Arterial Line Sources of Error
May 09, 2024
Invasive blood pressure monitoring provides you with 5 key pieces of information:
1️⃣ Mean arterial pressure (accurate if zeroed)
2️⃣ Systolic pressure (accurate if zeroed & normal trace)
3️⃣ Diastolic (accurate if zeroed & normal trace)
4️⃣ A waveform (provides important information about accuracy of reading)
5️⃣ The heart rate
It is a complex system, so it helps to group the sources of error like this:
👉🏻 Patient errors
🔺 Vessel spasm or occlusion
🔺 Patient movement/flexion at wrist
🔺 Unilateral arterial conditions (stenosis, coarctation, dissection)
🔺 NIBP inflating on same side OR proximal compression of artery
👉🏻 Transducer errors
🔺 Failure to zero
🔺 Incorrect transducer height
🔺 Loose connections
🔺 Pressure bag <300mmHg
🔺 Tubing system too stiff (underdamping)
🔺 Air bubble in system (overdamping)
🔺 Other causes of overdamping
👉🏻 Cannula errors
🔺 Kinking
🔺 Dislodged
🔺 Clotted cannula
We rely on an accurate invasive blood pressure to ensure our patient is safe, so if you see a problem with your arterial line trace:
🔺 Trace quality (steep rise, curved peak, dicrotic notch)
🔺 Numbers don’t look right
Then use our “TRUE BP” framework to troubleshoot the problem:
👉🏻 Tighten connections
👉🏻 Repeat zero (and confirm transducer height)
👉🏻 Use non-invasive (to compare & ensure patient is safe)
👉🏻 Extend the wrist (if radial)
👉🏻 Bubble check (purge if required)
👉🏻 Pressure (bag should be 300mmHg)
Remember, measurement errors can distract you from a real patient issue, so call for help early if you can’t get an accurate reading!
Build knowledge ✅
Improve safety ✅
Ref: https://resources.wfsahq.org/wp-content/uploads/uia28-Invasive-blood-pressure-monitoring.pdf
