The Centers for Disease Control (CDC) estimates that the average waiting time to see a doctor in an American emergency room is about 45 minutes, and even longer in some urban locations. This points up the importance of first aid measures performed on the scene. But what exactly can you expect to be called on to do?

If you are a healthcare professional, or had some other reason to take first aid courses, your training was actually geared to the most common occurrences (or should be, according to medical experts). Surveying the statistics on ER admissions and paramedic reports led to the creation of a fairly accurate list of the ten emergencies your first aid training will prepare you for, although a few may quibble over some inclusions or exclusions.

The following are not in any particular order, and represent common situations that can occur anywhere. In rural areas, there may be more occurrences of farm machinery accidents, while in urban centers there may be more auto-involved incidents. Generally, though, you will do well to consider the following as a good "prep list" of situations to be prepared for.

1. Poisoning, bad food, ingestion of chemicals

Unless you have specific training in this area (or are a paramedic, RN or MD) you should neither induce vomiting nor give any Ipecac syrup, a standard remedy with important exceptions to its use. What you should do is call a poison control hotline and get the victim to a doctor, bringing a sample of the food, poison or chemical that caused the condition.

2. Nosebleed

The sufferer should not be encouraged to lean back, which is a common miscue. When the bleeding stops, the person should neither blow her nose nor bend over. The person should sit up, lean slightly forward from the hips (not just tilt the neck and head) and pinch her nose just beneath the nasal bone for five or 10 minutes. If the bleeding last longer than 15 minutes, or the person is swallowing blood, then a visit to the ER is the right prescription.

3. Bleeding from wounds, cuts, abrasions

Forget the TV heroes and do not use a tourniquet. Improper use of a tourniquet can cause lasting damage to bones, tissue, veins and arteries and skin. You should apply a firm, steady pressure to any wound using clean towels or gauze. Wrap the wound securely and head to the ER if the bleeding is not stopping, if the wound begins to enlarge or if it was the result of an animal's bite. As always, keep the person warm so as to prevent their going into shock.

4. Being stabbed or impaled

Contrary to popular belief, you should not remove the penetrating object, as that can cause additional damage and accelerate bleeding. You should do what you can to "stabilize" the knife or object, and get the person to the ER quickly. Use other procedures detailed here and elsewhere to handle the bleeding, shock or fainting that may accompany the wound.

5. Seizures

Call 911 immediately. Again, forget the television version of first aid, and resist the temptation of putting something in seizure victims' mouths. Try to position the victims on the ground if you can, in a secure open spot, and roll them on their side.

6. Cut fingers

Interestingly, partial finger amputations are not particularly rare. Chopping up food for dinner, using electric saws and other tools, and working around moving machinery are just a few of the ways that finger tips (and more) are lost. If you are trying to save the amputated portion of a finger (or toe), don't do it by placing the object directly on ice. Instead, wrap the severed portion in damp gauze, put it in a waterproof plastic bag and place that on the ice. Bring it all with you and the victim to the ER. Treat the wound itself with ice to reduce the swelling, and wrap it in a dry, clean cloth.

7. Knocked-out teeth

Depending on how much of the tooth was lost (and recovered), there is the possibility that it could be reimplanted. Do not wash the broken off tooth, but rinse or wipe it gently. Place the tooth in milk and get to the ER or a dentist. By the way, milk works in this situation because it's sugar and mineral content approximates that of your body's own fluids, so it keeps the tooth moist without causing damage to the cells.

8. Burns from fire

Never, ever apply butter or grease of any kind to any type of burn, and do not cover burns with any fabric (towel, blanket) that could deposit fibers on the burned skin. In serious situations, do not break blisters or pull clothes off that are stuck to the burned areas. You can wash the area and apply antibiotic ointments to a mild burn, but head right to the ER for burns to the mouth, genitals, face or eyes, even if they are mild. Also get immediate emergency treatment for burns covering an area bigger than your hand, as well as and burns causing blisters that are followed in short order by a fever.

9. Electrical burns and "jolts"

Some 500 Americans die each year from electrical burns. Even when no damage is apparent, get medical attention when you receive a "jolt" of electricity from lightning, electrical cords or power lines. Electrical burn can cause serious, and invisible, injuries deep within the body. For any electrical mishap, you should get to the ER immediately.

10. Sprains

Most sprains are to ankles, followed by knees, wrists, shoulders and elbows. Again, contrary to some old wives' tales, do not use a heating pad but treat the sprain with an ice pack. If you cannot put weight on the ankle or knee, or use your wrist or arm normally, you just might have suffered a fracture, so an ER visit is mandatory.

Your first aid training has prepared you to handle a number of common mishaps and emergencies, but the techniques are merely the beginning of treatment. A doctor, nurse or paramedic is required to follow up on what you start. Do not mistake first aid for comprehensive treatment.

The fact is, you may not have to encounter such a clear-cut situation as those described here to consider making that 911 call or that ER visit. If you see or hear of people experiencing mental confusion, fainting, unstopped bleeding, shortness of breath or chest pain, you need to make the call and get that person medical treatment. Do not waste time, and always err on the side of caution. It just may be your training, and your cool head, that saves a life.