ObjectivesDiscuss some basic principles of ballistics and

tissue injury

Review basic management principles for extremity gunshot wounds In the field and definitive care

Factors in Tissue Injury

K = mv 2

2E K= Kinetic Energym= massV= velocity

Caliber Inside diameter of the barrel of the gun

Expressed in hundredths of inches Ex:

.38 caliber .22 caliber

Caliber Matters?

12 G .45 .38 .32 .22

Mass Matters

Weight12-15 g 250-350

8.7 – 10.2 g 230-400

1.7-1.9 g 250-350

Velocity (m/s)

Cavitation

Formation and then immediate implosion of cavities in a liquid that are the consequence of forces acting upon the liquid.

Fackler ML.Ballistic injury. Ann Emerg Med. 1986 Dec;15(12):1451-5

FragmentationTissue injury also proportional to the cross

sectional area of the missile

.38

Fackler ML.Ballistic injury. Ann Emerg Med. 1986 Dec;15(12):1451-5

.357

Fackler ML.Ballistic injury. Ann Emerg Med. 1986 Dec;15(12):1451-5

.22 Long Rifle

.306 Long Rifle

12 G Shotgun

Management of gunshot wounds to

the extremities

Hemorrhage Control in the Field

Direct pressure or compression dressings preferred and often successful

Avoid “clamping”

Consider the use of a tourniquet

Tourniquets

TourniquetsUse of tourniquets to control hemorrhage has

been documented as early as the 17th century

Advances and uses of tourniquets described by Joseph Lister and Harvey Cushing (among others)

TourniquetsUse became discouraged after WWI following

attention to complications (nerve damage, amputations, etc.)

More recent experience in Middle East conflicts has suggested a benefit with selected use 2006 Kragh et. al. prospective study from

Baghdad. 90% vs. 10% survival rate among tourniquet use in the presence of shock; 11% vs. 24% mortality for tourniquets placed in the field compared to ER.

Extremity GSWs in the ER- Priorities

• Overall patient condition (identification and treatment of shock)

• Identification of vascular injuries/control of hemorrhage

• Identification of orthopedic injuries

• Identification of nervous injuries

• Management of soft tissue injuries

“Hard Signs” of Vascular Injury

Active/pulsatile hemorrhage

Expanding hematoma

Pulse deficit

Palpable thrill/bruit

“Soft Signs” of Vascular Injury

Hematoma

History of significant blood loss

Proximity to major vessels

Incidence of arterial injury is 2-25%

Arterial Pressure Index (API)

Blood pressure ratio of lower to upper extremity

> 0.9 considered normal

Caution if pre-existing PVD

Physical ExamPhysical Exam

Hard Signs?Hard Signs?

Yes No

OR for Exploration

OR for Exploration

Soft Signs?Soft Signs?

Yes No

APIAPI

< 0.9< 0.9Imaging (CTA)Imaging (CTA)

ObservationObservation

NoYes

Injury?Injury?

Yes

No

Complex Extremity Trauma

Combined soft tissue, osseous, vascular/nerve injuries

More common with high energy weaponry (assault rifles, etc. ) or close range shotgun wounds

Risk Factors for Amputation

Gustilo III-C injuries

Prolonged ischemia (>4-6 hours)

Destructive soft tissue injury

Multiple/severely comminuted fractures/segmental bone loss

Old age/severe comorbidity

Lower vs. upper extremity

Failed revascularization

Vascular ShuntingDefinitive vascular repair takes time

Temporary solution to restore flow

Indications: HD instability/coagulopathy/acidosis/hypothermia Unstable skeleton Major wound contamination/infection or soft

tissue deficit Austere environment Poly-trauma with other life threatening injuries

Nerve Related InjuriesMay be caused by concussion zone of blast

injury (neuropraxic/contusion injuries) Will recover spontaneously

Progressive deficits may indicate an expanding hematoma or pseudoaneurysm Decompression/resection can reverse deficit

Nerve Related InjuriesDelayed operative intervention for neurologic

deficit most often favored Allows time for spontaneous recovery of

contusion injuries Allows determination of the the full extent of

injury (prevents inadequate debridement) Surrounding contusion can lead to epineural

softening and suture failure

Nerve Related Injuries If early exploration is indicated for other

reasons (i.e. vascular), nerve exploration is warranted in stable patients with deficits Primary repair for clean/sharp transections (rare

with GSWs) Nerve ends can be tacked to fascia to prevent

retraction Ends tagged or clipped for later identification

Case #1 24 year old man

“Minding his own business” when shot in the right upper ext

HD stable

Single GSW outer mid portion of upper arm

Clear radial pulse deficit

Grossly neurologically intact

Case #241 year old man shot during attempted robbery

HD stable

2 GSWs anterior/posterior right upper thigh (presumed entrace/exit)

Palpable left pedal pulses; Dopplerable right pedal pulses; ABI 0.2