DALLAS — The death of the first Ebola patient diagnosed in the United States renewed questions about his medical care and whether Thomas Eric Duncan’s life could have been extended or saved if the Texas hospital where he first sought help had taken him in sooner.

Duncan died in Dallas on Wednesday, a little more than a week after his illness exposed gaps in the nation’s defenses against the disease and set off a scramble to track down anyone exposed to him.

The 42-year-old Liberian man had been kept in isolation since Sept. 28 at Texas Health Presbyterian Hospital, where a fevered Duncan first showed up days earlier and told the staff he had been in West Africa. Doctors initially sent him home. He returned after his condition worsened.

Dr. Phil Smith is the director of the biocontainment center at the Nebraska Medical Center, where an NBC News freelance cameraman is being treated for Ebola. He said getting early treatment is key to survival.

When a patient reaches the point of needing dialysis and respiratory help, as Duncan did this week, there may be little doctors can do.

“At that point, any kind of intervention, whether it is an antiviral drug or convalescent plasma, is less likely to work,” said Smith, an infectious disease specialist.

Duncan carried the deadly virus with him from his home in Liberia, though he showed no symptoms when he left for the United States. He arrived in Dallas on Sept. 20 and fell ill several days later.

Of the six Ebola patients treated so far in the U.S., Duncan was the only one not cared for in one of the special hospital units set up to deal with highly dangerous germs. That’s because health officials knew the others had Ebola at the time they decided where the patients should go, whereas Duncan sought care at Texas Health Presbyterian hospital on his own.

Health officials also have said that any hospital with isolation capabilities can treat Ebola patients, but Duncan’s death is sure to renew attention on the hospital’s response.

There is no way to know whether any specific treatment or step might have saved Duncan’s life. At the time of his death, he was taking an experimental antiviral drug.