In the acute respiratory distress syndrome (ARDS), decreasing Ventilation-Perfusion $$\left( {{{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}} \right)$$ mismatch might enhance lung protection. We investigated the regional effects of higher Positive End Expiratory Pressure (PEEP) on $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ mismatch and their correlation with recruitability. We aimed to verify whether PEEP improves regional $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ mismatch, and to study the underlying mechanisms. In fifteen patients with moderate and severe ARDS, two PEEP levels (5 and 15 cmH2O) were applied in random order. $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ mismatch was assessed by Electrical Impedance Tomography at each PEEP. Percentage of ventilation and perfusion reaching different ranges of $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ ratios were analyzed in 3 gravitational lung regions, leading to precise assessment of their distribution throughout different $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ mismatch compartments. Recruitability between the two PEEP levels was measured by the recruitment-to-inflation ratio method. In the non-dependent region, at higher PEEP, ventilation reaching the normal $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ compartment (p = 0.018) increased, while it decreased in the high $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ one (p = 0.023). In the middle region, at PEEP 15 cmH2O, ventilation and perfusion to the low $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ compartment decreased (p = 0.006 and p = 0.011) and perfusion to normal $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ increased (p = 0.003). In the dependent lung, the percentage of blood flowing through the non-ventilated compartment decreased (p = 0.041). Regional $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ mismatch improvement was correlated to lung recruitability and changes in regional tidal volume. In patients with ARDS, higher PEEP optimizes the distribution of both ventilation (in the non-dependent areas) and perfusion (in the middle and dependent lung). Bedside measure of recruitability is associated with improved $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$ mismatch.

中文翻译：

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PEEP对急性呼吸窘迫综合征局部通气-灌注失配的影响

在急性呼吸窘迫综合征 (ARDS) 中，降低通气-灌注 $$\left( {{{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q }}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}} \right）$$ 不匹配可能会增强肺保护。我们调查了较高的呼气末正压 (PEEP) 对 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}} 的区域影响} \正确的。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 不匹配及其与可招募性的相关性。我们旨在验证 PEEP 是否改善了区域 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 不匹配，并研究其底层机制。在 15 名中度和重度 ARDS 患者中，随机应用两个 PEEP 水平（5 和 15 cmH2O）。$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 不匹配通过每次 PEEP 的电阻抗断层扫描进行评估。达到 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right 的不同范围的通气和灌注百分比。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 比率在 3 个重力肺区域进行分析，从而精确评估它们在不同 $${{\dot{V}} \mathord{\left/ 中的分布{\vphantom {{\dot{V}} {\dot{Q}}}} \对。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 不匹配的隔间。两个 PEEP 水平之间的可招募性通过招募与通胀比率法进行测量。在非依赖性区域，在较高的 PEEP 下，通风达到正常 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 隔间（p = 0.018）增加，而在高位 $${{\dot{V}} \mathord{\left/ {\vphantom { {\dot{V}} {\dot{Q}}}} \对。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 一（p = 0.023）。在中间区域，PEEP 15 cmH2O，通气和灌注到低 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}} }} \正确的。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 隔室减少（p = 0.006 和 p = 0.011）并且灌注正常 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \对。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 增加（p = 0.003）。在依赖肺中，流经非通气室的血液百分比降低（p = 0.041）。区域 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 错配改善与肺复张性和区域潮气量变化相关。在 ARDS 患者中，较高的 PEEP 可优化通气（在非依赖区域）和灌注（在中部和依赖肺）的分布。可招募性的床边测量与改进的 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right 相关。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 不匹配。较高的 PEEP 优化了通气（在非依赖区域）和灌注（在中部和依赖肺）的分布。可招募性的床边测量与改进的 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right 相关。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 不匹配。较高的 PEEP 优化了通气（在非依赖区域）和灌注（在中部和依赖肺）的分布。可招募性的床边测量与改进的 $${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right 相关。\kern-\nulldelimiterspace} {\dot{Q}}}$$ 不匹配。