Supplementary Material for: Intestinal Mucosal and Serosal Microcirculation at the Planned Anastomosis during Abdominal Surgery

<b><i>Introduction:</i></b> Intestinal blood flow is often named as a key factor in the pathophysiology of anastomotic leakage. The distribution between mucosal and serosal microperfusion during surgery remains to be elucidated. <b><i>Objective:</i></b> The aim of this study was to assess if the mucosal microcirculation of the intestine is more vulnerable to a surgical hit than the serosal microcirculation during surgery. <b><i>Methods:</i></b> In an observational cohort study (<i>n</i> = 9 patients), the microcirculation of the bowel serosa and mucosa was visualized with incident dark-field imaging during surgery. At the planned anastomosis, the following microcirculatory parameters were determined: microvascular flow index (MFI), percentage of perfused vessels (PPV), perfused vessel density (PVD), and total vessel density (TVD). Data are presented as median (interquartile range [IQR]). <b><i>Results:</i></b> Perfusion parameters and vessel density were significantly higher for the mucosa than the serosal microcirculation at the planned site for anastomosis or stoma. Mucosal MFI was 3.00 (IQR 3.00–3.00) compared to a serosal MFI of 2.75 (IQR 2.21–2.94), <i>p</i> = 0.03. The PPV was 99% (IQR 98–100) versus 92% (IQR 66–94), <i>p</i> = 0.01. The TVD was 16.77 mm/mm² (IQR 13.04–18.01) versus 10.42 mm/mm² (IQR 9.36–11.81), <i>p</i> = 0.01, and the PVD was 15.44 mm/mm² (IQR 13.04–17.78) versus 9.02 mm/mm² (IQR 6.43–9.43), <i>p</i> = 0.01. <b><i>Conclusions:</i></b> The mucosal microcirculation was preserved, while lower perfusion of the serosa was found at the planned anastomosis or stoma during surgery. Further research is needed to link our observations to the clinically relevant endpoint of anastomotic leakage.

<b><i>引言：</i></b> 肠血流常被认为是吻合口漏病理生理学中的关键影响因素。手术过程中黏膜与浆膜微灌注的分布情况仍有待阐明。<b><i>研究目的：</i></b> 本研究旨在评估手术过程中肠道黏膜微循环是否较浆膜微循环更易受手术操作的影响。<b><i>研究方法：</i></b> 本研究为观察性队列研究（<i>n</i> = 9名患者），术中采用入射暗场成像技术可视化肠浆膜与黏膜的微循环。在计划吻合部位，测定以下微循环参数：微血管血流指数（microvascular flow index, MFI）、灌注血管百分比（percentage of perfused vessels, PPV）、灌注血管密度（perfused vessel density, PVD）以及总血管密度（total vessel density, TVD）。数据以中位数（四分位间距[interquartile range, IQR]）的形式呈现。<b><i>研究结果：</i></b> 在计划吻合或造口部位，黏膜的灌注参数与血管密度均显著高于浆膜微循环。黏膜的微血管血流指数（MFI）为3.00（四分位间距3.00–3.00），而浆膜MFI为2.75（四分位间距2.21–2.94），<i>p</i> = 0.03。灌注血管百分比（PPV）为99%（四分位间距98–100），对应浆膜为92%（四分位间距66–94），<i>p</i> = 0.01。总血管密度（TVD）为16.77 mm/mm²（四分位间距13.04–18.01），对应浆膜为10.42 mm/mm²（四分位间距9.36–11.81），<i>p</i> = 0.01；灌注血管密度（PVD）为15.44 mm/mm²（四分位间距13.04–17.78），对应浆膜为9.02 mm/mm²（四分位间距6.43–9.43），<i>p</i> = 0.01。<b><i>研究结论：</i></b> 术中计划吻合或造口部位的黏膜微循环得以维持，而浆膜灌注水平较低。尚需进一步研究以将本研究观察结果与吻合口漏这一临床相关结局建立关联。