Institute of Surgical Research, Faculty of Medicine, University of Szeged, Szeged, Hungary.
Department of Cardiac Surgery, Faculty of Medicine, University of Szeged, Szeged, Hungary.
Crit Care Med. 2019 May;47(5):e403-e411. doi: 10.1097/CCM.0000000000003659.
Methane (CH4) breath test is an established diagnostic method for gastrointestinal functional disorders. Our aim was to explore the possible link between splanchnic circulatory changes and exhaled CH4 in an attempt to recognize intestinal perfusion failure.
Randomized, controlled in vivo animal study.
University research laboratory.
Anesthetized, ventilated Sprague-Dawley rats (280 ± 30 g) and Vietnamese minipigs (31 ± 7 kg).
In the first series, CH4 was administered intraluminally into the ileum before 45 minutes mesenteric ischemia or before reperfusion in non-CH4 producer rats to test the appearance of the gas in the exhaled air. In the porcine experiments, the superior mesenteric artery was gradually obstructed during consecutive, 30-minute flow reductions and 30-minute reperfusions achieving complete occlusion after four cycles (n = 6), or nonocclusive mesenteric ischemia was induced by pericardial tamponade (n = 12), which decreased superior mesenteric artery flow from 351 ± 55 to 182 ± 67 mL/min and mean arterial pressure from 96.7 ± 18.2 to 41.5 ± 4.6 mm Hg for 60 minutes.
Macrohemodynamics were monitored continuously; RBC velocity of the ileal serosa or mucosa was recorded by intravital videomicroscopy. The concentration of exhaled CH4 was measured online simultaneously with high-sensitivity photoacoustic spectroscopy. The intestinal flow changes during the occlusion-reperfusion phases were accompanied by parallel changes in breath CH4 output. Also in cardiac tamponade-induced nonocclusive intestinal ischemia, the superior mesenteric artery flow and RBC velocity correlated significantly with parallel changes in CH4 concentration in the exhaled air (Pearson's r = 0.669 or r = 0.632, respectively).
we report a combination of in vivo experimental data on a close association of an exhaled endogenous gas with acute mesenteric macro- and microvascular flow changes. Breath CH4 analysis may offer a noninvasive approach to follow the status of the splanchnic circulation.
甲烷（CH4）呼气试验是一种用于诊断胃肠道功能障碍的成熟方法。我们的目的是探索内脏循环变化与呼出 CH4 之间的可能联系，试图识别肠道灌注衰竭。
随机、对照的体内动物研究。
大学研究实验室。
麻醉、通气的 Sprague-Dawley 大鼠（280±30g）和越南小型猪（31±7kg）。
在第一系列实验中，在肠系膜缺血前 45 分钟或非 CH4 产生大鼠再灌注前，将 CH4 腔内给药至回肠，以测试气体在呼出空气中的出现。在猪实验中，逐渐阻塞肠系膜上动脉，在连续 30 分钟的流量减少和 30 分钟的再灌注期间实现完全阻塞，在四个循环后（n=6），或通过心包填塞（n=12）诱导非闭塞性肠系膜缺血，将肠系膜上动脉流量从 351±55 减少至 182±67mL/min，平均动脉压从 96.7±18.2 减少至 41.5±4.6mmHg 60 分钟。
连续监测宏观血液动力学；通过活体视频显微镜记录回肠浆膜或黏膜的 RBC 速度。同时通过高灵敏度光声光谱在线测量呼出 CH4 的浓度。在闭塞-再灌注阶段，肠道血流变化与呼气 CH4 输出的平行变化相伴随。在心脏填塞引起的非闭塞性肠缺血中，肠系膜上动脉血流量和 RBC 速度与呼出空气中 CH4 浓度的平行变化显著相关（Pearson's r=0.669 或 r=0.632）。
我们报告了体内实验数据的组合，表明内源性呼出气体与急性肠系膜宏观和微循环血流变化密切相关。呼气 CH4 分析可能提供一种非侵入性的方法来监测内脏循环的状态。
