His body temperature, lowered as part of the research, was being raised Tuesday in increments of about one-quarter-degree Centigrade per hour, a likely 16-hour procedure before his temperature reached a normal 98.6 degrees, or 37 degrees Centrigrade.
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Physicians hoped the Grammy-winning singer's recovery would be aided by his enrollment in a hypothermia research study even before he underwent surgery Easter Sunday to remove a blood clot that was putting pressure on his brain.
His body temperature, lowered as part of the research, was being raised Tuesday in increments of about one-quarter-degree Centigrade per hour, a likely 16-hour procedure before his temperature reached a normal 98.6 degrees, or 37 degrees Centrigrade.
Dr. Alex Valadka, director of neurotrauma services at Memorial Hermann-Texas Medical Center and vice chair of neurosciences at the University of Texas Health Science Center at Houston, described Navaira, known to fans simply as Emilio, as stable.
"In his case, that's good," he said. "We're still afraid something adverse can happen. The main thing we're watching continues to be the pressure in his brain."
Valadka said if the pressure increases, doctors would try medication to control it.
Valadka, who performed the two-hour surgery with his team, said some lab studies and research data suggest hypothermia may improve the outcome.
"That's the whole point of this study, to see if that actually holds true in a real-world situation," he said "It's one thing to get it to work well in the laboratory, but implementing it in a real live critical care situation is a very different task."
Navaira, 45, was behind the wheel of his tour bus before dawn Easter Sunday following a show at a Houston nightclub when it slammed into a freeway interchange barrier made of barrels. He was thrown through the windshield.
The wreck, which remains under investigation, left several members of Navaira's band with less serious injuries.
Police in Bellaire, the Houston enclave where the crash occurred at the interchange of Interstate 610 and U.S. Highway 59, said Navaira was not licensed to drive the 26,000-pound tour bus. Authorities said it was possible he may have fallen asleep. They also were awaiting the results of blood-alcohol tests.
Doctors have put his survival chances at 30 to 35 percent. Even if he lives, however, Valadka said it was possible he could remain in a coma, be paralyzed or have memory loss.
Navaira was in a coma when he was brought to the emergency room Sunday and has been kept in a medically induced coma. Valadka said there were no guarantees he quickly would regain consciousness once his temperature returned to normal.
"The time period is going to be pretty long," he said. "It's unusual for someone to wake up quickly when they were as badly injured as he was."
The San Antonio-born Navaira has five children, ranging in age from 2 to 18, from two marriages.
About 700 fans gathered Monday night outside the Alamodome in San Antonio for a candlelight prayer vigil. Other vigils were held at a church in Houston and outside his hospital in Houston.
Navaira and his band, Rio, had tour dates planned for later this week in California. They've released more than a dozen albums, including "Acuerdate," or "Remember," which won a Grammy in 2003 for best Tejano album.
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