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I recently spent a month with our colleagues in the MICU. Our team placed a fair number of arterial lines and I picked up a few tips that I thought were worth sharing. We don’t place a-lines very often in the ED, but it’s worth considering if you’re going to be boarding a MICU patient who is in shock. Arterial lines can also be useful if your non-invasive cuff pressures seem unreliable or you’re giving vasoactive medications that benefit from careful titration based on BP (i.e. Nicardipine). If you find yourself placing an arterial line in the future, here are some troubleshooting tips to help you succeed.

 

 

First, some general advice. Palpate the artery with at least 2 fingers to trace its path through the wrist. Use the same technique you would for an ABG, but drop the angle of your approach to facilitate threading the wire and then the catheter. Advance the needle with enough speed and force to ensure you get through the thicker wall of the artery without it rolling. If you are unable to palpate a good pulse, don’t hesitate to place these with ultrasound, it will actually save you time in the end. If you need to go off of landmarks, the radial artery typically lies just lateral to the the flexor carpi radialis tendon. If the radial artery isn’t an option, consider placing the line in the axillary artery.

 

Arterial Lines 1

Marieb, Elaine N. Human Anatomy & Physiology. San Francisco: Benjamin Cummings, 2001

 

The first arterial line tip was taught to me by Virgina Brady (Pulmonary and Critical Care Fellow) and it addresses what to do when you get a good flash, but no flow from the catheter after threading it. This is probably the result of the needle passing in one side of the vessel and out another during placement. To fix this, first remove the wire from the arterial line dart by carefully retracting it and pulling the black tab out of the plastic tube at the back end.

 

Arterial Lines 2

 

Next withdraw the catheter until you get good pulsatile blood flow, indicating that the tip is now in the lumen of the artery. Then thread the free wire into the hub and re-advance the catheter over the wire into the artery.

 

Arterial Lines 3

 

The second technique I picked up comes from Chris Erb (MICU Night Intensivist) and it will make suturing your a-lines in place easier. Ever been frustrated by the a-line catheter rolling around while you try to stitch it in place and then tie the suture around the groove on the hub? Place a tegaderm over the catheter, sew through the tegaderm, then carefully pull off the tegaderm off leaving the stitches in place.

 

Arterial Lines 4

 

For further reading and insight into how our MICU colleagues approach arterial lines, this 2013 retrospective study was recommended to me by Edward Manning (Pulmonary and Critical Care Fellow). 27,000 ICU patients were analyzed over a 6 year period in a pairwise comparison between non-invasive blood pressure measurements and invasive arterial monitoring. Results suggested that non-invasive blood pressure monitoring overestimated systolic BP during periods of hypotension. Patients with non-invasive systolic blood pressure measurements <70 mmHg had a higher incidence of AKI and higher ICU mortality than their counterparts with invasive BP monitoring. It’s worth noting that there was no difference in the incidence of AKI and ICU mortality for patients with systolic BP <60 and no significant difference in MAPs between methods of BP measurement.    

Jacob Schoeneck, MD
PGY-3 Yale Emergency Medicine

 
 

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