A person having difficulty breathing is in respiratory ditress. A person who can't breathe at all is in respiratory arrest. Both of them are breathing emergencies. Brain cells begin to die in four to six minutes without oxygen.
Respiratory Ditress :
Hyperventilation : Occurs when breathing is faster than normal.
Asthma : The air passages become narrower and breathing is difficult.
Allergic reaction : Are sensitivities to specific substances that can be absorbed through the skin, inhaled into the lungs, swallowed, or injected.
Anaphylaxis : Is a severe allergic reaction. The air passages may swell, making breathing difficult