SEATTLE — A UW Medicine study of critically ill coronavirus patients reveals a high mortality rate and an average of 10 days spent on a ventilator.

Researchers studied 24 patients in the Puget Sound region who were in intensive care due to COVID-19 and found that half of them died.

They were the sickest of the sick, and most had underlying conditions such as diabetes, high blood pressure, and kidney disease, researchers said. They ranged in age from 23 to 97.

“I think there's a lot of fundamental questions we still don't know about this infection, things such as why are some people more susceptible to developing critical illness than others,” said Dr. Pavan Bhatraju, a pulmonary and critical care physician with the UW School of Medicine and lead author of the study.

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Dr. Bhatraju said patients who had to use a ventilator to help them breathe spent an average of 10 days on the machine, longer than ICU patients with other common respiratory problems.

“Of the patients who required mechanical ventilation, the earliest a patient was able to come off a ventilator was eight days,” Dr. Bhatraju said. “Some of the findings are consistent with the reports that were published in China as well as reports we're seeing from Italy where the mortality rate is quite high in patients who require ICU care.”

Dr. Bhatraju said he hopes the findings will help hospitals better manage limited resources, knowing patients may spend weeks fighting the virus.

The researchers said they also hope their findings will make doctors think twice about the symptoms that people show when they first report the illness. 

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They said the most common early symptoms among patients in the study were cough and shortness of breath, not necessarily fever.

“The research indicated that relying on fever may not be a useful criterion to determine severity of illness and that diagnostic algorithms that require fever for COVID-19 testing may delay diagnosis,” the report stated.