Kyu-Il Lee¹ , Yu-Kyeong Yun² , Seung-Kyu Han^2,3 , Kyung-Chul Moon^2,3 , Sik Namgoong^2,3 ,

Seong-Ho Jeong³ , Eun-Sang Dhong³

¹Department of Plastic Surgery, Taean Public Health Office, Taean, Korea

²Diabetic Wound Center and Department of Plastic Surgery, Korea University Guro Hospital, Seoul, Korea

³Department of Plastic Surgery, Korea University College of Medicine, Seoul, Korea

Abstract

Background: Adequate tissue oxygenation is a key determinant of diabetic foot ulcer (DFU) outcomes. Though transcutaneous oxygen pressure (TcPO₂) is the gold standard for evaluating tissue oxygenation, its limited availability restricts routine clinical use. Consequently, toe pressure is frequently utilized as a practical surrogate; however, the direct correlation between these two modalities has yet to be rigorously investigated. This study aimed to assess the correlation and agreement between TcPO₂and toe pressure in patients with DFUs.

Methods: A retrospective review was conducted on 837 DFU patients who received simultaneous TcPO²and toe pressure assessments.

The correlation between the two tests was analyzed using the Pearson correlation coefficient, and agreement was evaluated using Bland– Altman analysis. To aid interpretation, a scatterplot and Bland–Altman plot were generated.

Results: TcPO₂and toe pressure demonstrated a strong correlation (R=0.66; 95% confidence interval, 0.62 to 0.70; P<0.001). Bland–

Altman analysis showed a mean bias of 26.9 mmHg (standard deviation of differences, 28.8 mmHg; 95% limits of agreement, −28.9 to 82.6 mmHg) between toe pressure and TcPO₂, reflecting limited agreement and increased variability at higher perfusion levels.

Conclusion: TcPO₂and toe pressure are strongly correlated. However, they are not interchangeable, particularly in DFU patients with high tissue perfusion.

Keywords: Diabetic foot; Foot ulcer; Ischemia; Microcirculation