Perioperative systemic haemostatic agents

A case report and brief review of the literature on bilateral retinal infarction following cardiopulmonary bypass for coronary artery bypass grafting

Postoperative visual loss is a devastating perioperative complication. The commonest aetiologies are anterior ischaemic optic neuropathy (AION), posterior ischaemic optic neuropathy (PION), and central retinal artery occlusion (CRAO). These appear to be related to certain types of operation, most commonly spinal and cardiac bypass procedures; with the rest divided between: major trauma causing excessive blood loss; head/neck and nasal or sinus surgery; major vascular procedures (aortic aneurysm repair, aorto-bifemoral bypass); general surgery; urology; gynaecology; liposuction; liver transplantation and duration of surgery. The non-surgical risk factors are multifactorial: advanced age, prolonged postoperative anaemia, positioning (supine v prone), alteration of venous drainage of the retina, hypertension, smoking, atherosclerosis, hyperlipidaemia, diabetes, hypercoagulability, hypotension, blood loss and large volume resuscitation. Other important cardiac causes are septic emboli from bacterial endocarditis and emboli caused by atrial myxomata. The majority of AION cases occur during CPB followed by head/neck surgery and prone spine surgery. CPB is used to allow coronary artery bypass grafting on a motionless heart. It has many side-effects and complications associated with its use and we report here a case of bilateral retinal infarction during routine coronary artery bypass grafting in a young male patient with multiple risk factors for developing this complication despite steps to minimise its occurrence.

Anemia and transfusion therapy: an update

Anemia is one of the most prevalent diseases in the general population and is a very frequently found condition in medical and surgical patients in all medical specialties. A good evaluation of its clinical impact and its therapeutic possibilities is essential. Allogenic blood transfusion is a useful procedure in anemia management, although it has important adverse effects. It is the responsibility of the clinician to know and to take into account all the available alternatives for the treatment of anemia. Blood transfusions, erythropoiesis-stimulating agents, iron therapy (oral and endovenous) and other therapeutic alternatives must be rationally used, in accordance with the currently available clinical evidence. This review article summarizes some epidemiological characteristics of anemia, its clinical evaluation and the main therapeutic possibilities based on the present knowledge, placing special emphasis on the critically ill patient.

Effects of tranexamic acid on blood loss during total hip arthroplasty

PURPOSE

To assess the effects of tranexamic acid (TA) in patients undergoing total hip arthroplasty (THA) for osteoarthritis.

METHODS

42 patients underwent primary THA for osteoarthritis by a single surgeon. 10 men and 11 women who did not receive TA were controls, whereas 9 men and 12 women who received TA constituted the treatment group. Both groups were matched for age, gender, body mass index, and American Society of Anesthesiologists grading. The type of prosthesis used (cemented or uncemented) was based on the surgeon's preference and patient age, activity level and demands. No hybrid prosthesis was used. 10 minutes prior to incision, a single dose of intravenous TA (10 mg per kg body weight) was given to patients in the treatment group. Comparison was made between both groups with regard to intra-operative blood loss, postoperative reduction in haemoglobin and haematocrit levels, blood transfusion, incidence of deep vein thrombosis, and the length of hospital stay.

RESULTS

The mean intra-operative blood loss (489 [SD, 281] vs. 339 [SD, 184] ml, p = 0.048) and the decrease in haemoglobin level (38 [SD, 12] vs. 29 [SD, 10] g/l, p=0.014) were significantly higher in the control than the treatment group. Two patients among the controls received a transfusion, compared to none in the TA group (p = 0.49, Fisher's exact test). The 2 patients who needed blood transfusion had blood losses of 600 and 690 ml, compared to a mean of 489 ml in the whole group. No patient in either group developed deep vein thrombosis or pulmonary embolism up to 3 months.

CONCLUSION

A single dose of intravenous TA (10 mg per kg body weight) given 10 minutes prior to THA is a cost-effective and safe means of minimising blood loss and reduction in haemoglobin concentrations as well as the need for allogenic blood transfusion, without increasing the risk of thromboembolic events.

[Anemia and transfusion therapy: an update]

Anemia is one of the most prevalent diseases in the general population and is a very frequently found condition in medical and surgical patients in all medical specialties. A good evaluation of its clinical impact and its therapeutic possibilities is essential. Allogenic blood transfusion is a useful procedure in anemia management, although it has important adverse effects. It is the responsibility of the clinician to know and to take into account all the available alternatives for the treatment of anemia. Blood transfusions, erythropoiesis-stimulating agents, iron therapy (oral and endovenous) and other therapeutic alternatives must be rationally used, in accordance with the currently available clinical evidence. This review article summarizes some epidemiological characteristics of anemia, its clinical evaluation and the main therapeutic possibilities based on the present knowledge, placing special emphasis on the critically ill patient.

Modulation of physiological hemostasis by irrigation solution: comparison of various irrigation solutions using a mouse brain surface bleeding model

Object

Intraoperative bleeding often obscures the surgical field and may cause neurological damage. The irrigation fluids used during surgery might affect physiological hemostasis because they modulate the extracellular fluid composition of the bleeding area directly. The authors therefore investigated the influence of irrigation fluid on hemostasis in a mouse brain surface bleeding model.

Methods

The cerebral cortices of ddY strain mice were exposed under irrigation with normal saline, lactated Ringer (LR) solution, or artificial CSF (ACF-95). To investigate the influence of electrolytes, calcium, potassium, or both were also added to the saline. After 10 minutes of irrigation at 100 ml/hour, sequential photographs of the surgical area were taken with a microscope, and the number of bleeding points was counted visually. Irrigation and counting were performed in a masked manner.

Results

There were significantly more bleeding points after irrigation with normal saline than with ACF-95; LR solution had a similar effect on physiological hemostasis as ACF-95. Saline augmented with calcium or potassium and calcium was superior to normal saline in terms of hemostasis.

Conclusions

The authors demonstrated that the irrigation fluid used in neurosurgery affects bleeding at the surgical site. To avoid surgical site bleeding, ACF-95 and LR solution should be used as irrigation fluids instead of normal saline. The calcium and potassium content of irrigation solutions seems to be important in hemostasis.

Permissive hypotension and desmopressin enhance clot formation

BACKGROUND

Experimental studies of uncontrolled hemorrhage demonstrated that permissive hypotension (PH) reduces blood loss, but its effect on clot formation remains unexplored. Desmopressin (DDAVP) enhances platelet adhesion promoting stronger clots. We hypothesized PH and DDAVP have additive effects and reduce bleeding in uncontrolled hemorrhage.

METHODS

Rabbits (n = 42) randomized as follows: sham; normal blood pressure (NBP) resuscitation; PH resuscitation-60% baseline mean arterial pressure; NBP plus DDAVP 1 hour before (DDAVP NBP) or 15 minutes after beginning of shock (DDAVP T1 NBP); and PH plus DDAVP 1 hour before (DDAVP PH) or 15 minutes after beginning of shock (DDAVP T1 PH). Fluid resuscitation started 15 minutes after aortic injury and ended at 85 minutes. Intraabdominal blood loss was calculated, aortic clot sent for electron microscopy. Activated partial thromboplastin time, platelet count, thromboelastometry, arterial blood gases, and complete blood count were performed at baseline and 85 minutes. Analysis of variance was used for comparison.

RESULTS

NBP received more fluid volume and had greater intraabdominal blood loss. DDAVP, when administered preshock, significantly reduced blood loss in NBP and fluid requirement when given postshock. Platelets, arterial blood gas, complete blood count, and activated partial thromboplastin time were similar at 85 minutes. NBP delayed clot formation and worsened thrombodynamic potential on thromboelastometry, whereas PH and DDAVP improved. Electron microscopy showed lack of fibrin on NBP clots, whereas DDAVP and PH clots displayed exuberant fibrin/platelet aggregates. DDAVP NBP presented intermediate clots.

CONCLUSION

PH reduced bleeding and improved hemostasis compared with normotensive resuscitation. DDAVP given preshock exerted similar effects with normotensive resuscitation.

[Haemostatic disorders in orthopaedic surgery: laboratory diagnosis]

Coagulative disorders may result from a breakdown in the balance between coagulation and fibrinolysis. It is important to assess relative physiological states of coagulation and fibrinolysis related to operation. An ideal outcome in orthopaedic surgical procedures is the achievement of adequate haemostasis without excessive bleeding despite transection of numerous blood vessels, a necessary part of any surgical procedure. Meticulous attention to secure intraoperative haemostasis is a surgeon's responsibility. The postoperative haemostatic response to injury must also lead to a hypercoagulable state and thrombosis because it is also accompanied by stasis and vessel injury, fulfilling Virchow's triad. For discussion of prophylaxis and treatment of venous thromboembolic disease and orthopaedic surgical bleeding, the reader is referred to other articles. This paper discusses selected conditions leading to postoperative bleeding and thrombosis after orthopaedic surgery as well as laboratory diagnosis.

Very long half-life plasminogen activator inhibitor type 1 reduces bleeding in a mouse model

OBJECTIVE

To investigate the potential for the future clinical use of a very long half-life plasminogen activator inhibitor type 1 (VLHL PAI-1) as a haemostatic agent.

MATERIALS AND METHODS

We developed a VLHL PAI-1 (half-life >700 h) recombinant mutant of PAI-1 and assessed VLHL PAI-1 for its ability to inhibit fibrinolysis in vitro using human, rabbit, mouse and rat blood. Fibrin clot lysis time, monitored by thromboelastometry, was determined at various concentrations of VLHL PAI-1. Also, we determined total bleeding time and total blood loss of control, VLHL PAI-1-, tissue-type plasminogen activator (tPA)- and tPA + VLHL PAI-1-treated mice.

RESULTS

Using a thromboelastometer, mouse blood was most similar to human blood in its coagulation and fibrinolytic characteristics. We evaluated the affect of VLHL PAI-1 on haemostasis using the mouse model and showed that VLHL PAI-1 is an effective inhibitor of fibrin clot degradation. It reduced time of bleeding and total blood loss.

CONCLUSION

VLHL PAI-1 may provide an important physiological mechanism to protect clots from premature dissolution in surgical and trauma settings.

Aprotinin attenuates genomic expression variability following cardiac surgery

BACKGROUND

Aprotinin was the subject of recent controversy regarding adverse clinical outcomes following cardiac surgery. We compared the role of Aprotinin and epsilon-aminocaproic acid on clinical outcomes and the attenuation of the postcardiopulmonary bypass (CPB) response at the genomic expression and cytokine (protein) level.

METHODS

Thirty-nine low-risk patients undergoing coronary revascularization (CABG) and/or valve procedures using cardiopulmonary CPB were enrolled into a prospective cohort study. Aprotinin or epsilon-aminocaproic acid was administered to patients. Gene expression was assessed from whole blood mRNA samples collected preoperatively (PRE) and 6 hours (6H) postoperatively. Validation of gene expression was performed with SYBR Green real-time polymerase chain reaction. Cytokine values were quantified from serum preoperatively and postoperatively at 6 H and 4 days and analyzed in a blinded fashion.

RESULTS

No difference was detected in baseline characteristics. Inflammatory markers measured did not reveal significant difference between patients receiving Aprotinin (APR) and those receiving epsilon-aminocaproic acid (Amicar). Intraoperative parameters and postoperative outcomes were not significantly different. Compared with PRE samples, 6H samples had 264 upregulated and 548 downregulated genes uniquely in the APR group compared to 4826 upregulated and 1114 downregulated genes uniquely in the Amicar group (p < 0.001). Compared to patients in the Amicar group, APR patients had significantly different gene expression pathways involving NF-kappabeta regulation, programmed cell death and cell-cell adhesion. None of the patients developed postoperative stroke, myocardial infarction, or systemic infections.

CONCLUSIONS

Aprotinin leads to significantly less genomic expression variability following CPB compared to Amicar and has a differential effect on specific genomic pathways.

Perioperative management of a child with von Willebrand disease undergoing surgical repair of craniosynostosis: looking at unusual targets

We report the successful management of a craniosynostosis repair in a child with severe Type I von Willebrand disease diagnosed during the preoperative assessment and treated by coagulation factor VIII and ristocetin cofactor. Collaboration among the anesthesiologist, the neurosurgeon, the clinical pathologist, and the pediatric hematologist is important for successful management.

Managing bleeding in anticoagulated patients with a focus on novel therapeutic agents

Heparin, low molecular weight heparin (LMWH) and coumarins are familiar to most clinicians, inexpensive, highly effective when correctly used and widely available. However, coumarin has a delayed onset of action, interacts with many medications, has a narrow therapeutic window, and can cause thrombosis in some settings (e.g. hereditary protein C deficiency, heparin induced thrombocytopenia, warfarin loading). Additionally, warfarin and heparin require monitoring of their therapeutic effect. These real and perceived limitations have led to the development of 'novel' anticoagulants. However, these new agents have one general limitation--a lack of a widely available antidote. We focus on the management of bleeding in anticoagulated patients, with particular regard to novel anticoagulants.

Complication of surgery for scoliosis in children with surgically corrected congenital cardiac malformations

INTRODUCTION

There is a high incidence of scoliosis in patients who have undergone cardiothoracic surgery for correction of congenital cardiac disease, this risk being 10 times higher than in the general population.

MATERIALS AND METHODS

So as to analyse the surgical and postoperative complications, we designed a retrospective study to include every child who underwent spinal orthopaedic surgery, and who had previously undergone cardiothoracic surgery because of a congenital cardiac malformation. We excluded those patients who had syndromes associated with the development of scoliosis.

RESULTS

We identified 18 patients with surgically treated congenital cardiac disease who had undergone surgery for scoliosis over a period of 7 years. This group came from a total number of 87 patients undergoing spinal fusion over the same period. Of those with congenitally malformed hearts, 61% had acyanotic lesions, with ventricular septal defect being the most frequent single lesion, present in 40%. All the patients needed blood transfusions during the surgery, with aprotinin used in 73% to reduce the bleeding, and inotropes needed for 4 children. During the immediate postoperative period, 1 patient died in the first 24 hours, while 7 (39%) had different complications, pneumonia in 4, pleural effusions in 2, and rhabdomyolysis in the other, as opposed to a rate of complications of 27% in patients without heart disease.

CONCLUSION

The surgical and postoperative complications in these patients depend on the specific cardiac lesion. A multidisciplinary team with experience in the treatment of congenitally malformed hearts is essential for appropriate management of these patients.

[Laboratory diagnosis in orthopaedic surgery]

Orthopaedic procedures and anaesthesia are not physiological states. To prevent orthopaedic sequelae, laboratory diagnoses are of proven value in preoperative and postoperative complications as well as preoperative diseases. Laboratory analyses have an important contribution to early diagnosis of infection, haemostasis disorders, electrolyte disbalance, and acid-base disturbance. Laboratory analyses also have a role in monitoring the effect of therapy. Metabolic bone diseases such as osteoporosis affect many patients. Laboratory analyses are useful in evaluating the treatment for preventing fractures. This article discusses specific factors causing postoperative bleeding and thrombosis after orthopaedic surgery.

Haemorrhagic shock therapy

BACKGROUND

Severe injury is often associated with haemorrhagic shock and this is the most common cause of preventable mortality after injury. Care of the injured patient in shock involves an overlapping continuum of care beginning during the prehospital phase of care and extending through the interventional and critical care phases.

OBJECTIVE

This study aimed to review emerging therapies in the treatment of haemorrhagic shock.

METHODS

A review of recent clinical articles (1996 - 2007) examining therapeutic measures for haemorrhagic shock treatment was undertaken.

CONCLUSIONS

Although the mainstay of therapy continues to be obtaining haemostasis and restoring tissue perfusion, a multitude of novel strategies are emerging, including advanced haemostatic agents, hypertonic resuscitation and massive transfusion protocols, as well as blood substitutes and an improved understanding of damage control principles, thereby allowing increased survival and improved outcomes in the severely injured patient with major haemorrhage.

Bleeding risk and the management of bleeding complications in patients undergoing anticoagulant therapy: focus on new anticoagulant agents

For more than 60 years, heparin and coumarin have been mainstays of anticoagulation therapy. They are widely available, inexpensive, effective, and have specific antidotes but are regarded as problematic because of their need for careful monitoring. In addition, coumarin has a delayed onset of action, interacts with many medications, has a narrow therapeutic window, and is paradoxically prothrombotic in certain settings (ie, can precipitate “coumarin necrosis”). Heparin may require monitoring of its therapeutic effect and can also cause thrombosis (heparin-induced thrombocytopenia/thrombosis syndrome). These limitations have led to the development of new anticoagulants with the potential to replace current agents. These newer agents fall into 2 classes, based on whether they are antithrombin dependent (low-molecular-weight heparin, fondaparinux) or antithrombin independent (direct inhibitors of factor Xa and thrombin [factor IIa]). This paper addresses newer anticoagulants, reviewing their efficacy and limitations, and focuses on the risk of major bleeding that may complicate their use. In contrast to heparin and coumarin, none of these newer agents has a specific antidote that completely reverses its anticoagulant effect. Available data on the efficacy and safety of current and experimental agents for anticoagulant reversal are reviewed, and a plan for management of anticoagulant-induced bleeding is presented.

Plasminogen potentiates thrombin cytotoxicity and contributes to pathology of intracerebral hemorrhage in rats

Thrombin and plasmin are serine proteases involved in blood coagulation and fibrinolysis, whose precursors are circulating in blood stream. These blood-derived proteases might play important roles in the pathogenesis of intracerebral hemorrhage by acting on brain parenchymal cells. We previously reported that thrombin induced delayed neuronal injury through extracellular signal-regulated kinase (ERK)-dependent pathways. Here, we investigated potential cytotoxic actions of plasminogen, a precursor protein of plasmin, using slice cultures prepared from neonatal rat brain and intracortical microinjection model in adult rats. Although plasminogen alone did not evoke prominent neuronal injury, plasminogen caused significant neuronal injury when combined with a moderate concentration of thrombin (30 U/mL) in the cerebral cortex of slice cultures. The cortical injury was prevented by tranexamic acid and aprotinin. The combined neurotoxicity of thrombin and plasminogen was also prevented by PD98059, an inhibitor of ERK pathway, as well as by other agents that have been shown to prevent cortical injury induced by a higher concentration (100 U/mL) of thrombin alone. Extracellular signal-regulated kinase phosphorylation after plasminogen exposure was localized in cortical astrocytes. Moreover, microinjection of plasminogen in vivo potentiated thrombin-induced cortical injury, and inhibition of plasmin ameliorated hemorrhage-induced neuronal loss in the cerebral cortex. These results suggest that plasminogen/plasmin system augmenting thrombin neurotoxicity participates in hemorrhagic cortical injury.

Hemostasis and hemostatic agents in minimally invasive surgery

As minimally invasive surgery (MIS) has grown in scope and complexity, new challenges have been introduced along the way, including the need for endoscopic hemostatic techniques. Traditional electrical and mechanical means are still the mainstay, but new technologies for hemostasis continue to emerge. Restricted access to the operative site can limit the use of some tools, and yet multiple chemical hemostats and tamponading agents are used in MIS today. Systemic agents also have been developed and have a role in certain MIS circumstances. These products allow surgeons to continue to approach more difficult procedures using minimally invasive techniques. On the horizon are the newer, even less-invasive approaches of natural orifice endoluminal and transluminal surgery, which will increase the difficulties with reliable hemostat agents and delivery mechanisms.

Causes and consequences of critical bleeding and mechanisms of blood coagulation

Pharmacists who practice in the critical care setting require a solid background on the causes and consequences of bleeding, as well as the mechanisms of hemostasis. This article provides an overview of these topics. Bleeding and outcomes as a result of surgery and trauma, from medical and pharmacologic causes, and in obstetrics and gynecology are discussed. Patients with brain trauma, those with inherited and acquired bleeding disorders, and patients undergoing therapeutic anticoagulation are addressed, as these are populations at special risk for severe bleeding. Bleeding events as a result of hypothermia, acidosis, and disseminated intravascular coagulation are also discussed, as is the pathophysiology of massive blood loss. Traditional and newer cell-based models of coagulation mechanisms are described and compared. Application of this information in pharmacy practice will help ensure that therapies to manage and arrest blood loss are used appropriately in a wide variety of clinical scenarios.

Recombinant activated factor VII (Novo7) in patients with ventricular assist devices: case report and review of the current literature

Postoperative bleeding might become a serious problem in the management of cardiac surgical patients, with marked medical and economic impact. In these life-threatening situations, massive haemorrhage represents frequently a combination of surgical and coagulopathic bleeding. Surgical bleeding results from a definite source at the operation site and can be corrected using surgical standard techniques. Acute coagulopathies, in contrast, result from impaired thrombin formation, and require optimized therapeutical strategies. Effective pharmacological treatment will be complicated by the presence of ventricular assist devices (VAD), which necessarily imply effective anticoagulation. In episodes of uncontrolled coagulopathic bleeding, the application of recombinant activated factor VII (rFVIIa) as a effective haemostatic agent has become more and more popular. However, only very few data are available on its use in patients with VAD in place. We researched the PubMed-database for case reports about the use of rFVIIa in patients with VAD and summarized them. In addition, we report a case from our hospital. In all cases cessation of bleeding without any thrombembolic complications could be achieved. In cases of uncontrollable, non-surgical bleeding rFVIIa seems to be a therapeutical option even for patients with VAD.

The use of desmopressin as a hemostatic agent: a concise review

Desmopressin, a synthetic derivative of the antidiuretic hormone vasopressin, is the treatment of choice for most patients with von Willebrand disease and mild hemophilia A. Moreover, the compound has been shown to be useful in a variety of inherited and acquired hemorrhagic conditions, including some congenital platelet function defects, chronic liver disease, uremia, and hemostatic defects induced by the therapeutic use of antithrombotic drugs such as aspirin and ticlopidine. Finally, desmopressin has been used as a blood saving agent in patients undergoing operations characterized by large blood loss and transfusion requirements, but studies suggest that this is not as effective as other methods. This review briefly summarizes the current clinical indications on the use of desmopressin as a hemostatic agent.

[Systemic hemostatic drugs]

Understanding the haemostatic changes is crucial in developing strategies for the management of haemorrhage syndroma. In recent years, the revised model of coagulation ("cell based" model) provided a much more authentic description of the coagulation process. Pharmacological intervention, especially desmopresin, antifibrinolytics (synthetics and nature) and increasingly recombinant activated factor VII are being used in prevention and therapeutically to control bleeding of variety etiologies. Skillfull surgery combined with blood saving methods and careful management of blood coagulation will all help in sucessfull haemorrhage prevention and treatment, and reduce unnecessary blood loss and transfusion requirements and its attendant risks. Among the all avalaible tests, the use of thromboelastography has allowed for more detailed dynamic assessment of the various steps of hemostasis.

Blood management

CONTEXT

We provide an overview of the principles of blood management: the appropriate use of blood and blood components, with a goal of minimizing their use.

OBJECTIVE

To review the strategies that exploit combinations of surgical and medical techniques, technologic devices, and pharmaceuticals, along with an interdisciplinary team approach that combines specialists who are expert at minimizing allogeneic blood transfusion.

DATA SOURCES

A search on Medline and PubMed for the terms English and humans used in articles published within the last 20 years.

CONCLUSIONS

Blood management is most successful when multidisciplinary, proactive programs are in place so that these strategies can be individualized to specific patients.

Pulmonary Embolism in the Critically Ill

Pulmonary embolism in the critically ill requires considerations beyond anticoagulant therapy. Measurements of chamber size by echocardiography and CT and of circulating biomarkers identify higher-risk patients with moderate accuracy and may aid determination of patient acuity. Preserving right ventricular function requires judicious use of volume administration, vasopressor, and perhaps vasodilator therapies. Obstructing thrombus can be treated with fibrinolytic drugs, percutaneous instrumentation, or surgically, but these treatments may not be equally effective or safe. Anticoagulant therapy in critically ill patients is likely best administered IV. Bleeding complications should be assiduously sought but do not necessitate anticoagulant discontinuation in every case. The antidotes protamine, desmopressin acetate, factor VIII inhibitory bypass activity, and recombinant factor VIIa may each have a place in controlling anticoagulant-related bleeding. The grave prognosis of heparin-induced thrombocytopenia warrants close surveillance, with rapid switching to lepirudin, argatroban, or fondaparinux necessary if it is suspected. Retrievable vena cava filters can be lifesaving, and at least one type may be safely removed after residence of nearly 1 year.

Use of blood and blood products in trauma

According to the global study of the burden of disease, violence and accidental injury account for 12% of deaths worldwide; 30-40% of trauma mortality is attributable to haemorrhage. The highly complex haemostatic system is severely impaired as a result of haemorrhagic shock, acidosis, hypothermia, haemodilution, hyperfibrinolysis, and consumption of clotting factors. Thus it is important to prioritize the prevention of the development of coagulopathy. Timely transfusion of red blood cells and plasma products becomes essential to restore tissue oxygenation, support perfusion, and maintain the pool of active haemostatic factors. The limits to this strategy to compensate for the loss of blood and coagulation factors are discussed. In the absence of international guidelines, there is an ongoing debate about a generally accepted treatment algorithm, mass transfusion protocols, and adverse events that have been observed as a result of transfusion. Thus many recommendations are based upon expert opinion rather than on evidence. In this chapter we address key issues of transfusions of red blood cells and plasma products in the acute control of bleeding in traumatized patients.

[Procedure for critical nonsurgical bleeding]

The improvement of surgical and nonsurgical approaches to control bleeding offers new strategies for overcoming coagulopathy. Massive hemorrhage is usually caused by a combination of surgical and coagulopathic bleeding. Coagulopathy is multifactorial and results from the dilution and consumption of both platelets and coagulation factors and dysfunction of the coagulation system. Blood component therapy continues to be a mainstay for this coagulopathy-related bleeding. However, the transfusion of red blood cells has been shown to be associated with post-injury infection and multiple organ failure. Therefore it is crucial to develop a clear strategy for correcting coagulopathy, preventing exsanguination, and minimizing the need for blood transfusion.

Möglichkeiten der lokalen und systemischen Blutstillung bei chirurgischen Eingriffen

Surgery inevitably leads to bleeding, and hemostasis aims at reducing the amount of blood loss and the need for transfusion as well as preventing rebleeding, hematoma formation, and the need for repeat surgery. Various locally applicable agents are in use including bone wax, gelatin, collagen, oxidized regenerated cellulose, fibrin sealant glues, and synthetic glues. Some evidence from randomized controlled trials (RCT) exists regarding the use of fibrin sealants on their own or combined with collagen fleece. Systemic hemostasis may be achieved with lysine analogs such as epsilon-aminocaproic acid or tranexamic acid and aprotinin, which are inhibitors of fibrinolysis. There is much albeit sometimes conflicting evidence from RCT regarding the use of these substances in surgery. The role of recombinant activated factor VII in achieving systemic hemostasis is being investigated.

Is There Still a Role for Aprotinin in Cardiac Surgery?

Cardiac surgery is associated with a systemic inflammatory response and systemic coagulopathy, which can result in significant organ dysfunction and bleeding. Aprotinin, a serine protease inhibitor, can limit systemic inflammation, and has been associated with myocardial, pulmonary and cerebral protection in addition to its proven haemostatic efficacy. Data are currently conflicting regarding the haemostatic efficacy of aprotinin relative to alternative agents including tranexamic acid. Recent studies have demonstrated aprotinin usage is associated with increased rates of thrombotic and renal complications, but these findings are at odds with the majority of studies relating to aprotinin safety to date. The lack of adequately powered, randomised studies evaluating aprotinin and alternative agents limits drawing conclusions about the complete use or disuse of aprotinin presently and requires individualised patient selection based on bleeding risk and co-morbidities for its usage.

Koagulopathie

Coagulopathy after trauma is a major cause for uncontrolled hemorrhage in trauma victims. Approximately 40% of trauma related deaths are attributed to or caused by exsanguination. Therefore the prevention of coagulopathy is regarded as the leading cause of avoidable death in these patients. Massive hemorrhage after trauma is usually caused by a combination of surgical and coagulopathic bleeding. Coagulopathic bleeding is multifactorial, including dilution and consumption of both platelets and coagulation factors, as well as dysfunction of the coagulation system. Because of the high mortality associated with hypothermia, acidosis and progressive coagulopathy, this vicious circle is often referred to as the lethal triad, potentially leading to exsanguination. To overcome this coagulopahty-related bleeding an empiric therapy is often instituted by replacing blood components. However, the use of transfusion of red blood cells has been shown to be associated with post-injury infection and multiple organ failure. In the management of mass bleeding it is therefore crucial to have a clear strategy to prevent coagulopathy and to minimize the need for blood transfusion.

Treatment of vaginal bleeding from a pelvic vascular malformation with desmopressin

We report the case of a 2-year-old female child with a pelvic vascular malformation complicated by chronic low-grade bleeding. Treatment with intranasal desmopressin significantly reduced vaginal bleeding. Therefore, we suggest that intermittent use of intranasal desmopressin may be useful in the treatment of chronically bleeding low-flow vascular malformations.

Efficacy of FDA-approved hemostatic drugs to improve survival and reduce bleeding in rat models of uncontrolled hemorrhage

Several FDA-approved intravenous drugs are used to reduce surgical bleeding. This series of studies tested whether these drugs (aprotinin, desmopressin, tranexamic acid, epsilon-aminocaproic acid) could reduce bleeding due to traumatic injuries in two models of uncontrolled hemorrhage in rats. In the first phase of each study, a nonlethal tail bleeding model was used that incorporated limited fluid resuscitation (lactate Ringer's solution). Four doses of vehicle or the test substance were given successively with bleeding time and blood loss measured after each dose. In the second phase of each study, a lethal liver injury was produced by excising a section of the median lobe (approximately 0.8% of body weight) and an infusion of either vehicle or the test substance was immediately begun. This model included aggressive fluid resuscitation and a severe dilutional coagulopathy. Blood loss, survival time and mortality rate were recorded. Three studies were performed, testing each of the drugs singly and in combination. None of the drugs significantly reduced either bleeding time or blood loss in the tail bleeding model, nor were blood loss, survival time or mortality rate altered in the liver injury model. Taken together, these results suggest that these FDA-approved drugs, when used either singly or in combination, are not efficacious in these models of traumatic uncontrolled hemorrhage.

Efficacy of aminocaproic, tranexamic acids in the control of bleeding during total knee replacement: a randomized clinical trial

BACKGROUND

Risks and costs of allogeneic blood transfusions mandate strategies to reduce blood loss in surgery. The objective of this study was to assess the efficacy of antifibrinolytic treatment in reducing perioperative blood loss during total knee replacement.

METHODS

A double-blind, randomized and placebo-controlled clinical trial was carried out on 127 patients undergoing total knee replacement. Patients in the study group received tranexamic acid 10 mg kg(-1) i.v. just before the tourniquet was deflated and 3 h later, or epsilon-aminocaproic acid 100 mg kg(-1) before tourniquet deflation followed by continuous perfusion (1 g h(-1)) during 3 h. External perioperative blood loss was measured and total blood loss was calculated. The number of patients transfused and number of packed red cell (PRC) units transfused was recorded and possible postoperative thromboembolic complications were investigated.

RESULTS

Total blood loss [mean (sd)] was 1099 ml (535) in the group that received antifibrinolytic agents and 1784 ml (660) in the control group (P<0.001). Five patients (7.5%) in the study group and 23 (38.3%) in the control group (P<0.001) received blood transfusions; the first group received a mean of 0.10 PRC unit per patient and the second, 0.58 (P<0.001). Mean reduction in haemoglobin levels (g dl(-1)) between preoperative and fifth day postoperative readings was 2.5 (0.9) in the study group and 3.4 (1.2) in the control group (P<0.001). Clinical assessment did not reveal any thromboembolic complications.

CONCLUSIONS

Antifibrinolytic agents produce a significant decrease in blood loss in patients undergoing total knee replacement, reflected in a reduction in the number of blood transfusions required.

Increased blood loss during posterior spinal fusion for idiopathic scoliosis in an adolescent with Fontan physiology

A 15-year-old patient with Fontan physiology experienced major blood loss during posterior spinal fusion for idiopathic scoliosis. Contributing factors for the increased blood loss and potentially useful measures to limit blood loss in patients with Fontan physiology are discussed.

Use of the platelet function analyser (PFA-100) to quantify the effect of low dose aspirin in patients with ischaemic heart disease

Continuing aspirin up until surgery in cardiac surgical patients may increase peri-operative blood loss. It is possible that there is a subset of patients particularly sensitive to aspirin. The platelet function analyser (PFA-100) can demonstrate the antiplatelet effect of aspirin. This study was designed to assess the effect of daily 75 mg aspirin on platelet function, as measured by the PFA-100, in 92 patients with ischaemic heart disease. Patients were classified into three groups according to their PFA-100 results; aspirin hyper-responders (16%), aspirin normal responders (33%) and aspirin non-responders (51%). The PFA-100 has potential as a screening tool to identify patients who are either hyper-responsive or resistant to aspirin. Pre-operative PFA-100 screening to isolate aspirin hyper-responders could enable the vast majority of patients to continue with aspirin therapy pre-operatively, avoiding the risks of stopping treatment.

Preoperative assessment of the patient with liver disease

Patients with liver disease are at appreciable risk when undergoing anesthesia and surgery. Attempts to quantify this risk have been thwarted by the diversity of disease states and illness severity that such patients bring to the operating theater and the myriad of procedures they may undergo. This review discusses the indications and contraindications for surgery in patients with liver disease and attempts to give specific recommendations for optimizing the clinical status of a patient with hepatic dysfunction prior to operative intervention.

Postoperative visual loss following prone spinal surgery

Postoperative visual loss is a rare but disastrous complication that has an estimated incidence of 0.01-1% after non-ocular surgery. We report a patient who underwent a prolonged spinal operation in the prone position and complained of blindness in one eye postoperatively. We consider the potential aetiological factors contributing to this unilateral postoperative visual loss and suggest strategies to reduce the incidence of this complication in spinal surgery.