Dr Murat Gunel said there was evidence of liver failure on the second day. "I told him he needed to get out of the water, and he refused me," he said.

"He said he did not want to let the people down."

The illusionist received food and air through tubes during the seven days he spent in a water-filled sphere in New York.

ABC television broadcast a two-hour special programme culminating in the record attempt. During the programme, Blaine - wearing a diver's helmet with a two-way communication system - told reporters he would give it his "best shot".

He had planned to put on chains and handcuffs, remove his oxygen tube and then escape while holding his breath for longer than anyone had managed before.

"He still feels today that he let people down." say his Doctor

"He is pushing his body insanely to the limits," Dr Murat Gunel, the head of Blaine's medical team and is associate professor of neurosurgery at Yale University School of Medicine, said before the attempt.

"I think he was a great success," said Krack, adding there are only a handful of people who can hold their breath for more than four minutes with training.

Blaine started training in December, with some help from Navy SEALS. The water temperature was regulated to help keep his core temperature near 98.6 degrees Fahrenheit (37 degrees Celsius), and he ate and relieved himself through tubes.

"I wasn't focused on records, I was thinking of a rescue," said trainer Kirk Krack, a free diving expert.

Blaine was convulsing and "unconscious when we brought him to the surface".

"If we hadn't intervened, he would still be at the bottom of the sphere doing a breath-hold," Krack said