Hemodilution reduces concentrations of blood constituents: concentration of hemoglobin, red blood cells (hematocrit), physiological ions and coagulation factors that can contribute to impaired hemostasis and increasing the risk of perioperative blood transfusions. This pilot study will assess the feasibility of a large RCT to evaluate 2 techniques for reducing hemodilution during cardiac surgery: 1) retrograde autologous priming and 2) intraoperative mannitol. The aim of this pilot trial is to demonstrate feasibility of a larger trial to evaluate whether retrograde autologous priming and/or mannitol are superior to conventional priming alone.
The use of large volumes of artificial priming fluids is still very high in cardiac surgery for routine CABG surgery with cardiopulmonary bypass. The resulting hemodilution is deleterious for patients and often requires counter measures to maintain fluid balance during and after surgery. Retrograde autologous priming and mannitol are simple low-cost solutions to the problem of hemodilution but their effectiveness, either alone or in combination, is unclear due to a lack of high-quality evidence. RAPPER-MAN is a single-centre 2x2 factorial cluster randomized trial. Participants will be randomly assigned (1:1:1:1 ratio) to the intervention groups: 1) Retrograde autologous priming (≥600 mL) + mannitol (0.3 g/kg bolus), 2) Retrograde autologous priming (≥600 mL) alone, 3) Conventional priming + mannitol (0.3 g/kg bolus), and 4) Conventional priming alone. The primary outcome is the change in hemoglobin concentration during cardiopulmonary bypass. Retrograde autologous priming will be performed within 10 minutes before, and mannitol will be added to the venous reservoir of the CPB machine within 5 minutes before, the start of cardiopulmonary bypass. The results of the larger trial are expected to have broad implications for fluid management in cardiac surgery in Canada.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Priming solution (≥600 mL) will be removed from the extracorporeal circuit within 10 minutes before the initiation of cardiopulmonary bypass. Priming solution may be removed from 3 locations within the extracorporeal circuit (i.e. arterial, venous and cardioplegia lines) as determined by the perfusionist team.
Mannitol will be added as a bolus (0.3 g/kg) to the venous reservoir of the cardiopulmonary bypass machine within 5 min before the start of cardiopulmonary bypass.
The conventional priming procedure will be used in the standardized cardiopulmonary machine used at the Hamilton General Hospital.
Hamilton General Hospital
Hamilton, Ontario, Canada
Feasibility Outcomes
Feasibility will be established in the pilot phase if all the following criteria are met: 1. Average recruitment rate of 7 patients per week. 2. Complete Hb data before and after cardiopulmonary bypass in 90% of patients. 3. Compliance of the research team members, OR staff and ward medical staff with the protocol of 90%.
Time frame: Start to end of study recruitment, which is anticipated to take 20 weeks
Change in hemoglobin concentration during cardiopulmonary bypass
Change in arterial hemoglobin concentration during cardiopulmonary bypass
Time frame: Start to end of cardiopulmonary bypass
Change in hemoglobin concentration after cardiopulmonary bypass
Change in arterial hemoglobin concentration from baseline to discharge
Time frame: Start of cardiopulmonary bypass to hospital discharge or 5 days maximum (whichever occurs first)
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