There is a vacuum system, about $4000.00
Here when they ask to clean the inside, they have plants growing in them and that means there is mud, granules from the roof, tons of leaves and other stuff in them.
I do them by hand with the gutter tools and extension poles so I can clean about 10' to 15' on each side of me before moving the ladder.
I tried power washing the gutters but the customer complained and wanted all that stuff out of their yard, garden, flower bed, off the plants, etc..... Leaf blower also made similar mess where the owner wanted everything cleaned up as they just had their yard guy there, this is why I do them by hand, I don't want to make another mess and don't want to upset my customers as they call me back every year to two years.