Prescriptive Patient Extracorporeal Circuit and Oxygenator Sizing Reduces Hemodilution and Allogeneic Blood Product Transfusion during Adult Cardiac Surgery

The goal of this cardiopulmonary bypass (CPB) quality improvement
initiative was to maximize hemoglobin nadir concentration by minimizing
hemodilution and, in turn, eliminating allogeneic blood product
transfusion. The effects of transitioning from “one-size-fits-all” to
“right-sized” oxygenators, reservoirs, and arterial-venous tubing loops
were evaluated through a 2-year retrospective review of 3852 patient
perfusion records. Using a sizing algorithm, derived from manufacturers’
recommendations, we were able to create individualized “right-sized”
extracorporeal circuits based on patient body surface area, cardiac
index, and target blood flows. Use of this algorithm led to an increase
in the percent of algorithm-recommended smaller oxygenators being used
from 39% to 63% (p < .01) and an increase in average hemoglobin nadir from 8.38 to 8.76 g/dL (p < .01). Decreased priming volumes led to increased hemoglobin nadir and decreases in allogeneic blood transfusion (p = .048). Patients with similar body surface areas who previously were exposed to larger oxygenators, reservoirs, and arterial-venous loops were now supported with smaller circuits as a result of the use of the right-sized algorithm. Adjustments to the algorithm were made for unique patients and procedural situations including age, gender, and length and type of procedure. Larger heat exchanger surface area oxygenators were used for circulatory arrest procedures as a result of the need for increased heat exchange capability. Despite the generally higher costs of smaller circuits, reduced transfusion-related expenditures and decreased exposure risks justify the use of smaller circuit components. This quality improvement initiative demonstrated that as an integral part of a multidisciplinary, multimodal blood conservation effort, the use of the "right-sized" circuit algorithm can help to elevate hemoglobin nadir during CPB and eliminate allogeneic blood transfusions to patients undergoing CPB. Keywords: cardiopulmonary bypass, oxygenator, perfusion index, extracorporeal circuit, hemodilution.