Page 131 - Hospital Authority Convention 2018

Service Enhancement Presentations

F3.4 Clinical Safety and Quality Services I 14:30 Room 421

Reduction of Allogeneic Blood Transfusions in Cardiac Surgery by Lowering Cardiopulmonary Bypass Prime
Volume
Ng W, Chau K, Leung TY, Choi KM, Yung EP
Perfusion Team, Division of Cardiothoracic Surgery, Department of Surgery, Prince of Wales Hospital, Hong Kong HOSPITAL AUTHORITY CONVENTION 2018

Introduction
Despite recent advances in blood conservation techniques, cardiac surgeries have the highest demand for blood transfusion
in most medical centres. A certain degree of haemodilution is inevitable with the current use of crystalloid priming for
cardiopulmonary bypass (CPB) circuit. Haemodilution is essential in reducing shear stress and promoting organ perfusion.
The magnitude of haemodilution depends on the volume of crystalloid solution used for priming, and the patient’s baseline
blood volume and haematocrit (HCT). In daily practice, the on-pump HCT is kept optimally between 24-30%.

Objectives
(1) To minimise allogeneic blood transfusion for small size adult in priming and during CPB; and (2) To maintain adequate
organ perfusion during CPB, i.e. HCT kept between 24-30%.

Methodology
A retrospective review was conducted to evaluate the impact of the lower prime volume on clinical outcome and allogeneic
blood transfusion. Since mid-2016 to 2017, a less priming volume oxygenator with integrated arterial filter was used for 285
small size adult body surface area (BSA) < 1.8m2 (LP group), compared with the convention group of 316 patients from mid-
2015 to mid-2016 with similar BSA (CP group). The total priming volume of the CPB circuit was reduced from 1400 ml to 1000
ml crystalloid. Monday, 7 May 2018

Results
There were no significant differences between both groups with respect to baseline characteristics, BSA, type and urgency
of the operation, perfusion technique and haemotologic profiles. However, allogeneic blood transfusion requirement was
significantly lower in the LP group versus CP group: percentage of patients required blood transfusion priming, 18% (n=52)
versus 25% (n=79) (p= 0.045). The percentage of patients required blood transfusion on CPB, 44%(n=127) versus 47%(n=150)
(p=0.475) were similar. Off bypass HCT for both groups were similar 24-30%. Blood transfusion requirement before leaving
operation room were similar in both groups. Chest drainage output, first 24 hour HCT and discharge HCT were similar in both
groups too. The small size adult patient is at higher risk of allogeneic blood transfusion when undergoing CPB. Lowering
cardiopulmonary bypass prime volume resulted in a significant decrease in the use of allogeneic blood product. Various
factors also indicate blood transfusion during CPB: patients conditions, baseline/on-pump HCT, types and length of the
cardiac surgeries. Further studies exploring the haemodilution affecting the requirement of blood transfusion during on CPB
are certainly recommended. In conclusion, the Prince of Wales Hospital is encouraging its surgical teams to adopt best blood
management practices in an effort to reduce allogeneic blood transfusions effectively.

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