Introduction to Trauma
This page discusses how to assess traumatic injuries based on the witnessed or interpreted mechanism of injury (MOI) and patient's AVPU level. The pathophysiology, signs, symptoms, assessment, treatment, and prevention of specific traumatic injuries are discussed in detail in subsequent pages.
Contents
Contents
MOI & Kinetic Energy
For a traumatic injury to occur, kinetic energy is generated during the event and then transferred to the patient's body. The mechanism of injury (MOI) can grossly identify a patient's possible problems; their AVPU during the event can help refine the list.
Kinetic energy equals 1/2 the mass times the velocity squared or:
Kinetic energy equals 1/2 the mass times the velocity squared or:
KE = 1/2 M x V2
Unless the mass is very large — think snow avalanche or large waves — speed typically causes more damage as doubling the mass only doubles the kinetic energy, while doubling the speed quadruples it.
The amount of kinetic energy, where, and how it contacts a patient's body determines the type and severity of their injuries. Keep in mind that kinetic energy dissipates over distance due to friction and as it travels through tissue. In order to develop a possible problem list, ask and answer the following questions:
How much kinetic energy was generated during the incident?
Where did the kinetic energy go?
The amount of kinetic energy, where, and how it contacts a patient's body determines the type and severity of their injuries. Keep in mind that kinetic energy dissipates over distance due to friction and as it travels through tissue. In order to develop a possible problem list, ask and answer the following questions:
How much kinetic energy was generated during the incident?
- How fast was the patient going when they fell?
- How fast was the object going when it hit them, and how large was it? Slow-moving, high-mass objects are less likely produce serious injury unless they pin a portion of the patient's body to another object causing a crush injury.
- Was any of the patient’s equipment damaged during the event? Cracked or broken helmets, broken skis, or damaged boats or vehicles can be indicators of high forces.
Where did the kinetic energy go?
- Was any dissipated gradually over distance during the event by sliding or absorbed by other obstacles (tree branches or brush), creating abrasions or superficial injuries? Was the surface rough (gravel, talus field) or smooth (grass, snow)?
- Did it enter the patient's body? If so, where, and at what angle? How much? How many impact points were there? Did the patient tumble?
- Was any energy absorbed during the incident? Helmets protective pads can absorb energy and ski bindings may release to lessen energy transfer to the patient.
Sample Incidents
The first pair of incidents shows how differing amounts of kinetic energy that enter a patient's body in the same place can yield a vastly different set of injuries. The second pair of incidents highlights how energy can be dissipated during an event and how angle and location affect the final injury.
Sea Kayak Incidents
Incident 1
A group of beginning solo sea kayakers were playing sea kayak polo in empty boats. During the game, a student accidentally hit another student with the nose of his kayak on his lower left rib cage from a few feet away, causing him to capsize.
Incident 2
A group of solo sea kayakers were floating outside a surf zone, contemplating if they could make a safe landing on the beach; their boats were fully loaded with camping gear for a four-day trip; the waves were two to three feet in height. During the ensuing discussion, two members of the group unknowingly drifted into the swells and started to surf towards shore. Unable to control their kayaks, one paddler was hit hard by the nose of his friend’s boat on his lower left rib cage as she surfed down the wave behind him. Although hurt, the paddler managed to safely land his boat on the beach.
Discussion
Even though the kayakers in both incidents were hit in the same place on their bodies—their left lower rib cages—they had very different injuries. When kayaker one surfaced, he had a slightly tender side that showed traces of a bruise the next day; his injury completely healed within a week. Kayaker two also had a tender side, but the additional mass of a fully-loaded boat, combined with the speed and force of the wave, ruptured his spleen. Kayaker two required emergency surgery to remove his spleen and eventually recovered months later to live the rest of his life without a spleen.
Mountain Bike Incidents
Cyclist Incident 1
A female cyclist was speeding down a steep gravel road when she accidentally laid her bike down sideways in the loose gravel. She slid about twenty feet on her left side with her bike, before gradually coming to rest against a large rock.
Cyclist Incident 2
A female cyclist was speeding down a hill when she hit soft sand, her front wheel dug in and turned, and she was thrown head-first over her handle bars into a large rock. Initially unresponsive, she awakened within a few minutes.
Discussion
The kinetic energy generated in both incidents was identical; however, in the first incident the energy was dissipated during the slide and transferred over time to the victim’s skin. As a result, the cyclist in the first incident suffered abrasions along her left side and, while painful, they healed with minimal scarring over the next three to four weeks. In the second incident, the kinetic energy was abruptly transferred into the cyclist’s head and neck. In this case, she suffered a brain injury and a fracture of her fifth cervical vertebra. She was extremely lucky and fully recovered over the next seven months.
Sea Kayak Incidents
Incident 1
A group of beginning solo sea kayakers were playing sea kayak polo in empty boats. During the game, a student accidentally hit another student with the nose of his kayak on his lower left rib cage from a few feet away, causing him to capsize.
Incident 2
A group of solo sea kayakers were floating outside a surf zone, contemplating if they could make a safe landing on the beach; their boats were fully loaded with camping gear for a four-day trip; the waves were two to three feet in height. During the ensuing discussion, two members of the group unknowingly drifted into the swells and started to surf towards shore. Unable to control their kayaks, one paddler was hit hard by the nose of his friend’s boat on his lower left rib cage as she surfed down the wave behind him. Although hurt, the paddler managed to safely land his boat on the beach.
Discussion
Even though the kayakers in both incidents were hit in the same place on their bodies—their left lower rib cages—they had very different injuries. When kayaker one surfaced, he had a slightly tender side that showed traces of a bruise the next day; his injury completely healed within a week. Kayaker two also had a tender side, but the additional mass of a fully-loaded boat, combined with the speed and force of the wave, ruptured his spleen. Kayaker two required emergency surgery to remove his spleen and eventually recovered months later to live the rest of his life without a spleen.
Mountain Bike Incidents
Cyclist Incident 1
A female cyclist was speeding down a steep gravel road when she accidentally laid her bike down sideways in the loose gravel. She slid about twenty feet on her left side with her bike, before gradually coming to rest against a large rock.
Cyclist Incident 2
A female cyclist was speeding down a hill when she hit soft sand, her front wheel dug in and turned, and she was thrown head-first over her handle bars into a large rock. Initially unresponsive, she awakened within a few minutes.
Discussion
The kinetic energy generated in both incidents was identical; however, in the first incident the energy was dissipated during the slide and transferred over time to the victim’s skin. As a result, the cyclist in the first incident suffered abrasions along her left side and, while painful, they healed with minimal scarring over the next three to four weeks. In the second incident, the kinetic energy was abruptly transferred into the cyclist’s head and neck. In this case, she suffered a brain injury and a fracture of her fifth cervical vertebra. She was extremely lucky and fully recovered over the next seven months.
Kinetic Energy & Injury Types
- Force passing across or through soft tissue typically causes minor tearing that causes wounds, bruising, and other soft tissue damage while offering some protection to underlying structures.
- Force delivered to long or flat bones at or near a right angle tends to cause fractures and may damage underlying structures causing bruising, rupture, and hemorrhage. For example:
- Force entering the chest cavity may damage ribs, lungs, heart, or great vessels leading to respiratory distress or volume shock.
- Force entering the upper abdominal cavity may damage the lower ribs, spleen, liver, and kidneys leading to volume shock
- Force entering the lower abdominal cavity may damage the pelvis and underlying blood vessels leading to volume shock.
- Direct force transmitted along the axial skeleton often causes pelvic or vertebral fractures.
- Rotational force can dislocate joints, fracture long bones, or injure ligaments and cartilage in joints.
- Equipment used in wilderness activities can increase the kinetic energy delivered to a patient's body as skis, snowshoes, and paddles often act as levers.
