In medicine, the area of trauma medicine practice principally is concerned with severe multisystem physical injury that can progress into irreversible shock. It encompasses both trauma surgery and trauma critical care. Victims of physical trauma may indeed suffer trauma (psychological), both acute and delayed-onset, but that is not the focus of this article.
The background of physicians who treat trauma varies by countries. In the United States, while it is not a specialty board, many of the leading practitioners are general surgeons who have had fellowship training in trauma. In other countries, it may be considered a collateral duty of general or orthopedic surgeons. Emergency physicians, obviously, are often the initial managers of the trauma patient.
A key aspect of trauma practice is that multiply injured patients die of a "lethal triad" of three interacting factors:
While viewers of television emergency dramas often think of intravenous fluids as the most important paramedic intervention, aggressive fluid resuscitation, in trauma, can kill the patient. The standard of care for most trauma with blood loss is permissive hypotension, where just enough fluid is given to keep oxygen flow to the brain, but deliberately not restoring the systolic blood pressure to normal. A normal systolic blood pressure is high enough to dislodge the clots the body produced to stop bleeding, and start a new cycle of hemorrhage.
As one esteemed trauma surgeon put it, the treatment for trauma-induced hypotension is surgery, not fluids. The use of vasopressors to raise blood pressure is almost always to be condemned, except perhaps as a heroic measure in a surgical or intensive care situation, only to buy a short amount of brain perfusion time.
- See also: Field medicine
While television paramedics may fidget getting more intravenous flow, "scoop and run" is often the best possible treatment. Field personnel indeed should establish intravenous lines since veins may collapse, but not necessarily put any substantial volume through them until the first surgical facility is reached. Animal models, however, show that controlled fluid replacement can improve survival when surgical care is delayed; colloid (i.e., hydroxyethyl starch) showed benefit over crystalloid (i.e. Lactated Ringer's injection). 
There are exceptions. Before extricating a victim of crush injury still under massive weight, specialized fluid and electrolyte loading is mandatory, or the victim may die within minutes after the weight is removed.
The U.S. Army has introduced "combat lifesaver" program to support battlefield-oriented "scoop and run." While the original goal was to give the training and equipment to 10 percent of combat soldiers, there is strong pressure to make it 100 percent. While establishing IV access is not part of traditional first aid, it does make sense in many combat situations, when an evacuation helicopter can swoop in only after the enemy is suppressed -- and having that IV access makes sense at the first surgical facility, which will be reached in an indeterminate time.
Further fluid and transfusion medicine
Even in the operating room, there are changes in the reasoning by which basic crystalloid fluids such as saline are given, but also with colloid administration and the administration of blood and blood components. The conventional wisdom was that giving packed red blood cells (PRBC) was the most efficient way to improve oxygenation, but new clinical research shows that giving PRBC alone may lead to fatal clotting disorders in the presence of excellent oxygenation.
In some cases, the older practice of giving whole blood provides coagulation support. Practice evolved to the coadministration of platelets and of fresh-frozen plasma, which contains coagulation factors. The most recent work, as seen in the multicenter CRASH II trial, shows a significant survival benefit from appropriate administration of other agents, such as tranexamic acid, which prevent or reverse developing coagulation disorders.
Damage control surgery
The consequence of these trauma-related metabolic derangements is that the patient can only be submitted to enough damage control surgery (DCS), at one time, for "control of hemorrhage, prevention of contamination and protection from further injury," without making the metabolic disorders worse. Trauma surgeons now routinely split what had been one lengthy procedure in many, then turning to surgical critical care to prepare for the next procedure. Damage control surgery first was widely used when 9mm gunshot wounds became common in civilian practice, inflicting damage that had previously been associated with battlefield weapons. The surgical approach then moved to Iraq and Afghanistan, and a new generation then came back for civilian use.
Before DCS had a theoretical base, it was still practiced — devotees of M*A*S*H would recognize it as "meatball surgery".
Policy, legal and ethical challenges
While their principal responsibility is treatment, trauma specialists are very aware of the potentially preventable causes of trauma and may become involved in education. They also may be key advisers to field medicine on the prehospital care of the trauma patient.
Trauma physicians often see victims of accidents or violence, who are otherwise in good physical condition but have injuries incompatible with life. As such, they are potential organ or tissue donors, and obtaining consent is often stressful for all involved. 
- Karim Brohi (1 June 2001), Damage control surgery, Trauma.org
- Burris D, et al. (February 1999), "Controlled resuscitation for uncontrolled hemorrhagic shock", J Trauma 46 (2): 216-23
- Janet Brooks (26 September 2006), ""Damage control" surgery techniques used on soldiers", CMAJ 175 (7), DOI:10.1503/cmaj.061095.
- Siminoff, Laura A.; Traino, Heather M.; Gordon, Nahida (3 June 2010), "Determinants of Family Consent to Tissue Donation (Abstract)", Journal of Trauma (online pre-publication), DOI:10.1097/TA.0b013e3181d8924b