There is little to no compensatory increase in heart rate or blood pressure when standing for up to 10 minutes. This is often due to an underlying disorder or medication use and is accompanied by other hypoadrenergic signs. Central nervous system ischemia
The central ischemic response is triggered by an inadequate supply of oxygenated blood in the brain. Common examples include strokes and transient ischemic attacks. While these conditions often impair consciousness they rarely meet the medical definition of syncope. Vertebrobasilar transient ischemic attacks may produce true syncope as a symptom.The respiratory system may compensate for dropping oxygen levels through hyperventilation, though a sudden ischemic episode may also proceed faster than the respiratory system can respond. These processes cause the typical symptoms of fainting: pale skin, rapid breathing, nausea, and weakness of the limbs, particularly of the legs. If the ischemia is intense or prolonged, limb weakness progresses to collapse. The weakness of the legs causes most people to sit or lie down if there is time to do so. This may avert a complete collapse, but whether the patient sits down or falls down, the result of an ischaemic episode is a posture in which less blood pressure is required to achieve adequate blood flow. An individual with very little skin pigmentation may appear to have all color drained from his or her face at the onset of an episode. This effect combined with the following collapse can make a strong and dramatic impression on bystanders.
A chest injury, also known as chest trauma, is any form of physical injury to the chest including the ribs, heart and lungs. Chest injuries account for 25% of all deaths from traumatic injury. Typically chest injuries are caused by blunt mechanisms such as direct, indirect, compression, contusion, deceleration, or blasts- caused by motor vehicle collisions or penetrating mechanisms such as stabbings. Classification
Chest injuries can be classified as blunt or penetrating. Blunt and penetrating injuries have different pathophysiologies and clinical courses. Specific types of injuries include:

Injuries to the chest wall
Chest wall contusions or hematomas. Rib fractures
Flail chest
Sternal fractures
Fractures of the shoulder girdle
Pulmonary injury (injury to the lung) and injuries involving the pleural space
Pulmonary contusion
Pulmonary laceration
Pneumothorax
Hemothorax
Hemopneumothorax
Injury to the airways
Tracheobronchial tear
Cardiac injury
Pericardial tamponade
Myocardial contusion
Traumatic arrest
Hemopericardium
Blood vessel injuries
Traumatic aortic rupture
Thoracic aorta injury
Aortic dissection
And injuries to other structures within the torso
Esophageal injury (Boerhaave syndrome)
Diaphragm injury

Diagnosis
Most blunt injuries are managed with relatively simple interventions like tracheal intubation and mechanical ventilation and chest tube insertion. Diagnosis of blunt injuries may be more difficult and require additional investigations such as CT scanning. Penetrating injuries often require surgery, and complex investigations are usually not needed to come to a diagnosis. Patients with penetrating trauma may deteriorate rapidly, but may also recover much faster than patients with blunt injury. See also
Transmediastinal gunshot wound
Commotio thoracis

References


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