Mechanism of Injury

CHAPTER 30 Mechanism of Injury



Kyle Madigan, RN, BSN, CEN, CFRN, CCRN



MAJOR TOPICS



Biomechanics and Kinematics


Definitions

Physics Laws and Application

Types of Injuries


Blunt Forces

Penetrating Forces

Blast Forces


I. BIOMECHANICS AND KINEMATICS


Understanding the laws and principles of the transfer of energy and their effect on the human body are key to providing thorough care to the trauma patient. Each of the tissues comprising the human body (connective, epithelial, nerve, muscle) has a specific tolerance and response to the effects of energy loading and transfer.



A. Definitions




1. Mechanism of injury (MOI)


a. Means in which energy is transferred from an object or the environment to the human body

b. Trauma statistics

1) Leading cause of death for persons between 1 and 34 years of age

2) Most common causes of unintentional injury death (2002)
a) Motor vehicle collisions

b) Firearms

c) Falls

2. Kinematics


a. Study of body motion or a system of bodies without consideration given to its mass or the forces acting on it

b. Kinetic energy (KE)

1) Energy that a body possesses as a result of its motion

2) Function of the relationship of body weight (Mass) and speed (Velocity): KE = (Mass × Velocity2)/2

3) Standard metric unit of measurement (SI) for KE is the joule

4) Production of KE influenced by velocity more than mass
a) Doubling the mass doubles the KE

b) Doubling the velocity quadruples the KE


B. Physics Laws and Application




1. Newton’s First Law


a. A body at rest or a body in motion will remain in that state unless acted on by an outside force

2. Law of conservation of energy


a. Energy can be neither created nor destroyed, only changed in form

b. As motion starts or stops, energy must be changed to another form

1) Mechanical energy
a) External forces: acceleration/deceleration
(1) In motor vehicle collisions, the moving vehicle strikes an immovable object, thereby causing a sudden deceleration of the vehicle, whereas the occupant accelerates until he or she strikes an immovable object (e.g. dashboard, steering wheel, restraint system)

(2) Organs within the body go through the same acceleration/deceleration sequence, causing internal injuries
(a) Brain: coup/contrecoup injuries

(b) Heart: ligamentum arteriosum, aortic arch disruption

(c) Duodenum: rupture between anchored and free segments

b) Internal forces: tissue strength
(1) Stress: internal condition of any physical tissue structure, under any load, that does not exceed the elastic limit of that tissue structure
(a) Tensile stress: when the length of a material (tissue) tends to increase in the tensile direction, thus causing the cells to separate

(b) Compressive stress: the stress applied to materials (tissue) resulting in their compaction (decrease of volume)

(c) Shearing stress: a state in which the shape of a material tends to change without particular volume change

(2) Strain
(a) Deformation (injury) caused by the action of stress on a physical body

(b) Dependent on tissue type

2) Thermal energy: transfer of heat from an area of higher temperature to an area of lower temperature
a) Heat may be transferred between objects by radiation, conduction, or convection

Related posts:

  1. Genitourinary Emergencies
  2. Shock Emergencies
  3. Disaster Preparedness and Response
  4. Cardiovascular Emergencies

Stay updated, free articles. Join our Telegram channel
Tags:
Nov 8, 2016 | Posted by in NURSING | Comments Off on Mechanism of Injury

Full access? Get Clinical Tree
Get Clinical Tree app for offline access