Variability of indices of hypoxemia in adult respiratory distress syndrome
Variability of indices of hypoxemia in adult respiratory distress syndrome
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DOI：
10.1097/00003246-199701000-00010
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发表时间：
1997-01-01
影响因子：
8.8
通讯作者：
Klocke, RA
中科院分区：
文献类型：
--
作者：
Gowda, MS;Klocke, RA
目的：确定充血指数在评估成人呼吸窘迫综合征（ARDS）患者中的有用性。设计：回顾性分析先前发表的描述ARDS通气和肺血流量分布的数据。设置：大学研究实验室。患者：16例ARDS患者。干预措施：在基于通气/灌注不均匀性加上真实分流和死腔的50室模型的气体交换计算机模型中，FIO 2在0.21和1.0之间变化。根据吸入氧浓度计算的低氧血症指标包括Pao（2）/Flo（2）、动脉/肺泡比值（Pao（2）/肺泡Po-2）、肺泡-动脉Po-2差、Pao（2）/Flo（2）、Pao（2）/Pao-2、Pao-2/Pao-2、Pao-2（P[A-a]o（2）），呼吸指数（P[A-a]o（2）/Pao（2））和静脉混合物。中度分流患者（30%）的Pao（2）/FIO 2比值在低FIO 2时较大，但Pao（2）/FIO 2比值在FIO 2值>0.5时降至相对稳定值。在所有患者中，Pao（2）/FIO 2保持相对稳定，FIO 2值大于或等于0.5，Pao（2）值小于或等于100 kPa（小于或等于13.3 kPa）。当Flo（2）变化时，其他基于Po-2的指数表现出较低的稳定性。如果低氧血症是由真正的分流引起的，则发现静脉混合液在所有FIO 2值下都是稳定的。然而，大约一半的患者由于通气和血流不匹配而出现临床重要的低氧血症。在这些患者中，静脉混合液随着FIO 2的变化而变化，变化程度与通气/灌注比为
Objective: To determine the usefulness of indices of hyperemia in assessing patients with the adult respiratory distress syndrome (ARDS).Design: Retrospective analysis of previously published data that describe the distributions of ventilation and pulmonary blood flow in ARDS.Setting: University research laboratory.Patients: Sixteen patients with ARDS.Interventions: The FIO2 was varied between 0.21 and 1.0 in a computer model of gas exchange, based on a 50 compartment model of ventilation/perfusion inhomogeneity plus true shunt and deadspace. The indices of hypoxemia that were calculated as a function of inspired oxygen concentration included Pao(2)/Flo(2), arterial/alveolar ratio (Pao(2)/alveolar Po-2), the alveolar-arterial Po-2 difference (P[A-a]o(2)), respiratory index (P[A-a]o(2)/Pao(2)), and venous admixture.Measurements and Main Results: The Pao(2)/FIO2 ratio in patients with moderate shunts (30%) had greater Pao(2)/FIO2, ratios at low FIO2, but the Pao(2)/FIO2, ratios decreased to relatively stable values at FIO2 values of >0.5. In all patients, Pao(2)/FIO2, remained relatively stable at FIO2 values of greater than or equal to 0.5 and Pao(2) values of less than or equal to 100 torr (less than or equal to 13.3 kPa). Other Po-2-based indices exhibited less stability as Flo(2) was varied. If hypoxemia resulted from true shunting, venous admixture was found to be stable at all FIO2 values. However, approximately one half of patients had clinically important hypoxemia resulting from mismatching of ventilation and blood flow. In these patients, venous admixture varied substantially with change in FIO2, and the degree of variation was proportional to the fraction of cardiac output perfusing gas exchange units with ventilation/perfusion ratios of