POTS - has anyone found "slow salt" supplements helpful (or tried saline drip therapy) ?

I've been listening to a UK doctor on Youtube called Dr.Sanjay Gupta, and some of what he's saying is resonating with me.

I'll be attempting to hydrate well, e.g. with sole water,... Dr.Gupta mentioned "slow salt" - I guess this is a supplement that releases salt slowly to help retain water, but has anyone got any experience or supplement recommendations ?

Also, he's relating that saline dip therapy made a significant difference to a majority of his POTS patients. Although here in the US...

POTS - has anyone found "slow salt" supplements helpful (or tried saline drip therapy) ?