It's not as healthy as it once was, it's been in danger of flatlining a few times and the need to shock it back to life has occurred more frequently of late…but ER is still alive and kicking.

The 14-year-old NBC drama marks its 300th episode Thursday with the promise that the consistently frazzled docs at County General—none of whom was there when ER bowed in 1994—will have 300 patients to put up with before the hour is through.

That's the sort of drama you've come to expect from ER, as the promos tend to go.

Maybe the series has lost a step or two over the seasons, not to mention about 2 million viewers since last year, but the stars are still happy to have their shot at a residency at the hospital that launched George Clooney's career.

The current roster boasts Clooney replacement Goran Visnjic and his onscreen mate Maura Tierney (both nine-year veterans now), John Stamos, Stanley Tucci, Mekhi Phifer, Linda Cardellini, Parminder Nagra and Scott Grimes.

Similarly, the list of actors who have swung through the emergency room doors at any given time, albeit for one episode or for a few seasons, is what Wikipedia was made for. Watching old seasons of ER is like a veritable stroll down character-actor—and big-name movie star—lane.

Grab some DVDs and you're going to spot Kirsten Dunst, Shia LeBeouf, Zac Efron, Dakota Fanning, Emile Hirsch, Monica Bello, Danny Glover, Marlee Matlin, Rebecca DeMornay, Cynthia Nixon, Mariska Hargitay, Lucy Liu, Bradley Whitford, David Krumholtz, Ed Asner, Marg Helgenberger and Bob Newhart...for starters.

While the series is only the second-oldest drama currently on television, thanks to another war horse by the name of Law & Order, it is currently the most Emmy-nominated program of all time, with 120. (Cheers is next with 117.)

The various kudos have resulted in 22 Emmy wins over the years, including acting honors for six-year regular Julianna Margulies and guest stars Sally Field and Ray Liotta, and a win for Outstanding Drama Series in 1996.

Back in the show's top-five heyday (32 million viewers in 1995-96), when Seinfeld and Friends were TV's ultimate lead-ins, Emmy nods were the norm for series regulars. Over the years, guest stars Forest Whitaker, James Woods, Red Buttons, Don Cheadle, James Cromwell, Mary McDonnell, Alan Alda, Swoosie Kurtz, William H. Macy, Veronica Cartwright, Ewan McGregor and Rosemary Clooney—among others—have also suffered their way to nominations.

Although the flavor of choice in these procedural-packed days appears to be Grey's Anatomy and House, the latter of which has an average viewership this season nearly double that of ER's 9.95 million, ER can easily be credited with piquing audiences' interest in the plight of earnest, hot doctors who always have 110 percent to give to their fascinating patients—unless the MDs are busy drinking and drugging, having sex and babies (often with each other) or dealing with problematic friends, relatives and existential crises.

Once upon a time, Omar Epps was just a young ER intern throwing himself in front of a train. (Lisa Edelstein also made an appearance on the NBC show back in the 1990s.)

In addition to being responsible for the obvious, such as the rise of Clooney and the stagnancy of Noah Wyle, ER was also the one that injected words such as "intubate," "v-tach" and "blood gases" into the popular lexicon.

The sheer amount of time bestowed upon ER—and always in the same timeslot no less—has also meant that the hour-long drama has had the opportunity to tackle a mindboggling number of issues, from AIDS, Darfur and the Iraq war to bipolar disorder, substance abuse and the imminent danger of helicopters.

Creator Michael Crichton "set up a terrific world where you can tell a lot of different stories, very emotional ones, and also do a lot of character work," executive producer John Wells, who finished directing Thursday's episode the day the writers strike began, told USA Today recently.

And as befitting a show that has defied the odds simply by lasting as long as it has in this time of fickle audiences, impatient networks, DVRs and a glut of similar concepts, ER might stand to gain from the Writers Guild of America walkout currently laying waste to prime time.

Wells & Co. had planned on this season being the series' last, but, now faced with the possibility of having only 13 episodes to show for it, the producers are considering extending ER's run for another year, E! Online's Kristin Dos Santos reported last month.    

Talks with NBC are on hold because of the labor impasse, and Wells hasn't worked on the show since the strike kicked off Nov. 5, but—as a County General doc would tell the family of a gunshot victim who's in stable yet critical condition—there's always hope.