A multicenter randomized controlled trial to assess the feasibility of testing modified ultrafiltration as a blood conservation technology in cardiac surgery

Boodhwani, Munir; Hamilton, Andrew; de Varennes, Benoit; Mesana, Thierry; Williams, K.; Wells, George A.; Nathan, H.; Dupuis, Jean Yves; Babaev, A.; Wells, P.; Rubens, Fraser D.

doi:10.1016/j.jtcvs.2009.11.056

« Previous Next »The Journal of Thoracic and Cardiovascular Surgery
Volume 139, Issue 3 , Pages 701-706, March 2010

A multicenter randomized controlled trial to assess the feasibility of testing modified ultrafiltration as a blood conservation technology in cardiac surgery

Munir Boodhwani, MD, MMSc, FRCSC
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottowa, Ontario, Canada
Andrew Hamilton, MD, FRCSC
- Division of Cardiac Surgery, Queen's University, Kingston, Kingston, Ontario, Canada
Benoit de Varennes, MD, FRCSC
- Division of Cardiac Surgery, Royal Victoria Hospital, Montreal, Quebec, Canada
Thierry Mesana, MD, PhD, FRCSC
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottowa, Ontario, Canada
K. Williams
- Department of Epidemiology and Community Medicine, University of Ottawa, Ottowa, Ontario, Canada
George A. Wells, PhD
- Department of Epidemiology and Community Medicine, University of Ottawa, Ottowa, Ontario, Canada
H. Nathan, MD, FRCPC
- Division of Cardiac Anaesthesia, University of Ottawa Heart Institute, Ottowa, Ontario, Canada
Jean Yves Dupuis, MD, FRCPC
- Division of Cardiac Anaesthesia, University of Ottawa Heart Institute, Ottowa, Ontario, Canada
A. Babaev, MD
- Division of Perfusion, University of Ottawa Heart Institute, Ottowa, Ontario, Canada
P. Wells, MD, MSc, FRCPC
- Department of Medicine, University of Ottawa, Ottowa, Ontario, Canada
Fraser D. Rubens, MD, MSc, FRCSC
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottowa, Ontario, Canada
- Address for reprints: Fraser D. Rubens, MD, MSc, FRCSC, Professor of Surgery, University of Ottawa Heart Institute, 40 Ruskin St, Ottawa, Ontario K1Y 4W7, Canada.

Received 13 July 2009; received in revised form 10 November 2009; accepted 23 November 2009.

Objectives

Modified ultrafiltration is a technique after cardiopulmonary bypass whereby blood withdrawn from the aortic cannula is passed across a semipermeable membrane to hemoconcentrate. Unblinded trials have suggested that modified ultrafiltration is efficacious for blood conservation. The objective of this trial was to assess the feasibility of a model testing modified ultrafiltration in which all members of the surgical team were blinded to the intervention.

Methods

Patients (<65kg) undergoing procedures involving cardiopulmonary bypass were randomized to undergo either modified ultrafiltration (n=29) or sham (circulation without an interposed filter, n=36) for 15minutes. The circuit was shielded from all members of the team except the perfusionist. A questionnaire was administered to determine the blinding success.

Results

Modified ultrafiltration resulted in a removal of 1000±251mL of fluid and a reduction in the pump balance (1025±807 vs 1804±838; P < .001) with an increase in hemoglobin immediately after intervention (increase of 7.7±8.8g/L in modified ultrafiltration vs 3.8±5.1g/L in sham; P=.04). Introduction or increase in dose of vasopressors was more frequent in the modified ultrafiltration group (52% vs 28%; P=.048). Differences in red cell transfusion rates between groups did not reach statistical significance (P=.59). Blinding was successful for the anesthetist (blinding index 0.13 [95% confidence interval, 0.11–0.38] and the intensivist (blinding index, 0.09 [95% confidence interval, 0.14–0.31]) but not for the surgeon (blinding index, 0.24 [95% confidence interval, 0.05–0.42]). The compliance rate for the transfusion protocol was greater than 90%.

Conclusions

Modified ultrafiltration was effective for hemoconcentration after cardiopulmonary bypass in patients of low body weight, but it is associated with an increased need for vasopressor support. The anesthetist and intensivist were successfully blinded to the intervention.

CTSNet classification: 1, 25, 37

Abbreviations and Acronyms: BI, blinding index, CPB, cardiopulmonary bypass, MUF, modified ultrafiltration