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.