The DanaRS. Marmite?

***Please note that the DanaRS used n this article was a trial device provided for free by Advanced Therapeutics***

One of the questions that has arisen multiple times following my use of CamAPS is “How did you find the DanaRS”? As someone who hasn’t been pumping for that long (around about five years), I’ve tried a fair few pumps (Roche’s Combo and Insight, Medtronic’s 640G and Paradigm series, an occasional Omnipod), so this was the sixth pump that I had the chance to use.

Before we go into this, it’s worth mentioning that the reason that the majority of people start using the DanaRS is because of the Sooil open support for AndroidAPS compatibility and that they maintain the warranty when used with this system. The pump was designed in conjunction with the developers of AndroidAPS in order that it worked well together. CamAPS has also been able to take advantage of these features in releasing their product. 

The pump itself

The pump is pretty compact for a 3ml reservoir containing pump, which is partly down to the unusual mechanism it uses to drive the plunger in the cylinder. For comparison with the 722, see the images below.

You’ll note that I’ve inverted the DanaRS to show it the same way around as the 722. It’s marginally narrower (around 7mm), but lengthwise, once the Luer adapter is added, it’s around the same height.

In terms of body depth, it’s not too dissimilar, with maybe 1mm separating across most of the body, although the cartridge tube on the 722 is slightly larger.

The other key point is that this is supposed to be waterproof. Physically, while it is slightly more compact than the older Medtronic pumps, there’s not really that much in it. What is noticeably different is that the buttons and screen are considerably smaller, which makes interaction with it, for ham-fisted lugs like myself, a bit more fiddly. 

The cartridge system

Most pump users are familiar with a cartridge that looks like this sort of thing:

However, the DanaRS uses a unique cartridge and drive system:

In most pumps, the piston is directly attached to the motor and the cartridge is placed into the pump and either slots in, screws in or sits on the piston.

In the DanaRS, the piston is integral within the cartridge and the drive screw clicks on to the piston, then you slot the whole lot into the pump. 

This presents the user with a couple of interesting challenges when using the system.

1. The pump doesn’t know, by virtue of the piston position relative to the datum on insertion, what the content of the cartridge is when you prime the pump, which means it has to be manually entered when you do a refill.
2. The pump figures out how much insulin has been expelled from the reservoir based on the number of rotations that the screw has made.
3. You have to rewind the screw to the appropriate point before entering it into the pump. Getting this right manually with a part filled cartridge is incredibly hard, and even with a fully filled cartridge, so the Easy Setter is an essential piece of kit to set the screw to the correct position. It is connected by bluetooth to the pump, and when you enter the refill units, rewinds the screw to the correct length. 
4. As a result of all of the above, the user needs to enter a conservative refill units value (i.e. lower than the actual value) to ensure you don’t run out of insulin, as you can’t be 100% sure that the value it is using is correct.

This might all seem like a bit of a faff if you’re used to other pumps, and indeed it is a bit of one, but if you have the Easy Setter, then, like everything else, it becomes routine the more you do it. 

Interaction

As a Bluetooth pump that I was mostly interacting with through the magic of an app, it worked pretty well.

In terms of using the interface on the pump, well, it has similar limitations to the 722 and Combo. A linear, menu-driven interface that has restrictions on how you move through it. As always with this type of interface, the more you use it, the more familiar you become with it and the faster you navigate. So rather than pass judgement on this, I’ll just say that it is what it is, and you eventually get used to it.

I don’t think it’s fair to make comparisons between linear interfaces, as in general, they supply all the required functionality (this does too) but just do it in slightly different order or route to get to a function. I’m not sure there’s really one good way, just that for most people, they will be more familiar with one manufacturer’s way of doing things.

The Human/Pump interface

Or what we commonly know as the infusion sets. And this, for me, was where the pump let us users down. You can live with the quibbles that I’ve already mentioned, but this is the real sticky one, or in my experience, perhaps not so sticky.

The Luer interface

Anyone who has used a Vibe or a Combo will be familiar with Luer locks. They are a standard way of connecting. Unlike the aforementioned pumps, Sooil decided to use a left-handed Luer on these systems, which means the only sets you can use on them come from Sooil. This is where the problems start. There are Left-to-Right adapters out there so you could use “normal” Luer sets like the Inset, but Dana have stopped supplying them due to concerns about them damaging the pump mechanism. The left-handed luer does take a while to get used to but once you done it three or four times, it’s less of an issue.

The sets

You have a choice of Teflon and Steel sets, that come in different forms. The most frequently used are Easy Release and Easy Release II steel and Soft Release O Teflon.

Easy Release steel

There are multiple cannula lengths, and starting with the 4.5mm, I found it didn’t really work at all. Moving to the 7mm, this worked very well, but as you can see from the first of these two images, the sticky pad is quite small and there’s nothing holding down the connector to the rest of the tubing. As a result I had some challenges keeping them stuck down for two days and the tubing levering the cannula into uncomfortable positions, and was waking with them pulling out and therefore losing insulin.

To resolve this, I had to overlay the cannula section itself with Hypafix and then apply an extra piece where the tubing connector was to  stop the level effect jiggling the cannula. Not a terribly welcome addition on every single cannula.

Soft Release O teflon

Like many teflon cannulas, you really need to use the inserter to make these work properly. The main feature of them is the 360^o rotating connector to the cannula.

After my initial use of a couple of these sets, I found that the hole that the set was generating in my skin was pretty severe compared to my experience with other teflon sets:

Yes, that looks pretty nasty, and I’m not talking about the hairs. As far as I can tell, the issue seemed to come, again, from the adhesion between my body and the set, and it having the smallest amount of capacity to move. I also noted in comparing the sets to some of the Mios that I have that the cannula itself seemed to be stiffer and less flexible. Once again, I ended up having to apply an overlay, this time using Tegaderm due to its thinness, to keep the set stable. 

Again, not the best experience of the sets, and overall, this is what I found to be the biggest let down of using this pump. I really didn’t get on with the probably the most important part of the pump. The bit that connects it to me. 

It’s been confirmed that Convatec will be producing something for the Dana series of pumps in the near future, and from what we understand this should be an equivalent to the Mio or Inset II, with the left-handed luer. For me this can’t come soon enough, as this was my real challenge with using the pump. 

Overall…

I think the DanaRS is an unusual beast. On the one hand, as a connected pump, it really demonstrates what all pumps could and should be capable of doing in terms of open connectivity and phone app integration. In that way it is unique (for now) and for that alone it should be applauded.

As a standalone pump? Well it’s a relatively small and light pump, and if that’s what you want then I’m sure you’d find it works, but I do think the Dana Anycare app or one of the Automated Insulin Delivery systems is required to justify this over some of the other pumps on the market. 

But physically, I keep coming back to the infusion sets. While it’s possible to make them work, they require extra effort and I found them to be comparatively uncomfortable compared to those used with other pumps. And ultimately, that’s the most important part of the set-up.

As you can tell, I’m decidedly on the fence with this one. I want to like it for what it stands for, but I find that I can’t love it due to how it works with me.

Would I recommend it to people? Again I find myself with a split voice on this. The answer has to be that if you want to use CamAPS or AndroidAPS, then it’s the best (or perhaps only) way to do that. But unless you trial it and decide whether you can live with the infusion sets, I wouldn’t go ahead and blindly recommend it. 

Maybe that will all change with the release of the Mio/Inset II-like sets.