There are no direct signs of TBI, but certain signs suggest the injury and raise a clinicians suspicion that it has occurred. Many of the signs and symptoms are also present in injuries with similar injury mechanisms such as pneumothorax. Dyspnea and respiratory distress are found in 76–100% of people with TBI, and coughing up blood has been found in up to 25%. However, isolated TBI does not usually cause profuse bleeding; if such bleeding is observed it is likely to be due to another injury such as a ruptured large blood vessel. The patient may exhibit dysphonia or have diminished breath sounds, and rapid breathing is common. Coughing may be present, and stridor, an abnormal, high-pitched breath sound indicating obstruction of the upper airway can also occur.Damage to the airways can cause subcutaneous emphysema (air trapped in the subcutaneous tissue of the skin) in the abdomen, chest, neck, and head. Subcutaneous emphysema, present in up to 85% of people with TBI, is particularly indicative of the injury when it is only in the neck. Air is trapped in the chest cavity outside the lungs (pneumothorax) in about 70% of TBI. Especially strong evidence that TBI has occurred is failure of a pneumothorax to resolve even when a chest tube is placed to rid the chest cavity of the air; it shows that air is continually leaking into the chest cavity from the site of the tear. Air can also be trapped in the mediastinum, the center of the chest cavity (pneumomediastinum).
Intentional
Intentional exposure is controversial as it involves the use of nuclear weapons, human experiments, or is given to a victim in an act of murder. The intentional atomic bombings of Hiroshima and Nagasaki resulted in tens of thousands of casualties; the survivors of these bombings are known today as Hibakusha. Nuclear weapons emit large amounts of thermal radiation as visible, infrared, and ultraviolet light, to which the atmosphere is largely transparent. This event is also known as "Flash", where radiant heat and light are bombarded into any given victims exposed skin, causing radiation burns. Death is highly likely, and radiation poisoning is almost certain if one is caught in the open with no terrain or building masking-effects within a radius of 0–3 km from a 1 megaton airburst. The 50% chance of death from the blast extends out to ~8 km from a 1 megaton atmospheric explosion.Scientific testing on humans done without consent has been prohibited since 1997 in the United States. There is now a requirement for patients to give informed consent, and to be notified if experiments were classified. Across the world, the Soviet nuclear program involved human experiments on a large scale, which is still kept secret by the Russian government and the Rosatom agency. The human experiments that fall under intentional ARS exclude those that involved long term exposure. Criminal activity has involved murder and attempted murder carried out through abrupt victim contact with a radioactive substance such as polonium or plutonium.