Written by Alex Chen
There were no statistically significant differences in pressure-bag flow rates for 1L of NS through all three ports of a standard triple-lumen catheter (TLC) compared to a 16 gauge peripheral venous catheter (PVC) or a 6Fr sheath introducer. On gravity-flow, it was not statistically different from a 16 gauge PVC. But 14ga PVC and 8.5Fr sheath rates were faster in both instances.
Why does this matter?
Previous literature (Mateer et al., 1983) demonstrates that 8 and 9Fr sheath introducers have significantly faster in vitro flow rates of saline and blood products compared to large bore PVCs. However, in these critically ill patients there is often a need for multiple ports, and a triple-lumen catheter is ideal for this purpose.
“If you ain’t first, you’re last.” –Reese Bobby, father of Ricky Bobby
This was a blinded observational study of flow rates with gravity compared to pressure bags through multiple different IV catheters. The TLC used was a standard 20cm CVC with one 16ga and 2x18ga ports. 1L of NS was placed on each lumen of the TLC, and they calculated the 1L NS flow time from the total time it took to empty the bags. For the pressure bag tests, each 1L bag of NS was placed at 300 mmHg.
Under pressure, flow rates of a TLC with all 3 ports running was statistically similar to a 16ga PVC and 6Fr sheath introducer; all took 6-7 minutes to infuse a liter. A 14ga PVC and 8.5Fr sheath infused faster in pressure bag trials (5-6 minutes). One could argue that the difference in infusing a liter in an extra 1-2 minutes is not clinically significant.
Under gravity, the TLC (3 ports) took just under 9 minutes to infuse and performed similarly to the 16ga PVC (about 7.5 minutes). A 14ga PVC and 8.5Fr sheath infused faster in gravity (6-7 minutes). Again, the clinical significance is debatable.
Flow Rates (in seconds)
I wonder how the viscosity of various fluids such as PRBCs or the usage of a rapid infuser would affect the flow rates. Also, it seems cumbersome to hook up three separate NS bags and blow up three pressure bags in a time sensitive situation, but this setup may be ideal for the septic patient who needs crystalloid quickly but also requires several medication infusions.
Are three ports better than one? An evaluation of flow rates using all ports of a triple lumen central venous catheter in volume resuscitation. Am J Emerg Med. 2018 May;36(5):739-740. doi: 10.1016/j.ajem.2017.09.058. Epub 2017 Oct 4.
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