Pediatric Subcutaneous Rehydration From Dr Tim Horeczko of Pediatric Emergency Playbook

The following is from the excellent podcast Subcutaneous Rehydration
Updated on August 1, 2016 By thoreczko from Pediatric Emergency Playbook:

So, how does it work?
In a nutshell, you place a butterfly needle or angiocatheter in the subcutaneous space and you run fluids into it. The tissues quickly absorb the fluids, making them available systemically.

That’s it. Everything else is just finesse.
The ideal candidate for hypodermoclysis is the stable patient, with mild to moderate dehydration who fails a trial of fluids by mouth, or who needs a bridge to gaining IV access later, after a slow subcutaneous fluid bolus is given.

Ok, so how do you do it?
Place a topical anesthetic cream, such as EMLA, cover with occlusive dressing (IV dressing), wait 15-20 min
“Pinch an inch” of skin anywhere, but the most practical site in young children is between the scapulae
Insert a 25-gauge butterfly needle or 24-gauge angiocatheter (preferred by the author), secure
Inject 150 U hyaluronidase SC, if available
Infuse 20 mL/kg isotonic solution over one hour, repeat as needed or use “bolus” as bridge to IV access

You can set the line to gravity, and if it is dripping in, you may leave it be. If you see a very slow drip by gravity, or worse, nothing is dripping, you can set the line on a pump, to deliver up to 20 mL/kg over an hour. Infusion at this rate optimizes the balance we want in minimal discomfort while maximizing the flow rate.
This is not a “bolus” in the true sense – but then, when you compare it to the alternative – like IV therapy – and we see a time and cost savings. Dr Mace and colleagues in the American Journal of Emergency Medicine report substantially decreased cost and ED length of stay when comparing the material and human resources needed to place an IV in a squirmy young child, compared with a simple subcutaneous stick.

There will be swelling
There will be swelling – that is the goal. It is really painless, and your patient may lie down on his back with the pump going – it is actually pretty comfortable for most children and adults to do.

Here’s a tip – since there will be swelling, we want to be careful about how we secure the line, so how you tape it down to the skin is important – we want to avoid a pulling sensation, which can be the beginning of the end of the tolerance for the procedure. Cover that with an occlusive dressing, as you would an IV site. The footprint of the occlusive dressing is relatively small, so it will travel up on top of the subcutaneous mound you’re creating. As the line exits the occlusive patch, place a thin layer of gauze between the skin and the IV tubing, so that the tubing doesn’t press into the skin. Then—as far away from the puncture site as possible—tape it down securely. The idea is not to tape on the growing mound itself, because the mound may pull at the anchored skin and set a nuclear chain reaction of annoyance and restlessness – and potentially a failed procedure.

The swelling will look indurated, a pinkish red. It’s not an allergic reaction: even with the old preparations of hyaluronidase, allergic reactions were rare, and now they are very rare with the recombinant preparation. It is supposed to swell and look ugly. The subcutaneous tissues will swell to a point where you have a steady state fluid administration rate, and as soon as you stop the infusion, the remaining fluid will start to subside as it is absorbed.