Students at Carnegie Mellon University (CMU) have created a wrist oximeter that monitors blood oxygen levels and can warn the wearer and others of an impending opioid overdose. Opioids such as heroin depress the central nervous system, including respiration, and an overdose kills by suppressing respiration to the point that a person’s heart and brain dies from insufficient oxygen. The CMU wrist oximeter continuously monitors oxygen levels and when low blood oxygen is detected, it will warn the wearer and can also send a text message to an emergency contact.
The Harm Reduction Coalition has a set of web pages explaining the principles behind an overdose and how the drug Naloxone (Narcan®) works to quickly reverse the effects of an opioid overdose and prevent death by restoring the central nervous system to normal operation and thereby restoring normal respiration.
For those interested in a more in depth exploration of the effect of heroin on mammals (rats are used in this experiment), I found the study Intravenous Heroin Induces Rapid Brain Hypoxia and Hyperglycemia that Precede Brain Metabolic Response helpful.
It’s worth noting that Naloxone is relatively easy to administer (with training available) and can be purchased without a prescription. This Time article has details on the legality and availability of Naloxone. If you’re around someone who uses opioids, having Naloxone available could save their life.