(CNN) Emergency room doctors say they are running into a new crisis as they struggle to treat patients with Covid-19 -- a shortage of dialysis machines and supplies.

They say they are overwhelmed, not only because patients are going into kidney failure, but also because the body's intense reaction to the virus is often causing their blood to clot too much, and the clots are literally clogging up the dialysis filters.

It's part of the new syndrome that doctors are seeing in Covid-19 patients. They are not dying from the pneumonia that has been one of the defining symptoms of serious Covid-19 disease, but from other systemic effects on their hearts and other organs.

"It's taken everyone by surprise because it is acting so different from everything else," said Dr. Sam Parnia, a critical care specialist at New York University Langone Medical Center.

"They are not dying because they can't get enough oxygen. They are actually dying because of other complications and it is predominately due to blood clots."

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