Jubran A, Tobin M J
Division of Pulmonary Medicine and Critical Care, University of Texas Health Science Center, Houston.
Chest. 1990 Jun;97(6):1420-5. doi: 10.1378/chest.97.6.1420.
Pulse oximetry is widely used in the critical care setting, but few studies have examined its usefulness in clinical decision making. One area where pulse oximetry might be useful is in the titration of fractional inspired O2 concentration (FIO2) in ventilator-dependent patients. Unfortunately, documented guidelines for this use do not exist, and in a survey of directors of intensive care units, we found that they employed a wide range of target O2 saturation (SpO2) values. Consequently, we undertook a study to determine if SpO2 could be reliably substituted for measurements of arterial O2 tension (PaO2) when adjusting FIO2 in ventilator-dependent patients. We examined a number of SpO2 target values in 54 critically ill patients aiming for a PaO2 of greater than or equal to 60 mm Hg, while minimizing the risk of O2 toxicity. In white patients, we found that a SpO2 target of 92 percent was reliable in predicting a satisfactory level of oxygenation. However, in black patients, such a SpO2 reading was commonly associated with significant hypoxemia (PaO2 as low as 49 mm Hg), and a higher SpO2 target, 95 percent, was required. In addition, inaccurate oximetry readings (ie, greater than 4 percent difference between SpO2 and direct SaO2 measurements) were more common in black (27 percent) than in white patients (11 percent, p less than 0.05). In conclusion, a SpO2 target of 92 percent was reliable when titrating supplemental O2 in white patients receiving mechanical ventilation; however, in black patients, such a SpO2 reading was commonly associated with significant hypoxemia, and a higher SpO2 target, 95 percent, was required to ensure a satisfactory level of oxygenation.
脉搏血氧饱和度测定法在重症监护环境中被广泛使用，但很少有研究探讨其在临床决策中的效用。脉搏血氧饱和度测定法可能有用的一个领域是在依赖呼吸机的患者中滴定吸入氧分数浓度（FIO₂）。不幸的是，目前尚无关于此用途的成文指南，并且在对重症监护病房主任的一项调查中，我们发现他们采用了广泛的目标氧饱和度（SpO₂）值。因此，我们进行了一项研究，以确定在调整依赖呼吸机患者的FIO₂时，SpO₂是否可以可靠地替代动脉血氧张力（PaO₂）的测量。我们在54例危重症患者中检查了多个SpO₂目标值，目标是使PaO₂大于或等于60 mmHg，同时将氧中毒风险降至最低。在白人患者中，我们发现92%的SpO₂目标值在预测满意的氧合水平方面是可靠的。然而，在黑人患者中，这样的SpO₂读数通常与显著的低氧血症（PaO₂低至49 mmHg）相关，需要更高的SpO₂目标值，即95%。此外，不准确的血氧饱和度测定读数（即SpO₂与直接测量的SaO₂之间的差异大于4%）在黑人患者中（27%）比在白人患者中（11%，p<0.05）更常见。总之，在接受机械通气的白人患者中滴定补充氧气时，92%的SpO₂目标值是可靠的；然而，在黑人患者中，这样的SpO₂读数通常与显著的低氧血症相关，需要更高的SpO₂目标值（95%）以确保满意的氧合水平。
