NEW YORK (MONEY Magazine) - Funny thing about emergencies: you don't see them coming.

So when my 84-year-old stepfather Jim quietly slumped out of his chair late last year, my mother and I were stunned.

Ten years of helping him manage Parkinson's disease hadn't prepared us for this. Barely conscious and unresponsive, Jim needed an emergency room—like, stat. You know the image: overcrowded halls filled with doctors who don't know you, overwhelmed with people unable to afford care elsewhere.

Panic.

We called 911, scrambled desperately for Jim's Medicare card, grabbed his many medications and told the paramedics as much as we could recall. A white-knuckled 30 minutes later, Jim became one of the 114 million E.R. visits last year.

The emergency department (it's not a "room" anymore) is a weirdly democratic institution. It's a place where crisis rules the day and sets the pace.

It doesn't matter how rich or well insured you are -- if you bleed, you lead.

To help you prepare for the unexpected, MONEY spoke with doctors, nurses, patient advocates and other experts to develop this user's guide to the E.R. Here's hoping you never need it.

Most health plans offer an 800 number staffed by nurses to help you determine whether an E.R. trip is truly needed. If you can hang in there, this will always get you cheaper, more personalized care.

But when facing a threat to life (loss of consciousness, breathing trouble, bleeding or serious trauma), calling 911 is clearly your best option, since care begins once paramedics arrive.

It's a trade-off: You lose your chance to choose the E.R. for your needs or budget because paramedics are required to take you to the closest hospital accepting patients. Yet some 80% of E.R. patients arrive without an ambulance, so you have more options than you think.

"There are real differences in how emergency departments are staffed and operated," says Dr. Larry Bedard, past president of the American College of Emergency Physicians.

Spend an afternoon calling local E.R.s or visiting their Web sites and find out if they are staffed with board-certified E.R. physicians. "It's a relatively new specialty," says Bedard. Some emergency centers rotate doctors from other hospital departments -- say, dermatology.

Not ideal.

"By and large, in medicine, the more you do it, the better you are at it. A trained E.R. doctor should provide sharper care." It's also vital to know in advance how your insurance plan covers emergency care.

Do you have to pay a percentage? Must you stay within a certain network?

Even if you preselect the ideal in-plan E.R. with the best doctors, you may still face out-of-pocket costs. "People don't realize that most hospitals employ groups of doctors who may not be covered by their insurance," says Nora Johnson, author of The Medical Bill Workbook. "Radiologists, pathologists and E.R. docs quite likely don't participate in a group plan."

One trip could trigger bills from several sources at out-of-network rates -- or, if part or all of your claim is denied by your insurer, even full freight. For people with chronic illnesses like asthma or heart disease, it's essential to find an E.R. connected to a medical team you already know and trust in a place where your medical history and previous providers can be tapped quickly to make better, faster decisions.

"For these patients, it's important to have a hospital that already has a relationship with the patient's caregiver or specialist," says Dr. Carolyn Clancy, director of the Agency for Healthcare Research and Quality.

Karen Kennedy's son Jimmy, 12, has had asthma since birth. After dozens of trips introducing a gasping kid to unfamiliar E.R. doctors, she's learned to keep a "grab it and go" folder with his test results, files from recent doctor and E.R. visits, her own notes and copies of itemized bills.

She can share Jimmy's history instantly, but she also has extra clinical clout if someone does something that doesn't seem right.

"One wrong diagnosis landed Jimmy in the hospital," she recalls. "I had a sense of what was right, but I couldn't back it up."

Toting your own medical file into the E.R. could also save you from paying for unnecessary tests. "Most physicians practice defensive medicine," says Bedard. "If you come in with chest pain and show me previous EKGs and lab results, I may feel more confident having you follow up with your physician rather than admitting you to the hospital."

In addition to medical files, you can stock a grab 'n' go bag with helpful items that can make your stay less stressful -- and less expensive. Items include: Your insurance card, a list of prescription drugs you use, key contacts such as doctors and friends, and other comfort items.

When my stepfather arrived at the E.R., he was deemed a true emergency, needing care that pre-empted that of others in the waiting room.

Once he was stabilized, however, he joined the ranks of patients -- and families -- who had to wait to be admitted to the hospital. And wait. And wait.

We hovered for more than nine hours as Jim shivered in his gown on a gurney in the hall, often hallucinating. This practice, known as "boarding," warehouses patients in rooms and halls when no beds are available. As miserable as it is, use any waiting time, whether for test results or a hospital admission, to fill info gaps (what's that pink pill I take?) for yourself or clinicians.

Tell your doctor and health plan that you've arrived at the E.R. and may need follow-up care. And remember: Triage (prioritizing cases) is an ongoing process. If your condition worsens, holler.

"It's not like we come over and check on people in the waiting areas," says Nancy Foster of the American Hospital Association. "Let us know."

This is also the time to start planning your exit home or transfer to a hospital bed. Ask to meet the case manager or social worker on duty. "Most people don't even know these case workers are there," says Dr. Donna Sweet, chairwoman of the board of regents for the American College of Physicians.

Essential allies in a scary environment, they can smooth your transition if you're being admitted to the hospital associated with the E.R. or help you find a bed in a facility that might be better for your condition.

Treat case workers like the godsends they are. They can help you get copies of test results or itemized bills and can work with your health plan for the approvals you may need to be referred anywhere but home. But the most important thing to do during the wait is to document everything. (The perfect task, by the way, for a worried loved one.)

Record the name of every person who treats you, what time he or she stopped by, what was said, what procedures were performed and what medications were given. This is evidence you may need to battle everything from possible treatment errors to future billing mistakes. And remember to get the contact information for any doctor who visits -- most carry business cards -- to help you with care or billing questions later.

"It's amazing how many times the wrong person gets the wrong pill," says Sweet. "If you're allergic to anything, tell everyone. And I mean everyone." Even if you don't have allergies, politely pipe up.

"Ask everyone who comes by what they're giving you and why," she says. And make sure they know who you are. "Don't accept being referred to as 'the lady in bed No. 2.' If you aren't expecting a pill, identify yourself and then ask them to identify the medication."

Indeed, my mother and I stopped what could have been a series of awful errors when a person with the same name was admitted to the hospital and well-meaning staff, newly on shift, tried to give our Jim the other Jim's tests.

Once you're well enough to go home, the E.R. will show you the door. Even if it's 2 a.m.

Don't leave until you've received discharge instructions in writing. These should include the names of the doctors you saw, your diagnosis, follow-up instructions and a schedule for continuing any regular prescriptions. Never buy medication from the E.R. if you don't need to; ask for a prescription instead.

"Everything costs significantly more," says Bedard. Same thing for bandages, crutches and canes. Rent or buy them at a drug or hospital-supply store for a fraction of what you'd be charged at a hospital.

Find out how you can get copies of your itemized bill mailed to you.

Don't assume they'll be sent to your doctor -- you may need to file a release form to grant him or her access (you can find one at money.com). You'll also want a copy of the emergency-room report, which is supposed to document everything.

You're home, happy and healthy, and the E.R. is a distant memory. Then the bills come. Stunning, no doubt. You may have been charged for things you didn't get or hit more than once for what you did get. If you were admitted to a hospital rom the E.R., the same procedure may show up on both institutions' bills.

Here's where you'll want to cross-reference your copious notes with your itemized bills from the E.R. and hospital, the emergency report and your hospital medical file. What to do about errors?

Write a letter to your biller in which you provide copies of your evidence and ask for an amended bill. If your claim is denied retroactively as a "nonemergency," fire off another letter.

You've got rights; specifically, there are state laws that say reasonable people shouldn't be required to self-diagnose. "You can't know if chest pains are a heart attack or indigestion," says Bedard. "A smashed thumb is a real emergency if you're a professional concert pianist."

Fighting back is worth the time: A recent Harvard study found that 90% of appeals of HMO denials for E.R. care were won. When faced with a claims mess, consider hiring a medical billing advocate, who, for a fee or a percentage of the savings wrangled, can launch a counterattack. (Go to billadvocates.com.)

Or turn to Quicken, whose terrific Medical Expense Manager software ($50 at quickenmedical .com) analyzes and cross-references bills and health plans. It can even generate customized dispute letters.

My stepfather died a few weeks after his E.R. visit, as a result of the stroke we'd witnessed. But because of our planning and some gumption under pressure, my family could focus on the big stuff: offering love and comfort to Jim in his last days. Despite the tragedy, there were even moments of real joy -- another thing we didn't see coming.

Can't put a price on that.