My ggma is 96 yr.'s old and lately she has been doing this “passing out” thing where she will just go unresponsive, still have a pulse like she is asleep. Any advice?

Is it possible her heart is stopping? Is she dehydrated? Obviously no UTI because you said she had tests

My mother did this when she was experiencing seizures.

Your grandmother needs to see a neurologist to determine what is causing her to pass out.

Some people have seizures without any warning like my mom had. Others will see auras when a seizure is coming on.

Best wishes to you and your family.

It could be her blood pressure dropping/changing. Personally, I have POTS so any change in position cause my Blood pressure to drop or go higher and can cause dizziness and passing out. The blood pressure can stabilize if laying flat and not moving and consciousness will return shortly.

Brenee,
You said your ggma is 98, and has been checked.
I know someone younger who frequently gets checked by her doctor.
It seems okay with him if she has anemia, thyroid issues, B-12 deficiency etc.
But falls every year at a holiday gathering with family.
She has "been checked" however, ignores treatment for low B-12, anemia, and thyroid. Wondering why she falls. It could be anemia, or a combination of factors. Sometimes when people fall, they are unaware of a mild seizure, event, or "spell" preceding the fall.

Getting back to your ggma and her "passing out". I found this:
(of course I am not a doctor, we cannot diagnose your ggma's passing out on a forum).
Common Anemia Symptoms
1. Breathing Issues, Dizziness, and Headaches
When you’re healthy, abundant oxygen is conveyed to the heart, muscles, and organs. With anemia, the lungs overcompensate in order to bring in more oxygen, causing breathing difficulties.
***Low levels of hemoglobin prevent adequate oxygen from reaching the brain. Blood vessels swell, blood pressure drops, and it can result in headaches, neurological issues, and vertigo.
Small exertions can cause shortness of breath or fainting spells.

Of course you don't want extensive tests for ggma at her age.
But she may be more comfortable if anemia is treated.

Pull down her lower eyelid, see if inside is pale, very pale.
Feed her some liver, or see her doctor if previously she was diagnosed with an anemia. Anemia can improve with treatment.

See a new doctor maybe.

My dad's mom had this and she called them spells. She had heart issues, no dementia or any other health problems.

I would encourage you to question her doctor about what could be going on.

These might be small seizures or possibly mini strokes.
What type of dementia has she been diagnosed with? If it is Vascular Dementia the mini strokes are part of that.
My Husband had been diagnosed with Alzheimer's and I think he had Vascular Dementia as well and he had what the Hospice Nurse call Myoclonic Seizures, she really did not seem concerned about them

Scary.

I had a care client like this years ago. She was not as old as your grandmother though.
She would literally "pass out" after having a shower or if she was sitting up in her wheelchair for more than ten or fifteen minutes.

She had Alzheimer's. Her doctor said that the activity of being showered, transferred, and sitting up was causing it. She would have a normal pulse but be unresponsive. There as really nothing to be done for it other than limit how much she was moved around and transferred.

We switched to bed baths. She was transferred from her bed to the recliner chair instad of the wheelchair. This way she could be reclined throughout the day with brief periods of sitting up. When the physical activity stopped the fainting did too.

My Grandmother, would have episdoes like that when in her last years. Absent, like sleeping, breathing but not responsive to light touch/talking. Would 'come to' herself after a short time. Described as probable TIAs by Doctor. No action was taken due to her advanced age & her wish to avoid unnecessary investigations.

Is it known what your GGMa's wishes are regarding medical intervention/investigation VS Mother Nature?

Why don't you call 911 and have her transported to an ER?

Because of her age, it might not be advisable to have a bunch of complicated tests done, but there may be some medication she could try to prevent these episodes. That would be a good idea because you wouldn't want her to fall down unconscious, painfuly break a bone or bleed to death from her falling injury before anyone knows it happened.

There are an awful lot of things besides diabetes to rule out. Syncope, seizures, cardiac problems.

The issue is, is it worthwhile to do a bunch of tests? To what end?

Would you do pacemaker surgery? Have her take seizure meds?

Has anyone considered hospice?

How long do these episodes last?
Does she lose control of bladder or bowel during these episodes?
She may need further neuro-psyc exams if this continues or it could be a part of her early dementia. Some do get brief brain glitches not unlike the little staring off into space thing that babies get (which are actually a kind of mini seizure as the brain develops, but normal).

Do these episodes occur only when at rest? Because some will fall asleep with eyes open but unfocused.

*98 *** sorry

Maybe this:

https://my.clevelandclinic.org/health/symptoms/23325-vasovagal-syncope

Is she a fall risk during these episodes or is she already bedridden? Is she in a facility or at home?

For a while my MIL, in LTC, would pass out briefly while having a bowel movement.

We aren't doctors so this is still a medical question for an internist or gerontologist.