One of the main barometers I use to rapidly characterize an ED as either a resuscitation shop or a standard (read resuscitation sub-standard) ED is are they placing arterial lines.
I have covered all things a-lines in the past:
Today's show will be a little different. It is a response to comments made on the EM:RAP show in June 2024. I also was sparked to discuss this by a tweet about the show, the PITT, in which an ICU doc said the show was unrealistic b/c they had never been in an ED in which arterial lines were placed.
Necessity Of Arterial Lines
Accuracy
When NIBP Cuffs are Inaccurate
All three- SBP, MAP, and DBP are all measured
Bradycardia only an issue < 40 BPM
Skinny or fat is not an issue unless pt doesn’t have the right cuff
Biggest issue is malperfused states or shock, especially with profound peripheral vasoconstriction. Hemorrhagic shock makes a-lines a necessity, with a femoral placement.
Cuff timing q 30 minutes
New Study
Perera et al. Non-invasive versus arterial pressure monitoring in the pre-hospital critical care environment: a paired comparison of concurrently recorded measurements
Prehospital Environment, >2000 paired observations of NIBP and Arterial Line
Bounds of agreement: <20 mmHg for systolic BP (SBP) and diastolic BP (DBP) and <10 mmHg
Only 64% of SBP, 76% of DBP, and 55% of MAP measurements fell within the pre-defined acceptable ranges. NIBP readings tended to overestimate SBP and MAP at low BP values (hypotension) and underestimate these values at high BP values (hypertension). DBP was consistently overestimated across its range.
- Impact of Hemodynamic Instability: Hemodynamic shock was associated with lower agreement for SBP (adjusted odds ratio [aOR] 0.52), DBP (aOR 0.65), and MAP (aOR 0.53).
- Impact of Severe Hypertension: Severe hypertension was associated with markedly reduced agreement for SBP (aOR 0.17), while DBP and MAP were less affected.
- Impact of Arterial Catheter Site: Femoral arterial lines were associated with reduced agreement for MAP (aOR 0.65) compared to radial lines, .
- from St Emlyns' Post
Ability to Real-Time Monitor
It is usually during the resuscitative period, not long-term that a-lines really shine–I still want them long term, obviously.
Opportunity Cost
Nursing
Should already be 1:2 nursing
What about: We have ED nurses, not ICU nurses; they are not trained on how to set-up arterial lines.
See this video for how to set-up a pressure transducer
Docs
Time to Place A-lines
London HEMs experience is 2 minutes. Only get that way if you are good, but this is a transferable skill from ultrasound-guided intravenous lines
Parker Labs Ultradrape & Ultradrape II
Indication Creep
There never would need to be an indication restriction, so there can't be indication creep
ICU Expectations
This is the one I hear most commonly–I think it is a straw man.
The one that truly galls me is, “If we allow arterial lines, the ICU won't feel the same urgency to get them upstairs!” So if we provide crappy care, the intensivists will doubt our capability of caring for sick patients and rush to get them to a safe place. That is not how I want Emergency Medicine thought of.
Additional New Information
More on EMCrit
- EMCrit 210.1 – Arterial Lines (Part 1)
- EMCrit 210.2 – Arterial Lines – Part 2
- Central Venous Pressure (CVP) and Arterial Line Set-Ups
- EMCrit 332 – Procedural Errors I See at the REANIMATE ECPR Course and How to Place an Intra-Arrest Femoral Arterial Line
- PulmCrit: A-lines in septic shock: the wrist versus the groin(Opens in a new browser tab)
Additional Resources
You Need an EMCrit Membership to see this content. Login here if you already have one.
Professor
Nassau University Medical Center
No conflicts of interest (coi).
- EMCrit Shadowboxing Case 9 – Spinal Cord Injury? - April 24, 2025
- EMCrit 399 – Serotonin Syndrome (SS) and Neuroleptic Malignant Syndrome (NMS) – Primer Episode - April 17, 2025
- 1:1 Nursing Podcast – Episode 0 – The Introduction - April 14, 2025
I’m not sure if I am more shocked or saddened by the fact that you were pushed to make this post in the year 2025
Sick patients needs an art line But I am not sure about the femoral art line though. It is really a hassle to put in compared to a radial. Obviously utile in the icu in big sick patients. We use PiCCO at the double/triple pressor level, often the femoral pressure is higher than the radial and we are able to wean pressors when we go for femoral, rather than radial MAP. Except from PiCCO we have not used regular femoral lines that much except for the occasional “dirty double” in the ED. Probably should use it more in hemorrhagic shock… Read more »
Ola,
I can do a full sterile central line in 7 minutes. Fem art is much easier to do full sterile. I think most of the time for this procedure is gathering equipment, so if everything is already there, you can bang through it in about 5 mins. The best way I have found to procedure streamline is to film yourself and then review the tape for where the time is going.
Hi Scott. Great rant! A few points I would add to the argument 1. If the patient’s physical location eg. ED, ICU, the western desert etc is the reason that you are choosing to insert or avoid an A-line – then you are doing it for the wrong reasons – patient first, politics second! 2. Sick AF (I mean atrial fib, not unwell as f$!k) who are in Ed – the NIBP often finds wildly different MAPS every cycle due to the beat-beat variation in pulse volumes – if you are cycling the cuff q5min you may end up making… Read more »
fantastic comments, Casey
Agree with Casey. If a patient needs invasion BP monitoring, the setting shouldn’t dictate if they get it or not. The clinical condition should. I think another area not discussed on the podcast is placing an arterial line for critical care transport. Vibrations, bumps in the road, etc, seems to always mess up the NIBP at the most inopportune time. I have found that having real time, beat to beat BP measurements on a patient while in the back of an ambulance, helicopter or airplane is extremely helpful, especially because you have limited care providers in the retrieval setting, and… Read more »
I think I’m going to lower the bar of the debate with this one, anyway…In my place some colleague tend to put in a-line just to “arterial samples” in COPD / respiratory patients, without connecting it to a pressure transducer. Given that VBG + SpO2 is enough for that reason…Can be harmful to leave the a-line “alone”? In the debate I wasn’t able to find evidence in the literature for this
i guess that is fine, but not seeing why you shouldn’t just hook it up to the monitor as long is it is on art line tubing set that is flushing
It can be harmful to have a non-transduced a-line if it’s hiding under blankets and the patient might move/ dislodge it, because the pressure alarms alert staff that it’s disrupted before you lose much blood. If the line is visible and the nurse is standing in front of the bed, not so much of a problem
Are there places where ER nurses are not trained to set up arterial lines? That has not been a problem anywhere that I have worked.
as mentioned in the piece, there are places that forbid a-lines so yes, those nurses have no idea how to set-up alines
Sorry, not sure how I missed that part in the podcast. A very weird philosophy from the suits.
Great post with valuable insights, thanks Scott! One thing I don’t quite understand: You write that with NIBP “All three- SBP, MAP, and DBP are all measured“. I couldn’t find a reference for that statement. My current understanding of oscillometric NIBP is that maximal oscillations correlate with MAP, and proprietary algorithms then calculate SBP and DBP based on oscillometric amplitude profile, often using percentages of maximal oscillations. To put it simply: All values of NIBP are calculations but MAP is often the most reliable parameter as the “peak” of the oscillometric amplitude profile is the easiest to distinguish. With NIBP… Read more »
I came to say something similar, that it is probably more fair to say “NIBP devices measure MAP and then calculate SBP & DBP” than to say “NIBP devices measure all 3 pressures directly” – but that both statements are not really accurate. The cuff is continuously detecting oscillations from the brachial artery as it inflates/deflates (typically just on deflation, but maybe some do it on inflation), the amplitude of these oscillations changes as the cuff pressure changes – amplitude starts small when cuff pressure>SBP, then starts to increase at time cuff pressure gets to SBP, before peaking at the… Read more »
I love A-lines and am the only one in my department who places them. Despite having put in a few dozen radial lines, I’m still often surprised at the discrepancy between non-invasive and A-line pressures. Do you have any more specific suggestions on when I should consider placing a femoral instead of a radial one? Are there scenarios where I could be fooled, or more importantly doing harm, by utilizing a radial line instead of a femoral? Thanks!
How can you do a sterile Seldinger arterial line with the Ultradrape? Surely you have to bring your probe/dirty hand round the for the guidewire/threading the cannula? Looks good for pIV or a FloSwitch mind…
Hey Tim,
If i am using the modified seldinger rather than standard iv cath for aline, i slap a large tegaderm on the handle of the probe.