Ranger IVs decrease flow

When you’re out in the field, IV access is precious. So you do everything you can to prevent losing a good line. In concept, Ranger IVs are perfect. They are a ruggedized field IV system in which an IV is started, and then converted to saline lock. This is secured to the patient using a clear dressing (tegaderm or the like). A second line of the same gauge is then placed through the hub of the saline lock. This system then allows for a quick release valve of sorts. In essence, if the tubing gets snagged and pulls out, the saline lock remains, and only the second line is removed. Then all you have to do is put the second line (or a new one) back into the saline lock instead of starting a new IV.

This is the same logic I use when I teach my residents to not tape the chest tube to the collecting system. If someone trips over the tubing, it simply disconnects, and you just reattach it. If they’re attached, then you pull out the chest tube, requiring another invasive procedure.

Now, the tactical combat casualty care (TCCC) guidelines recommend giving those patients with hemorrhage and signs of shock a 500mL bolus as quickly as possible using the 18 gauge needles they carry. 18s are easier to start than 14s or 16s, and in the interest of carrying as little as possible they are what is used by the military. Since they’re already starting out with a rate limiting step by using a smaller IV, the authors wanted to know if the Ranger IV setup further limited the rate of the infusion.

Well of course it did. Anybody that works in critical care knows that putting one of those luer lock adapters on your resuscitation line will do two things. Get you yelled at by someone, and slow down the rate of your rapid infusion. But is it a significant amount, both clinically and statistically?

They used two setups, one with a hard needle (variant 1), and one with a catheter (variant 2), and a control of a normal catheter. The hard needle was the slowest, taking 14:50 for a 500mL bolus of LR, compared to 9:33 for the control, and 12:20 for variant 2. When hextend was used, the difference was even more pronounced. The control took 24:39, and variant 2 took 39:46. Variant 1 took more than twice as long as the control, at 49:32.

If pressure infusion bags were used, the bolus times were markedly decreased. LR times were 2:56, 4:23, and 3:49 (control, V1, V2), and hextend took 5:26, 9:08, and 7:35 respectively.

These results were stastically significant, and the point can be made that they’re clinically significant, at least as far as gravity fed lines are concerned. Certainly, three take home points can be made from this.

  1. If you’re going to use a ruggedized IV, use the catheter instead of a hard needle. It’s certainly safer, and it flows faster as well.
  2. The ruggedized IV shouldn’t be used for bolus with gravity alone.
  3. Even a normal 18 gauge delivers 6% hetastarch slowly, so those truly in shock and receiving high viscosity fluids need a pressure bag setup.

Morgan TR. Evaluation of fluid bolus administration rates using ruggedized field intravenous systems. Wilderness Environ Med. 2014 Jun;25(2):204-9 [PMID 24631229]

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EBM Gone Wild

Wilderness Medicine

Emergency physician with interests in wilderness and prehospital medicine. Medical Director of the Texas State Aquarium, Padre Island National Seashore, Robstown EMS, and Code 3 ER | EBM gone Wild | @EBMGoneWild |

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