Nishida H, Akazawa T, Nishinaka T, Aomi S, Endo M, Koyanagi H
Department of Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical College.
Artif Organs. 1998 May;22(5):362-5. doi: 10.1046/j.1525-1594.1998.06140_22_5.x.
To evaluate the clinical meaning and effects of afterload-dependent flow fluctuation in a centrifugal pump, concomitant measurement of flow rate and mixed venous oxygen saturation (SVO2) was performed in 5 cases of open heart surgery in which the patients underwent cardiopulmonary bypass (CPB) with the Terumo Capiox centrifugal pump. Continuous measurement of SVO2 using the 3M CDI System 100 was performed with a disposable cuvette incorporated into the drainage circuit. After the target flow rate of 2.4 L/min/m2 was obtained under a nonbeating condition, the pump rotational speed was fixed. During the cooling and low temperature period, SVO2 decreased as the flow rate spontaneously decreased but still stayed around 80% even with a 15-20% decrease in blood flow rate. This indicates that a luxury perfusion condition is ensured as long as the body temperature is kept low. In contrast, during the rewarming period, SVO2 decreased to around 70-75% despite a 15-25% spontaneous increase in flow rate. Although this level of SVO2 still indicates adequate systemic perfusion, there is a possibility of regional hypoperfusion in patients with such conditions as cerebrovascular disease. In conclusion, although diligent adjustment of the physiological fluctuating flow rate in the centrifugal pump seems unnecessary during conventional open heart surgery, manual control may be necessary especially during the rewarming period, normothermic surgery, or circulatory assist for shocked patients. From this study, we also conclude that the major benefit of the afterload-independent autoflow control system of the centrifugal pump is the improvement of safety in terms of the fixed reservoir level and the handling of cardiopulmonary bypass.
为评估离心泵中后负荷依赖性流量波动的临床意义及影响，我们对5例接受心脏直视手术的患者进行了流量与混合静脉血氧饱和度（SVO2）的同步测量，这些患者使用Terumo Capiox离心泵进行体外循环（CPB）。使用3M CDI System 100通过置于引流回路中的一次性比色皿连续测量SVO2。在非搏动状态下达到目标流量2.4 L/min/m2后，固定泵的转速。在降温及低温期，随着流量自发降低，SVO2也降低，但即使血流速率降低15 - 20%，SVO2仍维持在80%左右。这表明只要体温保持较低，就能确保充足灌注状态。相比之下，在复温期，尽管流量自发增加15 - 25%，SVO2仍降至70 - 75%左右。虽然这个SVO2水平仍表明全身灌注充足，但对于患有脑血管疾病等情况的患者，仍有可能出现局部灌注不足。总之，在传统心脏直视手术期间，似乎无需刻意调节离心泵中生理性波动的流量速率，但在复温期、常温手术或对休克患者进行循环辅助时，可能需要手动控制。通过本研究，我们还得出结论，离心泵的后负荷独立自动流量控制系统的主要益处在于，在固定储液器液位及体外循环操作方面提高了安全性。
