If I live alone in a house, how can I tell relatives / civil defense / hospital when I am suffering from a severe health condition or a serious unexpected injury (let's say fainting, stroke, or severe injury that I cannot speak because of it)? I mean, is there a device installed in the body that sends basic health data (heartbeat, blood sugar, pressure, blood oxygen percentage, respiratory rate ...) daily to a health organization, and if critical data is received, a notification is sent to them and they call and then they come if there is no answer?
A device to constantly measure "vitals" such as pulse and blood oxygen would be expensive, possibly invasive (a pulse oximeter on your finger while you lie in a hospital bed is no big deal, but will really get in the way while you're cooking or gardening) and subject to many false positives, such as when the device slips or the person removes it. Further, daily reporting would be of no value, you would need to detect dangerous patterns and send immediate help: this raises the cost, the complexity, and so on.
Many older or medically fragile people do have "alert buttons" that they can push if they experience dramatic pain, weakness, neurological symptoms and so on. Often these are set up with two-way voice and if the person doesn't reply when the call centre responds to the button push, the call centre sends an ambulance.
You may worry that something would strike you without warning. In that case you would most likely collapse. Some of these "alert buttons" have fall detectors for this reason. They won't help if the medical emergency happens when the person is in bed, but covers all the rest of the possible problems. If you fall down and when the call centre responds, you don't talk -- we don't need to know your pulse, blood sugar, blood pressure, or anything else, an ambulance is on the way.
Finally some of these buttons are connected to the home's landline, others to the person's cell phone, while others have a SIM card of their own so that they work if the person has gone for a walk or is out doing errands.