Title: Perioperative transfusion in anaemic patients undergoing coronary artery bypass
Abstract: D Zindrou and colleagues (May 18, p 1747)1Zindrou D Taylor KM Bagger JP Preoperative haemoglobin concentration and mortality rate after coronary artery bypass surgery.Lancet. 2002; 359: 1747-1748Summary Full Text Full Text PDF PubMed Scopus (120) Google Scholar report on preoperative haemoglobin concentration and mortality after coronary artery bypass surgery (CABG). We have some comments on their findings. They enrolled 2059 consecutive patients undergoing isolated CABG. We assume all patients underwent CABG under cardiopulmonary bypass. The mean number of grafts per patient is not given, although 96% of the patients received a graft from the internal mammary artery and, consequently, one graft to the anterior descending or right coronary arteries might have been done in some. If patients underwent off-pump CABG, the number should be noted because the postoperative course differs notably from that after on-pump surgery.2Buffolo E Andrade JC Branco JN Aguiar LF Ribeiro EE Jatene AD Myocardial revascularization without extracorporeal circulation: seven-year experience in 593 cases.Eur J Cardiothorac Surg. 1990; 4: 504-507Crossref PubMed Scopus (132) Google Scholar If all patients underwent CABG under cardiopulmonary bypass, did any receive aprotinin? The number of treatments and the doses must be cited, since this drug can also modify patients' outcomes.3Levy M Cromheecke ME de Jonge E et al.Pharmacological strategies to decrease excessive blood loss in cardiac surgery: a meta-analyses of clinically relevant end points.Lancet. 1999; 354: 1940-1947Summary Full Text Full Text PDF PubMed Scopus (451) Google Scholar Zindrou and colleagues give no information about perioperative blood loss, blood-saving techniques, transfusion trigger, number of patients transfused in the non-anaemic group, number of units transfused per patient, or postoperative complications. This issue is important since there is a dosedependent association between blood transfusion and the development of severe postoperative infection and death in patients undergoing cardiac surgery.4Leal-Noval SR Rincón-Ferrari MD García-Curiel A et al.Transfusion of blood components and postoperative infection in patients undergoing cardiac surgery.Chest. 2001; 119: 1461-1468Summary Full Text Full Text PDF PubMed Scopus (294) Google Scholar For mortality, the crude data the investigators show in the figure are also confounded because discharged patients are not included. Despite this omission, the overall in-hospital mortality rate is slightly higher than that reported for a similar series of 2569 CABG patients, in whom transfusion trigger during cardiopulmonary bypass was a packed-cell volume of lower than 20%, and mortality was defined as death during hospital stay or within 30 days of surgery (3·37 vs 2·79%).5Utley JR Wilde EF Leyland SA Morgan MS Johnson HD Intraoperative blood transfusion is a major risk factor for coronary artery bypass grafting in women.Ann Thorac Surg. 1995; 60: 570-575Summary Full Text PDF PubMed Scopus (38) Google Scholar In Zindrou and colleagues' study, patients with a haemoglobin concentration less than 100 g/L had the pump primed with blood. Administration of blood during cardiopulmonary bypass may begin a cascade of events that contributes to postoperative organ dysfunction and morbidity associated with complement activation. Since low packed-cell volume during cardiopulmonary bypass is well tolerated, blood transfusion should be delayed until the intervention is stopped, when the packed-cell volume may need to be higher, thus reducing morbidity.5Utley JR Wilde EF Leyland SA Morgan MS Johnson HD Intraoperative blood transfusion is a major risk factor for coronary artery bypass grafting in women.Ann Thorac Surg. 1995; 60: 570-575Summary Full Text PDF PubMed Scopus (38) Google Scholar Finally, we agree that disease severity and comorbidity had the greatest effect on mortality in the anaemic group, which may have been aggravated by transfusion of stored blood, and the anaemia being just a consequence of some of the disorders, such as renal failure. Hence, whenever possible, preoperative pharmacological but not transfusional treatment of anaemia should be used. Perioperative transfusion in anaemic patients undergoing coronary artery bypassAuthors' reply Full-Text PDF