## 3 Results
Interestingly, the % median O\({}_{2}\) saturation in the wound area was higher in the CO\({}_{2}\) treated group up to 2 months of the intervention but were similar to the control group thereafter (Figure 2b). It can be seen from Figure 3 that patients randomly assigned to the CO\({}_{2}\) intervention group exhibited higher pain scores at baseline, which gradually decreased with the course of the treatment with CO\({}_{2}\)-enriched water. No differences in the serum levels of TNF\(\alpha\) and VEGF were seen in control and CO\({}_{2}\)-treated groups (Figure 4). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Wound/Limb Characteristics** & \multicolumn{3}{c}{**Control Wounds**} & \multicolumn{2}{c}{**CO\({}_{2}\) Wounds (N = 13)**} & \multicolumn{1}{c}{\(p\)**-Value**} \\ \hline Number of Wounds & 24 & 11 & 13 & - \\ Amputees, leg/toe & 8 & - & - & - \\ BKA & 6 & 4 & 2 & - \\ Toe & 4 & - & 4 & - \\ Wound Area Reduction (\%) & 0 (0–0) & 0 (0–0) & 0 (0–0) & 1.000 \\ Wound Area (cm\({}^{2}\)) & 0.9 (0.5–3.2) & 1.6 (0.6–6.1) & 0.7 (0.5–1.4) & 0.176 \\ Oxygenated Hb (\%) & 12.5 (\(-\)15.3–78.5) & 6.0 (\(-\)7.0–79.0) & 18.0 (\(-\)19.0–84.0) & 0.895 \\ Left ABI & 0.9 (0.8–1.1) & - & 0.9 (0.8–1.1) & - \\ Right ABI & 0.8 (0.6–0.9) & 0.9 (0.9–0.9) & 0.8 (0.6–1.0) & 0.439 \\ O2 Saturation (\%) & 44 (26–57) & 35 (15–58) & 44 (33–56) & 0.306 \\ Wound Depth Max (mm) & 1 (0–2) & 1 (0–4) & 1 (0–1) & 0.200 \\ Wound Depth Mean (mm) & 0 (0–0) & 0 (0–0) & 0 (0–0) & 0.420 \\ Wound Depth Volume (cm\({}^{3}\)) & 0 (0–0) & 0.0 (0.0–0.2) & 0 (0–0) & 0.072 \\ \hline \hline \end{tabular} Categorical variables expressed as N (%) and compared between study cohorts using [PERSON]’s exact test for non missing values. Continuous variables expressed as median (quartiles 1–3) and compared between study cohorts using Mann-Whitney Test for non-missing values. Individual characteristics are calculated based off the number of study participants; wound characteristics calculated based off the number of total wounds observed. Abnormal values for the resting ankle-bracchial index (ABI) are 0.9 or lower and 1.40 or higher. If the ABI is 0.91 to 1.00, it is considered borderline abnormal. Abbreviations and reference values: FBG, fasting blood glucose (reference values 3.6–6.0 mM); HbAIc, glycated hemoglobin (reference value 4.0–6.0%). ESRD, end-stage renal disease; total cholesterol (reference \(<\) 1.7 mM); triglycerides (reference \(>\) 1.0 mM); HDL-cholesterol (reference \(<\) 3.4 mM); LDL-cholesterol (reference \(<\) 4.5 mM); total total cholesterol/HDL-cholesterol levels (reference \(<\) 3.5 mM); C-reactive protein (normal range \(<\) 5 mg/L); ABI, ankle-bracchial index; BKA, below-knee amputation; TNF\(\alpha\), tumor necrosis factor \(\alpha\); VEGF, vascular endothelial growth factor.  
\end{table} 
Table 3: _Cont._Figure 1: Effect of CO\({}_{2}\)-water bathing on the dimensions of foot ulcers. Panel (**a**) percent wound area reduction of foot ulcers and panel (**b**) wound area in patients treated without and with CO\({}_{2}\)-enriched water. Study participants were randomized to undergo foot bathing either with CO\({}_{2}\)-enriched tap water (37 \(\pm\) 0.5 \({}^{\circ}\)C; CO\({}_{2}\) concentration of 1000–1200 ppm) or with regular tap water (37 \(\pm\) 0.5 \({}^{\circ}\)C) with an immersion time of 15 min for 3 times/week for up to 16 weeks for a total of 48 treatments. The Silhouette Mobile camera (ARANZ Medical, Christchurch, New Zealand) was used to measure the dimensions of the ulcer. Figure 2: Oxygenated hemoglobin and oxygen saturation levels in the wound area in patients treated without and with CO\({}_{2}\)-enriched water. Panel (**a**) oxygenated hemoglobin levels in the wound area and panel (**b**) oxygen saturation levels of the wound in patients treated without and with CO\({}_{2}\)-enriched water.