Mini Versus Conventional Cardiopulmonary Bypass In CABG in Asian Patients

Mini-bypass systems have the potential to reduce the problems associated with conventional cardiopulmonary bypass systems by preserving hematocrit, reducing transfusion requirements, and reducing inflammation. Intuitively, this system would be ideal for our smaller Asian patients, who as a result of their body sizes, are prone to severe hemodilution and increased transfusion requirements. However, our initial results based on established Western protocols were not as good as the investigators hoped. Using a modified protocol, the investigators were able to reduce perioperative blood transfusion. Therefore, the investigators intend to prospectively confirm the efficacy of mini-bypass in conjunction with our modified protocol in reducing haemodilution and reducing blood transfusions. The investigators will also establish the safety of this protocol, and investigate if this is associated with reduced inflammation and better cardiovascular, neurological, renal, respiratory and infection outcomes.

80 Asian patients undergoing primary coronary artery bypass grafting with cardiopulmonary bypass will be randomly divided either to utilize the mini-bypass system (Extra Corporeal Circuit Optimized; Phisio, Sorin Group, Italy) or the conventional system. Anaesthesia, surgical and perfusion management will be standardized, except for measures specific to the establishment of mini-bypass. The primary outcome measures will be haemodilution (first and lowest hematocrit) during cardiopulmonary bypass, blood loss in the first 24 and 48 hours post-operatively, and perioperative blood transfusions. Secondary outcomes include safety profile (air embolization, hypoperfusion), inflammation (TNF-alpha, interleukin-6, C-reactive protein, lactate dehydrogenase) in the first 72 hours after bypass, clinical outcomes (renal, neurological, cardiac, respiratory) and resource utilization (blood utilization, length of stay).

This project will allow us to confirm our retrospective findings that mini-bypass systems in conjunction with our modified protocol will benefit our smaller patients haematologically and lead to tremendous savings in blood utilization. The investigators will also establish if this protocol is safe, and if there are additional benefits in terms of inflammation, clinical outcomes and resource utilization. Our findings will also be applicable throughout East Asia, as patients in the region generally lag our Western counterparts in size.

Inclusion criteria

• first time on pump CABG revascularization

Exclusion criteria

• poor left ventricular ejection faction (< 30%)
• immunologic disease or malignancies
• acute inflammatory disease
• coagulopathy
• steroid treatment
• preoperative renal failure (currently receiving dialysis)
• significant carotid disease