Prescriptive patient extracorporeal circuit and oxygenator sizing reduces hemodilution and allogeneic blood product transfusion during adult cardiac surgery

Abstract

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.

Figure 1.

Flowchart depicts the selection process for the right-sized oxygenator, reservoir, and tubing arterial–venous loop. FX25 W40, FX15 W40, and FX15 W30 are Terumo trademark names for oxygenators and reservoirs. The volumes are minimal crystalloid circuit prime volumes before autologous priming.

Figure 2.

The percent use for the FX15 oxygenator and W30 reservoir devices, indicating an overall significant increase in adoption of the smaller devices.

Figure 3.

The increase in average operating room hemoglobin (Hgb) nadir over the nine quarters. The percent increase in patients receiving no transfusions in the operating room and intensive care unit.

Figure 4.

BSA is body surface area for male and female patients within these limits. RBC U is one unit of allogeneic red blood cells (330 mL). 2011:Q1 is year and quarter. RBC use is mean ± 1 standard deviation [median] units RBC per patient. Points above the interquartile range are individual outlier patients.