Physiologic Analysis and Clinical Performance of the Ventilatory Ratio in Acute Respiratory Distress Syndrome
Physiologic Analysis and Clinical Performance of the Ventilatory Ratio in Acute Respiratory Distress Syndrome
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DOI：
10.1164/rccm.201804-0692oc
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发表时间：
2019-02-01
影响因子：
24.7
通讯作者：
Kallet, Richard H.
中科院分区：
文献类型：
--
作者：
Sinha, Pratik;Calfee, Carolyn S.;Kallet, Richard H.
原理：肺死腔分数（V-D/V-T）是急性呼吸窘迫综合征（ARDS）死亡率的独立预测因子。然而，它很少在实践中使用。呼吸比是一个简单的床旁指数，可以使用常规测量的呼吸变量计算，是通气受损的指标。通气率定义为[每分钟通气量（ml/min）× Pa-CO2（mmHg）]/（预计体重× 100 × 37.5）。目的：确定ARDS中通气率与V-D/V-T的关系。方法：首先，在一项ARDS的单中心前瞻性观察研究中，我们检验了V-D/V-T与通气率的关系。以住院死亡率作为主要结局，无呼吸机天数作为次要结局，我们检验了呼吸机比率作为结局预测因子的作用。NHLBI ARDS网络的两项随机对照试验的二次分析进一步验证了本研究的结果。测量和主要结果：通气比与V-D/V-T呈正相关。V-D/V-T比值在各年龄组间差异有统计学意义（P <0.05）。在调整Pa-O2/FIO 2和呼气末正压（比值比，1.51; P = 0.024）以及调整急性生理评估和慢性健康评估II评分（比值比，1.59; P = 0.04）后，通气率与死亡风险增加独立相关。这些发现进一步复制在二次分析两个独立的NHLBI随机对照trials.Conclusions：通气比相关性以及与V-D/V-T在ARDS，在基线较高的价值与不良后果的风险增加。这些结果是有希望的使用呼吸比作为一个简单的床边指数呼吸功能受损的ARDS。
Rationale: Pulmonary dead space fraction (V-D/V-T) is an independent predictor of mortality in acute respiratory distress syndrome (ARDS). Yet, it is seldom used in practice. The ventilatory ratio is a simple bedside index that can be calculated using routinely measured respiratory variables and is a measure of impaired ventilation. Ventilatory ratio is defined as [minute ventilation (ml/min) x Pa-CO2 (mm Hg)]/(predicted body weight x 100 x 37.5).Objectives: To determine the relation of ventilatory ratio with V-D/V-T in ARDS.Methods: First, in a single-center, prospective observational study of ARDS, we tested the association of V-D/V-T with ventilatory ratio. With in-hospital mortality as the primary outcome and ventilator-free days as the secondary outcome, we tested the role of ventilatory ratio as an outcome predictor. The findings from this study were further verified in secondary analyses of two NHLBI ARDS Network randomized controlled trials.Measurements and Main Results: Ventilatory ratio positively correlated with V-D/V-T. Ordinal groups of ventilatory ratio had significantly higher V-D/V-T. Ventilatory ratio was independently associated with increased risk of mortality after adjusting for Pa-O2/FIO2, and positive end-expiratory pressure (odds ratio, 1.51; P = 0.024) and after adjusting for Acute Physiologic Assessment and Chronic Health Evaluation II score (odds ratio, 1.59; P = 0.04). These findings were further replicated in secondary analyses of two separate NHLBI randomized controlled trials.Conclusions: Ventilatory ratio correlates well with V-D/V-T in ARDS, and higher values at baseline are associated with increased risk of adverse outcomes. These results are promising for the use of ventilatory ratio as a simple bedside index of impaired ventilation in ARDS.