Fluid administration, priming solutions, and the use of cardiopulmonary bypass (CPB) during cardiac surgery are likely to promote hemodilution and inflammatory responses, leading to microcirculatory impairment. A new integrative investigation of microcirculatory hemodynamics, leukocyte activation, and extracellular water can reveal these alterations in patients throughout the perioperative phase of cardiac surgery.

This single-center observational study included consecutive patients undergoing elective open cardiac surgery with CPB at the Amsterdam University Medical Centers (location AMC), Netherlands, between December 2019 and March 2021. Sublingual microcirculation was assessed using incident dark-field imaging in 17 patients who underwent elective open cardiac surgery at seven different time points: at hospital admission (T0), after induction of anesthesia (T1), 10 min after induction of cardio-pulmonary bypass (T2), after removal of aortic clamp (T3), at the end of surgery (T4), on the day of discharge from intensive care unit (ICU) (T5), and on day 3 after ICU discharge (T6). Automated and manual analyses were performed to analyze microcirculatory hemodynamics and leukocyte activation, respectively. Non-invasive pulse contour assessment of cardiac output and body fluid composition was also included. Generalized mixed-effects models were used for statistical analysis.

During surgery, in line with macro-hemodynamics, the oxygen transport capability at the tissue level was impaired, as observed by a significant decrease in tissue red blood cell perfusion compared with the preoperative baseline ([53.4 ± 17.5] vs. [36.1 ± 10.5] µm/min, P <0.001). In the postoperative phase, the microcirculation recovered to baseline levels ([54.6 ± 12.5] µm/min). However, inflammation, indicated by an increased number of leukocytes at the microcirculatory level compared to baseline ([8.7 ± 3.4] vs. [23.9 ± 5.9]/4 s, P <0.001), began early during surgery and showed incomplete resolution by the last postoperative measurement ([16.4 ± 3.9]/4 s), paired with elevated plasma leukocytes, overhydration observed through bioimpedance, and weight gain.

Integrative monitoring of the microcirculation, hemodynamics, and body composition of patients who underwent CPB revealed a temporal association between tissue perfusion and hemodynamic changes during cardiac surgery and between leukocyte activation and fluid accumulation.