square wave test

[monkeyman1000]

Does anybody do this? I usually try it on my art lines and CVP but when I get a wierd result, either no one knows what I'm talking about or they say ignore it. For instance, the last 2 days one of my patients had an art line and a CVP. I checked both and on the art line I had a good square wave test but the CVP (it always seems to be the CVP) showed that it was underdamped. I removed an extra piece of tubing (little short piece with a stopcock) and it didn't improve anything. The AACN guide said to add a dampening device but I and everyone else had never heard of such a thing. The actual CVP wave form looked good and the doc's never seemed to care so should I just toss this practice. Serves me right for reading.

[wonderbee, BSN, RN]

RNKittyKat

Squarewave test is when you flush the line and observe the wave form on the monitor. It should be perfect square with 1-2 oscilation.

A square wave test checks the dynamic response of the entire catheter monitoring kit transducer system. It is extremely important to obtain a high quality square wave test in order to assure confidence that subsequent pressure measurements are relatively distortion free and accurate

Right, got that one. I square wave test with my safety checks and initial assessment. What I'm referring to though is the "device" others have referred to that is used to correct over or under dampening a poor wave form. We don't have such a device and I've never heard of it. We either move the pt. or the transducer, then zero and relevel.

[SanFranSRNA]

Yeah never use that device either.

[TennRN2004]

We reposition, relevel and zero the transducer or reposition the pt if over or underdamped. I wasn't aware of any device that does this. Are we in the dark ages in my unit?

We use it all the time in my unit. Whenever I see a nibp and aline not correlating well, it's the first thing I think of. It can be a big problem in my unit because we do open hearts and they like to keep bp well controlled between 90-120 ish, so if you got an aline saying a bp of 142, but a cuff of 84, which one do you believe? It usually makes a big difference when you put a rose on the aline and the pressures will be much closer more like a cuff of 84 and an aline of 110, which is more expected. We really need to know our pressures are as accurate as possible since we titrate gtts so much in my unit.

What kind of unit do you work in Kitty? I work in a SICU, the recovery room and OR are just outside our hallway, so we have easy access to these types of things with our patients. Maybe your hospital has them, they are just not stocked in your unit. We have a few things like this that we call over to OR or recovery for and we can get things we rarely use so we don't stock it.