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Anticoagulation, bleeding and blood transfusion practices in Australasian cardiac surgical practice.

SUMMARY

We surveyed contemporary Australasian cardiac surgical and anaesthetic practice, focusing on antiplatelet and antifibrinolytic therapies and blood transfusion practices. The cohort included 499 sequential adult cardiac surgical patients in 12 Australasian teaching hospitals. A total of 282 (5791o) patients received red cell or component transfusion. The median (I OR) red cell transfusion threshold haemogloblin levels were 66 (61-73) gel intraoperatively and 79 (74-85) gel postoperatively Many (40%) patients had aspirin within five days of surgery but this was not associated with blood loss or transfusion, 15% had clopidogrel within seven days of surgery. In all, 30 patients (6%) required surgical re-exploration for bleeding Factors associated with transfusion and excessive bleeding include pre-Existing renal impairment, preoperative clopidogrel therapy, and complex or emergency surgery. Despite frequent (67%) use of antifibrinolytic therapy, there was a marked variability in red cell transfusion rates between centres (range 17 to 79%, P < 0.001). This suggests opportunities for improvement in implementation of guidelines and effective blood-sparing interventions Many patients presenting for surgery receive antiplatelet and/or antifibrinolytic therapy, yet the subsequent benefits and risks remain unclear.

Key Words: anticoagulation, antiplatelet, antifibrinolytic, blood transfusion, red cells, bleeding

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Approximately 28,000 cardiac surgical procedures are done in Australia and New Zealand each year, mostly coronary artery bypass surgery (CABG). While the majority of patients benefit, some die or suffer long-term disability (1). Postoperative complications, including myocardial infarction, heart failure and stroke, increase morbidity and the costs associated with hospital and post discharge care (2,3).

Blood loss and the subsequent administration of blood products is associated with increased morbidity and mortality in cardiac surgery patients. Existing data support a link between blood transfusion utilisation and worse outcome (4-6). In contrast, severe anaemia could also increase the risk of complications.

There is limited information regarding blood product, antifibrinolytic and anticoagulant use in Australasian cardiac surgical and anaesthetic practice. Accordingly, we planned a prospective cohort study. The key objectives were to define the use of antiplatelet and antifibrinolytic therapies, the extent of surgical bleeding, blood transfusion practices and rates of complications.

METHODS

In anticipation of conducting a larger multicentre trial (www.atacas.org.au), 13 hospitals were approached to participate in this audit. Twelve hospitals across Australia (n= 10),New Zealand (n= 1) and Hong Kong (n= 1) agreed to participate. Human Research Ethics Committee approval was obtained at all centres and the requirement for informed consent was waived as the study was considered a quality assurance exercise.

All consecutive adult patients presenting for cardiac surgery in the month of November 2004 were included. Eligible surgery included CABG surgery, valve repair or replacement, cardiac tumour resection, cardiac transplantation, ventricular assist device insertion or central extra-corporeal membrane oxygenation (ECMO) and aortic surgery with cardiopulmonary bypass (CPB). We excluded those undergoing minor or intermediate procedures: sternal debridement, ECMO support via femoral cannulation (alone), pericardial procedures, cardiac biopsy or pacemaker insertion. Patients who were returned to the operating theatre within one week of primary surgery were also excluded.

We collected data on patient demographics and comorbidities, surgical and anaesthetic procedures, blood loss and blood transfusion practices. The cardiac anaesthetist prospectively collected these data at the time of surgery; missing data were retrieved via a medical record review by the site coordinator. Thirty-day morbidity and mortality data were collected by medical record review and telephone contact with the patient on or after day 30. The study population was sub-classified into primary CABG (the most prevalent type of cardiac surgery) and valvular/other surgeries.

Blood loss was measured as postoperative mediastinal drainage. Although this approach is commonly used in cardiac surgery (7), it has the limitation that it does not include blood lost intraoperatively or blood discarded with the CPB circuit.

We used the following transfusion terms:

* Red cell transfusion--the transfusion of packed red blood cells or whole blood.

* Component transfusion--the transfusion of platelets, fresh frozen plasma or cryoprecipitate.

* Blood transfusion--the transfusion of packed red blood cells, whole blood, platelets, fresh frozen plasma or cryoprecipitate.

Data are presented as median (IQR) and number (%) unless otherwise specified. All descriptive and comparative analyses were undertaken using STATA v9 (StataCorp. 2005, Stata Statistical Software: Release 9.0 College Station, TX: StataCorp) and SPSS for Windows 04 (SPSS Inc. Chicago, IL, U.S.A.). Median and range values for continuous variables and frequency tabulation for discrete variables were calculated to characterise the study population. Comparisons of continuous and discrete variables were done using Wilcoxon rank sum test and odds ratio (OR) and 95% confidence interval (CI), respectively. The associations between clinical parameters and excessive bleeding were examined in univariate analyses using chi square tests and significant (P < 0.01) factors included in a multivariable analyses using logistic regression. A P value of less than 0.05 was considered statistically significant.

RESULTS

During the study period, 499 patients met the inclusion criteria and data were collected for 498 patients (inclusion rate > 99%). Patient demographics and surgical risk factors are presented in Table 1. Nearly half (204/498 [41%]) of the patients underwent non-elective surgery and in these cases this resulted in antiplatelet agents not being stopped at least five days prior to surgery. Subsequently, 40% of patients (199/498) had taken aspirin within five days of their surgery and half of these were administered aspirin within 24 hours of surgery (Figure 1); 15% of patients had taken clopidogrel within seven days of surgery.

[FIGURE 1 OMITTED]

Two-thirds of patients (329/498) were administered antifibrinolytic drug therapy (aprotinin 42% [36% full-dose, 6% half-dose], tranexamic acid 25%) (Table 2).

Recent aspirin, defined as exposure within five days of surgery, had no apparent effect on bleeding: total mediastinal blood loss, aspirin 670 (466-1216) ml versus no aspirin 700 (463-1175) ml, FL- 0.84 (Table 3).

The overall blood transfusion rate was 57% (284/498), with red cell transfusion used in 49% (244/498) and component transfusion used in 27% (134/498). There was significant variation in red cell transfusion rates between centres (range 17 to 79%, P < 0.001) (Figure 2). The majority of patients who received red cell transfusion were given only one or two units (Figure 3).

The association between antiplatelet or anticoagulant therapy and transfusion is demonstrated in Table 4. Recent clopidogrel therapy was associated with increased component transfusion. Recent aspirin or warfarin exposure did not affect the rate of red cell or other transfusion (transfusion rate aspirin patients 58.3% vs. transfusion rate for non-aspirin patients 56.5%, P=0.69).

We estimated the transfusion trigger using the lowest haemoglobin level in patients who received red cell transfusion. Intraoperatively, the lowest recorded haemoglobin level was 66 (61-73) mg/l. Postoperatively, the lowest recorded haemoglobin was 79 (74-85) mg/l.

[FIGURE 2 OMITTED]

The overall rate of surgical re-exploration for bleeding was 6% (primary CABG 4.2%, other cardiac surgery 8%) (Table 5). Factors associated with transfusion and reoperation for excessive bleeding include pre-existing renal impairment, clopidogrel therapy, high risk procedure and complex (other than primary CABG) (Table 6). Emergency surgery was associated with increased reoperation for excessive bleeding.

[FIGURE 3 OMITTED]

DISCUSSION

Clinicians caring for cardiac surgical patients are faced with an increasing proportion of patients of advanced age and complexity. Our study demonstrates that the transfusion of allogeneic blood products is a common intervention in cardiac surgery and that preoperative or antiplatelet agents (clopidogrel but not aspirin) are associated with increased rates of transfusion.

In our study, about half (49%) of all cardiac surgical patients received a red cell transfusion. The purported link between transfusion and worse outcome raises some concern (4,5,8). However, severe anaemia has its own complications including increased risk of death (9). Blood transfusion may be associated with immunosuppression, ABO incompatibility, transfusion-related acute lung injury and an overall worse outcome that is multifactorial and complex due to microcirculation dysfunction (10). Platelet transfusion may increase the risk of stroke and deaths (11).

An observation study of 11,963 CABG surgery patients over a seven-year period at the Cleveland Clinic in the U.S.A. (6), of which 5,814 (49%) were transfused, found that red cell transfusion was associated with renal failure (OR 2.06 [95% CI, 1.87-2.27]), prolonged ventilatory support (OR 1.79 [95% CI, 1.72-1.86]), serious infection (OR 1.76 [95% CI, 1.68-1.84]), cardiac complications (OR 1.55 [95% CI, 1.47-1.63]), neurologic events (OR 1.37 [95% CI, 1.30-1.44]) and mortality (OR 1.77 [95% CI, 1.67-1.87]). The mortality increase was evident one year out from cardiac surgery. Mortality related to transfusion was dose-dependent: the more a patient received, the worse was the survival curve. However this study, despite using propensity matching to control for confounding, is prone to bias. The observed associations require randomised trials to demonstrate causation, but such trials of blood transfusion are rare. Hebert et al (12) conducted the largest randomised trial of transfusion to date, in 838 patients managed in an intensive care unit. In this landmark study patients were randomly allocated to receive red cell transfusion at a transfusion trigger of either 70 g/1 (restrictive group) or 100 g/1 (liberal group). Their data showed a trend towards lower overall mortality in their restrictive group, 19% vs. 23%, FL -0.11. Also the mortality rate during hospitalisation was significantly lower in the restrictive strategy group, 22% vs. 28%, FL- 0.05. The results of this trial have led to a more restrictive transfusion policy becoming a standard of care in critically ill patients. However, a later publication reporting on a subgroup of patients with severe coronary artery disease found that the restrictive group had poorer, but non-significant survival compared with the patients in the liberal group (13). This has led to a higher transfusion trigger, typically 90 g/l, in patients with coronary artery disease.

Recent randomised trials evaluating the use of leucodepleted red cell transfusion in cardiac surgery have shown at least a 50% reduction in infection and mortality with this intervention (14,15). Leucodepletion has subsequently been recommended as a standard for cardiac surgery patients (10).

Options for reducing transfusion in surgery include optimising red cell mass preoperatively, reducing blood loss, restrictive transfusion policy and utilisation of blood substitutes. Although the efficacy of these interventions warrants further investigation, the Society of Thoracic Surgeons and Society of Cardiovascular Anesthesiologists have recently published guidelines for blood transfusion and conservation (10). Key recommendations include:

1. Drugs that increase preoperative blood volume (e.g. erythropoietin) or decrease postoperative bleeding (e.g. antifybrinolytics).

2. Devices that conserve blood (e.g. intraoperative blood salvage and blood sparing interventions).

3. Interventions that protect the patients own blood from the stress of operation (e.g. autologous predonation and normovolaemic haemodilution).

4. Consensus, institution -specific blood transfusion algorithms supplemented with point-of-care testing.

5. Most importantly, a multimodal approach to blood conservation combining all of the above.

There is good rationale for preoperative optimisation of red cell mass. In some circumstances, a delay in surgery may be warranted to allow treatment with iron, folate and possibly erythropoietin (10). However in our study, 40% of cardiac surgical patients were non-elective, effectively precluding many patients from benefiting from such interventions.

In our study many patients presenting for surgery were receiving antiplatelet and other medications that impair coagulation and increase blood loss. There is a paucity of data to establish the true risk/benefit of continuing these medications in the perioperative period.

We found that recent aspirin therapy had no measurable effect on blood loss in this cardiac surgical population. Aspirin impairs platelet function (16) and so could reduce further risk of myocardial infarction or stroke, and graft thrombosis (17), but in other studies has a small effect on bleeding (18). It is routine practice in most cardiac surgical units to recommend stopping aspirin five to seven days before elective cardiac surgery. But, as was demonstrated in our study, contemporary cardiac surgical practice often does not allow an opportunity for this to occur because of the shortened time between presentation with an acute coronary syndrome and surgery. Belisle and Hardy (18) reviewed more than 50 studies including more than 10,000 patients, as well as data from 5,426 patients. They concluded that although aspirin therapy increases postoperative blood loss, it was by less than 300 ml and therefore should not increase the use of blood products if a strict transfusion protocol were followed. A large randomised trial of aspirin administration in cardiac surgery is warranted to evaluate whether the proposed beneficial effects of aspirin outweigh the potential increase in bleeding and possibly transfusion.

In contrast to aspirin, we found that recent exposure to clopidigrel was a risk factor for blood transfusion and in particular for component transfusion, despite most of these patients receiving antifibrinolytic therapy. Hongo et al (19) studied 224 consecutive patients undergoing primary elective CABG and compared those with preoperative clopidogrel exposure within seven days (n= 59) to those without exposure (n= 165). The clopidogrel group had greater blood loss and transfusion requirements and a tenfold increase in re-operation for bleeding (6.8% vs. 0.6%, FL- 0.018). These findings highlight the concern regarding the routine administration of clopidogrel for coronary stenting in patients subsequently needing CABG surgery.

Antifibrinolytics were used extensively in our study, particularly in non-CABG surgery. This may reflect concerns about excessive blood loss in some settings and with aprotinin use and graft patency in CABG surgery (7,20). Our survey design cannot reliably investigate the relationship between blood loss, mortality and antifibrinolytic therapy.

Several recent meta-analyses of randomised trials have found that antifibrinolytic therapy reduces blood loss, the need for blood transfusion and re-operation for bleeding in many types of cardiac surgery (21-23). Such therapy may also have a beneficial effect on mortality (22). However, despite this high level evidence, there is some concern that anti-fibrinolytic therapy may increase the risk of complications after cardiac surgery (7,20,24). The three main safety issues related to antifibrinolytic drugs are hypersensitivity reactions, renal dysfunction and potential thrombotic events. One controversial study has raised major safety concerns with aprotinin (24). This retrospective observational study used propensity matching and multivariable logistic regression techniques to attempt to compensate for confounding introduced because of lack of randomisation. Despite this, the possibility exists that not all bias was eliminated (25). Such studies are useful in generating hypotheses, but lack certainty in their results. More definitive data on the safety of antifibrinolytic drugs should be available from several trials currently underway.

Allogenic blood product administration is associated with morbidity and mortality in cardiac surgery (4-6,8,10,11). In our region, more than half of cardiac surgery patients receive a blood transfusion. We found that intraoperative red cell transfusion occurred at a haemoglobin level of 66 (61-73) mg/1 and postoperative red cell transfusion occurred at a haemoglobin level of 79 (74-85) mg/1. These results are reassuring and in keeping with existing guidelines (10,18). There was wide variation in the rate of transfusion between centres in our study, as has been reported elsewhere (26), supporting a need for transfusion guidelines. The risks and benefits of aspirin and antifibrinolytics require evaluation in large randomised trials.

ACKNOWLEDGEMENTS

Participating hospitals: (in alphabetical order): Alfred Hospital (Vic), Auckland City Hospital (NZ), Austin Health (Vic), Flinders Medical Centre (SA), Geelong Hospital (Vic), Monash Medical Centre (Clayton, Vic), Westmead Hospital (NSW), Prince of Wales Hospital (Hong Kong), Royal North Shore (NSW), Royal Perth Hospital (WA), St.Vincent's Hospital (Vic) and Sir Charles Gairdner Hospital (WA).

The authors wish to thank the many individuals who contributed their time and energy to this project: David Sidebotham, Mark Priestly, Caroline Yeoh, Jennifer Cope, Ian Nicholson, Richard Chard, Robert Costa, Hugh Paterson, Bill Meldrum-Hanna, Stephen Barratt, John Brereton, Adam Tucker, Elli Tutungi, Cassie Lowe, Peter Lillie, John Knight, Louise Pigot, Donald Esmore, Aushra Saldukas, Brendan Silbert, Simone Said, Anthony Wilson, Michael Yii, Ian Nixon, Alex Rosalion, Tony Plowman, Morteza Mohajeri, David Story, Stephanie Poustie, Brian Buxton, Matthew Chan, Ahmed Arifi, Chris Cokis, Robert Larbalestier and Shauna Fatovich.
APPENDIX
Definition of comorbidities and morbidities

Preoperative comorbidities Postoperative morbidity

Smoking--current or Serious bleeding--bleeding
previous history or tamponade necessitating
 return to theatre

Diabetes--type I or type Myocardial infarction--at
II including diet controlled least two of:

Renal impairment--creatinine Typical chest pain
>0.130 mmol/l

Hypertension--current or Enzyme rise
previous

Cerebrovascular New Q wave or left bundle
disease--carotid stenosis branch block on ECG
>70% or history of TIA or CVA

Peripheral vascular New arrhythmia--atrial
disease--symptomatic claudication fibrillation, supraventricular
or rest pain tachycardia, ventricular
 tachycardia or
 ventricular fibrillation

Myocardial infarction--Q New renal failure--serum
waves on ECG or prior diagnosis creatinine >0.20 mmol/l
 or increase >0.10 mmol/l

Angina--typical history Serious infection--evidence
 of a purulent discharge
 or collection

Heart failure--symptomatic Prolonged ventilation-->24
or echo diagnosis hours postoperative
 ventilation

Respiratory disease--symptomatic Acute lung injury--new
at any time ARDS or pulmonary embolus

 Mortality--30 day all
 cause


Accepted for publication on June 6, 2007.

REFERENCES

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(13.) Hebert PC, Yetisir E, Martin C, Blajchman MA, Wells G, Marshall J et al. Is a low transfusion threshold safe in critically ill patients with cardiovascular diseases? Crit Care Med 2001; 29:227-234.

(14.) van de Watering LM, Hermans J, Houbiers JG, van den Brock PJ, Bouter H, Boer F et al. Beneficial effects of leukocyte depletion of transfused blood on postoperative complications in patients undergoing cardiac surgery: a randomized clinical trial. Circulation 1998; 97:562-568.

(15.) Bilgin YM, van de Watering LM, Eijsman L, Versteegh MI, Brand R, van Oers MH et al. Double-blind, randomized controlled trial on the effect of leukocyte-depleted erythrocyte transfusions in cardiac valve surgery. Circulation 2004; 109:2755-2760.

(16.) Taggart D, Siddiqui A, Wheatly DJ. Low-dose preoperative aspirin therapy, postoperative blood loss, and transfusion requirements. Ann Thorac Surg 1990; 50:424-428.

(17.) Antithrombotic Trialists' Collaboration. Collaborative metaanalysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ 2002; 324:71-86.

(18.) Belisle S, Hardy JF. Hemorrhage and the use of blood products after adult cardiac operations: myths and realities. Ann Thorac Surg 1996; 62:1908-1917.

(19.) Hongo RH, Ley J, Dick SE, Yee RR. The effect of clopidogrel in combination with aspirin when given before coronary artery bypass grafting. J Am Coll Cardiol 2002; 40:231-237.

(20.) Alderman EL, Levy JH, Rich JB, Nili M, Vidne B, Schaff H et al. Analyses of coronary graft patency after aprotinin use: results from the International Multicentre Aprotinin Graft Patency Experience (IMAGE) trial. J Thorac Cardiovasc Surg 1998; 116:716-730.

(21.) Iaupacis A, Fergusson D. Drugs to minimize perioperative blood loss in cardiac surgery: meta-analyses using perioperative blood transfusion as the outcome. Anesth Analg 1997; 85:1258-1267.

(22.) Levi M, Cromheecke ME, de Jonge E, Prins MIL de Mol BJ, Briet E, et al. Pharmacological strategies to decrease excessive blood loss in cardiac surgery: a meta-analysis of clinically relevant endpoints. Lancet 1999; 354:1940-1947.

(23.) Henry DA, Moxey AJ, Carless PA, O'Connell D, McClelland B, Henderson KM et al. Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion. Cochrane Database Syst Rev 2001; 1:CD001886.

(24.) Mangano DT, Tudor IC, Dietzel C; Multicenter Study of Perioperative Ischemia Research Group; Ischemia Research and Education Foundation. The risk associated with aprotinin in cardiac surgery. N Engl J Med 2006; 354:353-365.

(25.) Datta M. You cannot exclude the explanation you have not considered. Lancet 1993; 342:345-347.

(26.) Hutton B, Fergusson D, Tinmouth A, McIntyre L, Kmetic A, Hebert PC. Transfusion rates vary significantly amongst Canadian medical centres. Can J Anaesth 2005; 52:581-590.

(27.) Parr KG, Patel MA, Dekker R, Levin R, Glynn R, Avorn J et al. Multivariate predictors of blood product use in cardiac surgery. J Cardiothorac Vase Anesth 2003; 17:176-181.

(28.) Despotis GJ, Files KS, Zoys TN, Hogue CW, Spitznagel E, Lappas DG. Factors associated with excessive postoperative blood loss and hemostatic transfusion requirements: a multivariate analysis in cardiac surgical patients. Anesth Analg 1996; 82:13-21.

D. J. DALY *, P. S. MYLES ([dagger]), J. A. SMITH ([double dagger]), J. L. KNIGHT ([section]), O. CLAVISI **, D. L. BAIN ([dagger][dagger]), R. CLEW ([double dagger][double dagger]), N. M. GIBBS ([section][section]), A. F. MERRY ***, ANZCA TRIALS GROUP

Cardiothoracic Unity Alfred Hospital; Austin Health, Monash Medical Centre Melbourne; Geelong Hospital, Geelong; St. Vincent's Hospital, Fitzoy Victoria; Royal Perth Hospital, Perth; Sir Charles Gairdner Hospital, Nedlands Western Australia; Flinders Medical Centre Bedford Park, South Australia, Royal North Shore, Westmead Hospital, Sydney, New South Wales, Australia; Auckland City Hospital, Auckland, New Zealand and Prince of Wales Hospital, Shatin, New Territories, Hong Kong

* M.B., B.S., F.A.N.Z.C.A., Staff Anaesthetist, Department of Anaesthesia and Perioperative Medicine, Alfred Hospital, Melbourne, Victoria.

([dagger]) M.B., B.S., M.P.H., M.D., F.C.A.R.C.S.I., F.A.N.Z.C.A., Professor and Director, Department of Anaesthesia and Perioperative Medicine, Alfred Hospital and Monash University, Melbourne, Victoria.

([double dagger]) M.B., B.S., M.S., F.R.A.C.S., F.A.C.S., Head, Cardiothoracic Surgery Unit, Monash Medical Centre and Professor, Department of Surgery, Monash University, Clayton and Steering Committee, ASCTS Victorian Cardiac Surgery Database, Victoria.

([section]) M.B., B.S., F.R.A.C.S., Head, Cardiac Services, Flinders Medical Centre and Associate Professor, Department of Surgery, Flinders University, Bedford Park, South Australia.

** B.Sc. (Hens.), M.P.H., Research Coordinator, ANZCA Trials Group, Australian and New Zealand College of Anaesthetists, Melbourne, Victoria.

([dagger][dagger]) M.B., B.S., F.A.N.Z.C.A., Staff Anaesthetist, Department of Anaesthesia and Perioperative Medicine, Alfred Hospital, Melbourne, Victoria.

([double dagger][double dagger]) M.B., B.S., Registrar, Green Lane Department Anaesthesia, Auckland City Hospital, Auckland, New Zealand.

([section][section]) M.B., B.S., M.D., F.A.N.Z.C.A., Director, Department of Anaesthesia, Sir Charles Gairdner Hospital, Perth, Western Australia.

*** M.B., B.S., M.D., F.A.N.Z.C.A., Specialist Anaesthetist, Green Lane Department Anaesthesia, Auckland City Hospital and Professor of Anaesthesiology, University of Auckland, Auckland, New Zealand.

Address for reprints: Dr D. Daly, Department of Anaesthesia and Perioperative Medicine, The Alfred Hospital, Commercial Road, Melbourne, Vic. 3004.
TABLE 1
Patient demographics, medical conditions and drug therapies by
type of cardiac surgery

 Primary
 CABG surgery*
 (n=285)

Mean (SD) age, y 66 (10)

Male gender 77%

Current or previous smoking 69%

Pre-existing medical conditions

Diabetes 33%

Renal impairment 11%

Hypertension 73%

Cerebrovascular disease 10%

Peripheral vascular disease 11%

Respiratory disease 14%

Myocardial infarction 55%

Current angina 89%

Heart failure 11%

Current endocarditis 1%

Preoperative anticoagulant drug therapy

Aspirin within five days 52%

Clopidogrel within seven days 20%

Warfarin within seven days 1%

LMWH (#) within 24 hours 8%

 Other cardiac
 surgery ([dagger]) Total
 (n=213) (n=498)

Mean (SD) age, y 61 (17) 64 (14)

Male gender 64% 71%

Current or previous smoking 51% 62%

Pre-existing medical conditions

Diabetes 16% 26%

Renal impairment 14% 12%

Hypertension 50% 63%

Cerebrovascular disease 10% 10%

Peripheral vascular disease 6% 9%

Respiratory disease 23% 18%

Myocardial infarction 25% 42%

Current angina 37% 67%

Heart failure 34% 21%

Current endocarditis 7% 3%

Preoperative anticoagulant drug therapy

Aspirin within five days 24% 40%

Clopidogrel within seven days 5% 15%

Warfarin within seven days 13% 6%

LMWH (#) within 24 hours 3% 6%

* Primary coronary artery bypass graft (CABG) surgery excludes
previous CABG surgery; ([dagger]) includes: valve repair or
replacement, aortic surgery, cardiac tumour resection, cardiac
transplantation and mechanical support devices; LMWH (#) =low
molecular weight heparin.

TABLE 2
Antifibrinolytic use in cardiac surgery

Antifibrinolytic Primary CABG Valvular/other All surgeries
use (n=286) (n=212) (n=498)

Antifibrinolytic 59% 77% 67%

Aprotinin 26% 50% 36%
(full dose)

Aprotinin 5% 7% 6%
(half dose)

Tranexamic acid 29% 21% 25%

TABLE 3
Median (IQR) blood loss from the mediastinal drains according to
recent (within five days) aspirin exposure

 Aspirin (n=199) No aspirin (n=299) P value
 ml ml

Primary CABG

At four hours 250 (145-380) 250 (152-375) 0.92
Total 725 (500-1230) 725 (480-1150) 0.94

Valvular/other

At four hours 252 (170-350) 225 (145-366) 0.67
Total 587 (430-1190) 700 (428-1208) 0.84

All surgeries

At four hours 250 (150-375) 240 (150-375) 0.65
Total 670 (46-1230) 700 (465-1180) 0.84

TABLE 4
Association of anticoagulant drug therapy with blood transfusion;
odds ratio (95% CI)

 Red cell Component
 transfusion transfusion

Aspirin within five days (n=199) 0.95 (0.7-1.4) 1.06 (0.7-1.5)

Clopidogrel within seven days (n=68) 1.05 (0.6-1.7) 2.21 (1.3-3.7)

Warfarin within seven days (n=29) 1.30 (0.6-2.7) 1.95 (0.9-4.1)

LMWH within 24 hours (n=29) 1.1 (0.5-2.3) 1.25 (0.6-2.6)

 Any blood
 product
 transfusion

Aspirin within five days (n=199) 1.07 (0.7-1.5)

Clopidogrel within seven days (n=68) 1.7 (0.9-2.8)

Warfarin within seven days (n=29) 1.2 (0.6-2.6)

LMWH within 24 hours (n=29) 1.45 (0.7-3.1)

TABLE 5
Complications within 30 days of cardiac surgery

 Other
Complications Primary cardiac Total
 CABG surgery surgery (n=498)
 (n=285) (n=213)

Serious bleeding 4% 8% 6%

Myocardial infarction 3% 3% 3%

New arrhythmia 29% 32% 30%

New renal failure 5% 10% 7%

Serious infection 8% 11% 10%

Stroke 2% 4% 3%

Prolonged ventilation 12% 18% 15%

Tracheal re-intubation 5% 8% 6%

Pneumonia 8% 11% 9%

Acute lung injury 1% 2% 1%

Death 2% 7% 4%

Any complication([section]) 24% 26% 25%
or death

([section]) excluding new arrhythmia.

TABLE 6
Association of transfusion and severe bleeding (requiring surgical
re-exploration) with clinical characteristics (a) Known risk
factors (27,28)

 Transfusion Transfusion

 Unadjusted OR P value
 (95% CI)

Age -- <0.001

Male gender 0.53 (0.35-0.80) 0.002

Weight <55 kg 3.65 (1.36-9.77) 0.006

LV* grade 3 or 4 1.31 (0.86-1.98) 0.21

Renal impairment 2.25 (1.23-4.11) 0.007

Diabetes 1.08 (0.72-1.62) 0.72

Aspirin 1.08 (0.75-1.55) 0.70
[less than or equal to]5 days

Clopidogrel 1.67 (0.97-2.88) 0.062
[less than or equal to]7 days

Warfarin 1.24 (0.57-2.68) 0.59
[less than or equal to]7 days

LMWH [less than or equal to] 1.45 (0.66-3.19) 0.35
24 hours

Platelet count <100,000 15 (n.d) ([section]) 0.022

INR >1.5 0.65 (0.23-1.81) 0.40

Primary CABG (#) 0.60 (0.42-0.86) 0.006

Reoperation 2.02 (1.03-3.93) 0.037

Emergency surgery 2.31 (0.83-6.46) 0.10

Antifibrinolytic 1.68 (1.15-2.44) 0.007

 Transfusion Transfusion

 Adjusted OR P value
 (95% CI)

Age 1.04 (1.02-1.05) <0.001

Male gender 0.58 (0.37-0.92) 0.020

Weight <55 kg 2.63 (0.89-7.76) 0.079

LV* grade 3 or 4

Renal impairment 2.14 (1.15-4.26) 0.017

Diabetes

Aspirin
[less than or equal to]5 days

Clopidogrel 1.94 (1.07-3.51) 0.030
[less than or equal to]7 days

Warfarin
[less than or equal to]7 days

LMWH [less than or equal to]
24 hours

Platelet count <100,000 not included

INR >1.5 0.16

Primary CABG (#) 0.58 (0.37-0.91) 0.017

Reoperation 2.14 (0.97-4.72) 0.059

Emergency surgery 2.86 (0.95-8.62) 0.062

Antifibrinolytic 1.35 (0.89-2.03) 0.16

 Re-operation Re-operation
 for severe for severe
 bleeding bleeding

 Unadjusted OR P value
 (95% CI)

Age -- 0.33

Male gender 1.59 (0.63-3.97) 0.17

Weight <55 kg 0.59 (0.08-4.46) 0.60

LV* grade 3 or 4 2.25 (0.56-55.1) 0.034

Renal impairment 3.69 (1.59-8.53) 0.001

Diabetes 1.11 (0.48-2.57) 0.81

Aspirin 0.78 (0.36-1.71) 0.54
[less than or equal to]5 days

Clopidogrel 2.60 (1.10-6.13) 0.024
[less than or equal to]7 days

Warfarin 2.84 (0.92-8.79) 0.057
[less than or equal to]7 days

LMWH [less than or equal to] 0.56 (0.07-4.29) 0.51
24 hours

Platelet count <100,000 2.74 (0.32-25.53) 0.34

INR >1.5 1.16 (0.15-9.15) 0.89

Primary CABG (#) 0.51 (0.24-1.09) 0.075

Reoperation 1.14 (0.33-3.93) 0.83

Emergency surgery 4.53 (1.41-14.56) 0.006

Antifibrinolytic 0.97 (0.44-2.13) 0.93

 Re-operation Re-operation
 for severe for severe
 bleeding bleeding

 Adjusted OR P value
 (95% CI)

Age

Male gender

Weight <55 kg

LV* grade 3 or 4 2.05 (0.91-4.60) 0.082

Renal impairment 3.58 (1.44-8.88) 0.006

Diabetes

Aspirin
[less than or equal to]5 days

Clopidogrel 3.36 (1.26-8.95) 0.016
[less than or equal to]7 days

Warfarin
[less than or equal to]7 days

LMWH [less than or equal to]
24 hours

Platelet count <100,000

INR >1.5

Primary CABG (#) 0.14 (0.84) 0.019

Reoperation

Emergency surgery 3.45 (1.01-11.78) 0.048

Antifibrinolytic 0.63 (0.27-1.50) 0.30

* Left ventricle; (#) coronary artery bypass graft; ([section]) zero
events in the control group (0.5 added to each group to estimate OR;
95% CI not done).

(b) High-risk procedures include any of the following risk factors
(ref): patient age > 70 years, weight <55 kg, poor LV function
(grade 4), renal impairment, emergency surgery, coagulopathy or
re-operation

 Blood Blood Blood
 transfusion transfusion transfusion

 Unadjusted OR P value Adjusted OR
 (95% CI) (95% CI)

High-risk 2.38 (1.65-3.42) <0.001 2.28 (1.58-3.29)
procedure

Antifibrinolytic 1.68 (1.15-2.44) 0.007 1.53 (1.05-2.25)

 Blood Re-operation for Re-operation for
 transfusion severe bleeding severe bleeding

 P value Unadjusted OR P value
 (95% CI)

High-risk <0.001 2.57 (1.08-6.13) 0.028
procedure

Antifibrinolytic 0.029 0.97 (0.44-2.13) 0.93

 Re-operation for Re-operation for
 severe bleeding severe bleeding

 Adjusted OR P value
 (95% CI)

High-risk procedure 2.62 (1.09-6.28) 0.031

Antifibrinolytic 0.86 (0.39-1.91) 0.71
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Article Details
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Title Annotation:Survey
Author:Daly, D.J.; Myles, P.S.; Smith, J.A.; Knight, J.L.; Clavisi, O.; Bain, D.L.; Glew, R.; Gibbs, N.M.;
Publication:Anaesthesia and Intensive Care
Article Type:Report
Geographic Code:8AUST
Date:Oct 1, 2007
Words:5483
Previous Article:Preoperative hypnotherapy in the management of a child with anticipatory nausea and vomiting.
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