Cardiac output (the volume of blood pumped by the heart) may be reduced, and hypotension (low blood pressure) is frequently present. The area of the chest wall near the contusion may be  tender or painful due to associated chest wall injury. Signs and symptoms take time to develop, and as many as half of cases are asymptomatic at the initial presentation. The more severe the injury, the more quickly symptoms become apparent. In severe cases, symptoms may occur as quickly as three or four hours after the trauma. Hypoxemia (low oxygen concentration in the arterial blood) typically becomes progressively worse over 24–48 hours after injury. In general, pulmonary contusion tends to worsen slowly over a few days, but it may also cause rapid deterioration or death if untreated. Causes
Pulmonary contusion is the most common injury found in blunt chest trauma, occurring in 25–35% of cases. It is usually caused by the rapid deceleration that results when the moving chest strikes a fixed object. About 70% of cases result from motor vehicle collisions, most often when the chest strikes the inside of the car. Falls, assaults, and sports injuries are other causes. Pulmonary contusion can also be caused by explosions; the organs most vulnerable to blast injuries are those that contain gas, such as the lungs. Blast lung is severe pulmonary contusion, bleeding, or edema with damage to alveoli and blood vessels, or a combination of these. This is the primary cause of death among people who initially survive an explosion.
It is less commonly used to indicate a pause in speech or an unfinished thought or to separate items in material such as show business gossip. The stylebook indicates that if the shortened sentence before the mark can stand as a sentence, it should do so, with an ellipsis placed after the period or other ending punctuation. When material is omitted at the end of a paragraph and also immediately following it, an ellipsis goes both at the end of that paragraph and at the beginning of the next, according to this style.According to Robert Bringhursts Elements of Typographic Style, the details of typesetting ellipses depend on the character and size of the font being set and the typographers preference. Bringhurst writes that a full space between each dot is "another Victorian eccentricity. In most contexts, the Chicago ellipsis is much too wide"—he recommends using flush dots (with a normal word space before and after), or thin-spaced dots (up to one-fifth of an em), or the prefabricated ellipsis character U+2026 … HORIZONTAL ELLIPSIS (&hellip;, &mldr;). Bringhurst suggests that normally an ellipsis should be spaced fore-and-aft to separate it from the text, but when it combines with other punctuation, the leading space disappears and the other punctuation follows. This is the usual practice in typesetting. He provides the following examples:

In legal writing in the United States, Rule 5.3 in the Bluebook citation guide governs the use of ellipses and requires a space before the first dot and between the two subsequent dots.