Mixed venous oxygen (O₂) saturation (SvO₂) is an important measure to evaluate sufficiency of cardiac output (CO) relative to whole body O₂ consumption (VO₂), while clinical utilization is limited for required invasive catheterization. By Fick's equation, VO₂ (ml/min) = CO (L/min) x Hb (g/dL) x 1.36 (ml/g) x (SaO₂ - SvO₂) / 10 [Hb = hemoglobin concentration, SaO₂ = arterial blood O₂ saturation]. Since VO₂, CO, Hb and SaO₂ can be measured noninvasively with expired gas analysis, echocardiography, simple blood test and percutaneous O₂ saturation, SvO₂ can be noninvasively calculated. We hypothesized that noninvasively calculated SvO₂ shows significant correlation and agrees well with invasively measured SvO₂. In 47 patients (29 men, mean age 70±12 years), SvO₂ was directly measured by sampling pulmonary artery blood. Calculated SvO₂ was also obtained by the method described above. Calculated SvO₂ was significantly correlated with measured SvO₂ (r = 0.79, P < 0.001) and significantly smaller than measured SvO₂ (70±5.1 vs 72.1±4.9%, p < 0.001). Bias at SvO₂ was -2.2% (95% confidence interval, -3.2 to -1.1%) with limits of agreement from -9.5 to 5.2%, demonstrating acceptable agreement. The optimal cut-offs values of calculated SvO₂ was < 69% for reduced measured SvO₂ < 70% with the area under the curve of 0.94. Reduced calculated SvO₂ < 69% indicated a sensitivity of 92.9% and specificity of 90.9% for reduced measured SvO₂. Noninvasively calculated SvO₂ significantly correlated and agreed well with directly measured SvO₂. This novel method allows practical evaluation of SvO₂ to assess sufficiency of CO according to VO₂.

中文翻译：

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通过超声心动图和呼出气体分析对混合静脉氧饱和度进行新型无创估计。

混合静脉氧 (O ₂ ) 饱和度 (SvO ₂ ) 是评估心输出量 (CO) 相对于全身 O ₂消耗量 (VO ₂ )充足性的重要措施，而临床应用受限于所需的侵入性导管插入术。通过Fick方程，VO ₂（毫升/分钟）= CO（L /分）X HB（克/升）×1.36（毫升/克）×（血氧饱和₂ - SVO ₂）/ 10 [血红蛋白=血红蛋白浓度，血氧饱和度₂ =动脉血O ₂饱和度]。由于 VO ₂、CO、Hb 和 SaO ₂可以通过呼出气体分析、超声心动图、简单血液检测和经皮 O ₂无创测量饱和度，SvO ₂可以无创计算。我们假设无创计算的 SvO ₂显示出显着的相关性，并且与有创测量的 SvO ₂非常吻合。在 47 名患者（29 名男性，平均年龄 70±12 岁）中，通过采样肺动脉血直接测量SvO ₂。计算的SvO ₂也通过上述方法获得。计算的 SvO ₂与测量的 SvO ₂显着相关（r = 0.79，P < 0.001）并且显着小于测量的 SvO ₂（70±5.1 vs 72.1±4.9%，p < 0.001）。SvO _{2 的}偏差为 -2.2%（95% 置信区间，-3.2 至 -1.1%），一致性范围为 -9.5 至 5.2%，表明一致性可接受。对于降低的测量 SvO ₂ < 70% ，计算的 SvO ₂的最佳截断值为< 69%，曲线下面积为 0.94。降低的计算 SvO ₂ < 69% 表明降低的测量 SvO ₂的灵敏度为 92.9%，特异性为 90.9% 。无创计算的 SvO ₂与直接测量的 SvO ₂显着相关并且非常吻合。这种新颖的方法允许对 SvO ₂进行实际评估，以根据 VO ₂评估 CO 的充足性。