A woman who needs a ventilator to breathe is considering legal action to get care she feels safe with.
Marilyn Smith, from Plymouth, Devon, has a genetic condition which means she requires care around the clock.
The 56-year-old said NHS staff shortages have resulted in carers "unfamiliar" with her needs are sometimes employed.
NHS Plymouth has insisted only properly trained and qualified staff look after her.
When cover staff were needed, it said skilled carers who have worked with similar clients, and who had the relevant training and experience were used.
This is disputed by Miss Smith, who told BBC News: "Some have come in here with no knowledge of my disability and no knowledge of my ability to speak.
"They know nothing of my signs and they have limited experience, if any, of the machinery I use."
Her genetic condition means she has no muscle power and cannot cough to clear her lungs.
She has a tracheotomy - a hole in her windpipe - and needs a ventilator to breathe and constant care to keep her airways clear.
Miss Smith said her condition makes her feel very vulnerable.
"I'm an accident - or death - waiting to happen and that's not a dramatisation, that's a reality," she said.
Miss Smith's brother Kevin, who is her back-up carer, said a shortage of properly trained staff means he has to cover more shifts than he should.
The family has taken legal advice to ensure Miss Smith has care she is happy with.
Solicitor Chris Thorne, from Foot Anstey, said he had a "positive" meeting with the health trust to discuss Miss Smith's concerns about four months ago, but the situation had not been resolved.
"In my view it's unacceptable to take this length of time to address those issues adequately," he said.
In a statement, NHS Plymouth spokesman Steve Waite said Miss Smith's regular carers' training included shadowing shifts and competence assessments.
He said temporary staff received a handover which included her specific needs and equipment and Miss Smith herself had helped to interview new people to ensure she liked them.
Mr Waite said the trust was sorry Miss Smith had expressed concerns and it would support her request to transfer care to an independent agency.