Case Western Reserve University School of Medicine, Cleveland, OH.
Department of Pulmonary, Allergy and Critical Care Medicine, Respiratory Institute, Cleveland Clinic, Cleveland, OH.
Med Sci Sports Exerc. 2018 Oct;50(10):1992-1997. doi: 10.1249/MSS.0000000000001658.
INTRODUCTION/PURPOSE: Peripheral capillary oxygen saturation (SpO2) is used as surrogate for arterial blood oxygen saturation. We studied the degree of discrepancy between SpO2 and arterial oxygen (SaO2) and identified parameters that may explain this difference.
We included patients who underwent cardiopulmonary exercise testing at Cleveland Clinic. Pulse oximeters with forehead probes measured SpO2 and arterial blood gas samples provided the SaO2 both at rest and peak exercise.
We included 751 patients, 54 ± 16 yr old with 53% of female gender. Bland-Altman analysis revealed a bias of 3.8% with limits of agreement of 0.3% to 7.9% between SpO2 and SaO2 at rest. A total of 174 (23%) patients had SpO2 ≥ 5% of SaO2, and these individuals were older, current smokers with lower forced expiratory volume in the first second and higher partial pressure of carbon dioxide and carboxyhemoglobin. At peak exercise (n = 631), 75 (12%) SpO2 values were lower than the SaO2 determinations reflecting difficulties in the SpO2 measurement in some patients. The bias between SpO2 and SaO2 was 2.6% with limits of agreement between -2.9% and 8.1%. Values of SpO2 ≥ 5% of SaO2 (n = 78, 12%) were associated with the significant resting variables plus lower heart rate, oxygen consumption, and oxygen pulse. In multivariate analyses, carboxyhemoglobin remained significantly associated with the difference between SpO2 and SaO2 both at rest and peak exercise.
In the present study, pulse oximetry commonly overestimated the SaO2. Increased carboxyhemoglobin levels are independently associated with the difference between SpO2 and SaO2, a finding particularly relevant in smokers.
简介/目的：外周毛细血管血氧饱和度 (SpO2) 可用作动脉血氧饱和度的替代指标。我们研究了 SpO2 与动脉血氧 (SaO2) 之间的差异程度，并确定了可能解释这种差异的参数。
我们纳入了在克利夫兰诊所进行心肺运动测试的患者。使用额部探头的脉搏血氧仪测量 SpO2，动脉血气样本提供静息和峰值运动时的 SaO2。
我们纳入了 751 名患者，年龄 54 ± 16 岁，女性占 53%。Bland-Altman 分析显示，静息时 SpO2 与 SaO2 之间存在 3.8%的偏差，一致性界限为 0.3%至 7.9%。共有 174 名（23%）患者的 SpO2 比 SaO2 高 5%，这些患者年龄较大，目前吸烟，用力呼气第一秒量较低，二氧化碳分压和碳氧血红蛋白较高。在峰值运动时（n = 631），有 75 个（12%）SpO2 值低于 SaO2 测定值，这反映了一些患者的 SpO2 测量存在困难。SpO2 与 SaO2 之间的偏差为 2.6%，一致性界限为-2.9%至 8.1%。SpO2 比 SaO2 高 5%的数值（n = 78，12%）与静息时的显著变量相关，加上心率、耗氧量和氧脉冲降低。多元分析显示，在静息和峰值运动时，碳氧血红蛋白均与 SpO2 和 SaO2 之间的差异显著相关。
在本研究中，脉搏血氧仪通常高估了 SaO2。较高的碳氧血红蛋白水平与 SpO2 和 SaO2 之间的差异独立相关，这一发现在吸烟者中尤为相关。
