I am burned out caring for a 81 year old spouse, and I am 74. I get no support from any family members he has. How do I get help?

Do you have insight in your shared finances? Are you the PoA for your husband? If not, is anyone? You reference "his children", so this is a marriage later in life? If you call them in for help, they may take over his care more than you may feel comfortable with. Blended families created later in life can be very complex when it comes to the juncture you and your husband are at.

Can you afford a companion-level caregiver to at least help you get him to dialysis and back, and other appointments? Can you afford a housecleaning service?

Also, please contact social services for your county (through the Dept of Health and Human Services) -- they can come out to give a needs assessment to see if he qualifies for any in-home services

Your local area's Agency on Aging can also point you towards available resources. Please understand that his children may not be in a position to help in an ongoing, weekly capacity, or feel obligated to even do anything, so I would not depend on their help, but it would be helpful if you could tell them specifically what kind of help you need from them and how often.

Yes, talk to someone where he gets dialysis and ask if there is transportation help. How far away from u is the facility he goes to? Maybe your County senior bussing can help. Do you get Medicaid for health insurance, they provide transportation.

There are children here from another marriage. They will show up for certain when your husband is gone, and they will want to be certain they inherit everything. I hope, for your sake, that your husband has made a good Trust and that you will receive a portion on his death.
I must assume that your husband and you have talked. That he wishes to continue this life on dialysis. I have already, as an old RN, written that I will under no circumstances accept parenteral (IV) or tube nutrition, dialysis, or intubations, even temporarily. When I witnessed patients living their lives on dialysis I saw little joy and little quality of life; I saw actually ONE professor who was fine about it, most of his work done on computer on his lap.
You are very unlikely to get help from the children. You can try one last family conference. Let them know loud and clear that you will now be spending Dad's money for Dad's care, that in home help is enormously expensive, and that you want one more conference with them to see if there are/and what tasks they are willing to help you with. Tell them you will reassess monthly how it is working if that's their wish. Otherwise you are free and clear to get help.
You can get help from agencies for in home care and in the case of some, with qualifications and insurance checks they can transport to dialysis. It is about miniimum of 4 hours three times a week and was several years ago about 32.00 and hour. I would say to get this help.
You may also want to consider now some division of assets. Their Dad, without their help, is almost certainly heading to 24/7 in facility care. You need an attorney to be certain that YOUR assets aren't used for his care. Do let the children know this is your intention, that you cannot go on in this manner.
Wish you the best. I will say, expect NOTHING, as more than likely they have their own lives and that is what you will get.

Speak with the social worker at the dialysis center about transportation options.

Call your local Area Agency on Aging for information about getting a bath aide, someone to do light housekeeping and the like.

Maybe you should start asking. Explain the situation to them and see what they can offer.