The definition of a possum, or opossum, is a tree-dwelling nocturnal marsupial with fur and a prehensile tail. A small Australian mammal that lives in a tree and only comes out at night is an example of a possum. possum. possum.
More than two thirds of patients who die of anaphylaxis do so within the first: half hour. ____, a harsh, high-pitched inspiratory sound, occurs when swelling in the upper airway closes off the airway; the swelling can eventually lead to total obstruction. Stridor.
Severe Allergic Reaction Facts. Anaphylaxis is a severe allergic reaction that occurs rapidly and causes a life-threatening response involving the whole body. This reaction can lead to difficulty breathing and shock ultimately leading to death. For an anaphylactic reaction to occur, you must have been exposed in the past to the substance that causes the reaction, called the antigen. A bee sting, for example, may not cause an allergic reaction the first time.