Photo cases and methods explanation
Increased filling of hand veins
Increased filling of hand veins in a patient with radiocephalic native fistula. The cephalic vein abruptly „ends“ – this phenomenon is highly suspect of a significant stenosis.
Vascular access flow volume calculation by ultrasonography
The flow volume (Qa) calculation should be performed in a straight segment, far from any stenosis or arch. In native fistulas, brachial artery flow volume measurement is adviced, while in grafts it could be done close to the venous anastomosis as in this case. The calculation is based on the following equation : Qa = r2 * TAMean *60, where r = radius (=diameter/2), TAMean is the time velocity integral of the mean velocity layer. Sometimes, flow calculation is incorrectly provided using TAMAx, which overestimates the value. TAMax is the time integral of the velocity of the fastest layer (usually in the middle).
In this case, diameter = 0.52 cm, TAMean 109 cm/s.
The calculation could be done manually as follows Qa= 0.26*0.26*3.14*109*60 = 1388 ml/min.
The evidence of finger pressure decrease below 50 mmHg (or digital-brachial index 0.6) is mandatory for the diagnosis of hand ischemia. Easily, the finger pressure could be measured with the use of digital sphygmomanometer cuff and pulse oximeter. Select an oximeter, which also draws the plethysmographic curve.
Place the cuff and the oximeter sensor according to the Figure. Inflate the cuff slowly to ca. 200 mmHg until the curve disappears. Then deflate slowly the balloon and mention at which pressure value the plethysmographic curve reappears. This is the finger systolic pressure. Repeat measuremen on 1-2 other fingers and compare the obtained values with the brachial-artery pressure on the contralateral upper extremity