In the rush of an emergency, when a heart attack patient or car accident victim needs oxygen, it may not matter that the breathing tube stuffed down his throat chips a tooth or scratches the trachea.

But Dr. Jeffrey Parker has long felt there must be a better way, ever since medical school in the 1970s, when he struggled to intubate patients with a metal blade laryngoscope, still in wide use.

''I consider it a primitive device - an oral crowbar,'' Parker said. ''I set out to find a better way.''

Parker's invention, created in the workshop of a rented house in Hyde Park, won a national medical design award this year. The Parker flex-tip endotracheal tube is on the market now, to be followed early next year by its companion, a curved, hard plastic guide that slides the tube into the windpipe.

The doctor's six-year-old company, Parker Medical, now has a roster of four related products marketed under the slogan, ''Innovation in Intubation.'' The firm has a distribution agreement with medical supplier Tri-anim.

''The initial reactions by the anesthesiologists who have seen the Parker tube have been extremely positive,'' said Dan Pearson, Tri-anim vice president of sales and marketing.

Inventing and running his company with partner Marvin Hersh is just Parker's day job, and not the one that pays the bills. Parker's nights are spent at Mercy Hospital in Fairfield, where he has been director of critical care physicians for more than 17 years.

''I take care of emergencies that arise in the hospital overnight,'' Parker explained. ''It's nice to be able to earn a living at night, because what I do during the day is pretty speculative.''

Parker, 58, always has had too many interests for just one profession. He earned a law degree in 1982, ''as an intellectual lark,'' he said.

But he ended up practicing law for 12 years, specializing in medical cases.

''I also like mechanical challenges,'' Parker said, to explain his shift from law to designing medical devices.

''And I felt there was more potential to help more people with inventions than law,'' he said.

''Jeff isn't in this for the money,'' agreed Hersh, the other half of Parker Medical, who focuses on sales and marketing from an office in Englewood, Colo.

''He's always been in this for patients of trauma. I've been in this business for 35 years, and I've never seen anyone more dedicated.''

The trick to intubating a patient - whether to help inflate the lungs or administer oxygen or anesthetic gases - is to guide the flexible plastic tube over the tongue, between the vocal chords in the larynx into the trachea, or windpipe.

This common procedure has so many potential pitfalls ''that even physicians expert in it sometimes make mistakes,'' Parker said.

He believes his products will make intubation easier and safer.

First, Parker's breathing tube has a center tip so soft and flexible that it slips away from anything it hits on the way to the windpipe. Parker won Food and Drug Administration approval for the tube last year.

Then, Parker's intubation guide - PIG, for short - acts as a conduit to direct the tube into the larynx and trachea.

His newest product is Parker TrachView, an intubating videoscope that is smaller and less expensive than those used now in hospitals.

Parker's time-consuming devotion to his medical inventions will pay off in patients helped, he said.

''This is my opportunity to do something for mankind,'' he said. ''This is my legacy.''