Biomedicines | Free Full-Text | Oxygen Saturation Increase in Ischemic Wound Tissues after Direct and Indirect Revascularization
The aim of this study was to evaluate and compare intraoperative oxygen saturation changes in ischemic wound regions after performing either indirect or direct angiosomal revascularization in below-the-knee arteries.
Every patient had angiographically verified lesions in all three below-the-knee arteries. In total, 30 endovascular below-the-knee procedures were performed, and 44 arteries were revascularized. The revascularization locations were as follows: 21 anterior tibial arteries, 10 posterior tibial arteries, 8 peroneal arteries, 2 tibioperoneal trunks, and 3 popliteal arteries. A total of 15 patients (50%) underwent direct angiosomal revascularization, and the other half of the patients underwent indirect revascularization.
Post-Hoc Power Analysis
A post-hoc power analysis showed that, for an independent group t-test with a significance level of 0.05 and a power of 0.95, the required sample size was 884 subjects.
Even though our clinical trial is the largest trial to date investigating intraoperative angiosomal versus non-angiosomal revascularization results using NIRS, our sample was too small to divide the patients into the four previously mentioned subgroups. Future clinical trials evaluating and comparing revascularization outcomes among these less straightforward patient subgroups can potentially help gather higher-quality data on the use of the angiosome concept and might shed some light on the ongoing debates on whether direct angiosomal revascularization is superior to indirect. Also, a larger multi-center study including wound healing and limb salvage results can be beneficial.
Our study reveals only a minor difference in the rSO2 increase between the angiosomal and non-angiosomal revascularization groups (17.9% and 16.8% increases in tissue oxygen saturation, respectively). Moreover, the post-hoc power analysis showed that a very large sample of approximately 900 patients is needed to obtain a statistically significant difference between the aforementioned groups. This indicates that the difference between angiosomal and non-angiosomal revascularization is extremely small and shadowed by other variables, such as early recoil, later restenosis of treated arteries, wound depth, inflammation, etc. In addition, the existing large randomized clinical trials concerning revascularization success take into account several other factors, such as patient comorbidities or the type of debulking devices/balloons/stents used, which appear to be more influential in this clinical setting.
Being the first of this kind, this study has some limitations, such as the absence of patient randomization, which can have caused selection bias. Patient assignment to direct or indirect revascularization group was performed solely by the operating doctor based on angiographic image evaluation and the doctor’s experience in this field. However, in every case, the revascularization method selection was adequate for the patient. Therefore, our results might have been affected slightly more by the operator’s level of clinical expertise rather than the differences in revascularization technique.
Randomization for this type of study might need a significantly higher number of participants. However, not all occluded BTK vessels can be opened equally successfully, and there might be a huge shift among the groups for the intended treatment and actual revascularization. In this case, the sample size was too small to efficiently stratify patients regarding their angiographic baseline characteristics, MAC-SAD score, and other existing scoring systems. In this study, WIfI classification was used to assess the ischemic wounds of all participants. However, this classification itself has more possible combinations than the sample size of this study. Hence, we decided to not stratify the patients according to this classification as well.
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