The old expression that “Necessity is the mother of invention” may never have been more on target.

The wife and son of a 65-year-old California man whose heart had stopped had no CPR training. Desperate, they grabbed a nearby plumber’s helper to perform chest compressions until rescuers arrived.

Unorthodox, sure, but it kept the man alive.

Thirty-something years later, Texas doctors reported results of 380 patients who couldn’t be revived by defibrillation but were treated with a new CPR method — inspired by that family’s experience.

The researchers’ data showed that using a plunger-type machine led to far better than the usual outcomes.

But first: Unless we work in a hospital emergency room, thanks to TV and movies, we likely have unrealistic expectations about how well CPR works.

Only about 7% of those who undergo CPR outside a hospital are later discharged with full brain function. In general, the odds aren’t in our favor.

The three-machine setup recently discussed by emergency medical officials is called neuroprotective CPR. One component is a silicone plunger, which pushes the chest up and down, distributing blood through the body. A breathing tube helps control lung pressure. The third piece holds a patient in close to a sitting position to help oxygen-thin blood in the brain drain better.

All three components are separately approved by the FDA. They cost about $20,000 together and fit into a backpack.

Emergency officials in Memphis, Tennessee, early adopters of the new system, said they had a 7% survival rate with traditional CPR. Now, that rate is up to about 23%.

Better odds? That’s something we can all get pumped up about.