Google is sharpening its health-feature teeth to catch more than everyday wellness and irregular heartbeats. At the company's Made by Google event on Tuesday, it announced Loss of Pulse Detection, a new feature for Pixel Watch 3 that can sense when the wearer is experiencing a loss of pulse. 

Having a weakened or lost pulse is potentially a deadly medical emergency that signals the heart isn't beating and pumping blood properly. It's caused by cardiac arrest, poisoning, drug overdose or other events. If Pixel Watch 3 detects a loss of pulse on the person wearing it, Google says you'll be sent an alert with a timer to respond. 

If you don't respond, an automated voice message will be dispatched to emergency services with your location. 

"We know that a lot of the time, these events are unwitnessed, so no one is able to help or make a call on someone's behalf," Dr. Jake Sunshine, a research scientist who worked on the new feature, told CNET. "That was the problem we were trying to solve with this feature." 

The company is careful to say Loss of Pulse Detection wasn't built for one specific event or health condition; the classification and alert that follows is made through machine learning and based on sensors on Pixel Watch 3, including heart rate sensing. But Loss of Pulse Detection is a feature that may catch more rare but very serious health events. And it also touches on broader, public health problems, like rising rates of opioid overdoses, as untreated drug overdose is one type of catalyst for a loss of pulse event. 

Dr. Andrew Freeman, a cardiologist with National Jewish Health, said the new smartwatch feature appears to be targeting "out-of-hospital" cardiac arrest, which is a "major killer" since it requires immediate help. While "the devil is in the details" in terms of how it'll actually work to help people (and it relies on people actually wearing the Pixel Watch 3, of course), anything that gets emergency help to a person with lost or weakened pulse activity could save a life. 

"Anything that can move the need on these very lethal, high risk issues is amazing," Freeman said.

While other wearables, including some Google products and Apple Watch, have fall detection and other safety features, Loss of Pulse Detection on Pixel Watch 3 will be the first of its kind. It'll be available with the launch of Pixel Watch 3 in some European countries including the UK, Austria, Denmark, France, Ireland, Netherlands, Norway, Sweden and Switzerland. 

Google hasn't provided information yet on when or how the loss of pulse feature would be greenlit by the Food and Drug Administration, which it would need for use in the US.

In building Loss of Pulse Detection, Google said it consulted with emergency medical services, dispatchers and other groups that would have insight into how to respond to a loss of pulse event. The company also weighed the absolutely crucial element of time in loss of pulse events against the risk of sending false alerts, according to Florence Thng, Health Product manager at Google. And, she added, it's important to leave room for error.

"No feature is perfect," Thng said. "We built this very thoughtfully, but even with AI, we know that Loss of Pulse will not detect every event."