That’s why emergency call operators ask questions specifically designed to identify the condition, ideally within 90 seconds.

Panicked and emotional callers don't always give simple answers, though, and evidence suggests cardiac arrests go unidentified in at least a quarter of emergency calls.

In Denmark, a team of computer engineers is using new technology to listen in on emergency phone calls and look for clues in the conversation that the operator may have missed.

We visit an emergency call centre in the Danish capital to see the system in action and find out if a computer really can detect cardiac arrests faster than humans working alone.

Producer / Reporter: Sam Judah

Photo Credit: Getty Images