The Role of Continuous Monitoring of Venous Drainage Flow and Integrated Oxygen Extraction (ERiO2) via Bilateral Near-Infrared Spectroscopy in Cerebral Perfusion During Aortic Arch Surgery.

Background and

Objective

Effective cerebral perfusion monitoring is essential in aortic arch surgery, particularly when employing the Kazui technique under moderate hypothermia. Near-infrared spectroscopy (NIRS) provides real-time regional oxygen saturation (rSO2) measurements, while the continuous monitoring of venous drainage flow and oxygen extraction ratio (ERiO2) delivers additional insights into cerebral oxygenation and metabolic balance. This study investigates the correlation between NIRS-derived rSO2, venous drainage flow, and ERiO2 during selective antegrade cerebral perfusion (SACP) to better understand their interplay and clinical significance. Materials and

Methods

This retrospective study analyzed data from 10 patients undergoing aortic arch surgery with the Kazui technique, including 4 patients with type I A dissections and 6 with aortic arch aneurysms. Bilateral NIRS (Masimo system) was used to measure rSO2, while venous drainage flow and ERiO2 were continuously monitored using the Landing system. Intraoperative parameters such as cardiopulmonary bypass (CPB) time, cooling and rewarming duration, venous return flow, and perfusion delivery rates were collected and analyzed. The correlations between rSO2, venous drainage flow, and ERiO2 were statistically evaluated.

Results

The mean CPB time was 182 ± 15 min, with a mean cross-clamp time of 98 ± 12 min. Cooling to 20 °C was achieved in 29 ± 3 min, followed by a controlled rewarming phase of 10 ± 1.5 min. The venous return flow averaged 570 ± 25 mL/min, while the perfusion delivery rates exceeded 600 ± 30 mL/min. Bilateral NIRS monitoring revealed stable rSO2 values averaging 65 ± 5%, while ERiO2 averaged 28 ± 4%. A strong correlation (r = 0.91, p < 0.01) was observed between rSO2 and ERiO2, with venous drainage flow playing a critical role in maintaining this relationship.

Conclusions

This study demonstrates a robust correlation between NIRS-derived rSO2, continuous venous drainage flow, and ERiO2 during SACP in aortic arch surgery.