of the patient's treatment status biasing the results in favour of cell salvage.

Fibrin sealant use for minimising peri-operative allogeneic blood transfusion

BACKGROUND

Fibrin sealants have gained increasing popularity as interventions to improve peri-operative (intra/post-operative) haemostasis and diminish the need for allogeneic red cell transfusion (blood from an unrelated donor).

OBJECTIVES

To examine the efficacy of fibrin sealants in reducing peri-operative blood loss and allogeneic red blood cell (RBC) transfusion.

SEARCH STRATEGY

Studies were identified by: searches of MEDLINE, EMBASE, Current Contents, the Cochrane Library (July 2002), manufacturer web sites (to July 2002), and bibliographies of published articles.

SELECTION CRITERIA

Controlled trials in which adult patients, scheduled for elective surgery, were randomised to fibrin sealant treatment or to a control group who did not receive fibrin sealant treatment. Trials were eligible if they reported data on the number of patients exposed to allogeneic red cell transfusion, the volume of blood transfused, or blood loss (assessed objectively).

DATA COLLECTION AND ANALYSIS

Primary outcomes measured were: the number of patients exposed to allogeneic red cells, the amount of blood transfused, and blood loss. Other outcomes measured were: re-operation due to bleeding, infection, mortality, and length of hospital stay. Treatment effects were pooled using a random effects model.

MAIN RESULTS

Seven trials, including a total of 388 patients, reported data on peri-operative exposure to allogeneic RBC transfusion. Fibrin sealant treatment, on average, reduced the rate of exposure to allogeneic red cell transfusion by a relative 54% (relative risk [RR] = 0.46: 95%CI = 0.32 to 0.68). Eight trials, including a total of 442 patients, provided data for post-operative blood loss. Fibrin sealant treatment reduced blood loss on average by around 134 per patient (95%CI = 51 to 217 ). However the trials reviewed were small and of poor methodological quality (91% unblinded).

REVIEWER'S CONCLUSIONS

Overall the results suggest that fibrin sealants are efficacious in reducing both post-operative blood loss and peri-operative exposure to allogeneic RBC transfusion. However, due to the lack of blinding, transfusion practices may have been influenced by knowledge of the patient's treatment status. This raises concerns about the use of blood transfusion practice as an outcome variable in trials of fibrin sealant. In the case of blood loss, the results must be interpreted with caution, in view of the statistically significant heterogeneity in treatment effect observed. Large, methodologically rigorous, randomised controlled trials of fibrin sealants are needed.