IntroductionThe aim of this study was to evaluate dynamic indices of fluid responsiveness in a model of intra-abdominal hypertension.MethodsNine mechanically-ventilated pigs underwent increased intra-abdominal pressure (IAP) by abdominal banding up to 30 mmHg and then fluid loading (FL) at this IAP. The same protocol was carried out in the same animals made hypovolemic by blood withdrawal. In both volemic conditions, dynamic indices of preload dependence were measured at baseline IAP, at 30 mmHg of IAP, and after FL. Dynamic indices involved respiratory variations in stroke volume (SVV), pulse pressure (PPV), and systolic pressure (SPV, %SPV and Δdown). Stroke volume (SV) was measured using an ultrasound transit-time flow probe placed around the aortic root. Pigs were considered to be fluid responders if their SV increased by 15% or more with FL. Indices of fluid responsiveness were compared with a Mann-Whitney U test. Then, receiver operating characteristic (ROC) curves were generated for these parameters, allowing determination of the cut-off values by using Youden's method.ResultsFive animals before blood withdrawal and all animals after blood withdrawal were fluid responders. Before FL, SVV (78 ± 19 vs 42 ± 17%), PPV (64 ± 18 vs 37 ± 15%), SPV (24 ± 5 vs 18 ± 3 mmHg), %SPV (24 ± 4 vs 17 ± 3%) and Δdown (13 ± 5 vs 6 ± 4 mmHg) were higher in responders than in non-responders (P < 0.05). Areas under ROC curves were 0.93 (95% confidence interval: 0.80 to 1.06), 0.89 (0.70 to 1.07), 0.90 (0.74 to 1.05), 0.92 (0.78 to 1.06), and 0.86 (0.67 to 1.06), respectively. Threshold values discriminating responders and non-responders were 67% for SVV and 41% for PPV.ConclusionsIn intra-abdominal hypertension, respiratory variations in stroke volume and arterial pressure remain indicative of fluid responsiveness, even if threshold values identifying responders and non-responders might be higher than during normal intra-abdominal pressure. Further studies are required in humans to determine these thresholds in intra-abdominal hypertension.
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机译：前言本研究的目的是评估腹腔高压模型中液体反应的动态指标。方法9头机械通气的猪通过腹部束扎直至30 mmHg然后增加液体负荷（FL）来提高腹腔内压力（IAP）在此IAP。在通过抽血导致低血容量的同一动物中执行相同的方案。在这两种情况下，均在基线IAP，IAP 30 mmHg以及FL后测量预负荷依赖性的动态指数。动态指标涉及呼吸量的中风量（SVV），脉压（PPV）和收缩压（SPV，％SPV和Δdown）。使用放置在主动脉根周围的超声时移流量探头测量中风量（SV）。如果用FL将猪的SV增加15％或更多，则认为猪对液体有反应。将流体反应性的指标与Mann-Whitney U检验进行了比较。然后，针对这些参数生成接收器工作特性（ROC）曲线，从而可以使用Youden方法确定临界值。结果抽血前的5只动物和抽血后的所有动物都是流体反应者。 FL前SVV（78±19 vs 42±17％），PPV（64±18 vs 37±15％），SPV（24±5 vs 18±3 mmHg），％SPV（24±4 vs 17±3％） ）和Δdown（13±5 vs 6±4 mmHg）高于无反应者（P <0.05）。 ROC曲线下的面积分别为0.93（95％置信区间：0.80至1.06），0.89（0.70至1.07），0.90（0.74至1.05），0.92（0.78至1.06）和0.86（0.67至1.06）。区分SVV和SVP的阈值分别为67％和PPV的41％。结论在腹腔内高压中，即使识别响应者和未响应者的阈值可能会引起中风量和动脉压的呼吸变化，仍指示体液反应性高于正常腹腔内压力。为了确定这些腹腔内高血压的阈值，需要对人类进行进一步的研究。
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