The emergency crew then brought out the AutoPulse, a brand new device the San Francisco Fire Department was testing.

The device, which mechanically performs CPR, was used eight times in the field and two more in the hospital, bringing Weich's pulse back.

"I don't think I would have made it if they hadn't been using that on me," Weich said.

Doctors and paramedics working with her later said, "People just don't come back after that amount of time."

According to information from the website of Revivant Corp., the company that makes the AutoPulse, the device is 30 percent more effective than manual CPR. Here's how it works:

The affected person is laid on a special board that extends from the head to the waist. A band attached to the board is placed around the person's chest. With the push of a button, the band automatically adjusts to his or her chest size. Another button push starts chest compressions.

The reason the AutoPulse is so effective is that it is able to reinstate normal levels of blood flow to and from the heart. It's also more consistent than humans who often get physically tired from performing CPR, don't always compress in the right place or sometimes don't time the proper compressions.

Not only does it perform the actual compressions more effectively, but it also allows emergency responders to focus on other needs during a rescue operation, said Capt. Steve Warner of Santa Clara County Fire Department. It also provides the oxygen needed to make resuscitative drugs and defibrillator shocks work.

Warner and other fire personnel at the Shannon Station in Los Gatos have been testing an AutoPulse on loan from Revivant for the last few months. Warner said it has been used several times already, and represents a major step forward in lifesaving technology.

"This machine is probably one of the biggest changes in CPR in several years," Warner said. "It's pretty exciting when you have a piece of machinery that's viable. It's like, wow, something's working."

The loaner will soon have to be returned. Though the department actually owns three AutoPulses, they were purchased through donations to the Los Altos Hills County Fire District, and are kept at stations there. Battalion Chief Joe Parker said he applied for federal grant funding to purchase more of the $16,000 units, but the grant was denied. The department cannot afford to outfit all 19 of its fire companies with AutoPulses at once.

"We'll probably have to, realistically, just chip away at it," he said.

Weich's daughter, Los Gatos resident Shannon Weich, said she plans to lead a fundraising effort to buy several of the devices for Los Gatos fire stations, most likely through a dinner and silent auction.

"When my mom was waking up and [my family] realized that she was going to recover, we were just all so incredibly thankful," she said. "We said, 'What can we do to give back?' "

Caralee was lucky to be saved by the AutoPulse, but Warner said it doesn't guarantee survival. During November, for example, Shannon crews used the device on four people and revived two of them. Warner said there is always the chance that a revived patient will still die later. For people with existing conditions, especially seniors, a functioning heart doesn't necessarily mean that the brain and other organs are working well enough to sustain life.

But for Weich, who exercises regularly, eats healthy food and had not been diagnosed with any heart problems prior to her mysterious cardiac arrest, her body kicked right back into action once her heart was working again.

Shannon acknowledged that the nurses, emergency medical technician, paramedics, doctors and every one else who came to her mother's aid were largely to thank for her mother's revival and return to a normal life. But she said the AutoPulse is what gave them something to even work with.

"I absolutely think it saved her life," she said. "Without it, we just don't think she'd be here."

To assist with fundraising efforts to purchase AutoPulse units for the county fire department, contact Shannon Weich at 408.219.9636 or sweich@cisco.com. For more information about the unit, contact Battalion Chief Joe Parker at 408.378.4010.