Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Emergency Med > 6 - Gunshot Wounds > Flashcards

6 - Gunshot Wounds Flashcards

You may prefer our related Brainscape-certified flashcards:
Royal College: Emergency Medicine flashcards
1
Q

Key learning points

A
  • Understand ballistic principles of GSW
  • Interpret how missile ballistics influence the pathophysiology of a GSW
  • Discuss basic guidelines for management of projectile wounds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Epidemiology

A

223 million firearms in the US in the last century
o 2/3 of American households have a gun

Civilian injuries are common
o 115,000 GSW in 1993
o 40,000 deaths
o Second episode increased from 26% in 1987 to 43% in 1990

1 million civilians killed since 1933 ( more than in all wars combined)

Many civilian GSW are in the extremities
o 30% noted by Demetriades @ LA County Medical Center

Low or mid range velocity
o Trend is higher power and faster delivery
o Trend is for more numbers of wounds

Close range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Simpson et al – A synopsis of urban firearm ballistics (2003)

A
  • Review of police records
  • Review of cost data
  • 57% of confiscated weapons were semi automatic, 11% shotguns
  • 23% of surrendered weapons were semiautomatic
  • Evolution between 1970 and 2000:
    o More firepower
    o Faster delivery
  • Average cost $15,000 for treatment, $40,000 for rehab per incident
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Ballistics

A

Internal Ballistics - Bullet in the barrel
o Bullet and casing design
o Caliber

External Ballistics - Bullet flight in the air
o	Spinning due to riffling of the barrel
o	Yaw
o	Range
o	Velocity

Terminal Ballistics - Bullet hitting the target
o Anatomic site
o Tissue density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Wounding variables

A
  • KE of projectile (velocity, mass, range)
  • Transfer of energy to the tissue (design of projectile, jacketed, hollow point)
  • Density of the tissue (Increased density = increased energy transfer)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

More energy = bigger injury?

A

It’s not that easy

- KE = (M x V2) / 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Parameters controlling ballistics

A
  • Casing size
  • Propellant
  • Projectile material
  • Projectile design
  • Velocity
  • Range
  • Contact tissue density
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does a gun work?

A

Cartridge
o Case
o Gun powder
o Primer

Powder is ignited when the firing pin of the gun hits the primer

Hot gas expansion accelerates the bullet through the barrel
o The longer the barrel the faster the bullet
o The barrel may be rifled to induce spin of the bullet and stabilize its flight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Bullet projectile materials

A
  • Most bullets are lead due to the high specific gravity
  • Some bullets have other substances such as glues or coatings
  • Bullets are non-explosive and cause damage directly by projectile energy and transfer of that energy at tissue contact
  • Explosive rounds are “shells”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Projectile design - unjacketed

A

o Soft material is exposed leading to more deformation therefor more energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Projectile design - fully jacketed

A

o Bullet stays intact
o Passes through tissue
o Less energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Projectile design - hollow point

A
  • Designed specifically to mushroom at impact
  • Transfers more energy to the tissues
  • Deformation at contact increases energy transfer to tissue
  • Exit wound averages 27 times larger than entrance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Projectile design - soft point

A

o Same as hollow point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Velocity

A
  • Velocity: this definition is completely arbitrary but is widely used to describe GSW – You must know the definition & also understand the reality and new research
  • Low Velocity 2500 feet/second (30/30, 3006, 9 mm, m-16 (7.62) and other military rifles)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Range

A
  • Energy is dissipated over time of flight
  • Close range injury has higher projectile energy
  • Burns may occur due to hot gasses at very close range
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Tissue damage (BE PREPARED TO DISCUSS THESE PRINCIPLES)

A

Direct
o Laceration
o Crush
o Contusion

Indirect
o Concussion zone
o Cavitation
o Secondary missiles

Velocity
o Lower velocity allows pushing of vital structures aside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Temporary cavity

A
  • Out ward explosion of the tissues occurs as the KE is transferred from the missile to the tissues
  • Happens in both high and low velocity wounds but is greater with higher velocity
  • Cavity 30 x the bullet diameter is created momentarily
  • Collapse can create a vacuum
  • The higher the KE and the denser the tissue the more energy is transferred
  • Bullet design also has an effect
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

General management rules

A
  • ABC’s
  • Vascular Evaluation
  • Bullet Removal
  • Debridement
  • Antibiotics
  • We should no longer treat based solely on velocity of firearm - Transfer of energy to the tissues is multifactorial (velocity, design, tissue density)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

LA County/USC Medical Center Survey

A

For life threatening GSW:
o Rapid transit to definitive care facility is the most important determinant of survival
o For every 10 minutes of delay, 10% reduction in survival
o Patients transported by non-medical personnel did better than those who waited for EMS
o Minimal on scene treatment seemed to improve outcomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Injury severity scores – Reconstruct vs. amputate

A
  • Mangled Extremity Severity Score (MESS)
  • Injury Severity Score (ISS)
  • Predictive Salvage Index (PSI)
  • Limb Salvage Index (LSI)
  • Hanover Fracture Scale (HFS-97)
  • NISSSA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Multiple studies unable to scientifically validate any of the current severity scores

A
  • Lower Extremity Assessment Project (LEAP) JBJS 2001
  • Ly et al, JBJS 2008
  • Togawa et al, JBJS 2005
22
Q

Vascular injury

A
  • Indication for angiography is the indication for exploration
  • “Routine angiography (another time consuming invasive procedure) is no longer the standard of care in extremity GSW.” Cornwell, CORR 2003
23
Q

Antibiotics

A
  • Bullet injuries are contaminated (bullet is not sterilized upon firing, external contamination dragged inward, cavitation vacuum)
  • Debridement and wound care is the most important part of preventing infection, more important than antibiotics
  • When fracture is present follow open fracture protocol
24
Q

Efficacy of antibiotics in low velocity gunshot fractures – Dickey et al (1989)

A
  • Prospective investigation of antibiotics vs. wound care alone for GSW
  • 73 fractures divided into the two groups
  • No high velocity or shotgun wounds
  • Level 2
  • 1 infection in each group
  • Found no value for antibiotics for low velocity GSW
25
Q

Antibiotic therapy in GSW injuries – Simpson et al (2003)

A
  • Systematic Review
  • Level 1
  • Antibiotic prophylaxis indicated for high energy, shotgun, and intra-articular injury
    o 48 hours of therapy
    o Drug choice based on injury pattern
  • Now distinct advantage in low velocity injury
26
Q

Bullet removal

A
  • Bullet becomes encapsulated by fibrous tissue
  • Lead intoxication is not common
  • Remove if:
    o Intra articular
    o Adjacent to vital structures
    o Expected functional compromise
27
Q

Debridement

A
  • Previous recommendation was to widely excise the entire cavity for all high energy wounds
  • Staged debridement similar to open fracture management is now recommended
  • Appropriate debridement is the cornerstone of therapy
28
Q

Shotgun wound

A
  • Low velocity but high energy
    o 1000-1500 ft/sec
    o Large combined mass of “shot”
    o Large amount of gun powder
    o Pellets act as a single missile within 8-10 feet
    o Varies with the choke design of the barrel
  • Contamination of the wadding
  • Twice the mortality of other fire arms
  • Treatment is based on principles of high energy wounds
29
Q

Shot (pellets)

A 
00 “Buckshot” 
o	Largest (eight pellets per once)
o	Caries higher energy longer distance

9 “Birdshot”
o Smallest (585 pellets per once)
o Loses energy very quickly

Materials
o Most common is lead
o Water fowl shot is steel

“Choke” of the barrel
o Determines the spread pattern of the shot

30
Q

Shotgun wound classification

A

Type I
o Penetrating Subcutaneous
o > 7 yard range
o Small shot (buckshot can penetrate at longer distance)

Type II
o Perforating below fascia
o 3-7 yard range

Type III
o Massive
o Point blank

31
Q

CASE STUDY 1

A
  • Small caliber
  • Entry and exit are the same size, so full metal jacket
  • Less energy transfer means that it has energy left when it exits
  • Need x-ray – always
  • Need to know the principles of open fracture in order to treat gunshot wounds (essentially the same thing)
32
Q

True or false… More energy = bigger injury?

A
  • It is more complicated than this
  • If it goes right through a very low density area, it may not have a big injury
  • Need to know velocity, mass, range
  • Transfer of energy into tissue is the key factor
  • The more energy that gets transferred into the tissue, the bigger the injury
33
Q

CASE STUDY 2

A
  • Very small caliber

- Exit wound is much bigger than entry wound

34
Q

Hollow point bullet

A
  • Deformation at contact increases energy transfer to tissues
35
Q

Bullet design

A
  • Tumbling bullets
  • Bigger caliber, went all the way through
  • So much bone damage because it is higher density energy transfer and a temporary cavity was formed
  • When the round hits the bone, it causes internal explosion of the bone, expansion of cavity
  • Temporary cavitation zone
  • Entry and exit wounds are small, but there can be devastating damage due to cavitation
36
Q

CASE STUDY 3

A
  • Comminuted fracture of the 3rd metatarsal
  • Fragmentation of metal
  • Secondary missile into the toe
37
Q

Classification systems for GSW

A
  • Low vs high = no
  • Gustillow and Anderson = no
  • There are many different classification systems, many of which are not useful clinically
  • **BEST classification system is the Red Cross Classification on War Wounds **
38
Q

BEST classification = Red Cross Classification on War Wounds

A
  • Incorporates all the important, relevant factors in treating a GSW
  • ** Entry, exit, cavity, fracture, vital structures, metallic products **
39
Q

CASE STUDY 4

A
  • Entry = huge, large caliber weapon with a lot of high energy transferred to tissue
  • Exit = same (huge)
  • Cavitation = high cavitation due to size of cavity within the foot, much larger than the bullet itself, so we know there has been cavitation
  • Fracture = yes
  • Vital structures = 2nd and 3rd toes are blue due to compromised vasculature
  • Metallic = bullet retained
40
Q

Treatment plan for case study 4

A
  • X-ray first
  • Debride the wound
  • Get all contaminated tissue out
  • I & D is the first thing for treatment
  • Remove all necrotic tissue
  • Do not initially do a large amputation, wait and see what tissues will survive and which ones will need to be amputated – you may be able to save more tissue this way
  • At 48 hours, take the 2nd toe off because it is necrotic
41
Q

General evaluation

A 
Patient 
o	ABCs
o	Vascular
o	Tissue damage
o	Fracture via x-ray

Management
o Abx
o Deridement
o Bullet removal

42
Q

Vascular injury

A
  • If you have a patient with GSW and clinical evidence for compromised vasculature need vascular surgery right away, not necessarily
43
Q

CASE STUDY 5

A
  • No exit

- All energy from the bullet was transferred to the tissue

44
Q

Treatment for case study 5

A
  • Debridement
  • Antibiotics for 48 hours
  • Then we wait – we don’t’ widely excise
  • We wait and see if it demarcates
45
Q

Debridement

A
  • Monitor and wait for tissues to demarcate

- Excessive removal of tissue initially is unnecessary

46
Q

Antibiotics

A

Are antibiotics necessary for GSW?
o Yes if it is an open fracture
o Open fracture protocol is antibiotics for 48 hours

No if there is just soft tissue damage
o Don’t necessary need to

47
Q

Bullet removal

A
  • Bullets become encapsulated over time
  • Reasons to remove it (Depends on location - in subtalar joint, you would want to remove it)
  • You don’t go looking around for something because it will not release lead
  • Don’t need to go in after each individual tiny piece
48
Q

CASE STUDY 6

A
  • High energy injury
  • Lots of soft tissue damage locally
  • Entry and exit all the same wound
  • A lot of cavitation
  • Certainly have fracture and compromised vital structures
49
Q

Treatment for case study 6

A
  • Conservative I & D
  • Try to leave it and limit it to a hallux amputation
  • Final debridement with flap once found out what would live and what would not
50
Q

Summary

A

Energy and velocity
o How much energy has been transferred to tissue?
o Soft tissue damage is the basis of healing and infection

Ballistic principles include: 
o	Velocity 
o	Missile design 
o	Contact tissue density 
o	Range
51
Q

Test questions

A
  • All of the things that are on the test are in the prep work
  • There are pictures on the exam

Emergency Med (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions