Double Product and Shock Index: Can These Macrocirculatory Parameters Provide Sufficient Information About Microcirculation?

Objectives: This study aims to examine the relationship between microcirculation and macrocirculation in the early period after extracorporeal circulation (ECC). Specifically, it investigates whether macrocirculation parameters such as Double Product (DP) and Shock Index (SI) can predict microcirculation by studying their correlation with lactate levels, a marker of microcirculation, in the early post-ECC period.
Methods: The study analyzed the demographic, hemodynamic, and laboratory data of 2039 patients who underwent isolated coronary bypass surgery with ECC at Acýbadem Kadýköy and Acýbadem Altunizade Hospitals between 1999 and 2023. The data included serum lactate levels, DP, and SI measurements taken before induction and after ECC for all patients, as well as for the subgroup with DP values above 12,000.
Results: The analysis did not find any correlation between plasma lactate levels and DP and SI during the post-ECC period; p=0.11, r=0.04 (-0.01; 0.08) and p<0.001, r=0.11 (0.06; 0.15), respectively. Similarly, no correlation was found between plasma lactate values and DP in patients with DP values >12,000 (n=284) (p=0.643, r=0.03 (-0.09; 0.14)).
Conclusion: Vital parameters do not fully capture circulatory disorders. It would be more appropriate for critically ill patients to assess microcirculation using parameters such as lactate directly. Therefore, further studies are necessary to evaluate microcirculation and develop independent parameters.