McDaniel L B, Zwischenberger J B, Vertrees R A, Nutt L, Uchida T, Nguyen T, Kramer G C
Department of Anesthesiology, University of Texas Medical Branch, Galveston 77555-0591.
Anesth Analg. 1995 Mar;80(3):466-72. doi: 10.1097/00000539-199503000-00006.
Mixed venous oxygen saturation is generally accepted as an indicator of adequacy of systemic oxygen delivery; however, cardiopulmonary bypass (CPB) may alter this relationship. Major postoperative complications potentially secondary to inadequate oxygen delivery during CPB indicate that mixed venous oxygen saturation may not detect regional venous desaturation during CPB. We therefore tested the hypothesis that mixed venous oxygen saturation and pH did not predict regional venous oxygen saturations and pH during 2 h of bypass in a swine model. Six immature swine (27-34 kg) received standard normothermic CPB. Sagittal sinus and portal vein oxygen saturations and blood gases were measured at 30, 60, 90, and 120 min of bypass. Although the venous reservoir oxygen saturation remained unchanged during 2 h of bypass, sagittal sinus saturation and pH decreased significantly (66% +/- 3.3% to 33% +/- 2.2% and 7.38 +/- 0.04 to 7.23 +/- 0.05, respectively). Likewise in the portal vein, oxygen saturation and pH also decreased (82% +/- 2.4% to 59.3% +/- 3.9% and 7.39 +/- 0.03 to 7.27 +/- 0.06, respectively). We conclude that profound regional venous desaturation and progressive regional acidemia may go undetected even when a standard pump flow rate of 100 mL.kg-1.min-1 is used and mixed venous oxygen saturation is normal.
混合静脉血氧饱和度通常被认为是全身氧输送充足与否的指标；然而，体外循环（CPB）可能会改变这种关系。CPB期间因氧输送不足而潜在引发的主要术后并发症表明，混合静脉血氧饱和度可能无法检测到CPB期间局部静脉的氧饱和度降低情况。因此，我们在猪模型中检验了这一假设，即在2小时的体外循环期间，混合静脉血氧饱和度和pH值无法预测局部静脉血氧饱和度和pH值。六只未成熟猪（体重27 - 34千克）接受了标准的常温CPB。在体外循环30、60、90和120分钟时测量矢状窦和门静脉的血氧饱和度及血气。尽管在2小时的体外循环期间静脉储血器的血氧饱和度保持不变，但矢状窦的饱和度和pH值显著下降（分别从66%±3.3%降至33%±2.2%，以及从7.38±0.04降至7.23±0.05）。同样，门静脉的血氧饱和度和pH值也下降了（分别从82%±2.4%降至59.3%±3.9%，以及从7.39±0.03降至7.27±0.06）。我们得出结论，即使使用100 mL·kg-1·min-1的标准泵流量且混合静脉血氧饱和度正常，仍可能无法检测到严重的局部静脉氧饱和度降低和进行性局部酸中毒。
