Line management

This month’s questions:

1. What determines whether we anticoagulate our patients with line related thromboses? And when is the optimum time for line removal?

2. Should we be placing midlines instead of peripheral cannulas when the need arises for non-cvc related access in our ICU patients ?

This month’s paper:

Essential reading in the  form of https://www.nejm.org/doi/full/10.1056/NEJMoa1714919 , or is this just another example of a negative trial?

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A –

I would value the opinions of the group on this first question as I have to admit I have absolutely no idea what to do with patients with line related thrombosis. I think part of the reason for this, is that they are a very disparate group. I would treat an incidental finding much differently to a symptomatic thrombosis.

Whilst I have not formalised this process in my own mind (until now) I think the pathway I would follow is:
1. Is the line needed? If not remove. I think the optimum time for removing the line is “as soon as it is not needed”.
2. If it is needed what are the risks of moving it?
3. Once the need for the line is ascertained, what are the risks of anticoagulation? If very high then I would probably leave the line alone if the patient was asymptomatic with a view to removing the line when possible.

However, having said all the above, in practice what I actually do (I am ashamed to say) is “Ring Vascular” and ask them what they recommend.

With regards to the second question I would theorise that we would end up reducing our larger bore veins which would be useful for PICC lines if we went for midlines instead of peripheral cannulae, without a massive improvement in infections. Should we not be asking whether we should be using midlines instead of CVP lines for patients who don’t need multi lumen CVCs, or who aren’t receiving really unpleasant drugs? This would be especially relevant following the discussions about peripheral Norad.

With regards to the NEJM article- the debate about GI prophylaxis- ulcers or C diff? continues. I am none the wiser but will continue to prescribe some form of GI protection until someone tells me not to, or until I get buried in a pile of c. diff provoked effluent.

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B –

Not an intensivist but do have some experience with MID/PICC lines so thought I’d stick my head above the parapet for once.

I’m sure there’s some more experienced vascular access practitioners in the group but I’ve got a few resources to hand that might prove useful. (See attachments)

Our experience with midlines at LTHT is that the complication rate seems low.

The line we are using is effectively apart from length, identical to a PICC line. Importantly it has a class 3 licence allowing to be used for more than 30 days.

Although it’s not perceived as a common complication I would like to add a caveat that if thrombus is occurring, it can be sub clinical, often without symptoms making it difficult to spot.

Similarly most of our patients are ambulatory and often fit for discharge apart from the need for continuing antibiotic therapy.

ICU patients due to immobility and underlying pathology are likely to be much more prone to thrombus formation.

The biggest risk for line thrombosis is the size of the target vessel verses the diameter of the line. Rule of thirds applies, with the line diameter being  less then 1/3 of the vessel diameter to try and minimise complications.

If you are contemplating insertion make sure you’ve got a nice big target and ideally measure it on the US machine if there is that functionality.

Similarly flow rate at the tip of the line is likely to play a part in the risk of thrombus formation.

 Maximal flow is at the artriocaval junction, and I aim for two vertebral bodies below the carina when using fluoroscopy. (See article link below)

https://bjanaesthesia.org/article/S0007-0912(17)31198-4/fulltext

With that in mind are standard CVC lines being sited optimally to reduce tip thrombus risk?

Is line failure due to tip thrombosis, especially in CVVH patients still problematic?

Or is this less of an issue since the move to fancier citrate based anticoagation systems?

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C –

There is no strong evidence base for such decisions.

Most CVC catheters will develop some clot or fibrin sleeves around the vein entry site which are non occlusive and can be seen with ultrasound but don’t warrant anticoagulation.

Patients with acute venous occlusion ( as opposed to chronic blockage with collateral formation) who are symptomatic with upper or lower limb swelling/pain/redness, or facial swelling/neck tenderness should have imaging to demonstrate presence and extent of clot and should be fully anti coagulated unless this is contraindicated.  This is to prevent clot extension centrally and peripherally and prevent PE which is described in this scenario. Further it helps reduce unpleasant late sequelae of DVT.  Most cases will settle but if the limb is very swollen, painful and viability is questioned urgent discussion with vascular surgery or interventional radiology will guide benefits of directed thrombolysis (mechanical clot removal not used at Leeds when I last asked the question).  The choice and duration of anticoagulation typically follows trust guidance for DVT and PE, i.e. therapeutic dose LMWH then oral drug for 6 months.

CVC removal whilst intuitive probably does little to restore early limb vein patency and should be considered in overall clinical picture.  If easy and safe, then remove and resite but this may not always be right choice.

Piccs and midlines are in general a good choice for alternative central type venous access.  However they are not risk free and newer literature in relation to long term venous access suggests considerably higher risks of DVT with PICCs (midlines similar entry site) than more centrally placed catheters (e.g.port or hickman type devices IJV/subclavian sites) in oncology patients.

Hope this makes sense.