Microcirculation parameters are related to hemodynamic indices in postoperative cardiac patients

Introduction

Peripheral microcirculation is affected by extra-corporeal circulation, hypothermia and anesthesia in patients undergoing cardiac surgery. The alterations of peripheral microcirculation and their relation to the hemodynamic status in these patients have not yet been studied.

Objective

To compare microcirculation parameters with the postoperative hemodynamic status of these patients.

Methods

We studied seven postoperative cardiac patients (five males/two females, 69 ± 6 years) during the immediate postoperative period. All were receiving inotropic agents (11 nor-epinephrine, 15 dobutamine, three adrenaline, four levosimendan). We used Swan-Ganz catheterization to assess the cardiac index and mixed venous blood oxygen saturation (SvO₂) values. We used the InSpectra near-infrared spectrometer (NIRS) to monitor the thenar muscle tissue oxygen saturation (StO₂) and the total hemoglobin index (THI) (which reflects the sum of oxyhemoglobin and deoxyhemoglobin) at baseline.

Results

The hemodynamic parameters of our patients were: MAP 79 ± 10 mmHg, CVP 8 ± 4 cmH₂O, PCWP 11 ± 2 mmHg, MPAP 27 ± 7 mmHg, CI 2.6 ± 0.7 l/min/m², SVR 1243 ± 318 dyne × s/cm⁵, PVR 309 ± 139 dyne × s/cm⁵, HR 93 ± 7 bpm, DO₂ 706 ± 209 l/min. Laboratory values were: Hb 10.4 ± 1.5 g/dl, lactate 2.4 ± 1.2 mg/dl. We found a significant correlation between StO₂ at baseline and the cardiac index (r = 0.85, P < 0.001) and between the THI at baseline and the cardiac index (r = 0.88, P <0.001). The StO₂ at baseline also significantly correlated with SvO₂ (r = 0.94, P < 0.001).

Conclusion

Non-invasively acquired tissue oxygen saturation values correlate with hemodynamic indices. This suggests that non-invasive monitoring of the microcirculation might be used for the management of postoperative cardiac patients. Further studies are needed to confirm these findings.