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The effect of needle gauge on recirculation, venous pressure and bleeding from puncture sites.

We performed a prospective, randomized study of various needle gauges and the effect on recirculation, venous pressure, and puncture site bleeding. All patients (n = 21) in our unit consented and participated. We studied 14, 15, 16, and 17 gauge needles, 2.5 cm in length with a backeye conformation. Each of the four needle gauges were studied twice in a randomized order. Needles were placed with the arterial needle pointed toward the arterial anastomosis and the venous needle pointed toward the venous anastomosis. The arterial and venous needles were placed at least 6 cm apart. Venous pressure and bleeding from puncture sites were recorded and analyzed in relation to needle gauge. Recirculation was calculated using the 3 needle technique. Blood pump flow rates (Q B s) of 200 and 500 cc/min were studied with each needle gauge during the first 0.5 hour of dialysis. Data were analyzed using MANOVA and chi square. Recirculation at a Q B of 200 cc/min was similar for all needle gauges (13-15%). At a Q B of 500 cc/min the recirculation was 19% for the 17 gauge needles and 27% for the 14 gauge needles (p <0.01). Venous pressure increased with decreasing needle size : 83 mmHg at Q B 200 cc/min for 14 gauge needles, 147 mmHg at Q B 200 cc/min for 17 gauge needles, and 204 mmHg and 382 mmHg respectively for Q B 500 cc/min with needle gauges of 14 and 17. Bleeding occurred with 15 gauge needles on two occasions and four times with 14 gauge needles. There were no bleeding episodes with 16 or 17 gauge needles (p <0.03). In conclusion, recirculation is greater with larger gauge needles at Q B 500 cc/min. Bleeding is related to larger gauge needles. Hence, smaller gauge needles (17 gauge) appear move advantageous than larger gauge needles.