The placing of peripheral IVs is arguably the most common procedure that we do in the ED. However, although common, it’s not always easy and on those occasions when it’s difficult and needed quickly, it can be one of the most challenging procedures we do.
Do you use longer IVs when placing them under USS in the ED?https://t.co/OKuZVQ9kh0— Simon Carley (@EMManchester) January 25, 2020
In recent years we have seen the widespread adoption of IO access as an alternative, and also the development of technologies such as ultrasound to help. Ultrasound in particular has allowed us to find veins that are seemingly invisible to the naked eye or to touch1. I use it regularly to find veins and to then guide the needle tip into the vein.
If you’re not doing this yet, or want a reminder then please pop overt to 5-min Sono for a reminder of the technique and for some very practical top tips.
Ultrasound guided IVs are not perfect though. Past work suggests that we often end up going for ‘deeper’ veins which inevitably leads to less cannula in the vein, which then means a higher failure rate. This has led to the development of longer IV cannulas, and more recently ultralong cannulas (up to 20cm long) to try and improve success and survival rates. This month we have a randomised controlled trial that aims to assess the potential survival benefits of ultralong IV cannulas2.
What kind of paper is this?
This is a randomised controlled trial which is exactly what we want to see in a trial testing a clinical intervention.
Tell me about the patients.
This was a ED based study which importantly looked at a subgroup of patients requiring IV access, notably those who were deemed to be difficult access. This is important as we only really want to study this question in patients in whom we would try the intervention. It’s important that they screened out those who were considered ‘easy’.
What did they do?
Patients were randomised to either a standard long line (SLL), which was 4.78 inch in length, or a ultra- long line (ULL) which was 6.35cm in length. Both were 20G cannulas which in the UK is pink in colour (so fairly small). The ultra-long catheters were B. Braun Introcan Safety intravenous catheters. The standard catheters were 4.78-cm, Becton Dickinson Insyte Autoguards.
Cannulas were placed under USS control using a linear high frequency probe in the same way that we would do in Virchester. According to the study protocol the lines should have been placed in the upper arm, proximal to the antecubital fossa.
What were the outcomes?
The primary outcome was median catheter survival time. They powered the study to detect a 30 hour difference between the two techniques. That’s quite a long time in my opinion. Personally I’d consider a much shorter time to be clinically important, but obviously larger numbers of patients would have been required to detect a smaller difference. Analysis was by intention to treat.
A number of secondary analyses were planned. Many were relevant to us here in Virchester such as success rate to cannulate and infection rates. In addition they looked to measure the length of catheter in the vein as previous studies have shown this to be a critical determinant of longeivity.
You might argue that this is a rather circular argument. If we know that catheter length is a determinant of longevity then ‘surely’ a longer cannula would be better? Perhaps, but there must be a point at which the benefit of length diminishes and so I think it is worth including in the research protocol.
What did they find?
270 patients were randomised on the intention to treat protocol. Of those 257 were included in the final analysis. Patients appear to be similar at baseline
Success at achieving access was similar between the two IVs.
The authors’ primary analysis was by intention to treat. In that analysis of 257 patients there was a difference of 44 hours in the average survival rate of the catheters (5.7 vs. 3.9 days). A per-protocol analysis (of 194 patients) also showed a benefit to long lines, but we must be mindful that this is a large number of patients who failed to follow protocol either by leaving within 24 hours, or by having insertions in the forearm.
The risk of losing an ultralong line was roughly 50% less that that of losing a standard IV.
The authors also looked to see if the length of cannula in the vein affected how long the IV remained usable. In keeping with past studies, more line in the vein made a difference. They found that IVs lasted longer if >2.75cm remained in the vein once inserted.
The most common reasons for needing a cannula change (in both groups) was infection or infiltration (into soft tissues).
What does this mean.
USS guided IVs are increasing in popularity in our practice. In Virchester most people use standard IV cannulae, which often leads to failure (Ed – it’s on my list of things to sort out). Our experience matches previous studies where survival of this approach is often very poor, especially when ‘deeper’ veins are cannulated2–5.
This study tells us again that catheter length is important as it allows more cannula to reside within the vein6,7, with perhaps a distance of 2.75cm being important (you can estimate this using USS). If you don’t have the super long cannulae in your department, it’s worth opting for at least an 18G (green) as these are often longer that the standard 20/22G sizes. We all know that bigger is better too, right?
What about Midlines?
You may have heard of these over on the EMCRIT site. Essentially it’s a similar concept, using even longer catheters (8-25cm) for peripheral access. It’s worth reading an excellent review on these from Scott Weingart here8. The related paper9 describes the use of midlines in critical ill patients, which is probably where I see them being used. For standard ED patients I think a longer IV is enough, but for those with very difficult access heading to ICU/HDU then perhaps we do need to look at midlines too (Ed – a question for another day, but interested to hear if anyone is using them in the UK).
Scott has done a great video on midlines here. It clearly shows them to be a different device and technique to the usual USS based lines.
So don’t confuse midlines with USS placed IVs, they are similar in concept but different.
For those of us struggling in Virchester the message here is that we need to order some longer IVs for the difficult to cannulate patients.
- 1.Egan G, Healy D, O’Neill H, Clarke-Moloney M, Grace PA, Walsh SR. Ultrasound guidance for difficult peripheral venous access: systematic review and meta-analysis. Emerg Med J. August 2012:521-526. doi:10.1136/emermed-2012-201652
- 2.Bahl A, Hijazi M, Chen N-W, Lachapelle-Clavette L, Price J. Ultralong Versus Standard Long Peripheral Intravenous Catheters: A Randomized Controlled Trial of Ultrasonographically Guided Catheter Survival. Annals of Emergency Medicine. January 2020. doi:10.1016/j.annemergmed.2019.11.013
- 3.Bahl A, Hang B, Brackney A, et al. Standard long IV catheters versus extended dwell catheters: A randomized comparison of ultrasound-guided catheter survival. The American Journal of Emergency Medicine. April 2019:715-721. doi:10.1016/j.ajem.2018.07.031
- 4.Elia F, Ferrari G, Molino P, et al. Standard-length catheters vs long catheters in ultrasound-guided peripheral vein cannulation. The American Journal of Emergency Medicine. June 2012:712-716. doi:10.1016/j.ajem.2011.04.019
- 5.Keyes LE, Frazee BW, Snoey ER, Simon BC, Christy D. Ultrasound-Guided Brachial and Basilic Vein Cannulation in Emergency Department Patients With Difficult Intravenous Access. Annals of Emergency Medicine. December 1999:711-714. doi:10.1016/s0196-0644(99)70095-8
- 6.Fields JM, Dean AJ, Todman RW, et al. The effect of vessel depth, diameter, and location on ultrasound-guided peripheral intravenous catheter longevity. The American Journal of Emergency Medicine. September 2012:1134-1140. doi:10.1016/j.ajem.2011.07.027
- 7.Pandurangadu AV, Tucker J, Brackney AR, Bahl A. Ultrasound-guided intravenous catheter survival impacted by amount of catheter residing in the vein. Emerg Med J. July 2018:550-555. doi:10.1136/emermed-2017-206803
- 8.Weingart S. Midlines part 1. EMCRIT. https://emcrit.org/emcrit/midlines-1/. Published 2019. Accessed 2020.
- 9.Spiegel RJ, Eraso D, Leibner E, Thode H, Morley EJ, Weingart S. The Utility of Midline Intravenous Catheters in Critically Ill Emergency Department Patients. Annals of Emergency Medicine. December 2019. doi:10.1016/j.annemergmed.2019.09.018