Harris David E, Massie Maribeth
University of New England Nurse Anesthesia Program in Portland.
Columbia University School of Nursing Nurse Anesthesia Program.
AANA J. 2019 Jun;87(3):214-221.
Assessment of pulmonary dysfunction is vital to anesthetists. Measurements including the gradient between the alveolar partial pressure of oxygen (PAo) and the arterial partial pressure of oxygen (Pao), called the PAo - Pao , and the ratio of the Pao to the fraction of inspired oxygen (FIo) (Pao/FIo ratio) are useful in determining the extent of acute lung injury. A literature review via MEDLINE using the terms PAo - Pao , Pao/FIo ratio, and pulmonary dysfunction was performed to identify articles on the use of these measures in the perioperative period. Both measures have been found to predict clinical outcomes in most settings. We also developed a mathematical model to calculate values of the PAo - Pao and the Pao/FIo ratio. In model results, as in clinical findings, both respond appropriately to reflect worsening pulmonary dysfunction when shunt or diffusion barrier (alveolar Po - pulmonary capillary partial pressure of oxygen) is increased. However, both are also sensitive to the FIo. The increase in the Pao/FIo ratio as the FIo increases is particularly problematic because it could disguise a deterioration in the patient's pulmonary status. The PAo - Pao and the Pao/FIo ratio should be used with an understanding of their limitations.
评估肺功能障碍对麻醉医生至关重要。包括肺泡氧分压（PAo）与动脉血氧分压（Pao）之间的差值（称为PAo - Pao）以及Pao与吸入氧分数（FIo）的比值（Pao/FIo比值）等测量指标，对于确定急性肺损伤的程度很有用。通过MEDLINE进行文献综述，使用PAo - Pao、Pao/FIo比值和肺功能障碍等术语，以识别关于这些指标在围手术期应用的文章。已发现这两个指标在大多数情况下都能预测临床结果。我们还开发了一个数学模型来计算PAo - Pao和Pao/FIo比值的值。在模型结果中，与临床发现一样，当分流或弥散障碍（肺泡氧分压 - 肺毛细血管氧分压）增加时，两者都能适当地反映肺功能障碍的恶化。然而，两者也都对FIo敏感。随着FIo增加，Pao/FIo比值升高尤其成问题，因为这可能掩盖患者肺部状况的恶化。使用PAo - Pao和Pao/FIo比值时应了解其局限性。
