Normally, when we swallow food, a little flap called the epiglottis blocks the airway (trachea) so that the food is pushed down the esophagus down to the stomach. But sometimes this process doesn't work and the food gets stuck resulting in a blocked airway. This is called choking. With young children, choking often occurs when they attempt to swallow a small toy.

Emphysema is a serious lung condition. It results in labored breathing and an increased susceptibility to infections. It occurs because the alveoli, the small sacks in the lungs that allow for gases to exchange, have become enlarged, or the thin sensitive walls of the alveoli have become damaged. The end result is difficulty in gas exchange of oxygen and carbon dioxide.

Secondary drowning is a condition where water, or other fluids, has entered the lungs but the person may be conscious and not fully aware of what has occurred. This also sometimes happens with a near drowning victim. That is, prior to being pulled out of the water they inhale fluid into their lungs.

Shock is a life-threatening emergency in which insufficient oxygenated blood reaches vital body organs and tissues because of extremely low blood pressure. One type, traumatic hemorrhagic, or hypovolemic, shock, results from a severe loss of blood. Typical causes range from a major accident to a ruptured tubal pregnancy, a perforated intestinal ulcer, or ruptured aneurysm.

Breathing requires the respiratory, circulatory, nervous, and musculoskeletal systems to work together. Injuries or illnesses that affect any of these systems may impair breathing. For example, if the heart stops beating, the casualty will stop breathing.

Clinical death is simply when a casualty has stopped breathing. This results in oxygen not entering the body which eventually results in death of body tissues and cardiac arrest.

Hyperventilation is a situation where a person is breathing too fast and too deeply, in a situation where their body is not using up the extra air they are inhaling. This causes an imbalance of oxygen and carbon dioxide in the blood and can lead to unconsciousness and death.

Asthma is a medical condition that a person can be born with or can develop later in life, but is most common in children and young adults. When someone has an asthma attack, their air passages (throat, trachea, bronchioles) constrict, spasm, and secrete mucous. This makes it very hard for the person to breath.

Rescue breathing, sometimes called artificial resuscitation, is a way of breathing air into someone to give the person the oxygen needed to survive. This technique should be used on casualties that are not breathing, but still have signs of circulation.

Anaphylaxis is a very serious condition in which someone has come in contact with something they are allergic to. This can include, but is not limited to, bee stings, eggs, peanuts or peanut butter, sea food, medications, and latex gloves.

Some people may have a hole in their throat just below the Adam's apple. This is their airway i.e. they breathe through this hole. The stoma is done surgically because of cancer or because of physical injury to the area. We never perform this on the field, it is much too dangerous, despite what we might see on television.

One way to open a person's airway is the jaw thrust. This technique should be used when spine or neck injuries are suspected which are typical of car accidents, falls, and some sports injuries. The advantage of the jaw thrust is that it minimizes movement of the head as compared to the more common head-tilt/chin-lift method.

Oxygen is a vital gas found in our atmosphere. It is what we need to be able to perform physiological processes and to live. The air around us has approximately 21% oxygen, which is plenty for normal use. When oxygen deprivation occurs, the body's tissues die (hypoxia).