Besarab A, Dorrell S, Moritz M, Michael H, Sullivan K
Department of Surgery, College of Medicine of Thomas Jefferson University, Philadelphia, Pennsylvania.
ASAIO Trans. 1991 Jul-Sep;37(3):M270-1.
Venous pressure measured at the venous bubble trap (VPdm) is a complex function of true intra-access pressure (VP0), hematocrit, needle gauge, and blood flow. In a patient free circuit, needle gauge, hematocrit, and blood flow influenced the pressure drop through the venous return needle. Measured intra-access pressure (VPm) and VPdm also were determined 149 times in 83 subjects. The increase in VPdm above VP0 under conditions of flow through 16 gauge needles was affected by blood flow rate, hematocrit, and VP0 with coefficients similar to those found in vitro. Calculation of VP0 from VPdm produced an absolute difference greater than 20 mmHg in 35-40% of cases. Mean VP0 was significantly lower in subjects with native compared with expanded polytetrafluorethylene accesses. It was concluded that VP0 is influenced by access type and can be estimated but that direct measurement is preferred. Direct measurement of VP0 may be a sensitive test to screen for venous outlet stenosis because it should vary with access flow and outlet geometry.
在静脉气泡捕捉器处测得的静脉压力（VPdm）是真实的内瘘压力（VP0）、血细胞比容、针规格和血流量的复杂函数。在无体外循环的患者中，针规格、血细胞比容和血流量会影响通过静脉回血针的压力降。还对83名受试者进行了149次测量内瘘压力（VPm）和VPdm。在通过16号针有血流的情况下，VPdm高于VP0的增加值受血流速度、血细胞比容和VP0的影响，其系数与体外研究结果相似。由VPdm计算VP0时，在35%-40%的病例中绝对差值大于20 mmHg。与使用膨体聚四氟乙烯内瘘的受试者相比，自体血管内瘘受试者的平均VP0显著更低。研究得出结论，VP0受内瘘类型影响，可以进行估算，但直接测量更为可取。直接测量VP0可能是筛查静脉流出道狭窄的一项敏感检查，因为它应随内瘘血流量和流出道几何形状而变化。
