Ballistics for the EMS Provider How guns work, what they can do, and how to treat gun shot wounds

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Ballistics for the EMS Provider How guns work,
what they can do, and how to treat gun shot wounds

• Jeff Brosius,
• B.S., NREMT-P, CCEMT-P

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Basic Principles of Ballistics

• Physics
• Firearm mechanics
• Bullet properties
• Tissue response to force
• Treatment

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Basic Principles of Physics

• Kinetic Energy is a function of mass and velocity
• Force is a function of mass and
  acceleration/deceleration
• Energy can not be created or destroyed, only
  changed from one form to another

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Newtons Laws of Energy

• Kinetic Energy ½ Mass x Velocity²
• Force mass x G (where G Gravity Force
• A body in motion will continue in motion until
  acted upon by an outside force (tissue, gravity,
  friction, solid object, etc.)

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Firearm Mechanics

• All firearms share some basic principles.
• There is a barrel, which functions to direct the
  projectile in a certain direction.
• There is a pin, which causes the powder in the
  bullet to ignite.
• There is a trigger, which causes the pin to
  strike the bullet.

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Firearm Mechanics, cont.

• The bullet contains powder, which will burn
  rapidly, creating gas vapors.
• These vapors expand inside the barrel, creating
  pressure.
• The pressure forces the bullet out of the barrel.
• The speed of the bullet depends on several
  factors (size, friction, etc.)

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Bullet Characteristics

• Caliber of the bullet (.22, .45, .357, 9mm, etc.)
• Blunt vs. Hollow vs. Pointed end
• Casing (unjacketed/full metal jacket)
• Density of material

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Handguns, by the Numbers
Caliber Velocity Muzzle Energy Energy at 45 feet
Ft/sec
.25 810 73 60
.32 745 140 120
.357 1410 540 475
.38 855 255 255
.40 985 390 365
.44 1470 1150 875
.45 850 370 350
9 mm 935 345 315
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Rifles, by the Numbers
Caliber Velocity Muzzle Energy Energy at 300 ft

.22 Hornet 3770 1735 1262
.243 3500 1725 1285
M-16 3650 1185 805
Uzi 1500 440 277 (150 ft)
AK-47 3770 1735 1262
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Tissue Response

• Cavities temporary and permanent
• Temporary is larger than the size of the bullet,
  and is caused by compression of air around the
  projectile.
• Permanent is the destroyed tissue from the bullet
  itself.

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Cavities

• The size of the cavity is not simply a factor of
  the bullet size. Other factors are important,
  but often unknown
• Deflection
• Yaw of bullet at impact
• Speed of bullet at impact
• Angle of impact
• Range from gun to target

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Cavity Formation
Tissue
Temporary Cavity
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M-16 Rifle Wound
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NATO 7.62 Wound
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.22 Long Rifle Wound
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AK-74 Rifle Wound
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.22 cal Hollow Point Wound
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Tissue Response

• Dense tissue will suffer more damage than hollow
  tissue. (Bone vs. lung)
• Elastic tissue will suffer less damage than rigid
  tissue. (Muscle vs. liver)
• Strong tissue will withstand damage better.

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Treatment Goals

• Safety!!!!!!!!!!!!!!!!!!
• ANY penetrating trauma should be treated with the
  utmost urgency.
• A small hole on the outside might be hiding a
  large hole inside.
• A large hole outside can mask massive internal
  damage.

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Treatment Goals

• ABCs, as always.
• Rapid scene times grab em and get moving to the
  hospital.
• Airway support to include intubation (more often
  needed for thorax injuries.)
• Ventilatory support as needed.
• IV enroute, fluids as protocol/Med Control
  requests.

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Treatment Goals

• Hemorrhage control if possible.
• Occlusive dressings for sucking chest wounds.
• Needle Thoracostomy as needed for tension
  pneumothorax.
• Bilateral needle decompression ONLY in an
  intubated patient.

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Treatment Goals

• Early notification of the hospital.
• Constant reassessmentA GSW to the chest can
  cause the patients condition to change RAPIDLY.
  Be vigilant.
• Again, rapid transport is the single best method
  for treating a gunshot victim.
• Nothing else will be as helpful as a physician
  and hospital trauma care.

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Treatment Pitfalls

• Wasting time looking for the bullet or shell
  casing.
• Thinking that a small hole is not a major issue.
• Wasting time trying to classify wounds as
  entrance or exit.
• Closest facility vs. Closest appropriate
  facility.
• Delaying transport for ANY reason, other than EMS
  crew safety.

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Controversial Issues

• Cervical Spine Immobilization.
• Large volumes of fluid replacement.
• Traumatic cardiac arrest treatment.

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Pictures of injuries from firearms.
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Acknowledgements

• Andres M. Rubiano, MD
• David H Livingston, MD, FACS
• Manuel Sotelo, MD
• Errington C. Thompson, MD
• Eric D. Ladenheim, MD
• M.L. Fakler, MD
• Grady Memorial Hospital, Atlanta, GA
• Emory University School of Medicine, Department
  of Surgery

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Web Sites

• ww.umds.ac.uk
• http//medstat.med.utah.edu
• http//igm.nlm.nih.gov/
• http//www.vnh.org/EWSurg/EWSTOC.html
• http//internet.cybermesa.com/jbm/ballistics/calc
  ulations.html
• http//www.firearmstactical.com

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Web Sites

• http//www.iwba.com/
• http//www.milnet.com/milnet/weapons.htm
• http//www.wwa.com/dvelleux/html
• http//www.vnh.org/EWSurg/EWSTOC.html

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Final Words.

• Dont waste time. What you cant see will kill
  the patient.
• Be safe.
• Treat the patient.
• Do not treat the bullet, and dont waste time on
  details that dont matter.
• Understand that a .22 is just as lethal as a
  .357.
• Dont waste time.

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Questions?