Do preoperative laboratory tests predict blood transfusion needs in cardiac operations?

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.

Preoperative platelet transfusions and perioperative red blood cell requirements in patients with thrombocytopenia undergoing noncardiac surgery

BACKGROUND

Perioperative hemorrhage impacts patient outcomes and health care resource utilization, yet the risks of transfusion therapies are significant. In patients with preoperative thrombocytopenia, the effects of prophylactic preoperative platelet (PLT) transfusion on perioperative bleeding complications remain uncertain.

STUDY DESIGN AND METHODS

This is a retrospective cohort study of noncardiac surgical patients between January 1, 2008, and December 31, 2011. Propensity-adjusted analyses were used to evaluate associations between preoperative thrombocytopenia, preoperative PLT transfusion, and the outcomes of interest, with a primary outcome of perioperative red blood cell (RBC) transfusion.

RESULTS

A total of 13,978 study participants were included; 860 (6.2%) had a PLT count of not more than 100 × 10(9) /L with 71 (8.3%) receiving PLTs preoperatively. Administration of PLTs was associated with higher rates of perioperative RBC transfusion (66.2% vs. 49.1%, p = 0.0065); however, in propensity-adjusted analysis there was no significant difference between groups (odds ratio [OR] [95% confidence interval {95% CI}], 1.68 [0.95-2.99]; p = 0.0764]. Patients receiving PLTs had higher rates of intensive care unit (ICU) admission (OR [95% CI], 1.95 [1.10-3.46]; p = 0.0224) and longer hospital lengths of stay (estimate [95% bootstrap CI], 7.2 [0.8-13.9] days; p = 0.0006) in propensity-adjusted analyses.

CONCLUSION

Preoperative PLT transfusion did not attenuate RBC requirements in patients with thrombocytopenia undergoing noncardiac surgery. Moreover, preoperative PLT transfusion was associated with increased ICU admission rates and hospital duration. These findings suggest that more conservative management of preoperative thrombocytopenia may be warranted.

Preoperative Thrombocytopenia and Postoperative Outcomes after Noncardiac Surgery

Background:

Most studies examining the prognostic value of preoperative coagulation testing are too small to examine the predictive value of routine preoperative coagulation testing in patients having noncardiac surgery.

Methods:

Using data from the American College of Surgeons National Surgical Quality Improvement database, the authors performed a retrospective observational study on 316,644 patients having noncardiac surgery who did not have clinical indications for preoperative coagulation testing. The authors used multivariable logistic regression analysis to explore the association between platelet count abnormalities and red cell transfusion, mortality, and major complications.

Results:

Thrombocytopenia or thrombocytosis occurred in 1 in 14 patients without clinical indications for preoperative platelet testing. Patients with mild thrombocytopenia (101,000–150,000 µl−1), moderate-to-severe thrombocytopenia (<100,000 µl−1), and thrombocytosis (≥450,000 µl−1) were significantly more likely to be transfused (7.3%, 11.8%, 8.9%, 3.1%) and had significantly higher 30-day mortality rates (1.5%, 2.6%, 0.9%, 0.5%) compared with patients with a normal platelet count. In the multivariable analyses, mild thrombocytopenia (adjusted odds ratio [AOR], 1.28; 95% CI, 1.18–1.39) and moderate-to-severe thrombocytopenia (AOR, 1.76; 95% CI, 1.49–2.08), and thrombocytosis (AOR, 1.44; 95% CI, 1.30–1.60) were associated with increased risk of blood transfusion. Mild thrombocytopenia (AOR, 1.31; 95% CI, 1.11–1.56) and moderate-to-severe thrombocytopenia (AOR, 1.93; 95% CI, 1.43–2.61) were also associated with increased risk of 30-day mortality, whereas thrombocytosis was not (AOR, 0.94; 95% CI, 0.72–1.22).

Conclusion:

Platelet count abnormalities found in the course of routine preoperative screening are associated with a higher risk of blood transfusion and death.

The effects of pre- and postoperative fibrinogen levels on blood loss after cardiac surgery: a systematic review and meta-analysis

OBJECTIVES

Fibrinogen concentrate is increasingly used in cardiac surgery when bleeding is anticipated or ongoing. Since randomized clinical studies to support this are lacking, it is relevant to know whether lower fibrinogen levels are associated with excessive bleeding. We performed a systematic review and meta-analysis to define the association between fibrinogen levels and blood loss after cardiac surgery.

METHODS

A database search (January 2013) was performed on publications assessing the association between pre- and postoperative fibrinogen levels and postoperative blood loss in adult patients undergoing cardiac surgery. Cohort studies and case-control studies were eligible for inclusion. The main outcome was the pooled correlation coefficient, calculated via Fisher's Z transformation scale, in a random-effects meta-analysis model stratified for the time point at which fibrinogen was measured.

RESULTS

A total of 20 studies were included. The pooled correlation coefficient of studies (n = 9) concerning preoperative fibrinogen levels and postoperative blood loss was -0.40 (95% confidence interval: -0.58, -0.18), pointing towards more blood loss in patients with lower preoperative fibrinogen levels. Among papers (n = 16) reporting on postoperative fibrinogen levels and postoperative blood loss, the pooled correlation coefficient was -0.23 (95% confidence interval: -0.29, -0.16).

CONCLUSIONS

Our meta-analysis indicated a significant but weak-to-moderate correlation between pre- and postoperative fibrinogen levels and postoperative blood loss in cardiac surgery. This moderate association calls for appropriate clinical studies on whether fibrinogen supplementation will decrease postoperative blood loss.

Use and utility of preoperative hemostatic screening and patient history in adult neurosurgical patients

OBJECT

The utility of preoperative hemostasis screening to predict complications is uncertain. The authors quantified the screening rate in US neurosurgery patients and evaluated the ability of abnormal test results as compared with history-based risk factors to predict hemostasis-related and general outcomes.

METHODS

Eleven thousand eight hundred four adult neurosurgery patients were identified in the 2006-2009 American College of Surgeons National Surgical Quality Improvement Program database. Multivariate logistic regression modeled the ability of hemostatic tests and patient history to predict outcomes, that is, intra- and postoperative red blood cell [RBC] transfusion, return to the operating room [OR], and 30-day mortality. Sensitivity analyses were conducted using patient subgroups by procedure.

RESULTS

Most patients underwent all 3 hemostatic tests (platelet count, prothrombin time/international normalized ratio [INR], activated partial thromboplastin time), but few had any of the outcomes of interest. The number of screening tests undergone was significantly associated with intraoperative RBC transfusion, a return to the OR, and mortality; an abnormal INR was associated with postoperative RBC transfusion. However, all tests had low sensitivity (0.09-0.2) and platelet count had low specificity (0.04-0.05). The association between patient history and each outcome was approximately the same across all tests, with higher sensitivity but lower specificity. Combining abnormal tests with patient history accounted for 50% of the mortality and 33% of each of the other outcomes.

CONCLUSIONS

This is the first study focused on assessing preoperative hemostasis screening as compared with patient history in a large multicenter sample of adult neurosurgery patients to predict hemostasis-related outcomes. Patient history was as predictive as laboratory testing for all outcomes, with higher sensitivity. Routine laboratory screening appears to have limited utility. Testing limited to neurosurgical patients with a positive history would save an estimated $81,942,000 annually.

Evaluation of prolonged aPTT values in the pediatric population

To assess the likelihood of significant bleeding disorders in children with prolonged activated partial thromboplastin times (aPTTs), a retrospective chart review was performed. Data analyses determined that in the absence of symptoms and a negative family history, the diagnosis of a bleeding disorder was unlikely in an individual with a prolonged aPTT (negative predictive value = 80%). Conversely, a prolonged aPTT was predictive (positive predictive value = 62%) in the presence of both clinical symptoms and a documented family history. The scope of laboratory investigation in any child with a prolonged aPTT should be tempered by the clinical presentation and the associated personal and family histories.

The effect of non-steroidal anti-inflammatory drugs on bleeding during periodontal surgery

BACKGROUND

With the increasing prevalence of individuals taking non-steroidal anti-inflammatory drugs (NSAIDs), there is concern as to whether low-dose NSAIDs cause bleeding problems during periodontal surgery.

METHODS

A controlled, single-blind study was designed to measure the effect of ibuprofen at peak plasma levels on intraoperative bleeding. Fifteen medically healthy subjects (seven males and eight females), each having two sites requiring periodontal surgery of similar complexity, type, and duration, were selected for the study. The subjects were instructed to take ibuprofen prior to one of the surgeries. A standard bleeding time and papillary bleeding index score were recorded at initial consultation, and prior to the first and second surgeries. The volume of aspirated blood was measured during each surgery by subtracting the amount of water used for irrigation from the total volume of fluid (blood + irrigation water) collected at 15-minute intervals during the surgery.

RESULTS

An analysis of the results showed an increase in intraoperative bleeding when ibuprofen was taken prior to surgery (31.93 +/- 15.72 versus 17.80 +/- 9.57 ml; P <0.01). Ibuprofen appeared to have its greatest effect on bleeding mid-surgery. The average bleeding time also increased significantly (P <0.01) when ibuprofen was preadministered (4.17 +/- 0.96 versus 3.8 +/- 0.92 minutes), although the bleeding remained within the normal range. Papillary bleeding did not show a significant difference between the two surgeries. Surgeries involving osseous resection showed a significant increase in bleeding when ibuprofen was preadministered.

CONCLUSION

Taken prior to periodontal surgery, ibuprofen increases intraoperative blood loss in patients up to almost two times that of those who did not take ibuprofen.

Bleeding in Cardiac Surgery: Its Prevention and Treatment—an Evidence-Based Review

Expected and unexpected bleeding occur frequently in patients undergoing cardiac surgery. Bleeding after cardiac surgery can be broadly divided into two groups: surgical (unrecognized bleeding vessel, anastomosis, or other suture line) or nonsurgical bleeding (caused by coagulopathy). Factors influencing both surgical and nonsurgical bleeding can be further broken down into those occurring preoperatively and those that occur intraoperatively and postoperatively. A thorough understanding of these factors is necessary to reduce bleeding. This is a desirable clinical goal, because excessive bleeding is associated with adverse outcomes.

Preoperative assessment

Although anaesthetic and surgical procedures should be individualised for every patient, in practice many preoperative protocols and routines are used generally. In this article, we aim to emphasise: why preoperative assessment is important; how it should be done, and by whom; what can be expected; and the importance of test selection based on patients' needs and on scientific evidence of effectiveness. We outline the roles of preoperative medical assessment in otherwise healthy patients. Clinical history, preoperative questionnaires, physical examination, routine tests, individual risk-assessment, and fasting policies are investigated by review of published work. Cost of routine preoperative assessment, the anaesthetist's legal responsibility, and patients'views in the preoperative process are also considered. A thorough clinical preoperative assessment of the patient is more important than routine preoperative tests, which should be requested only when justified by clinical indications. Moreover, this practice eliminates unnecessary cost without compromising the safety and quality of care. Education and training of medical doctors should be more scientifically guided, emphasising the relevance of effectiveness, and cost-effectiveness in clinical decision-making and complemented by audit.

Evaluation and management of anemia and bleeding disorders in surgical patients

The perioperative period offers a unique hemostatic and physiologic challenge. Evaluation of anemia and the decision to transfuse play an important role in the perioperative period. Achievement of adequate hemostasis is important. A bleeding-oriented history and physical, along with some baseline tests, may help alert the physician to the possibility of a bleeding disorder. Finally, some patients may need correction of their bleeding disorder before surgery or careful monitoring in the perioperative period.

Value of preoperative coagulation tests: reappraisal of major noncardiac surgery

In a retrospective case-control review, we evaluated preoperative coagulation testing in patients undergoing major noncardiac operations to determine if routine testing benefits this group of patients. The platelet count (PC), prothrombin time (PT), and activated partial thromboplastin time (aPTT) in all patients undergoing major noncardiac surgery over a 22-month period were reviewed. The review was done both manually and by the computerized hospital information system. Major surgery was defined as procedures usually associated with significant bleeding. For each patient with abnormal results, another two control patients undergoing the same surgery and matched for age and gender were identified. Case and control patients were compared regarding a change in the management plan, use of blood products, blood loss, and bleeding complications by detailed chart review. A total of 828 patients undergoing nine different surgeries were reviewed. The incidence of abnormal PCs was 2.2% [95% confidence interval (CI) 1.2-3.2%] and that of abnormal PT/aPTTs was 2.1% (95% CI 1.1-3.1%). There were only two cases each of thrombocytopenia and prolonged PT/aPTT where the coagulation tests were not indicated clinically. Although (compared to controls) patients with abnormal tests had more changes in their anesthesia plan (36% vs. 2%, p < 0.001) and platelet or fresh frozen plasma transfusions (50% vs. 9%, p < 0.001), blood loss and the incidence of bleeding complications were not different. We conclude that the use of preoperative coagulation tests in patients undergoing major noncardiac surgery should still be guided by clinical assessment. The surgical procedure itself does not constitute an indication for testing.

Extracorporeal shockwave lithotripsy in patients treated with antithrombotic agents

PATIENTS AND METHODS

Between January 1996 and December 1999, 749 patients underwent electromagnetic SWL. Among them, 23 patients, 19 with renal and 4 with ureteral stones, were receiving antithrombotic drugs (aspirin, ticlopidine, dipyridamole). According to the cardiologist and hematologist, we divided these patients into two groups: Group 1 had a low thromboembolic risk (previous myocardial infarction), and Group 2 had a high thromboembolic risk (aortocoronary bypass, atrial fibrillation, cerebrovascular disease, peripheral occlusive arterial disease). Group 1 patients discontinued their antiplatelet therapy 8 days prior to SWL to permit a sufficient number of functioning platelets to remain. Group 2 patients suspended antiplatelet therapy, and unfractioned heparin 5000 IU tid (8 a.m., 4 p.m., and 12 p.m.) was administered for the 8 days prior to SWL. On the ninth day of withdrawal, SWL was performed in all patients. Close follow-up was performed during the postoperative period (hemoglobin, hematocrit, kidney ultrasonography, plain abdominal film). The antithrombotic therapy was restored in all patients within 10 to 14 days of withdrawal.

RESULTS

Hematomas and thromboembolic events were not observed. At 3 months' follow-up, 14 patients (61%) were stone free, 3 (13%) had <4-mm fragments, and 6 (26%) had >4-mm residual fragments.

CONCLUSION

Our schedules for the suspension or substitution of antithrombotic therapy, although tested in a small number of patients, allowed us to perform SWL without hemorrhagic or thromboembolic complications.

Prediction of the mediastinal drainage after coronary artery bypass surgery

Using multiple correlation and linear regression approaches, we investigated the association between the amount of mediastinal drainage for the first 24 postoperative hours and clinical variables as well as multiple haematological tests performed at three time points: before anaesthesia induction, 10 minutes after protamine administration and just after skin closure, on 46 patients undergoing primary coronary artery bypass grafting. Three models from the three times were then developed to predict mediastinal drainage. The number of internal mammary grafts, the total number of grafts and plasma fibrinogen concentration were useful predictors of mediastinal drainage at all three times. The platelet count taken only after skin closure was found to provide additional predictive information. Each regression model explained approximately 60% of the variation in postoperative mediastinal drainage. The information obtained from these predictive models is useful in defining high-risk populations.

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.

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.

Blood use in patients undergoing repeat coronary artery bypass graft procedures: multivariate analysis

BACKGROUND

The prevailing clinical opinion is that patients undergoing repeat coronary artery bypass graft (CABG) operation require more blood transfusions than do patients undergoing primary CABG operation. To determine the extent of this increased demand and the variables responsible for it, the cases of 196 patients who had undergone primary procedures and 65 patients who had had repeat procedures at the same institution were reviewed.

STUDY DESIGN AND METHODS

To analyze the differences in transfusion requirements for these two groups, the following data were obtained: number of transfusions given between the time of surgery and the time of hospital discharge; preoperative hemoglobin (Hb), hematocrit (Hct), prothrombin time, and platelet count; Hb and Hct at hospital discharge; time the patient was on cardiopulmonary bypass; number and type of grafts; estimates of intraoperative blood loss; and chest-tube blood shed during the first 48 hours after surgery.

RESULTS

The groups were comparable with respect to age, body weight, preoperative Hb and Hct, number of grafts, and aspirin exposure. Patients in the repeat group had 35-percent greater blood loss and required 75-percent more blood components than did the patients undergoing primary procedures. The mean number of blood components transfused per patient was as follows: red cells, 3.8 +/- 0.5 units in repeat patients and 2.2 +/- 0.2 units in primary patients (p = 0.002); platelets, 2.9 +/- 0.9 vs. 1.1 +/- 0.2 (p = 0.043); fresh-frozen plasma, 1.6 +/- 0.4 vs. 0.8 +/- 0.1 (p = 0.044). Analysis of variables by regression method for repeat patients showed a predictive effect of blood loss (p < 0.0001), prolonged time on cardiopulmonary bypass (p < 0.0001), preoperative Hb (p = 0.0003), and aspirin exposure (p = 0.0094) on red cell transfusion rate in repeat patients (R-square = 0.7778, Prob > f = 0.0001).

CONCLUSION

Repeat CABG patients have higher transfusion rates. These findings may be attributed to the increased microvascular bleeding, prolonged time on cardiopulmonary bypass, lower preoperative Hb, and the use of preoperative antiplatelet medications.

The skin bleeding time test as a predictor of brain bleeding time in a rat model

Previous studies have indicated that the skin bleeding time test does not accurately reflect visceral bleeding time (BT). The present study examines the predictive value of the skin bleeding time for brain bleeding tendency. Sixteen Sprague-Dawley rats were divided into equal groups. The first group (controls) underwent standardized skin and brain bleeding time tests under general anesthesia. Mean skin BT was found to be 168.8 sec with a standard deviation of +/- 20.8 sec. Mean brain BT was found to be 172.5 sec with a standard deviation of +/- 19.6 sec. The second group was given 23.2 mg/kg of aspirin per day for five days prior to skin and brain BT testing. Mean skin BT in this group was 315 seconds with a standard deviation of +/- 72.2 sec which proved to be significantly different from the control skin BT (P = 0.0005). Brain BT in the aspirin treated group was 155.6 sec with a standard deviation of +/- 22.6 sec. Brain BT in both control and aspirin treated groups was not significantly different (P = 0.13). All animals were euthanized 30 minutes after brain BT and their brains harvested. One animal in the control group showed evidence of a small subcortical hemorrhage upon brain sectioning. Sectioned brains in the aspirin-treated group showed no evidence of subcortical hematoma. The results indicate that skin BT is prolonged by aspirin administration, but brain bleeding time is unaffected. Brain hemostasis is likely more dependent on intrinsic procoagulant than platelet function. The skin BT test may therefore be of little utility as a preoperative screening test for neurosurgical patients.

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.

Economic impact of inappropriate blood transfusions in coronary artery bypass graft surgery

PURPOSE

In addition to historically important issues of blood inventory and blood safety, the costs of blood transfusion are anticipated to have an increasingly important impact on transfusion practices. To address this, we analyzed costs of blood support given to patients undergoing coronary artery bypass graft (CABG) surgery, along with costs of blood components whose transfusions were identified to be unnecessary.

PATIENTS AND METHODS

Blood components transfused as part of a previously reported national, multicenter audit of 30 adult patients each at 18 institutions undergoing primary, elective CABG surgery were reviewed.

RESULTS

The range of blood purchase costs among institutions was broad, varying over two-fold. The range of red cell units transfused varied over 10-fold, and the range of total components transfused varied over 40-fold. The number of blood components transfused unnecessarily represented 27% of all blood units transfused, ranging from 7% to 43% among institutions. Inappropriate transfusions accounted for 47%, 32%, and 15% of all platelet, plasma, and red cell units transfused. The mean institutional cost for all blood components transfused per patient was $397 +/- $244. The cost per patient of components transfused inappropriately was 24% of this, or $96 +/- $89 (mean +/- SD).

CONCLUSION

These costs could be reduced with practice guidelines and quality improvement programs aimed at reducing the number of inappropriate transfusions.

Influence of ketorolac tromethamine on clot elastic strength in humans as assessed by thromboelastography

STUDY OBJECTIVE

To evaluate the effect of ketorolac tromethamine on coagulation using thromboelastography (TEG).

DESIGN

TEGs were performed in each patient before and after ketorolac administration. Each patient's predrug results were used as control measurements for comparison with the postdrug results.

SETTING

Medical center surgical unit.

PATIENTS

Twenty ASA physical status I and II patients undergoing minor elective surgery; 12 healthy volunteers.

INTERVENTIONS

TEGs were performed in all subjects before and 60 minutes after the intramuscular (IM) administration of ketorolac tromethamine 60 mg. Ten surgical patients were studied in the intraoperative period, and 10 surgical patients were studied in the postoperative period. The 12 healthy volunteers did not undergo a surgical procedure.

MEASUREMENTS AND MAIN RESULTS

Specific parameters assessed from the TEGs were reaction time (R time), coagulation time (RK time), clot formation rate (angle of deflection), and maximum clot strength (maximum amplitude of deflection). Ketorolac administration did not cause statistically significant changes in these parameters in any of the three groups studied.

CONCLUSIONS

IM administration of ketorolac tromethamine 60 mg did not significantly alter the speed of formation or viscoelastic strength of clots as measured by TEG. These results provide additional support for prior clinical studies confirming the safety of ketorolac administration in the perioperative period.

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.

Guidelines for transfusion support in patients undergoing coronary artery bypass grafting. Transfusion Practices Committee of the American Association of Blood Banks

We have reviewed the impact of evolving issues in coronary artery bypass grafting (CABG) on transfusion support for these patients. Issues include increased awareness of transfusion risks, reappraisal of traditional indicators triggering transfusion, and evolving alternatives to homologous blood transfusion such as autologous blood and pharmacologic therapy. These issues have been prompted by programs, such as the National Institutes of Health Consensus Conferences, to provide physicians with guidelines for appropriate use of blood components. However, evidence suggests that transfusion practice in coronary artery bypass grafting procedures remains variable and does not take into account the results of recently published clinical studies. We have therefore developed guidelines and recommendations for transfusion support in patients undergoing coronary artery bypass grafting. In summary, they are the following. 1. Institutions with coronary artery bypass grafting programs should establish a multidisciplinary approach to use a combination of interventions designed to minimize homologous blood exposure. 2. Prophylactic transfusion of plasma and platelets are of no benefit and therefore carry an unnecessary risk to the patient. 3. Special request products such as designated blood donation from first-degree relatives should not be used because of the risk of transfusion-associated graft versus host disease. 4. For support of intravascular volume, crystalloids or colloids should be used because they do not have the potential to transmit infection.

Aspirin-induced bilateral renal hemorrhage after extracorporeal shock wave lithotripsy therapy: implications and conclusions

We report a case of bilateral intrarenal, subcapsular and perirenal hematomas after extracorporeal shock wave lithotripsy. Following treatment chest pain developed necessitating monitoring in the intensive care unit and cardiac evaluation. Serial hematocrit levels during the next 2 days revealed a decrease from 48 to 23%, requiring multiple transfusions. After therapy it was recognized that the patient had taken aspirin on a daily basis within 1 week before lithotripsy. We postulate that the aspirin ingestions acted as a potential predisposing factor in the formation of the bilateral renal hematoma.

The causes of cancelled elective surgery

We reviewed causes of cancelled elective surgery in a community hospital. Over a 6-month period, during which 4100 operating room procedures were completed, cancellations occurred in 13% of cases scheduled for outpatient surgery, 9% of cases scheduled for admission the same day, and 17% of cases scheduled for inpatient surgery. Dental procedures had significantly higher rates of cancellation among outpatient procedures, and cardiovascular surgical procedures had significantly higher rates among inpatient procedures. Chart review of cancelled inpatient cases showed 43% due to administrative reasons with unsigned consent the most common cause. Medical factors were responsible in the remaining cases, with reevaluation of the surgical condition and associated medical illnesses equally common as reasons in this category. Appreciation of the usual reasons for cancellation can improve utilization by permitting administrators and providers to anticipate those cases in which problems might arise so that additional attention can be paid to them.

Hemotherapy in open heart surgery

The clinical charts and transfusion records of 216 patients who underwent open heart surgery with cardiopulmonary bypass between August 1983 and July 1684 were reviewed. The patients were categorized into five groups according to their operative procedures. Findings from preoperative hemostatic function tests in all groups were normal. Heparin rebound was observed in all groups, probably due to underneutralization by protamine. The results suggest that the neutralization dose of protamine per milligram of heparin should be increased to a range of between 1.5 and 1.7 mg in the post-cardiopulmonary bypass period. This should also reduce the need for fresh frozen plasma. Non-blood priming of the pump for adults and acceptance of a degree of thrombocytopenia (in the range of 60 to 80 x 10(9)/L) after cardio-pulmonary bypass will lower the blood component usage. A preoperative blood order schedule for patients with open heart surgery/cardiopulmonary bypass has been suggested.

Prolonged bleeding time

The bleeding time is the most frequently used test of platelet function. This review of the literature relating to the bleeding time outlines the causes and management of prolonged bleeding time. The bleeding time appears to have its greatest utility in evaluation of a patient with active bleeding or one with a well-documented bleeding history. It should not be used as a substitute for a clinical history, since there is insufficient information available to calculate its sensitivity, specificity, or predictive value with regard to peri- or postoperative hemorrhage.