Hess D, Agarwal N N
Department of Research, York Hospital, PA 17405.
J Clin Monit. 1992 Apr;8(2):111-5. doi: 10.1007/BF01617428.
We evaluated the short-term variability of PaO2, PaCO2, pulse oximeter saturation (SpO2), and end-tidal PCO2 (PETCO2) in mechanically ventilated trauma patients. All patients were stable and undisturbed during the evaluation periods. Blood gases were obtained from an arterial catheter 4 times at 20-minute intervals. SpO2 and PETCO2 were recorded when the blood gases were obtained. Fifty evaluations were made in 26 patients; 24 patients were evaluated twice, with greater than or equal to 24 hours between evaluation periods. Variability was expressed as coefficient of variation (%CV) for each evaluation period. The median %CVs were 3.6% for PaO2 (95th percentile = 9.8%), 0.5% for SpO2 (95th percentile = 1.4%), 2.8% for PaCO2 (95th percentile = 7.4%), and 2.4% for PETCO2 (95th percentile = 7.1%). The overall correlation between PaCO2 and PETCO2 was r = 0.80, and the mean difference between PaCO2 and PETCO2 was 0.9 +/- 3.6 mm Hg. The variability of PETCO2 was similar to the variability of PaCO2. However, the variability of PaO2 was considerably greater than that of SpO2, which was probably related to the shape of the oxyhemoglobin dissociation curve and the relatively high saturations of the patients in this study. Variability of blood gases, SpO2, and PETCO2 should be considered when these values are clinically interpreted.
我们评估了机械通气创伤患者动脉血氧分压（PaO₂）、动脉血二氧化碳分压（PaCO₂）、脉搏血氧饱和度（SpO₂）和呼气末二氧化碳分压（PETCO₂）的短期变异性。在评估期间，所有患者病情稳定且未受干扰。每隔20分钟通过动脉导管采集4次血气样本。采集血气样本时记录SpO₂和PETCO₂。对26例患者进行了50次评估；24例患者接受了两次评估，评估间隔时间大于或等于24小时。变异性以每个评估期的变异系数（%CV）表示。PaO₂的%CV中位数为3.6%（第95百分位数 = 9.8%），SpO₂为0.5%（第95百分位数 = 1.4%），PaCO₂为2.8%（第95百分位数 = 7.4%），PETCO₂为2.4%（第95百分位数 = 7.1%）。PaCO₂与PETCO₂之间的总体相关性为r = 0.80，PaCO₂与PETCO₂之间的平均差值为0.9±3.6 mmHg。PETCO₂的变异性与PaCO₂的变异性相似。然而，PaO₂的变异性明显大于SpO₂的变异性，这可能与氧合血红蛋白解离曲线的形状以及本研究中患者相对较高的饱和度有关。在对这些值进行临床解读时，应考虑血气、SpO₂和PETCO₂的变异性。
