Variable Pump Flow–Based Doppler Ultrasound Method

Abstract

Decreasing vascular access flow (Qa) is an important predictor of future access thrombosis and malfunction for hemodialysis (HD) patients. Among all of the methods for determining Qa, the variable pump flow (VPF) Doppler method measures Qa according to the change in Doppler signal between the arterial and the venous needles under different pump flow. After this technique was combined with spectral analysis of Duplex Doppler imaging, the variable pump flow-based Doppler ultrasound method (VPFDUM) for Qa measurement was developed. This study compared the reproducibility and correlation of Qa measurements for three different methods-VPFDUM, ultrasound dilution method (UDM), and conventional Doppler ultrasound method (CDUM)-in 55 HD patients. The mean value of Qa by VPFDUM (870.8 +/- 412.0 ml/min) was close to that by UDM (868.6 +/- 417.9 ml/min) but higher than that by CDUM (either of the above values versus 685.1 +/- 303.6 ml/min; P < 0.005). The mean values of coefficient of variation were similar by VPFDUM (1.6%) and UDM (1.4%) but lower than that by CDUM (either of the above values versus 6.8%; P < 0.01). The correlation coefficient and intraclass correlation coefficient of the repeated Qa measurements by VPFDUM (0.985 and 0.993; P < 0.001) were also similar to those by UDM (0.992 and 0.995; P < 0.001) but slightly higher than those by CDUM (0.917 and 0.948; P < 0.005). Either the reproducibility of VPFDUM (r=0.98, P < 0.0001) or the correlation between VPFDUM and UDM (r=0.99, P < 0.0001) in Qa measurements is good. The unassisted patency of vascular access at 6 mo was significantly poorer in patients with Qa <500 ml/min than those with Qa >500 ml/min (13.6% versus 92.2%; P < 0.0001). In conclusion, VPFDUM is a noninvasive, accurate, and reliable procedure for Qa measurement and prediction of the prognosis of vascular access in HD patients.

Far-Infrared Therapy

“…According to Kidney Disease Outcomes Quality Initiative guidelines for vascular access, HD patients with Qa Ͻ600 ml/min or Qa Ͻ1000 ml/min that has decreased by Ͼ25% during 4 mo should be referred for fistulogram to detect potential stenotic lesions (23). Our previous study found that the unassisted patency of vascular access at 6 mo was significantly poorer in patients with Qa Ͻ500 ml/min than in those with Qa Ͼ500 ml/min (13.6 versus 92.2%) (4). Therefore, the increase of Qa may contribute to the higher patency of AVF of our patients in this study.…”

“…First, we would like to control the interfering effect of the great individual variation in flow. This may explain why there was no statistical significance for Qa 4 even with a difference of 119.4 ml/min between the two groups but there was significance for ⌬(Qa 4 Ϫ Qa 3 ) with only a difference of 48.9 ml/min in Table 3. Second, several incremental changes of Qa were helpful to quantify and elucidate the roles of the various effects (e.g., hemodynamic effect of HD, the thermal and nonthermal effects of FIR) in the change of access flow.…”

“…This change then is calculated by the Transonic software, giving the result of Qa (ml/min). If Qa could not be obtained by this method, then it would be measured by the variable pump flow-based Doppler ultrasound method (4). The CO can be measured by injection of 30 ml of saline (37°C) into the venous catheter without reversing the tubing lines.…”

“…Approximately 80 to 85% of AV access failures arise from AV access thromboses, more than 80% of which result from AVF stenoses (3). An access flow (Qa), Ͻ500 ml/min was associated with an increased risk for access failure and predictive of poorer unassisted patency of native AVF (4). The pathologic features of stenosis of vascular access are composed of intimal hyperplasia, proliferation of smooth muscle cells in the media with subsequent migration to intima, and excessive accumulation of extracellular matrix (5).…”

Protocolo de Investigación: Correlación entre el Flujo de la Fístula Arterio-Venosa con el Flujo Extracorpóreo. Hospital José Carrasco Arteaga 2016.

“…Existen algunos determinantes de la recirculación fistular, lo que incluye la velocidad del flujo de la bomba peristáltica, la posición de las puntas de las agujas, la orientación de las líneas, la estenosis del acceso y el tipo del acceso. Existen múltiples métodos para medir la recirculación, basados en mediciones de urea, glucosa y la termodilución, sin embargo el gold estándar actualmente es el método dilucional con ultrasonido [9,10,[14][15][16][17][18][19][20]. …”