Assessment of a goal-directed perfusion strategy through an oxygen delivery audit

Abstract

Introduction: Evidence supports the role of oxygen delivery (DO₂) in ameliorating acute kidney injury (AKI). While instrumentation for continuous DO₂ measurement exists, a simplified method has been reported for targeting a specific DO₂ index (DO₂i), commonly referred to as a goal-directed perfusion (GDP) strategy, by using a reference table and available data such as body surface area and continuous haematocrit values. This simplified approach can also be used for quality auditing via archived data.

Methods: This retrospective sequential audit was conducted to assess the impact of employing a GDP strategy within our institution by examining perfusion practices, DO₂ levels and renal outcomes before and after implementation. A total of 246 patients undergoing elective primary coronary revascularisation were included: 125 patients in the pre-change group and 121 patients in the post-change group. A DO₂i threshold above 280 mL/min/m² was targeted in the post-GDP group.

Results: While both groups maintained a mean DO₂ above the threshold, the post-GDP group exhibited a higher average DO₂i (311 vs 291 mL/min/m²). The GDP strategy led to higher nadir DO₂i (255 vs 225, p < .001) and was coupled with a reduction in the time below the 280 mL/min/m² threshold (30 min vs 50 min, p < .001). The average cardiac index in the post-GDP group was higher (1.87 vs 1.65, p < .001) while also demonstrating a smaller creatinine rise of 6.8% compared to 13.5% in the control group (p = .035). There was no difference in AKI or mortality rates between the groups.

Conclusion: The implementation of the GDP strategy demonstrated an enhancement in oxygen delivery during cardiopulmonary bypass, primarily attributable to elevated pump flow rates. A statistically significant decrease in serum creatinine levels was observed. The published reference table emerged as a simple yet effective tool in optimising our GDP strategy.

Keywords: acute kidney injury; cardiopulmonary bypass; goal-directed perfusion; oxygen delivery.