Effect of haemodynamic variables on surgically created arteriovenous fistula flow

Abstract

Background. The immediate success and flow rate of a newly constructed arteriovenous fistula is dependent on several haemodynamic factors affecting the inflow and outflow of the fistula. Methods. In this study we evaluated the effect of preoperative arterial blood pressure, arterial inflow, subclavian venous flow, and operative venous outflow resistance on the immediate success, with special reference to the quantity of the fistula flow in 32 patients undergoing internal arteriovenous fistula operations. Flow measurements were done by utilizing colour flow duplex imaging and measurement of venous resistance of the fistula vein was accomplished indirectly by a newly developed simple system. Results. A preoperative subclavian venous flow rate of less than 400 ml/min was associated with higher rate of immediate failures (P < 0.05) with a negative predictive value of 100% with 100% sensitivity. Regarding immediate failures, no other haemodynamic measurement was found to affect the success of a newly constructed fistula significantly. A linear correlation between the measured haemodynamic values and the quantity of postoperative fistula flow was not found. However, an arterial inflow value of ≤ 40 ml/min was associated with higher fistula flow rates (P < 0.05). Conclusions. The immediate success and flow of a newly constructed arteriovenous fistula is mainly dependent on arterial inflow and subclavian venous flow. An arterial inflow rate of 40 ml/min or more and subclavian venous flow rate of 400 ml/min or more measured by colour flow duplex imaging prior to the operation will be associated with better outcomes, and therefore the use of colour flow duplex imaging is warranted during the evaluation of patients who are candidates for an arteriovenous fistula operation.