What is good working order?

If a UAC is in good working order:

There is a good blood return.
It flushes easily.
The line is in good position.
The transducer is kept at the same level as the baby's heart. A transducer above the baby's heart will give a false low BP. A transducer below the baby's heart will give a false high BP.
The transducer is zeroed. Should be done at least once a shift before correlating with a cuff pressure, and after rate changes and tubing system changes. To zero, turn stopcock off to baby and open to air with transducer at level of heart, then "zero" on the monitor. Monitor BP should read all zeroes before closing the system and turning the stopcock back open to the baby.
The waveform has a dicrotic notch - when the waveform starts to come back down it then goes back up a little before coming all the way down. The dicrotic notch corresponds with the closure of the aortic valve.
The waveform is not flattened out - it has distinct upward and downward slopes. A flattened waveform may indicate that there is an air bubble in the line; a leak in the system; the catheter tip is laying against the vessel wall; or the transducer needs to be change. Don't trust the blood pressure transduced from a line when the waveform is flattened. Try flushing the system to remove any hard to see air first; make sure the stopcock is off to the baby before flushing.

UAC Waveform
dicrotic notch

If a UVC is in good working order:

There is a good blood return.
It flushes easily.
The line is in good position.

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Procedure for drawing blood specimens off of lines:

Maintain sterile technique.
Turn off fluids to avoid contaminating/diluting blood specimen with IV fluid.*
Place clean syringe on stopcock to slowly draw back "waste" - draw at least twice the catheter volume to clear line of fluid
Turn T-connector off to syringe, or turn a quarter turn.**
Keep syringe sterile while replacing w/new syringe.
Turn t-connector on to syringe and draw the required amount of blood. Avoid drawing an excessive amount of blood as neonates do not have blood to waste.
Turn t-connector off to syringe and replace syringe of blood with syringe of "waste" to return slowly.
Remove syringe, clean port with alcohol pad (or per unit policy) and replace with a fresh syringe of fluid for flushing*** (typically normal saline or half-normal saline). Unit policy might also be to change the valve connector, if used, as well. Flush with the minimum needed to clear blood from the line (or per policy). Restart infusion of fluids and open stopcocks to fluids and baby.
Document flushes and blood out per unit policy.

*When drawing from a line that is running anything other than normal saline or half-normal saline, clamp fluids and flush well prior to drawing back to decrease the risk of altering the results. It is particularly easy to get 'funny' results when TPN and high concentrations of dextrose are running through the line. Before choosing to draw off of a line, consider what you might bolusing the baby with when flushing if there are meds running through the line (i.e fentanyl or dopamine).
** Practice varies amongst institutions. A quarter turn will in theory turn the stopcock off to all directions (baby, line and syringe) although some will argue that some fluid can leak through. Thus, turning off the fluids and/or clamping the line above the stopcock will prevent fluid leaking into the specimen. If a valve connector (i.e. Clave) is used turning off to the line should be sufficient as the valve will prevent blood from backing up and out of the t-connector (or air from being introduced into the line in the case of a UVC).
*** Flushing or returning blood should be done with a push-pause method. A larger-sized syringe (10cc) should be used whenever pushing into a line. These measures limit the amount of pressure put on a line and reduce the risk of catheter rupture.
NOTE - When rapidly pushing or drawing back on an umbilical artery catheter the blood supply and pressure directed to the micropremie's brain can be affected. (Gordon, M. et al. PubMed.) Theoretically, the pressure from rapid infusion of fluids can also cause physical damage to the vessel it lies within. Push and pull back slowly!

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