Treatment with desmopressin acetate to reduce blood loss after cardiac surgery. A double-blind randomized trial

Aprotinin therapy for reoperative myocardial revascularization: a placebo-controlled study

We tested the efficacy and safety of aprotinin in 169 patients undergoing isolated reoperative myocardial revascularization. Patients were randomly assigned to high-dose aprotinin, low-dose aprotinin, or placebo treatment groups in a double-blind, placebo-controlled study. Treatment groups did not differ significantly with respect to age, sex, red cell mass, number of grafts, use of internal thoracic artery, or incidence of preoperative aspirin therapy. Patients treated with aprotinin had a significant reduction in postoperative chest tube drainage (720 +/- 753, 866 +/- 1,636, and 1,121 +/- 683 mL, respectively, for high-dose aprotinin, low-dose aprotinin, and placebo; p < 0.001). Transfusion requirements were reduced in aprotinin-treated patients (2.1 +/- 4.2, 4.8 +/- 11.8, and 4.1 +/- 6.2 units for high-dose, low-dose, and placebo, respectively; p < 0.001). A similar reduction in chest tube drainage and transfusion requirements was seen in patients using aspirin preoperatively. Q-wave myocardial infarctions were increased in the aprotinin subgroups (17.5%, 14.3%, and 8.9% for high-dose, low-dose, and placebo groups; not significant). Acute vein graft thrombosis was found in six of 12 vein grafts studied at postmortem examination in patients receiving aprotinin but not in any of five grafts in patients receiving placebo. We conclude that aprotinin is extremely effective in reducing bleeding and transfusion requirements and may increase the risk of graft thrombosis.

Effects of desmopressin on blood loss in hip arthroplasty. Controlled study in 50 patients

50 patients undergoing elective total hip replacement under epidural anesthesia and dextran infusion were given two doses of the vasopressin analogue desmopressin 0.3 micrograms/kg BW or placebo in a double-blinded randomized prospective study. Intraoperative blood loss and drainage loss did not differ significantly between groups, but desmopressin reduced the mean total blood loss (calculated from hemoglobin decrease and blood transfusions) by 310 mL (P less than 0.05).

Reoperation, emergency and urgent open cardiac surgery in Jehovah's Witnesses

Progressive advances in perfusion technology and perioperative supportive management have made it possible for members of the Jehovah's Witnesses religious group to undergo open cardiac operations with remarkable safety. However, hospital mortality remains high in (1) patients requiring reoperation (in whom both technical and bleeding problems tend to be more frequent) and (2) patients with significantly compromised cardiac performance requiring urgent or emergency operation. Employing a number of perioperative measures designed to minimize blood loss and maintain hematocrit levels (including use of the recently available recombinant human erythropoietin in two patients whose cases are reported herein), 13 reoperations and five urgent or emergency operations were performed. The one death in the entire series occurred in a patient (reoperation group) who died of a cerebrovascular accident of presumed embolic etiology, having undergone combined debridement of a stenotic heavily calcified aortic valve and a second coronary artery revascularization procedure. None of the patients required surgical exploration for bleeding. We suggest that currently available methodology permits Jehovah's Witnesses to undergo reoperation, emergency surgery, or urgent open cardiac operation at a level of risk not dissimilar to that seen in patients who permit use of homologous blood and products in their treatment.

High-dose aprotinin in cardiac surgery: three years' experience in 1,784 patients

The effect of the proteinase-inhibitor aprotinin on blood loss and homologous blood requirement in cardiac surgery was investigated. In a prospective study, 902 adult patients were treated with high-dose aprotinin (total greater than 5 x 10(6) kallikrein inactivator units [KIU]; group A), while 882 patients without aprotinin administration served as the controls (group C). Both groups were operated on between January 1987 and October 1989, and included patients with primary coronary artery bypass grafting (n = 525 group C, n = 560 group A), valve replacement (n = 292 group C, n = 264 group A), or combined procedures (n = 65 group C, n = 78 group A), as well as cardiac reoperations (n = 91 group C, n = 110 group A). The average blood loss 36 hours postoperatively in the aprotinin group was 679 +/- 419 mL, compared with 1,038 +/- 671 mL in the control group (P less than 0.05). Total homologous blood requirement was also significantly less in group A (942 +/- 1,630 mL) compared with group C (1,999 +/- 2,283 mL) (P less than 0.05), a reduction of 53%. Serum creatinine concentrations did not show intergroup differences on the first postoperative day (group A, 1.2 +/- 0.7; group C, 1.3 +/- 0.5 mg/dL) or on discharge from the intensive care unit (ICU). Thus, impairment of renal function as a consequence of aprotinin treatment was not observed. Three patients developed signs of mild circulatory depression after injection of aprotinin, which responded promptly to vasopressor therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

A cluster of severe postoperative bleeding following open heart surgery

OBJECTIVE

To investigate a cluster of postoperative bleeding following open heart surgery.

DESIGN

A cohort and case/control study.

SETTING

Palo Alto Veterans Administration Medical Center, Palo Alto, California.

PARTICIPANTS

Six (21.4%) of 28 patients undergoing open heart surgery who developed severe, nonsurgical, postoperative bleeding from July 1 through August 30, 1988 (outbreak period). All case-patients had chest tube drainage of greater than or equal to 1000 ml within 4 hours of surgery but did not have identifiable bleeding vessel(s) on exploration.

RESULTS

Upon comparison of the pre-outbreak (January 1986 through June 1988) and the outbreak period, a significant increase was found in the incidence of postoperative nonsurgical bleeding (5/440 versus 6/28, p = .0006), but not of postoperative surgical bleeding (8/440 versus 0/28, p = 1.0). Of all patients undergoing open heart surgery during the outbreak period, case patients were found to be older (67.8 versus 60.6, p = .02) and to have received a larger volume of hetastarch (HES), a synthetic colloidal plasma-volume expander (mean = 19.4 ml/kg versus 14.1 ml/kg, p = .02).

CONCLUSIONS

We conclude that the use of large volumes of HES during surgery in the elderly open heart surgery patient may increase the risk for severe, nonsurgical postoperative bleeding, probably caused by alterations of the coagulation system. As the incidence of open heart surgery increases among the elderly, surgeons and anesthesiologists should be alert to possible adverse reactions from exposures not associated with adverse reactions in younger patients.

Reversal of streptokinase-induced bleeding with aprotinin for emergency cardiac surgery

Two patients requiring emergency cardiac surgery following the administration of streptokinase are described. In each case aprotinin was given to counteract the haemorrhagic effects of the streptokinase.

Ischemic stroke and intracranial hemorrhage following thrombolytic therapy for acute myocardial infarction: a risk-benefit analysis

Stroke is a potentially serious complication of acute myocardial infarction (AMI). In the prethrombolytic era, most strokes were attributed to cerebral embolism. On the basis of available information, the occurrence of stroke in the thrombolytic era appears to be less than in the prethrombolytic era. In the thrombolytic era, the occurrence of various forms of intracranial hemorrhage has increasingly been documented in addition to cerebral embolism, with intriguing features. In general, however, the delineation of specific stroke subtypes has been imprecise and must take into account factors that are unique to this setting. Age is a risk factor for both ischemic and hemorrhagic stroke. Potential risk factors for intracranial hemorrhage include hypertension, dosage of fibrinolytic agents, and prior neurologic disease. Potential causes of intracranial hemorrhage include combined fibrinolytic/adjunctive therapies, various cerebrovascular lesions, and head trauma. Existing data suggest that mortality related to stroke complicating AMI is on the decline as well. More research is needed in order to quantify precisely the occurrence and proportions of stroke subtypes, risk factors, and causes in order to define mechanisms and preventive measures.

Hemorrhage associated with dacryocystorhinostomy and the adjunctive use of desmopressin in selected patients

Of 150 consecutive patients who underwent dacryocystorhinostomy, postoperative hemorrhage requiring treatment occurred in 2 patients, both of whom had endogenous platelet dysfunction without thrombocytopenia. The first patient had macroglobulinemia, and the second patient had congenital platelet hypofunction. Prophylactic 1-deamino-8-D-arginine vasopressin (desmopressin; DDAVP) was used successfully to decrease intraoperative bleeding in the second patient. Of the 15 patients with exogenous platelet dysfunction secondary to the use of aspirin or nonsteroidal anti-inflammatory agents within 1 week of operation, none had hemorrhaging. Dacryocystorhinostomy should be undertaken cautiously and with hematologic consultation in patients with blood dyscrasias.

Hemostatic effects of tranexamic acid and desmopressin during cardiac surgery

BACKGROUND

Desmopressin-induced release of tissue plasminogen activator from endothelial cells may explain the absence of its hemostatic effect in patients undergoing cardiac surgery. Prior administration of the antifibrinolytic drug tranexamic acid might unmask such an effect, and combination therapy might thereby improve postoperative hemostasis.

METHODS AND RESULTS

A double-blinded design randomly allocated 163 adult patients undergoing coronary revascularization, valve replacement, both procedures, or repair of atrial septal defect to four treatment groups: placebo, tranexamic acid given as 10 mg/kg over 30 minutes followed by 1 mg.kg-1.hr-1 for 12 hours initiated before skin incision, desmopressin given as 0.3 micrograms/kg over 20 minutes after protamine infusion, and both drugs. One surgeon performed all operations. Blood loss consisted of mediastinal tube drainage over 12 hours. Follow-up visits sought evidence of myocardial infarction and stroke. Desmopressin decreased neither the 12-hour blood loss nor the amount of homologous red cells transfused. Tranexamic acid alone significantly reduced 12-hour blood loss, by 30% (mean, 318 versus 453 ml; p less than 0.0001), without enhancement by desmopressin. Tranexamic acid also decreased the proportion of patients receiving homologous blood within 12 hours of operation (8% versus 21%, p = 0.024) and within 5 days of operation (22% versus 41%, p = 0.011).

CONCLUSIONS

Desmopressin exerts no hemostatic effect, with or without prior administration of antifibrinolytic drug. Prophylactic tranexamic acid alone appears economical and safe in decreasing blood loss and transfusion requirement after cardiac surgery.

Effect of tranexamic acid on platelet ADP during extracorporeal circulation

Seventeen adults received the antifibrinolytic drug tranexamic acid during cardiac surgery utilizing extracorporeal circulation (ECC). In 8 patients, drug administration began prior to skin incision (pre-ECC); infusions commenced after ECC and protamine administration in another 9 patients (post-ECC). Compared with the post-ECC group, the pre-ECC group exhibited less bleeding via mediastinal drains (420 vs. 655 mL/12 h median, P = 0.024), decreased frequency of the presence (greater than or equal to 10 micrograms/mL) of fibrin split products (P less than 0.05), and greater platelet dense granule content of adenosine diphosphate after surgery (15.47 vs. 4.05 nmoles/mg protein median, P = 0.021). Follow-up in vitro study of tranexamic acid inhibition of plasmin-induced platelet activation utilizing normal human platelet rich plasma and porcine plasmin revealed a 13-fold lower concentration of tranexamic acid for 50% inhibition when plasmin was preincubated with the drug (1.2 micrograms/mL, 95% CI = 1.13-1.60 micrograms/mL) compared to when platelet rich plasma was preincubated with the drug (16 micrograms/mL, 95% CI = 7.3-99. micrograms/mL). Plasmin inactivated with tranexamic acid retained its ability to inhibit thrombin-induced platelet activation, thus suggesting that tranexamic acid inhibits plasmin's catalytic activity and not its binding to platelets. Both clot lysis and platelet dysfunction may contribute to bleeding after ECC. Tranexamic acid blocks plasmin-induced partial platelet activation during ECC, thus preserving platelet function and promoting hemostasis after ECC.

Conventional blood conservation techniques in 500 consecutive coronary artery bypass operations

With use of a nonpharmacological, simple, and inexpensive program for blood conservation, 500 consecutive patients underwent elective coronary artery bypass grafting without need of homologous red cell transfusions in 493 (98.6%). At least one internal mammary artery was grafted in all but 1 patient, with supplemental saphenous vein grafts. Intraoperatively, autologous heparinized blood was removed before bypass and retransfused at the conclusion of extracorporeal circulation. The volume remaining in the oxygenator and tubing set was returned without cell processing or hemofiltration. Using the hard-shell cardiotomy reservoir from the heart-lung machine, autotransfusion of the shed mediastinal blood was continued hourly up to 18 hours after operation. The mean postoperative mediastinal blood loss was 643 +/- 354 mL, whereas 624 +/- 296 mL was autotransfused. Thirteen patients (2.6%) needed reexploration for bleeding, of whom 7 (7/500, 1.4%) received homologous blood. No other patients required red cell transfusions. In addition, 9 patients were given a mean of 2.6 units of fresh frozen plasma because of suspected coagulopathy. No platelets were transfused, and no cryoprecipitate therapy was undertaken. Thus, in total, 484 patients (96.8%) were not exposed to any homologous blood products during the hospital stay. At discharge, the mean hemoglobin concentration was 121 +/- 14 g/L (12.1 +/- 1.4 g/dL) and the hematocrit, 0.36 +/- 0.04. Postoperative complications were few. There was one in-hospital death (0.2%).

Preoperative hemostatic activity and excessive bleeding after cardiopulmonary bypass

The rationale for predicting the risk of excessive postoperative bleeding by assessing the hemostatic status of a patient before cardiopulmonary bypass was investigated. A novel, rapid, overall test (hemostatometry) consisting of a physiologically relevant test of platelet function (shear-induced hemostasis) and coagulation was performed using nonanticoagulated blood and compared with the routine coagulation screen. Two hundred five patients undergoing elective coronary revascularization were studied 3 to 4 days before operation. Forty-nine bled excessively for nonsurgical reasons; none were predicted by the routine coagulation tests. Using a stepwise discriminant analysis, hemostatometry correctly predicted 31 of 49 (63%). Thirty of 156 predicted as bleeders by hemostatometry did not bleed. Thus, preoperative hemostatometry predicted 77% of the true outcome. The false predictions suggest, however, that certain bleeding abnormalities probably acquired during cardiopulmonary bypass cannot be predicted. These findings do not justify the routine use of preoperative tests in assessing the bleeding risk in patients undergoing cardiopulmonary bypass.

Quality of life as outcome measures in randomized clinical trials. An overview of three general medical journals

A survey of 75 randomized trials published in 1986 in the Annals of Internal Medicine, American Journal of Medicine, and New England Journal of Medicine was carried out by two observers using predetermined criteria about the importance of health status as an outcome measurement and the quality-of-health status measurement that was used. The kappa statistic was used to measure agreement among the two observers. Although a number of investigators used well-established quality-of-life measurements, in only 10 of 55 trials in which health status was judged crucial or important were measures with established validity and responsiveness used. Despite the fact that reliable measurement of quality of life is now feasible, it is underutilized in randomized clinical trials.

Methods of reducing blood loss and non-blood substitutes

A variety of techniques can aid the anaesthetist in reducing requirements for perioperative blood products. These include careful preoperative assessment of the patient, and employing techniques during surgery which reduce the blood pressure and help preserve the normal haemostatic mechanism. If the level to which haematocrit will be permitted to decrease is decided, then physiological crystalloid and/or colloid solutions may be used to maintain circulating volume. Where large volumes of fluids are required cardiac filling pressures should be monitored because of the complex nature of the fluid shifts which occur. There is no evidence that any one fluid (physiological crystalloids, colloids) is better than any other in terms of the incidence of perioperative morbidity.

Con: desmopressin is not of value in the treatment of post-cardiopulmonary bypass bleeding

Following two early promising reports that treatment with intravenous DDAVP was helpful in reducing postoperative hemorrhage and the amount of transfusion with homologous blood products in patients who had undergone cardiac surgery with CPB, these results were not repeated in any of the follow-up studies. At the present time, the routine prophylactic use of DDAVP in cardiac surgery cannot be recommended for patients undergoing closure of atrial septal defect, valve repair or replacement, primary CABG, or in children requiring cardiac surgery. The use of DDAVP in complicated procedures or for control of severe postoperative bleeding remains controversial. In the authors' opinion, DDAVP should not be used in cardiac surgery except in patients with a presurgical DDAVP-responsive coagulopathy.

Correlation of circulating von Willebrand factor levels with cardiovascular hemodynamics

BACKGROUND

Valvular heart disease is associated with a decreased platelet circulating time and a thrombotic tendency. The possibility that these events are related to changes in von Willebrand factor (vWF), a multimeric glycoprotein released from endothelial cells and platelets that mediates platelet adhesion to the vascular subendothelium, has not been examined.

METHODS AND RESULTS

We measured the vWF antigen (vWF:Ag) concentration in 43 patients undergoing cardiac catheterization for the evaluation of mitral (n = 17) or aortic (n = 10) stenosis or nonvalvular heart disease (n = 16). Mean vWF:Ag concentration was significantly higher in patients with mitral stenosis than in those without (212 +/- 84 versus 150 +/- 79 units/dl, p less than 0.02); this elevation was associated with a significant elevation of pulmonary vascular resistance (PVR) in the patients with mitral stenosis (186 +/- 49 versus 133 +/- 81 dynes-sec-cm-5, p less than 0.02). The vWF:Ag levels in the entire group of patients (regardless of the presence or type of valvular disease) varied directly with PVR (r = 0.72, p less than 0.0001) and with pulmonary artery pressure (r = 0.60, p less than 0.0001) and inversely with cardiac output (r = 0.64, p less than 0.0001). Changes in PVR, pulmonary artery pressure, or cardiac output could not be correlated with circulating levels of fibrinogen or beta-thromboglobulin, which may be released from activated platelets, nor with the endothelial cell product tissue plasminogen activator.

CONCLUSIONS

The association of high vWF:Ag levels with increased PVR and decreased cardiac output in patients both with and without mitral stenosis suggests a hemodynamically induced increase in the endothelial release of vWF, which might contribute to a thrombotic tendency in these patients.

The stratification of cardiac surgical procedures according to use of blood products: a retrospective analysis of 1480 cases

The use of blood products in 1480 consecutive cases of adult cardiac surgical procedures over a period of 15 mth was studied retrospectively using the database of the Department of Anaesthesia of the Institut de Cardiologie de Montréal. Use of blood products was compared in patients having (1) coronary artery bypass grafting, (2) valvular surgery, (3) or a combination of 1 and 2. First operations were compared with reoperations. Overall, the use of homologous blood products was greatest in patients of Group 3, intermediate in patients of Group 2, and smallest in patients of Group 1. Reoperations were associated with an increase in intraoperative transfusion of packed red blood cells, but postoperative chest drainage was similar to first operations. When all blood products (packed red blood cells, fresh frozen plasma and platelets) were taken into consideration, patients undergoing primary CABG or valve surgery were the least exposed to homologous blood donors (five and six units transfused respectively). Repeat CABG was associated with an intermediate exposure to homologous blood products (eight units). Finally, primary and repeat combined procedures, and repeat valve surgery were associated with the greatest exposure to foreign blood products (10, 13 and 10 units respectively). The data presented in this study provide a rational basis for stratification of procedures according to the expected use of blood products, particularly in view of future studies which may be planned to examine the efficiency of blood conservation strategies.

Hemodynamic responses to desmopressin acetate after CABG: a double-blind trial

Despite controversial results concerning its effectiveness, cardiac surgical patients commonly receive desmopressin acetate (DDAVP) after cardiopulmonary bypass (CPB) in an effort to prevent or control bleeding diathesis. The side effects associated with DDAVP are usually considered benign. However, numerous authors have observed episodes of severe hypotension after DDAVP. As a part of a larger trial of DDAVP in routine first-time coronary artery bypass grafting (CABG), this randomized double-blind study of the hemodynamic effects of DDAVP was performed. Fifteen patients received DDAVP (0.3 microgram/kg over 15 minutes) and another 15 received saline placebo after skin closure. A statistically significant decrease in mean arterial pressure (MAP) was observed at 5 minutes after the beginning of DDAVP administration and the maximum decrease (mean change, -21 +/- 8 mm Hg, P less than 0.001) was reached as the infusion was completed. MAP did not change significantly in the control group. Hypotension after DDAVP was associated with a corresponding decrease in systemic vascular resistance. Postoperative blood loss was not different between the groups. It is concluded that routine administration of DDAVP to CABG patients is inadvisable because hemodynamic side effects are potentially dangerous and therapeutic benefit is highly unlikely.

Hemodynamic performance and histamine levels after desmopressin acetate administration following cardiopulmonary bypass in adult patients

Sixteen patients undergoing cardiac surgical procedures were prospectively randomized into two groups to study the hemodynamic and histamine-releasing effects of desmopressin acetate (DDAVP) administration after cardiopulmonary bypass. Ten minutes after administration of protamine for reversal of heparin, DDAVP, 0.3 microgram/kg, was infused intravenously over 5 seconds in group 1, and the same dose of DDAVP was administered over 5 minutes as an infusion in group 2. There were no statistical differences between baseline values in groups 1 and 2. DDAVP decreased mean arterial pressure by 30% and 25% in groups 1 and 2 (69 +/- 5 mm Hg to 52 +/- 8 mm Hg, P less than 0.005, and 79 +/- 20 mm Hg to 55 +/- 8 mm Hg, P less than 0.005), respectively. The hypotension in both groups was related to decreases in systemic vascular resistance (1,616 +/- 262 dyne.s.cm-5 to 1,073 +/- 199 dyne.s.cm-5, P less than 0.005, and 1,850 +/- 541 dyne.s.cm-5 to 1,144 +/- 214 dyne.s.cm-5, P less than 0.005). Phenylephrine infusion successfully treated the DDAVP-induced hypotension in all patients. Arterial histamine levels at 3 and 5 minutes after infusion of DDAVP did not differ significantly from baseline values. It is concluded that DDAVP at 0.3 microgram/kg is a potent vasodilator when administered intravenously and that histamine is not involved in producing its hypotensive effects.

Blood loss and safety with desmopressin or placebo during aorto-iliac graft surgery

In a double blind, placebo controlled study in 50 patients undergoing aorto-iliac graft surgery, we studied the effects of desmopressin given prior to surgery on blood loss and blood transfusion requirements. Desmopressin reduced the number of patients with clinically significant bleeding. Blood loss volumes and transfusion requirements were lower in the desmopressin group, but this could not be verified statistically. Even if our study population has a high incidence of generalised arteriosclerotic disease, there were no clinical manifestations of venous thromboembolism, no increase of graft occlusions and no myocardial infarction during the operative or early postoperative period. Desmopressin may be used in patients with excessive peroperative bleeding or a prolonged preoperative bleeding time. In patients where desmopressin is considered to be haemostatically efficacious, it may be used with a maintained margin of safety.

Desmopressin acetate is a mild vasodilator that does not reduce blood loss in uncomplicated cardiac surgical procedures

Desmopressin acetate (DA) is a synthetic analog of vasopressin that may improve perioperative coagulation in cardiac surgical patients. Twenty-seven adult patients with good left ventricular function and normal preoperative coagulation profiles scheduled to undergo elective cardiac surgery participated in the double-blinded, placebo-controlled study. The 14 patients in the DA group received the drug over 10 minutes (starting 15 minutes after protamine administration). The 13 patients in the placebo group received an equal volume of saline. Preoperative template bleeding time was longer in the placebo group (P = 0.04). Otherwise, there were no statistically significant differences between the groups in demographics, coagulation variables, renal concentrating function, blood loss, or transfusion requirements at any study interval. The only significant hemodynamic differences detected were an increase in cardiac output in the DA group and a corresponding decrease in systemic vascular resistance. Five of 13 patients who received DA required treatment for hypotension, whereas none of 12 patients who received placebo required treatment during the infusion (P = 0.008). The authors conclude that DA causes mild vasodilation, but does not reduce blood loss or transfusion requirements in patients undergoing primary uncomplicated cardiac surgical procedures.

Limiting the usage of blood products in cardiovascular surgery

We studied the effect of the initiation of a five part program of blood component conservation on blood product utilization in patients undergoing major cardiovascular surgery. We encouraged physicians and nurses to adhere to a set of guidelines that would limit the exposure of these patients to complications associated with blood product administration. Through this effort the amounts of packed red cells, fresh frozen plasma, platelets, and cryoprecipitate used were markedly reduced. After the start of the conservation program, overall blood product usage was reduced 29% despite a 46% increase in the surgical caseload, and there was a 53% decrease in the amount of donor exposure (units of individual blood products administered) per patient.

Transfusion associated graft-versus-host disease after cardiac surgery: response to antithymocyte-globulin and corticosteroid therapy

A 63-year-old patient developed graft-versus-host disease (GVHD) after the transfusion of stored, random donor red cell concentrates with coronary artery surgery. The disease was characterised by skin rash, fever, diarrhoea, hepatic dysfunction, pancytopenia and the acquisition of cells bearing human leukocyte antigens of a blood donor. Clinical and histologic improvements were noted with antithymocyte-globulin and corticosteroid therapy, as seen in some patients with acute GVHD following allogeneic bone marrow transplantation, but the pancytopenia failed to resolve prior to a fatal cerebral haemorrhage. Early aggressive immunosuppressive therapy may be beneficial for transfusion-associated GVHD but strategies for its prevention by limitation of the use of homologous blood need to be addressed.

Effect of desmopressin on vein graft patency in a microvascular model

Desmopressin acetate decreases blood loss after cardiac surgery by activating platelets. We studied whether this effect was detrimental to small-caliber vein grafts in rats. Thirty minutes before femoral artery grafting with 0.75-mm-diameter reverse autogenous saphenous vein grafts, 20 rats received desmopressin acetate intravenously at 1.0 micrograms/kg over 10 minutes, and 20 control rats received normal saline intravenously over 10 minutes. In each group, 10 rats received a 6-mm-long graft and 10 an 18-mm-long graft. Graft patency was evaluated at 20 minutes, 24 hours, and 30 days. Intimal thickening was assessed by light and scanning electron microscopy. At 30 days, 9 short grafts and 8 long grafts in the desmopressin-treated group were patent, whereas only 8 short control grafts and only 6 long control grafts were patent. Intimal thickening and platelet deposition were the same in both groups. These data show no detrimental effects of desmopressin acetate on saphenous vein graft patency.

Life threatening haemoptysis in cystic fibrosis: an alternative therapeutic approach

Desmopressin and vasopressin were used to control massive haemoptysis in a patient with cystic fibrosis. After bolus doses a continuous infusion of vasopressin was maintained for 36 hours and haemoptysis stopped.

Blood coagulation and autologous blood transfusion in cardiac surgery

STUDY OBJECTIVE

To review the basic pathophysiology of altered coagulation associated with cardiopulmonary bypass and autologous blood transfusion in cardiac surgery.

DESIGN

Review of rational use of heparin, mechanisms and treatment of coagulation disorders, and autologous blood transfusion.

SETTING

Cardiac surgery in community and academic hospitals.

PATIENTS

Adult cardiac surgical patients.

MAIN RESULTS

Heparin is most commonly used for anticoagulation during cardiopulmonary bypass. Although activated clotting time is widely used to assess heparin-induced anticoagulation, the minimum time to prevent clotting during cardiopulmonary bypass remains unclear. Activated clotting time is affected by many factors other than heparin, such as antithrombin III, blood temperature, platelet count, and age. The rational use of activated clotting time still must be defined. The frequency of abnormal bleeding after cardiopulmonary bypass is significant. Although inadequate surgical hemostasis is the most frequent cause of bleeding, altered coagulation often is present. A decreased number of functional platelets is one of the important causes of bleeding diathesis. Platelet dysfunction is induced by perioperative medication such as aspirin. Cardiopulmonary bypass decreases functional platelets by degranulation, fragmentation, and loss of fibrinogen receptors. Medications such as prostacyclin and iloprost may be useful to protect these platelets. Desmopressin increases factor VIII:C and von Willebrand's factor, leading to a decrease in bleeding time. Desmopressin may be useful to decrease blood loss in repeat cardiac operations, complex cardiac surgery, and abnormal postoperative bleeding. Patients undergoing coronary artery bypass grafting immediately after streptokinase infusion also are at risk for abnormal bleeding. Transfusion of fresh-frozen plasma and cryoprecipitate may be necessary. Autologous blood transfusion is cost-effective and the safest way to avoid or decrease homologous blood transfusion. Predonation, intraoperative salvage, and postoperative salvage are encouraged. Erythropoietin may be useful in increasing the amount of predonation red cells.

CONCLUSIONS

Coagulation disorders in cardiac surgery are caused by many factors, such as heparin, platelet dysfunction, and fibrinolysis. Rational use of blood component therapy and medications such as heparin, protamine, and desmopressin are mandatory. Autologous blood transfusion is very useful in decreasing or obviating the use of homologous blood transfusion.

Blood conservation in cardiac surgery

We reviewed current blood conservation techniques and their use in cardiac surgery. Avoidance of aspirin preoperatively is an important blood conservation measure. Patients scheduled for an elective operation should participate in autologous predonation programs. With careful monitoring, patients with major coronary artery disease can safely donate blood preoperatively. Intraoperative processing of blood withdrawn before cardiopulmonary bypass provides autologous platelet-rich plasma for infusion after reversal of heparin sodium. Blood collected from the field during operation and blood remaining in the oxygenator after bypass can also be processed to yield washed and concentrated red blood cells for reinfusion. Randomized, prospective studies document that postoperative autotransfusion is both safe and effective in reducing homologous blood use. Aprotinin reduces plasma protein activation and platelet damage during bypass. The integration of available blood conservation techniques into a comprehensive program combined with careful consideration of the indications for transfusion may allow more patients to avoid transfusion entirely.