N470: Arterial lines

indications for an A-line

- BP monitoring (vasoactive meds)

- blood sampling (ABGs or frequent blood draws)

What do we never do with an A-line?

NEVER infuse anything into it

Which arteries can an A-line be placed in?

- radial (most common)

- brachial

- femoral

Who can insert an A-line?

MD, RT, certified RN

Equipment for an A-line insertion

- pressure bag

- 500 ml bag NS

- pressure tubing with transducer

- occlusive dressing

- immobilizer prn

- pressure cable

- monitor

A-line waveform basics*

should have:

-swift systolic uptake (S1)

- diastolic runoff (S2)

- dicrotic notch on diastolic runoff

where is the transducer placed?

at the level of the R atrium aka the phlebostatic axis

- 4th ICS

- midclavicular line (R atrium)

- midaxillary line (transducer)

What occurs if the transducer is above the level of the R atrium?

BP reading falsely low

What occurs if the transducer is below the level of the R atrium?

BP reading falsely high

Purpose of zeroing the A-line

to eliminate gravitational forces affecting pressure readings from the transducer

When should an A-line be zeroed?

- upon insertion

- questionable readings

- when there is a disconnect

square wave test

pulling the flush valve opens it and the transducer reads the 300mmhg pressure from the pressure bag. This creates a sharp rise and a plateau in the wave form that drops off sharply when the valve is closed

What is a normal square wave test (indicates accurate BP reading)? *

2 oscillations only

What indicates under-dampening?*

more than two oscillations on the square wave test

What can under-dampening do the the A-line reading?*

make BP falsely high

causes of under-dampening* (4)

- turbulent flow

- catheter whipping in artery

- too many connections/extensions

- pressure tubing overly stiff

What indicates over-dampening?*

one oscillation only

What can over-dampening do the the A-line reading?*

make BP falsely low

causes of over-dampening* (5)

- loose connections

- bubbles in tubing

- kinked tubing

- overly-compliant pressure tubing

- catheter tip occlusion (clot/stuck against artery wall)

5 Ps of assessing A-line*

1) pain

2) pallor

3) paresthesia (numbness)

4) paralysis

5) pulses (cap refill)

Assessment pieces for A-line equipment (4)

- connections tight

- pressure bag filled to 300 mmHg

- flush bag has enough fluid

- tubing not expired (Q96H)

Describe the VAMP system on an A-line

- closed system=reduced infection risk

- 5 ml reservoir holds "waste" during blood sampling

- needless port used for sampling (pt blood sample "waste" cannot be returned to pt)