Risk Factors For Postoperative Bleeding Research Articles

Decreased plasma ADAMTS-13 activity as a predictor of postoperative bleeding in cyanotic congenital heart disease

OBJECTIVE:To analyze the preoperative plasma antigenic concentration and activity of von Willebrand factor and its main cleaving protease ADAMTS-13 in pediatric patients with cyanotic congenital heart disease undergoing surgical treatment and investigate possible correlations with postoperative bleeding.METHODS:Plasma antigenic concentrations (von Willebrand factor:Ag and ADAMTS-13:Ag) were measured using enzyme-linked immunoassays. Collagen-binding assays were developed to measure biological activities (von Willebrand factor:collagen binding and ADAMTS-13 activity). The multimeric structure of von Willebrand factor was analyzed using Western immunoblotting. Demographic, diagnostic, and general and specific laboratory data and surgery-related variables were subjected to univariate, bivariate, and multivariate analysis for the prediction of postoperative bleeding.RESULTS:Forty-eight patients were enrolled, with ages ranging from 9 months to 7.6 years (median 2.5 years). The plasma concentrations of von Willebrand factor:Ag and ADAMTS-13:Ag were decreased by 65 and 82%, respectively, in the patients compared with the controls (p<0.001). An increased density of low-molecular-weight fractions of von Willebrand factor, which are suggestive of proteolytic degradation (p = 0.0081), was associated with decreased ADAMTS-13 activity, which was likely due to ADAMTS-13 consumption (71% of controls, p = 0.0029) and decreased von Willebrand factor:collagen binding (76% of controls, p = 0.0004). Significant postoperative bleeding occurred in 13 patients. The preoperative ADAMTS-13 activity of <64.6% (mean level for the group), preoperative activated partial thromboplastin time, and the need for cardiopulmonary bypass were characterized as independent risk factors for postoperative bleeding, with respective hazard ratios of 22.35 (95% CI 1.69 to 294.79), 1.096 (95% CI 1.016 to 1.183), and 37.43 (95% CI 1.79 to 782.73).CONCLUSION:Low plasma ADAMTS-13 activity is a risk factor for postoperative bleeding in children with cyanotic congenital heart disease, particularly in children undergoing cardiopulmonary bypass.

Posttonsillectomy Hemorrhage in Children With von Willebrand Disease or Hemophilia

It is uncertain whether children with bleeding disorders are at higher risk of posttonsillectomy hemorrhage compared with the general pediatric population. To estimate the national rate of posttonsillectomy hemorrhage in children previously diagnosed with von Willebrand disease (VWD) or hemophilia, and to analyze potential risk factors for postoperative bleeding in these children. A cross-sectional analysis of the Healthcare Cost and Utilization Project Kids' Inpatient Database (KID) from the Agency for Healthcare Research and Quality for 2000, 2003, 2006, and 2009. Academic and community-based nonrehabilitation hospitals from 44 states participating in the KID project. An estimated 508 children with either VWD or hemophilia. Tonsillectomy with and without adenoidectomy, and subsequent hospitalization. Treatment for posttonsillectomy hemorrhage. We extracted all cases of tonsillectomy, adenotonsillectomy, and posttonsillectomy hemorrhage in patients with VWD or hemophilia using International Classification of Diseases, Ninth Revision diagnostic and procedure codes and applied national weights to estimate rates of posttonsillectomy hemorrhage. Using data regarding patient demographic characteristics, surgical indication, blood transfusion, hospital length of stay, and mortality, we conducted bivariate analyses to identify associations between possible risk factors and posttonsillectomy hemorrhage. Mean age was 7 years, and most patients were male, white, urbanites who had private insurance and underwent tonsillectomy for airway obstruction. The hemorrhage rate within 1 day of tonsillectomy (immediate) was 1.6% while the hemorrhage rate at least 2 days after tonsillectomy (delayed) was estimated at 15%. Delayed hemorrhage was associated with older age (P < .001) and was as high as 35% in children at least 16 years old. The rate of blood transfusion was 2.4%. There were no fatalities. The frequency of immediate posttonsillectomy hemorrhage in children with VWD or hemophilia is similar to rates in the general healthy population. However, among children with VWD or hemophilia, the rate of delayed hemorrhage is substantially higher, especially in older children.

Perforation and Postoperative Bleeding of Endoscopic Submucosal Dissection in Gastric Tumors: Analysis of 1,190 Lesions in Low- and High-Volume Centers in Saga, Japan

Background: This retrospective study aimed to determine risk factors associated with serious complications of endoscopic submucosal dissection of gastric tumors in multicenters compared between high- and low-volume centers. Methods: Between 2001 and 2010, gastric endoscopic submucosal dissection was performed in 1,190 lesions of 1,082 patients in five hospitals in Saga, three high-volume and two low-volume centers. Risk factors for serious complications were evaluated. Patients’ background characteristics were evaluated, including anticoagulants use and underlying diseases. Results: Postoperative bleeding was detected in 75 patients (6.9%), and perforation was detected in 40 patients (3.7%). Most postoperative bleeding and perforation cases were recovered with endoscopic procedures, although one case of each complication was treated by emergency surgery. Multivariate analysis indicated that risk factors for perforation were tumor location, massive submucusal invasion, endoscopists’ experience of 100–149 cases and hypertension, and that risk factors for postoperative bleeding were tumor location, resected tumor size, and scar lesion. The serious complications were not different between high- and low-volume centers. Conclusions: The present study indicated that risk factors for perforation during endoscopic submucosal dissection were tumor, endoscopist and patient related, although risk factors for postoperative bleeding were tumor related. There was no difference in complications between high- and low-volume centers.

Risk factors for postoperative bleeding after thyroid surgery (Br J Surg 2012; 99: 373–379)

Risk factors for postoperative bleeding after thyroid surgery (<i>Br J Surg</i> 2012; 99: 373–379)

Risk factors for postoperative bleeding after thyroid surgery

Postoperative bleeding after thyroid surgery is a feared and life-threatening complication. The aim of the study was to identify risk factors for postoperative bleeding, with special emphasis on the impact of the individual surgeon and the time to diagnosis of the complication. Data on consecutive thyroid operations were collected prospectively in a database over 30 years and analysed retrospectively for potential risk factors for postoperative bleeding. There were 30,142 operations and postoperative bleeding occurred in 519 patients (1·7 per cent). Risk factors identified were older age (odds ratio (OR) 1·03 per year), male sex (OR 1·64), extent of resection (OR up to 1·41), bilateral procedure (OR 1·99) and operation for recurrent disease (OR 1·54). The risk of complications among individual surgeons differed by up to sevenfold. Postoperative bleeding occurred in 336 (80·6 per cent) of 417 patients within the first 6 h after surgery. Postoperative bleeding was diagnosed after 24 h in ten patients (2·4 per cent), all of whom had bilateral procedures. Nine patients required urgent tracheostomy. Three patients died, giving a mortality rate of 0·01 per cent overall and 0·6 per cent among patients who had surgery for postoperative bleeding. Observation for up to 24 h is recommended for the majority of patients undergoing bilateral thyroid surgery in an endemic goitre area. Same-day discharge is feasible in selected patients, especially after a unilateral procedure. Quality improvement by continuous outcome monitoring and retraining of individual surgeons is suggested.

Nationwide Multicenter Study on Posttonsillectomy Bleeding

Objective: 1) Assess risk factors for the frequency of postoperative hemorrhage. 2) Apply a new classification of postoperative hemorrhage using a clear definition and 7 grades depending on severity. 3) Assess multiple bleeding episodes after tonsil surgery. Method: The study is based on a complete census of tonsillectomies (TE), tonsillotomies (TO), and adenoidectomies (AE) within 9 months in Austria. Postoperative hemorrhage was defined as every bleeding episode after extubation and classified in grades A1, A2, B1, B2, C, D, and E according to severity and the treatment needed. Results: Included were 9,405 patients: 48.5% TE with or without (±) AE, 37.1% AE, and 14.0% TO ± AE. Postoperative hemorrhage was far more frequent for TE than for TO or AE ( P &lt; .001). A return to theater was necessary for 4.6% after TE. Adults had a significantly higher risk of postoperative bleeding than children for all types of surgeries ( P &lt; .05). Males had a significantly higher risk of postoperative bleeding episodes ( P &lt; .05). The “hot” operation techniques (bipolar diathermy or Coblation) showed a significantly increased risk of hemorrhage ( P &lt; .05). The evidence of a light bleeding episode increased the risk of a severe bleeding episode ( P &lt; .05). Conclusion: Assessing all grades of postoperative hemorrhage offers a far more precise picture about postoperative bleeding. Risk factors for postoperative hemorrhage have been the type of surgery, age, and operation technique.

Risk factors for postoperative hemorrhage following tonsillectomy

To identify the main risk factors associated with postoperative hemorrhage following tonsillectomy. Prospective multicenter observational study. The Surgical Instrument Surveillance Programme (SISP) was established in 2003 to monitor tonsil and adenoid surgery and the associated complications in all hospitals in Wales. Data were examined between April 1, 2003, and June 30, 2008, by using binary logistic regression, for risk factors that may contribute to primary (R1) or secondary (R2) postoperative hemorrhage of a severity sufficient to require a return to the operating theater. A total of 17,480 procedures were included. Patients aged ≥12 years were 1.5 (1.0-2.1; P < .05) and 3 times (2.2-4.9; P < .0001) more likely to experience R1 and R2 complications, respectively. There were 2.5 times as many females as males aged ≥12 years who underwent tonsillectomy, but males were almost twice as likely to experience R1 (1.4-2.8), P < .0001, or R2 (1.2-2.5), P < .001, postoperative hemorrhage. There was a 1.9-fold increased likelihood of R1 (1.1-3.3), P < .05, with the most junior surgeon, and no relationship with R2. All techniques that used heat had a significantly greater adjusted odds of R2 as compared with cold dissection, with odds ranging from 2.7 (1.5-4.7), P < .001, for dissection plus bipolar diathermy and ties, to 13.0 (5.8-29.1), P < .0001, with coblation when used with other techniques. No additional risk was associated with specified single-use instruments. Patient age and sex and operative technique were the most significant factors affecting the risk and timing of serious postoperative hemorrhage, with no additional risk associated with the use of specified single-use instruments.

Prevention and nursing for postoperative hemorrhage among patients with thyroid surgery

Objective In order to know the proper prevention and nursing measures for postoperative hemorrhage among patients with tyroid surgery. Methods Analized the medical history of 19 patients with postoperative hemorrhage after thyroid surgery retrospectively. Results The 19 patients with postoperative hemorrhage were all recovery smoothly by careful nursing and proper treatment. Conclusions Uncomplete intraoperative hemostasis, intraoperative breathholding and improper placement of drainage structures are the risk factors for postoperative hemorrhage. Careful postoperative observation and nursing can avoid certain postoperative hemorrhage. Key words: Thyroid; Postoperative hemorrhage; Prevention; Nursing

Risk factors for complications of endoscopic submucosal dissection in gastric tumors: analysis of 478 lesions

Endoscopic submucosal dissection (ESD) technique has facilitated en bloc removal of widely spread lesions from the stomach. This retrospective study aimed to determine factors associated with serious complications of ESD. Between December 2001 and March 2007, we have performed ESD for 478 lesions in 436 patients. We experienced 39 patients with post-operative bleeding and 17 patients with perforation. Risk factors of patients who received ESD in gastric mucosal tumors for complications were evaluated, focusing on resected size, location, scar lesions, operation time, and experience of endoscopists. We evaluated the patients' background characteristics including sex, age, body mass index (kg/m(2)), drug history of anticoagulant, and underlying diseases including cerebrovascular disorder, ischemic heart disease, liver dysfunction, renal dysfunction, hyperuricemia, hypertension and diabetes mellitus. Multivariate analysis indicated a risk factor for perforation was long operation time. Multivariate analysis indicated a significant risk factor for post-operative bleeding was size of the resected tumor. This study indicated risk factors for serious complications of ESD. Large resected tumor size was a risk factor for post-operative bleeding, while long operation time was a risk factor for perforation. Information regarding operation risk factors should be useful for planning strategies for ESD.

Posters_Tuesday 13 October 2009

INTRODUCTION. Cardiopulmonary bypass (CPB) affects platelets, and platelet dysfunction is considered to be an important risk factor for post-operative bleeding after coronary artery bypass graft (C ...

Diathermy power settings as a risk factor for hemorrhage after tonsillectomy

To investigate bipolar diathermy power settings as a risk factor for postoperative hemorrhage following tonsillectomy. A prospective cohort study was undertaken between July 2003 and September 2004 in National Health Service (NHS) and independent hospitals in England and Northern Ireland. Data were collected on patient characteristics, tonsillectomy technique, and postoperative hemorrhage within 28 days of surgery. Among the 9572 patients who had a tonsillectomy performed with bipolar diathermy dissection and hemostasis, the overall rate of hemorrhage was 4.6 percent and the risk of hemorrhage was not associated with the diathermy power setting. Among the 8465 patients who had tonsillectomy with cold steel dissection and bipolar diathermy hemostasis, the rate of hemorrhage increased from 1.8% in patients with the lowest power settings (6 to 8 watts) to 3.7% in those with settings above 18 watts (P value for trend = 0.005). In tonsillectomies using cold steel dissection and bipolar diathermy for hemostasis, the risk of postoperative hemorrhage becomes greater as diathermy power increases.

ABO blood group and bleeding after coronary artery bypass graft surgery

Low circulating von Willebrand factor levels increase the risk of bleeding after cardiac surgery. Patients with blood group O may be at greatest risk owing to lower baseline levels of von Willebrand factor compared with patients with other blood groups, and perioperative hemodilution during cardiac surgery may reduce von Willebrand factor to critical levels in these patients. This study tested the hypothesis that patients with blood group O are at increased risk for postoperative bleeding following cardiac surgery, and determined whether the blood group affected perioperative assessment of primary hemostasis. Using multivariate linear regression models that included preoperative and intraoperative covariates, the risk factors for postoperative bleeding were evaluated in 877 patients undergoing primary, nonemergent coronary artery bypass surgery at a university hospital. In a subset of these patients, we measured perioperative in-vitro bleeding times (PFA-100 analyzer) to determine whether there were measurable differences in primary hemostasis between patients with blood type O and those with other blood groups. Patients with blood group O did not have increased bleeding after cardiac surgery compared with patients with other blood types. In addition, while blood group O patients had laboratory evidence for abnormal primary hemostasis before surgery, there were no measurable differences in postoperative primary hemostasis in patients with different blood types. In conclusion, although we identified clinical and procedural factors that were independently associated with bleeding, blood group was not one of these factors.

Preoperative Fibrinogen Levels as a Predictor of Postoperative Bleeding after Open Heart Surgery

Open heart surgery still involving major bleeding continues to be a major challenge after cardiac surgery and is also a significant cause of morbidity and mortality. Most hemostatic factors are intercorrelated with postoperative bleeding, and fibrinogen seems the most fundamental hemostatic risk factor for open heart surgery. The study included 97 patients who underwent elective coronary artery surgery (78 men and 19 women; mean age, 60.9 +/- 10.3). Preoperative blood samples were obtained and preoprative quantitative determination of plasma fibrinogen levels were measured by the clotting method of Clauss using the fibrinogen kit. Patients were operated on by the same team and the same technique. The total amount of drainage blood from chest tubes was recorded after termination of operation. There were statistical significance between the fibrinogen levels and the drainage (r = -0.897, P < .001). Chest drainage was a mean of 972 mL (range, 240-2445 mL) in the first 48 hours after sternotomy closure. Fibrinogen level and relation to age was statistically significant (P = .015). There was no statistical significance between fibrinogen levels and gender (male gender = 400.7 +/- 123.0 versus female gender = 395.6 +/- 148.1; P = .877) and between drainage and gender (male gender = 968.2 +/- 538.5 versus female gender = 990.0 +/- 554.7; P = .876). Two patients (2%) died early after the surgery. There were no significant differences between the postoperative bleeding and cardiopulmonary bypass time (P = .648) or cross-clamp time (P = .974). The results of this study suggested that low preoperative fibrinogen level appears to be a useful diagnostic marker to assess the activity of the coagulation system, and that its preoperative level may serve as a potential risk factor for postoperative bleeding after coronary artery bypass surgery.

Bleeding complications in skin cancer surgery are associated with warfarin but not aspirin therapy

The aim was to identify risk factors for postoperative bleeding following skin cancer surgery. This was a prospective study of 5950 skin lesions excised in 2394 patients. No patient stopped taking aspirin or warfarin unless the international normalized ratio (INR) exceeded 3.0. The rate of postoperative bleeding was 0.7 per cent overall and 2.5 per cent in the 320 patients taking warfarin. The rate of bleeding was 1.0 per cent for skin flap repairs, 0.4 per cent for simple excision and closure, and 5.0 per cent for skin grafts. Diabetic patients and smokers were not at increased risk of bleeding. There were four independent factors for bleeding: age 67 years or older (odds ratio (OR) 4.7 (95 per cent confidence interval 1.8 to 12.2); P = 0.002), warfarin therapy (OR 2.9 (1.4 to 6.3); P = 0.006), surgery on or around the ear (OR 2.6 (1.2 to 5.7); P = 0.012) and closure with a skin flap or graft (OR 2.7 (1.4 to 5.3); P = 0.004). Aspirin therapy was not an independent risk factor for bleeding. Most postoperative bleeds were inconvenient but not life threatening, unlike the potential risk of thromboembolism after stopping warfarin or aspirin. There was no case for discontinuing aspirin before skin surgery, but the INR should be monitored in patients taking warfarin.

Risk Factors for Postoperative Hemorrhage after Vitrectomy for Diabetic Retinopathy

Objective: To identify the potential risk factors for postvitrectomy diabetic vitreous hemorrhage (PDVH). Methods: A matched case-control nested into a retrospective follow-up study was done to review the surgical results in 68 consecutive eyes undergoing primary pars plana vitrectomy for vitreous hemorrhage. The eyes were divided into two groups based on the presence of PDVH (19 cases and 49 controls) and were matched on surgeon and the date of surgery. Twenty-three factors related to the preoperative examination and eight factors related to the operative procedure were analyzed. Statistical analysis was based on conditional logistic regression models with PDVH as the dependent variable. The mean follow-up interval was six months. Results: The factors associated with the incidence of PDVH were iris neovascularization (OR = 9.8, P = 0.03), lower extremity amputations (OR = 8.3, P = 0.02) and the use of antihypertensive agents within three months before vitrectomy (OR = 0.2, P = 0.04). Phakic and aphakic eyes of diabetic patients with lower extremity amputations would have a 70% probability of developing PDVH. This probability would have dropped to 30–40% had they been taking antihypertensive treatment. Conclusions: Iris neovascularization and lower extremity amputations increase the risk of PDVH. Antihypertensive treatment before vitrectomy decreases this risk.

Fatores de risco de sangramento no pós-operatório de cirurgia cardíaca em pacientes adultos

OBJETIVO: Determinar os fatores de risco de sangramento no pos-operatorio de cirurgia cardiaca, na tentativa de racionalizar as medidas preventivas em populacoes especificas. METODO: No periodo outubro de 2001 a marco de 2002, foram estudados prospectivamente 411 pacientes consecutivos submetidos a tratamento cirurgico de cardiopatias adquiridas, excluindo o transplante cardiaco. No intuito de identificar os fatores preditores de sangramento excessivo, foram analisadas 20 variaveis pre-operatorias, 17 operatorias e seis pos-operatorias por analise univariada e regressao linear multipla. RESULTADOS: Os procedimentos cirurgicos incluiram a revascularizacao do miocardio em 227 (55,2%) pacientes, cirurgia valvar em 198 (48,2%), tratamento cirurgico de doencas da aorta em 25 (6,1%) e procedimentos combinados em 60 (14,6%). A circulacao extracorporea foi empregada em 335 (81,5%) pacientes e o uso de drogas antifibrinoliticas em 148 (36%). A mortalidade em 30 dias foi de 5,6% (23 pacientes). O volume medio de sangramento em 24 horas foi de 610 ± 500 ml (variacao 10-4900). A revisao cirurgica de hemostasia foi necessaria em 15 (3,7%) pacientes. Os fatores preditores independentes de sangramento excessivo pos-operatorio foram a operacao de emergencia (p=0,049), acidose metabolica pos-operatoria (p=0,001), plaquetopenia pre-operatoria (p=0,034) e tempo prolongado de circulacao extracorporea (p=0,021). CONCLUSOES: Pacientes submetidos a operacoes de emergencia e aqueles com plaquetopenia necessitam, na medida do possivel, de otimizacao das condicoes clinicas pre-operatorias. O uso de circulacao extracorporea deve ser minimizado ao maximo, principalmente em relacao a sua duracao. A acidose metabolica no pos-operatorio deve ser corrigida agressivamente, na busca da sua causa principal.

Preoperative use of enoxaparin is not a risk factor for postoperative bleeding after coronary artery bypass surgery

Background The purpose of this study was to determine whether the use of low-molecular-weight heparin before coronary artery bypass surgery would be associated with an increase in bleeding and use of blood products after the operation. Methods Sixty-four patients (48 men and 16 women) aged 64 ± 10 years who were undergoing primary coronary artery bypass surgery were prospectively studied. Forty-one patients were treated with either subcutaneous enoxaparin 1 mg/kg twice daily (n = 21; enoxaparin group) or intravenous heparin (n = 20; heparin group). Patients received the last dose of enoxaparin 8.7 ± 0.75 hours (range, 8-10 hours) before skin incision. Heparin was stopped before transfer to the operating room. An additional 23 consecutive patients who received neither enoxaparin nor heparin served as controls (n = 23). Anti–factor Xa activity, a measure of enoxaparin and heparin activity, was measured at the start of the operation in all patients. Results There was no perioperative mortality. The length of stay and frequency of postoperative complications were similar between groups. Preoperative anti–factor Xa activity was present only in the enoxaparin group (0.43 ± 0.25 IU/mL). Chest tube drainage at 24 hours was 553 ± 160 mL, 532 ± 140 mL, and 587 ± 230 mL for the enoxaparin, heparin, and control groups, respectively ( P = .48). There was no difference among groups in the amount of blood products transfused. Conclusions Enoxaparin administration more than 8 hours before coronary artery bypass surgery is not associated with increased postoperative bleeding or blood product transfusion.

Chronic kidney disease as a risk factor for bleeding complications after coronary artery bypass surgery

Background: The aim of the study is to define the role of chronic kidney disease (CKD) as a risk factor for postoperative bleeding in patients undergoing coronary artery bypass graft (CABG) surgery. Methods: This is a retrospective cohort study of 238 consecutive patients who underwent isolated CABG surgery. Patients were followed up for the event of a significant bleed, defined as administration of either three or greater units of packed red blood cells, three or greater units of platelets, three or greater units of fresh frozen plasma, or any cryoprecipitate within 72 hours after a CABG procedure or undergoing a surgical revision for bleeding. Glomerular filtration rate (GFR) at baseline was calculated using the Cockroft-Gault formula. A final multiple logistic regression model was selected from a large set of presurgical and intraoperative covariates by using backward elimination (P > 0.20). Results: After controlling for age, sex, elective versus emergent surgery, intraoperative activated clotting time, serum albumin level, extracorporeal bypass time, and baseline hematocrit, we found that even mild levels of renal impairment were associated with increased risk for postoperative bleeding: patients with a GFR of 40 mL/min or less had six times the odds of postoperative bleeding than patients with a GFR greater than 100 mL/min (odds ratio [OR], 6.51; 95% confidence interval [CI], 1.87 to 22.66); those with a GFR of 41 to 60 mL/min had nearly four times the risk (OR, 3.87; 95% CI, 1.21 to 12.35). Even patients with mild CKD at a GFR of 61 to 80 mL/min were at an elevated risk (OR, 2.11); however, the 95% CI of 0.79 to 5.64 included the null value. Similar results were found when using the cruder Kidney Disease Outcomes Quality Initiative classification of CKD. Conclusion: CKD is associated with risk for postoperative bleeding in patients undergoing CABG surgery, not only at more advanced stages, but probably at relatively mild levels of renal impairment, as well. Am J Kidney Dis 41:84-89. © 2003 by the National Kidney Foundation, Inc.

The effect of "high dose" aprotinin and other factors on bleeding and revisions for bleeding in adult coronary and valve operations: an analysis of 2190 patients during a five-year period (1987-1991).

We retrospectively evaluated risk factors for postoperative bleeding and for revisions due to bleeding in 2190 adult coronary and valve patients who underwent surgery at our hospital during the 5-year period from 1987 to 1991. During this period 889 (40.6%) patients were given "high dose" aprotinin. Their mean age was 59.3 +/- 8.8 years, 1636 (74.7%) were males, 200 (9.1%) underwent surgery on an emergency basis and 72 patients (3.3%) underwent redo-operations. The patients were divided into four groups according to the type of surgery: all patients pooled together (2190), coronary artery surgery patients (1384, 63.2%, group I), valve surgery patients (706, 32.2%, group II) and combined (coronary plus valve) surgery patients (100, 4.6%, group III). Stepwise logistic regression analysis, performed to assess the risk factors for revisions due to bleeding showed aprotinin treatment to be the sole protective factor in all patients, group I and group II. In group III only the use of a hollow fiber membrane oxygenator proved a protective factor. Risk factors for revisions for bleeding were found to be aortic cross-clamp time in all patients, group I and group II. Use of the internal thoracic artery (ITA) was significant in group I patients and age at operation in group II. Multiple stepwise linear regression analysis, performed to evaluate the effect of various risk factors on cumulative postoperative blood loss in all patients, confirmed aprotinin as the only factor capable of reducing blood loss, while aortic cross-clamp time, coronary surgery and male gender showed a positive linear relation with postoperative bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)