Chapter 29: Ready for Review Trauma is the primary cause of death and disability in people between ages 1 and 44 years. The amount of force and energy delivered are factors in the extent of trauma sustained. Duration and direction of the force of application are also important. Understanding the effects of forces and energy will help in developing a high index of suspicion for the mechanism of injury and the likely types of injuries. Kinetic energy (KE) of an object is the energy associated with that object in motion. It reflects the relationship between the weight (mass) of the object and the velocity at which it is traveling. The law of conservation of energy states that energy can be neither created nor destroyed; it can only change form. Blunt trauma refers to injuries in which the tissues are not penetrated by an external object, as commonly occurs in motor vehicle crashes, in pedestrians hit by a vehicle, in motorcycle crashes, in falls from heights, in serious sports injures, and in blasts when no shrapnel is involved. In a motor vehicle crash, the angle of impact, mechanical characteristics of the vehicle, and the occupant’s position at the time of impact will determine types of injury. Trauma in a crash is composed of five phases representing the effects of progressive deceleration: deceleration of the vehicle, deceleration of the occupant, deceleration of internal organs, secondary crashes, and additional impacts. There are five primary types of impacts: frontal or head on, lateral or side, rear, rotational, and rollover. The front seat occupants of vehicles during a frontal or head-on crash usually follow one of two trajectories, a down-and-under pathway or an up-and-over pathway. Protective devices such as seat belts, air bags, and helmets are designed to manipulate the way in which energy is dissipated into injury. In a motorcycle crash, any structural protection afforded to the victims is not derived from a steel cage, as is the case in an automobile, but from protective devices worn by the rider such as helmets and leather or abrasion-resistant clothing. There are four types of motorcycle impacts: head-on collisions, angular collisions, ejected riders, or laying the bike down. Adult pedestrians involved in a crash experience three predominant mechanisms of injury: lower extremity injuries from the initial hit, second impact injuries from being thrown onto the hood or grille, and third impact injuries when the body strikes the ground or another object. The severity of injuries from falls from heights depends on the height, position, and orientation of the body at the moment of impact; the area over which the impact is distributed; the surface onto which the person falls; and the physical condition of the patient. Penetrating trauma involves a disruption of the skin and underlying tissues in a small, focused area, as commonly occurs with stab wounds and gunshot wounds. The severity of a stab wound depends on the anatomic area involved, depth of penetration, blade length, and angle of penetration. Firearms are the primary mechanism resulting in penetrating trauma. The magnitude of tissue damage depends on the projectile’s velocity, the orientation of the projectile as it entered the body, the distance from which the weapon was fired, the design of the projectile, and the type of tissue through which the projectile passed. Blast injuries include primary, secondary, tertiary, quaternary (miscellaneous) injuries. A blast wave or shock wave is dependent on many factors including the size of the explosive charge, the nature of the surrounding medium, the distance from the explosion, and the presence or absence of reflecting surfaces. Air-containing organs such as the middle ear, heart, lungs, major blood vessels, and gastrointestinal tract are most susceptible to pressure changes and blast injuries. Multisystem trauma describes trauma that involves several body systems. Most trauma affects more than one system, often includes both blunt and penetrating trauma, and has a high level of morbidity and mortality. Management of trauma patients requires a thorough and accurate assessment of the patient as well as a good working knowledge of the mechanisms of injury. In treating multisystem trauma, remember that if a generalized mechanism is present, you should anticipate multisystem injuries. It is also important to remember that multisystem trauma patients cannot be stabilized in the field. The criteria for transport to a trauma center vary from system to system. However, there are key variables for transport to a trauma center as defined by the Centers for Disease Control and Prevention National Trauma Triage Protocol. There are four categories of trauma centers. Your system may include a Level I, which is the highest level trauma center. The Association of Air Medical Services and MedEvac Foundation International identify criteria for the appropriate use of emergency air medical services for trauma patients. The criteria include situations in which there is extended transport time by ground, masscasualty incidents, prolonged extrication times, critically injured patients, or when there is a long distance to an appropriate facility.