The preoperative bleeding time as a predictor of postoperative hemorrhage after cardiopulmonary bypass

A Critical Reappraisal of the Bleeding Time

Seminars in Thrombosis and Hemostasis (STH) celebrates 50 years of publishing in 2024. To celebrate this landmark event, STH is republishing some archival material. This manuscript represents the second most highly cited paper ever published in STH. The manuscript published without an abstract, and essentially represented a State of the Art Review on the bleeding time, a relatively invasive procedure that required an incision on the skin or earlobe of a patient, and timing how long it took for the incision to stop bleeding. The bleeding time test was first described in 1901 by the French physician Milian, who presented three studies of bleeding from stab wounds made in the fingertips of healthy and diseased subjects. In 1910, Duke observed the duration of bleeding from small incisions of the ear lobe, and pointed out that the duration of bleeding was increased in instances of reduced platelet counts. The test was subsequently repeatedly modified, and numerous variants of the test, including semiautomated methods, were described by several workers. The most frequently utilised test reflected one described by Ivy and coworkers, who shifted the location of the incision to the volar aspect of the forearm and applied a blood pressure cuff to the arm to maintain a standard venous pressure. The bleeding time has been proposed for use as a diagnostic test for platelet-related bleeding disorders, a measure of efficacy in various forms of therapy, and as a prognosticator of abnormal bleeding. The authors to the current review reevaluated the bleeding time literature using methods to assess the performance of the test in 1990, locating 862 printed documents that discussed the bleeding time, the majority in peer-reviewed professional journals. As this is a republication of archival material, transformed into a modern format, we apologise in advance for any errors introduced during this transformation.

Early antiplatelet therapy in coronary artery bypass grafting: a calculated benefit

Studies have demonstrated that antagonists of platelet activity, including aspirin and clopidogrel, reduce the risk of major adverse events in patients with acute coronary syndromes. Although antiplatelet agents also convey an increased risk of bleeding, particularly in patients proceeding to coronary artery bypass graft surgery, in most cases, the benefits of early initiation of antiplatelet therapy outweigh the risks. The purpose of this review is to distinguish perceived and actual risk versus the benefit associated with early antiplatelet therapy to help clinicians make informed decisions on using these agents in an acute setting where patients may require coronary artery bypass grafting.

Nonsurgical bleeding diathesis in anemic thrombocytopenic patients: role of temperature, red blood cells, platelets, and plasma-clotting proteins

Research at the Naval Blood Research Laboratory (Boston, MA) for the past four decades has focused on the preservation of red blood cells (RBCs), platelets (PLTs), and plasma-clotting proteins to treat wounded servicemen suffering blood loss. We have studied the survival and function of fresh and preserved RBCs and PLTs and the function of fresh and frozen plasma-clotting proteins. This report summarizes our peer-reviewed publications on the effects of temperature, RBCs, PLTs, and plasma-clotting proteins on the bleeding time (BT) and nonsurgical blood loss. The term nonsurgical blood loss refers to generalized, systemic bleeding that is not corrected by surgical interventions. We observed that the BT correlated with the volume of shed blood collected at the BT site and to the nonsurgical blood loss in anemic thrombocytopenic patients after cardiopulmonary bypass surgery. Many factors influence the BT, including temperature; hematocrit (Hct); PLT count; PLT size; PLT function; and the plasma-clotting proteins factor (F)VIII, von Willebrand factor, and fibrinogen level. Our laboratory has studied temperature, Hct, PLT count, PLT size, and PLT function in studies performed in non-aspirin-treated and aspirin-treated volunteers, in aspirin-treated baboons, and in anemic thrombocytopenic patients. This monograph discusses the role of RBCs and PLTs in the restoration of hemostasis, in the hope that a better understanding of the hemostatic mechanism might improve the treatment of anemic thrombocytopenic patients. Data from our studies have demonstrated that it is important to transfuse anemic thrombocytopenic patients with RBCs that have satisfactory viability and function to achieve a Hct level of 35 vol percent before transfusing viable and functional PLTs. The Biomedical Excellence for Safer Transfusion (BEST) Collaborative recommends that preserved PLTs have an in vivo recovery of 66 percent of that of fresh PLTs and a life span that is at least 50 percent that of fresh PLTs. Their recommendation does not include any indication that preserved PLTs must be able to function to reduce the BT and reduce or prevent nonsurgical blood loss. One of the hemostatic effects of RBC is to scavenge endothelial cell nitric oxide, a vasodilating agent that inhibits PLT function. In addition, endothelin may be released from endothelial cells, a potent vasoconstrictor substance,to reduce blood flow at the BT site. RBCs, like PLTs at the BT site, may provide arachidonic acid and adenosine diphosphate to stimulate the PLTs to make thromboxane, another potent vasoconstrictor substance and a PLT-aggregating substance. At the BT site, the PLTs and RBCs are activated and phosphatidyl serine is exposed on both the PLTs and the RBCs. FVa and FXa, which generate prothrombinase activity to produce thrombin, accumulate on the PLTs and RBCs. A Hct level of 35 vol percent at the BT site minimizes shear stress and reduces nitric oxide produced by endothelial cells. The transfusion trigger for prophylactic PLT transfusion should consider both the Hct and the PLT count. The transfusion of RBCs that are both viable and functional to anemic thrombocytopenic patients may reduce the need for prophylactic leukoreduced PLTs, the alloimmunization of the patients, and the associated adverse events related to transfusion-related acute lung injury. The cost for RBC transfusions will be significantly less than the cost for the prophylactic PLT transfusions.

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Monitoring anticoagulation and hemostasis in cardiac surgery

The need to monitor anticoagulation and hemostasis during and after cardiac surgery has led to recognition of the importance of evaluation and use of hemostasis monitors in this setting. Consequently, rapid and accurate identification of abnormal hemostasis has been the major impetus for the development of point-of-care tests and their use in transfusion algorithms for cardiac surgical and other critically ill patients.

Assessing the medical literature: let the buyer beware

As many as 30% of journal articles may contain errors. Most of these errors involve the use of simple statistical tests or elementary principles of research design. Assessment of the thoracic surgical literature involves cautious circumspection. This does not mean that it is necessary to have in-depth knowledge of sophisticated statistics, rather it means that common sense understanding of a few principles of research design and simple statistics are necessary to determine the usefulness and believability of literature publications.

Effects of platelet transfusion on post cardiopulmonary bypass bleeding

A common complication of cardiopulmonary bypass (CPB) surgery is post-operative bleeding that may result in re-exploration. Bleeding is often due to the coagulopathy that follows the procedure, rather than the surgical technique. Etiology of this coagulopathy has been attributed to platelet dysfunction. We reviewed the medical records of 592 patients who had undergone CPB surgery between 1992 and 1994. Bleeding times (both pre and post operative) in treated (those who received platelets) and untreated patients were recorded where available. Both groups showed a rise in bleeding time (295 sec versus 192 sec, respectively, p<0.001). However, the treated group had a greater increase in the bleeding time compared to the un-treated (p<0.05). The result was the same when we compared 2 subgroups with similar pre-operative bleeding times. When the treated group was subdivided into those who received >10 units of platelets and those who received <10 units, there was no significant difference in the increase in their bleeding times (p>0.1). Administration of platelets did not improve bleeding time abnormalities induced by CPB. Both treated and untreated groups had a significant rise in their bleeding times, irrespective of the amount of platelets administered. The mean rise in the bleeding time in patients who bled significantly to require surgical re-exploration (but did not receive platelets) was not significantly different from those who received platelets. These observations suggest that the administration of platelets has no clinical benefit in improving bleeding time following CPB.

Relationship between leukocyte count and patient risk for excessive blood loss after cardiac surgery

OBJECTIVE

To evaluate the relationship between leukocyte counts and risk for excessive blood loss after cardiac surgery when including numerous demographic, operative, and laboratory factors in the comparison.

DESIGN

A prospective, clinical evaluation.

SETTING

A point-of-care laboratory and the cardiac surgical unit of a university-affiliated tertiary center.

PATIENTS

Patient-related and hematologic variables were measured, using blood specimens obtained from 89 hospitalized patients who underwent cardiac surgery involving cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographic, operative, and transfusion-related data were recorded for each patient. Routinely obtained measurements of laboratory-based prothrombin time, partial thromboplastin time, complete blood count, and bleeding time were recorded. Hemoglobin concentration, platelet count, and red and white blood cell counts were measured with an on-site instrument before initiation (pre-cardiopulmonary bypass) and before discontinuation (end-cardiopulmonary bypass) of cardiopulmonary bypass. Hematocrit was calculated using recorded variables, and white blood cell percent change values were calculated using white blood cell counts from both periods, using the following formula: [(end-cardiopulmonary bypass - pre-cardiopulmonary bypass)/pre-cardiopulmonary bypass] x 100. When we excluded four patients who had a surgical source of post-cardiopulmonary bypass bleeding, significant (p < .0001) relationships were observed between white blood cell count (r2 = .46) and white blood cell percent change values (r2 = .71) and cumulative mediastinal chest tube drainage in the first 4 postoperative hours in 85 patients. Bayes theorem was used to evaluate the predictive ability of hematologic measurements in identifying patients with excessive bleeding (n = 24), defined as >1000 mL of cumulative chest tube drainage in the first 24 postoperative hours, when compared with patients without excessive bleeding (n = 61). Demographic and operative variables were similar between these patients except that patients with excessive bleeding required more red blood cell, platelet, and plasma transfusions during the postoperative interval. Significantly (p < .0001) greater white blood cell percent change values were obtained in the excessive bleeding cohort (119 +/- 93 percent change) when compared with patients without excessive bleeding (28 +/- 36 percent change).

CONCLUSIONS

On-site measurements of white blood cell count, as an index of the inflammatory response to extracorporeal circulation, may be useful in identifying patients at increased risk for excessive bleeding. Further studies are needed to examine whether white blood cell counts during multiple cardiopulmonary bypass periods may identify patients with an exaggerated inflammatory response to extracorporeal circulation. By using this information, physicians may be able to intervene with anti-inflammatory medications and blood preservation techniques.

Desmopressin and bleeding during invasive surgery

Peri-operative bleeding is associated with invasive surgery and has traditionally been compensated for by blood transfusion. Concerns about the risk of transfusion-transmitted disease have led to an increasing interest in synthetic haemostatic agents. Desmopressin (1-deamino-8-D-arginine vasopressin), a synthetic analogue of vasopressin, has been shown to be of benefit in the peri-operative management of von Willebrand's disease or mild haemophilia A. This paper addresses the role of desmopressin and bleeding during invasive surgery, particularly during cardiopulmonary bypass. Clinical trials using desmopressin in open cardiac surgery indicate that it may reduce blood loss in those with an excessive bleeding tendency. However, it is difficult to identify this group pre-operatively.

Laboratory evaluation of hemostasis before cardiac operations

BACKGROUND

Several opinions prevail on the necessity and on the choice of laboratory coagulation tests to perform before cardiac operations. This review aims at providing simple and clinically relevant recommendations.

METHODS

The literature on preoperative coagulation testing was reexamined, taking into account the low prevalence of unknown and unsuspected hemorrhagic disease, and the risk of false positive results.

RESULTS

Carefully controlled, randomized trials are lacking but it seems appropriate to perform a few inexpensive tests (platelet count, activated partial thromboplastin time, and prothrombin time), mainly to obtain baseline values for patients who are about to undergo a major hemostatic challenge. A more complete coagulation profile (eg. bleeding time, fibrinogen concentration, thrombin time) should be considered in patients who present with a history of bleeding.

CONCLUSIONS

A careful medical history is the key element to detect a bleeding disorder. Only a very limited coagulation profile should be obtained in asymptomatic patients before cardiac operations.

Effect of ketorolac on bleeding time and postoperative pain in children: a double-blind, placebo-controlled comparison with meperidine

STUDY OBJECTIVE

To determine whether ketorolac 0.75 mg/kg would provide a comparable degree of analgesia to that of meperidine 1 mg/kg in terms of postoperative opioid requirements and pain scores in children undergoing surgeries associated with mild to moderate postsurgical discomfort.

DESIGN

Randomized, prospective, placebo-controlled, double-blinded study of the initial 6 postsurgical hours.

SETTING

University affiliated teaching hospital.

PATIENTS

90 healthy ASA status I and II children scheduled for elective general, orthopedic, or genitourinary procedures associated with mild to moderate postsurgical pain. Extensive surgical procedures associated with a significant risk of bleeding were excluded.

INTERVENTIONS

Ketorolac 0.75 mg/kg, meperidine 1 mg/kg, or placebo (normal saline) was administered intramuscularly (IM) at the beginning of surgery.

MEASUREMENTS AND MAIN RESULTS

Bleeding times were measured prior to and 180 minutes after study drug administration. Time to first rescue medication, total opioid requirement, pain scores, incidence of vomiting and length of stay were evaluated. Placebo-treated patients were rescued earlier (p < 0.0001) and required twice the rescue dosage (p = 0.013) when compared with either the ketorolac or meperidine groups. The ketorolac and meperidine groups did not differ with regard to time until first rescue, cumulative proportion requiring rescue, or the number of rescue doses required. A single dose of IM ketorolac prolonged bleeding time by 53 +/- 75 seconds (p = 0.006).

CONCLUSIONS

Ketorolac provided analgesia comparable to that of meperidine and significantly reduced opioid requirements. Since ketorolac was not associated with a reduction in postoperative vomiting or length of stay, and in view of the uncertain risk of bleeding, it offers no advantage over meperidine in the management of mild to moderate acute postsurgical pain.

Effect of aspirin and nonsteroidal antiinflammatory drug therapy on bleeding complications in dermatologic surgical patients

BACKGROUND

Aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) inhibit platelet cyclooxygenase activity, resulting in altered platelet function and thus potentially enhanced bleeding.

OBJECTIVE

We examined the frequency of operative bleeding complications in dermatologic surgical patients taking these drugs and the value of template bleeding time estimates in predicting this complication.

METHODS

Bleeding time was measured with and without therapy in 23 patients and was correlated to bleeding complications after skin tumor or benign lesion excision in 40 patients taking aspirin, 21 taking NSAIDs, and 20 taking neither drug.

RESULTS

Bleeding time dropped significantly (p < 0.01) when patients stopped therapy for at least 5 days (median, 7 days), although bleeding time was prolonged in only 6 of 16 patients taking aspirin and 2 of 7 taking NSAID. In patients who continued antiplatelet drugs during surgery, bleeding time was prolonged in 8 of 40 patients taking aspirin and in 1 of 21 treated with NSAIDs. Excessive intraoperative bleeding occurred in three aspirin-treated patients, all of whom had a prolonged bleeding time, compared with none of those with normal bleeding times (p < 0.001, Fisher's exact probability test) and with none of those taking NSAIDs. Postoperative ooze requiring a dressing replacement occurred in one NSAID-treated patient and in three patients taking neither drug.

CONCLUSION

Bleeding time is increased by aspirin and NSAID therapy but is prolonged beyond the normal range in only approximately 25% of aspirin-treated and 10% of NSAID-treated patients. Intraoperative bleeding complications occurred only in patients receiving aspirin who had a prolonged bleeding time. Postoperative oozing occurred only in NSAID-treated and in untreated patients and thus is probably unrelated to antiplatelet therapy. Patients with a normal bleeding time can continue aspirin or NSAID therapy before dermatologic surgery.

Predictive value of blood clotting tests in cardiac surgical patients

This study prospectively evaluated numerous tests of clotting function in 897 consecutive adult cardiac surgical patients over 18 months. This included coronary operation, valve replacement, and reoperative patients. The tests included activated clotting time, activated partial thromboplastin time, prothrombin time, thrombin time, fibrinogen, fibrin/fibrinogen degradation products, platelet count, and Duke's earlobe bleeding time. Other variables such as age, sex, and cardiopulmonary bypass duration were included in the multivariate analysis. Statistically significant correlations were found between 16-hour mediastinal drainage and activated partial thromboplastin time, fibrinogen, activated clotting time, fibrin/fibrinogen degradation products, platelet count, and prothrombin time. Scatter plots indicate that these relationships, although statistically significant, had little predictive value and were largely significant as a result of the large number of patients in each group, which permitted weak correlations to reach statistical significance. The best multivariate model constructed could explain only 12% of the observed variation in postoperative blood loss. Because the predictive values of the tests are so low, it does not appear sensible to screen patients routinely using these clotting tests shortly after cardiopulmonary bypass.

Comparison of blood reinfusion techniques used during coronary artery bypass grafting

A comparison of intraoperative autologous blood conservation techniques was carried out in 100 patients undergoing coronary artery bypass grafting. To facilitate comparisons of similar groups, patients were stratified into high-risk and low-risk groups based on the ratio of preoperative bleeding time to preoperative red blood cell volume. Our previous work suggested that patients with an elevated ratio have increased risk of excessive post-operative blood transfusion. We used this ratio to stratify the 100 patients to either the high-risk (39 patients) or low-risk (61 patients) strata. Within each stratum, patients were randomized to one of three groups: no intraoperative autologous blood conservation (control group), infusion of autologous platelet-rich plasma obtained from intraoperative plasmapheresis (PRP group), and infusion of autologous whole blood harvested immediately before cardiopulmonary bypass (whole blood group). Variables of postoperative blood loss and transfusion requirements were measured in each patient. Analysis of variance showed significant differences in blood product transfusions between groups. Patients in the high-risk stratum required significantly more blood product transfusions than those in the low-risk stratum (5.4 +/- 0.7 versus 2.0 +/- 0.6 units per patient; p < 0.001). In the high-risk stratum, PRP patients required significantly less postoperative blood transfusion compared with patients in the high-risk control group (2.9 +/- 2.1 versus 8.1 +/- 2.2 units per patient; p = 0.05). In the low-risk stratum, no intraoperative blood infusion method resulted in significant improvement in postoperative blood use.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

The bleeding time: its potential utility among patients receiving thrombolytic therapy

The BT as a test of hemostatic function was first described 80 years ago. It has generally been considered a primitive and tedious test. Improvements in technique and standardization have increased the BT's reliability and led to its consideration as a preoperative screening measure. Current use has not been widespread, however, except for patients undergoing neurosurgery and organ biopsy. Recently, though, there has been a renewed interest in the BT for patients receiving thrombolytic therapy because levels of fibrinogen and fibrin(ogen) degradation products have been only weak predictors of hemorrhagic complications. The rationale for using the BT in this setting is that thrombolysis appears to impair platelet function, either through depletion of platelet granules or through direct proteolytic actions on platelets. Further research will determine whether these platelet effects are manifest as BT prolongation; whether increased BT will correlate with hemorrhagic complications; and, finally, whether patients who fail to achieve clot lysis or those at risk for bleeding can be identified prospectively.

Clinical application of a new in vitro bleeding time device on surgical patients

A new in vitro bleeding time (BT) device was applied to various surgical patients. After setting the optimal assay condition, the normal in vitro bleeding time (T2) and volume (V2) were obtained from healthy volunteers, being 114.7 secs +/- 25.8 (SD) and 272.2 microliter +/- 69.1 (SD), respectively. When the T2 was below 210 secs, the platelet count was inversely proportional to the T2 and V2 of the in vitro BT with p less than 0.01. The value of the in vitro BT was not affected by heparin. Agents, which modify platelet functions, such as PGI2, DN9693 (an inhibitor of phosphodiesterase) and aspirin, prolonged the in vitro BT (T2, V2) dose-dependently. Administration of aspirin (660 mg) to volunteers prolonged the T2 from 108 to over 300 secs and the V2 from 253 to over 600 microliter but ticlopidine (500 mg/day for 3 days) had no effect. In 8 patients with liver cirrhosis who underwent hepatectomy, one patient with a prolonged T2 (260 secs) and a normal skin BT bled postoperatively, however, 3 patients with a prolonged skin BT (greater than 15 min) and a normal T2 had no hemorrhagic complications. From these observations it was concluded that in vitro BT is a convenient and useful tool to examine primary hemostasis or platelet function.

Preoperative aspirin ingestion increases operative blood loss after coronary artery bypass grafting

Thirty-four patients were entered into a non-blinded, randomized study to test the effect of preoperative aspirin ingestion on postoperative blood loss and transfusion requirements after coronary artery bypass grafting. Sixteen patients in the aspirin-treated group had significantly increased chest-tube blood loss 12 hours after operation (1,513 +/- 978 versus 916 +/- 482 ml; p = 0.038). In addition, aspirin users had significantly increased requirements for postoperative packed red blood cells (4.4 +/- 3.5 versus 1.8 +/- 1.3 units; p = 0.014), platelets (1.3 +/- 1.3 versus 0.2 +/- 0.4 six-donor units, p = 0.0049), and fresh-frozen plasma (3.6 +/- 5.0 versus 0.78 +/- 1.6 units; p = 0.042) transfusions. The only patients requiring reoperation for bleeding were in the aspirin-treated group (2 patients). Six patients were not entered into the randomized part of the study because of excessively prolonged post-aspirin bleeding times (greater than 10 minutes). This finding suggests that a subset of patients are particularly sensitive to aspirin and have significantly prolonged bleeding times after aspirin ingestion. We conclude that aspirin ingestion increases postoperative blood loss and transfusion requirements, and we recommend discontinuation of aspirin therapy before cardiac procedures.