#sorry for any errors ive been staring ata screen all day

[glitteraffe-art]

@sanguith​ first of all, THANK YOU THANK YOU THANKYOU FOR THE FEEDBACK! I’m a biomedical engineering student (engineering for medical devices), so most of my information for my MIP headcanons comes from ‘reading free online nursing textbooks at 11PM’ haha, so I’m glad to see actual feedback (and a video! I actually never even THOUGHT to look up videos as a source… ) from someone with real-life experience!

Onto the questions:

How is the needle+catheter placed inside the suit? / What happens to this discarded needle? It would need to be removed and thrown away somehow, and safely.

Presumably, the placing of the catheter & discarding of the needle would be done by a person (likely a trained staff member of Black Mesa in the case of the Mark IV), not by the suit itself.

This would be done prior to putting on the LCVG layer of the HEV (i.e., while the user is just wearing their undergarments). The LCVG and the Mechanical Compression Suit would probably have specialized splits/openings allowing for the tube to be passed through while minimizing lost cooling- and compression- coverage area.

 How is the pump-tube connected to the PVC after the original insertion-needle is removed?

In my version of the HEV suit, I think that the MIP’s tubes would be attachable & removable from the main body of the suit (since being able to remove them would make it easier to put in a sterile tube for every use). The MIP itself would be accessible by opening up the back of the HEV torso armor (Haven’t decided where the opening/closing parts would be, but just based on the torso armor’s dimensions it would need to be able to come apart somewhere to be able to wear it at all.)

In order to connect the PVC to the pump’s tube, I think the pump’s tube would be replaceable for every use and would likely have a specially made sterile packaging that allows it to be put in as sterile-ly as possible. (Something like “just like the normal packaging that standard IV tubing comes in, but packaged so that the tube is straight, not coiled, and it can open at both ends”).

The steps to connect the pump-tube to the PVC would kind of be somewhere between ‘connecting to an IV’ and ‘replacing a cartridge on an insulin pump’. It would be like this, very roughly (didn’t put in every Use Hand Sanitizer/similar steps):

(Person doing this procedure is assisting the person who will be wearing the HEV; the wearer has had the PVC placed and is wearing the LCVG and Mechanical Compression suits. The PVC is threaded through the suits in such a way that its cap is free & not stuck under the layers)

(The HEV opens up at the torso and at the forearm areas when wearing—haven’t quite decided exactly How but it opens in those places)

Open up PUMP end of sterile tube packaging (careful not to open up the wrong end or all the way)

Attach sterile saline cartridge to PUMP end of tube

Place & lock cartridge + tube into the MIP on the back of the opened up HEV armor

Align & lock tubing into attachment areas on the inside of the armor up to a certain point (ensures it doesn’t get loose during movement)* , allowing some tube closer to the CATHETER end (which is still enclosed in its sterile packaging) to be loose for ease of maneuvering about

Put on armor except for the left-hand forearm armor/sleeve (left arm/hand still Unarmored)

Open up CATHETER end of sterile tube packaging, hold this end of the tube as the HEV internal computer instructs the MIP to flush the tubing with the saline (gets rid of air bubbles; saline will travel down the tubing. May need to catch drips from the other end, though)

Sanitize PVC’s cap with alcohol wipe & flush with saline from a syringe

Attach CATHETER end of tube to PVC

Align & lock remaining length of tube in place into the inside of the HEV armor as it is put onto the left arm (very carefully…)

 (Admittedly this is a pretty rough answer)

 *Kinda embarrassed to say I don’t have a 100% good answer for how the pump tube would be embedded/attached to the inside of the HEV, though.

I never got around to thinking too deeply about HOW they would be connected to the suit in such a way to be removable, since I wasn’t satisfied with any of the ideas I came up with, so ‘exactly where the needle and catheter are in the suit layers’ never made it to the final Anatomy of a HEV Suit 2.5. The only really finalized idea I came up with is that “the tubes are under the radiation-shielding layer but above the Mechanical Compression Suit” (since it would be bad to have the drugs be exposed to radiation, but also bad to compress the tubes)

Some examples of ideas I had:

 Velcro or a Slipcover: fine for the accordion-like parts, but would squish the tube between the wearer and the armor, resulting in impaired flow

Recess into the radiation liner with Velcro or snap system: bad since that removes most of the protective liner from the tube area

A recess in the armor with Velcro or snap system: worried that would eat into structural integrity

Another idea—a raised/stiffened sheath underneath the radiation-shielding layer where the tube can fit in: again, squishes against the wearer, so probably irritating to wearer. Still not great.

Plastic U-shaped snaps that tubes can be attached into (cant remember what they are called): prone to breaking off, again irritates/pokes into wearer

Sorry for not having a definite answer there! Maybe I’ll have a strike of inspiration (or find a similar device from which I can draw inspiration, which is what I’ve mostly done) and figure out a better way to attach the MIP to the HEV in a month or three…

 How is the catheter tube guaranteed to stay perfectly inside the vein when the user moves around, as well as minimizing the risk of blood loss or infection?

This was one of the fictional concessions that I made that made it into the final post. It’s straight-up not guaranteed to stay perfectly inside the vein as the user moves, but I figured, with so much of the HEV being only plausible with fictional materials, a fictional tape sticker that stays on & makes sure the needle doesn’t move at all even during extreme movement would be the least of my concerns with the build.  (That clear sticker is called a sticker? I had no idea! I just assume all sticky things can be called a variant of a tape…my bad for not looking it up!)

 A very plausible alternative to a peripheral IV-cannula could be a central venous catheter.

I actually did consider a central venous catheter, but I chickened out, haha! The mantra of engineering a medical device is “if it can be done in a less invasive way, do it in a less invasive way” With that in mind, I went with the peripheral venous catheter instead of the central venous catheter, despite the whole host of issues that come along with it (which you articulated very nicely!). Anyways I 100% endorse the idea of using a central venous catheter for the MIP instead of peripheral!