Trauma
Gunshot Wounds
Background
- Definition
- Wound ballistics determined by characteristics of missile, energy, and tissue
- Synopsis
- Gunshot wounds (GSWs) to the head, neck, chest, abdomen, and pelvis are associated with high rates of morbidity and mortality
- GSWs to the extremities may result in neurovascular injury
- GSWs are best managed at trauma centers
Pathophysiology
- Mechanisms and Principles of Ballistics
- Theodore Kocher: energy from bullet dissipated in 4 ways
- Heat
- Energy used to move tissue radially outward
- Energy used to clear a primary path for the bullet
- Energy expended in deforming the projectile itself
- Terminology
- Penetration: distance from surface of skin to final resting point of bullet
- Fragmentation: process and pattern of projectile matter separation
- Permanent Cavity: tissue disintegrated by direct contact with the missile
- Temporary Cavity: surrounding tissue stretched during passage of projectile
- Damage
- Three things determine damage: Energy of bullet, Construction of bullet, and Target
- Energy = 1/2 mv2
- Bullet weight (caliber) varies somewhat
- Velocity can vary considerably (700-4000 feet/sec)
- High velocity > 2000 feet/sec
- Low velocity < 2000 feet/sec
- Energy from missile dissipated to tissue
- Bullets that travel perfectly straight through tissue dissipate less energy
- Four ways bullets are constructed to deliver more energy to tissues
- Yaw: bullet tilts back and forth through tissue
- Tumble
- Mushroom
- Fragmentation
- Permanent Cavity
- Direct crush of tissue from contact with projectile
- Represents destroyed tissue
- Related to size of projectile and path taken (yaw, tumble, fragmentation)
- Temporary Cavity
- Can be 11 times the diameter of the permanent cavity
- Lasts only a few milliseconds
- Can disrupt blood vessels, break bone
- Substantial effects in
- Minimally elastic tissue (brain, liver)
- Fluid filled organs
- Tissue struck (Target)
- Factors such as elasticity and density of tissue play important role
- Physiological importance of the tissue
- Heart/brain > hand/arm/gut
- Etiology/Risk Factors
- Ammunition:
- Inherent "controllable" characteristics
- Mass
- Shape, construction
- Velocity
- Conferred "uncontrollable" characteristics
- Angle of attack at impact
- Composition of target
- Civilian rounds
- Usually deformable; expands on impact
- Size of injury is increased
- More tissue is crushed
- Can potentially cause more damage than military equivalents
- Military rounds
- More often have full metal jacket
- Tend to "tumble" in target
- May pass through target with little deformation
- Risk Factors
- Gender: 87% of firearm related deaths involve males
- Age and Race: firearm related deaths are the leading cause of death in black males ages 15-34 years old
- Gun violence tends to be higher in the west and south
- Gun violence is much higher in urban areas compared to rural
- Epidemiology
- Incidence/Prevalence
- Injuries as a whole rank 4th as cause of death in all age groups
- Approximately 31,000 deaths/year related to firearms (98% intentional)
- Approximately 57% of firearm deaths are suicide and 40% are homicide
- Less than 1% of non-fatal injuries related to firearms
- 25-34 years of age have highest rate of fatal firearm injury
- Mortality/Morbidity
- Overall, approximately 33% of GSWs die
- Mortality/morbidity increase significantly depending on location injured
- Approximately 90% of GSWs to the head are fatal and most survivors have significant morbidity
- 251,000 deaths resulted from firearm injuries (2016, not related to war)
- 46 deaths/day (estimate in USA)
- 462,043 Americans dead due to firearm-related injuries (USA 1999-2013)
Diagnostics
- History/Symptoms
- EMS will frequently have information about timing, location, and extent of injury
- If patient is alert
- Ask what, when, where, how
- AMPLE History: Allergies, Medications, Previous medical/surgical history, Last meal, Events/environment surrounding injury
- If patient is obtunded, move to physical exam
- See etiology/risk factors
- Physical Exam/Signs
- ABCDEs (ATLS Survey), IV, O2, Monitor and Vital Signs
- Airway: evaluate by asking patient name and listening to airway movement
- Also examine oropharynx, head, and neck for evidence of penetrating injury
- Breathing: auscultate for breath sounds, evaluated work of breathing, and examine thorax for evidence of penetrating injury
- Cardiac: location of penetrating injury in conjunction with vital signs and auscultation will provide initial cardiac evaluation
- Disability: Glasgow Coma Score (GCS) and Pupils; particularly important in GSW to head
- Exposure: Remove ALL clothing and examine anterior and posterior of patient, inspecting for wounds and hemorrhage
- Labs/Tests
- Physical exam essential to determining which tests (if any) are done
- CBC, Type and Screen/Cross most useful laboratory studies
- Additional trauma labs sent per institutional policy, location of injury, and stability of the patient
- Imaging
- E-FAST
- Most useful initial study for possible GSW to chest, abdomen, or pelvis
- Allows for rapid and accurate assessment of pneumothorax, tamponade, and intraabdominal hemorrhage
- Positive findings in context of GSW warrant surgical exploration
- Portable X-Rays
- CXR extremely useful in diagnosing hemo/pneumothorax when chest trauma is suspected
- Pelvis X-rays may be used to identify presence of bullet fragment within the pelvis in order to guide further imaging
- X-Ray Chest Frontal (View image)
- X-Ray Humerus Frontal (View image)
- X-Ray Lower Leg Oblique (View image)
- CT Scan
- Useful in clinically stable individuals for locating bullet fragments and diagnosing injured structures
- As in the case with blunt trauma, certain injuries can be missed (e.g., bowel, pancreas, etc.)
- CTA of the extremities has become test of choice at most centers for diagnosing vascular injuries in GSWs to the extremities
- CT Chest Axial (View image)
- CT Chest Coronal (View image)
- CT Chest Sagittal (View image)
- CT Head Axial (View image)
- Other Tests/Criteria
- Wound classification
- Be careful classifying "entrance" and "exit" wounds
- Misclassified > 50% of time by ED, surgeons
- What matters is path of projectile
- If there is only 1 wound, then it's clearly an entrance wound
- Entrance wounds
- Do not necessarily correlate with bullet caliber
- May be smaller
- Elastic tissue contracts around wound defect
- Contact wounds
- Weapon in contact with skin
- Usually see burning of skin around wound
- May see stellate laceration
- Close range wounds
- Weapon 6-12 inches from target
- Soot deposited around wound
- Intermediate range wounds - short
- See "tattooing or stippling" around wound
- Punctate abrasions
- From unburned gunpowder
- Usually weapon < 60 cm from tissue
- Long-distance wounds
- Usually see "abrasion collar" around bullet hole
- From friction between bullet and epithelium
- Exit wounds
- NOT consistently larger than entrance wounds
- Skin everted outwards
- NEVER any abrasion collar, soot, or tattooing
Treatment
- Initial/Prep/Goals
- Follow ATLS protocols
- TREAT THE PATIENT AND THE WOUND - NOT THE WEAPON
- Base decisions on exam and x-rays, NOT "high-velocity/low-velocity" conjecture
- Wound care
- Initial care aimed at stopping hemorrhage
- Direct pressure preferred over tourniquet
- Avoid probing wounds
- Medical/Pharmaceutical
- Blood Products
- Debate as to whether bleeding or hypotensive patients should first receive blood products versus a trial of crystalloid
- Also debate regarding empiric administration of FFP and Platelets with all transfusions and what the correct ration is
- Most agree that 1:1:1 is correct ration for massive transfusions
- Unclear if this should start with initial administration of PRBCs or only if patient will need > 2 units
- PTC and Factor VII used at some trauma centers
- Analgesics: Fentanyl generally preferred (least degree of hypotension)
- Tetanus prophylaxis
- Antibiotics Indications
- A controversial topic; gunshot wounds are contaminated
- Antibiotics should be prescribed on a case-by-case basis
- High risk wounds:
- Contaminated by soil, dirt
- Open fractures
- Patient immune status compromised
- Diabetes
- HIV
- Massive transfusion
- Steroid/immunosuppressant use
- Penetrating head trauma
- Penetrating chest trauma
- Penetrating abdominal trauma
- Penetrating GU trauma
- Fracture from GSW
- Simple extremity GSWs
- Surgical/Procedural
- Emergency Thoracotomy
- Indication: Penetrating injury arriving to Emergency Department in extremis (shock or no vital signs)
- Success rate can be as high as 30% in this population
- Goals of the procedure
- Release pericardial tamponade
- Control cardiac hemorrhage
- Control intrathoracic hemorrhage
- Perform open cardiac massage
- Cross clamp the aorta
- Thoracostomy Tube
- Indication: Suspected hemothorax/pneumothorax associated with GSW
- Very small pneumothoraces seen on CT only, may be monitored
- Operative Management
- Decision to proceed to operating room is at the ultimate discretion of the trauma surgeon and takes into account location of injury, stability of patient, and survivability
- Head
- When surgery is performed, all attempts should be made to evacuate hematomas causing mass effect, obtain hemostasis, reduce infection, and obtain watertight closure to prevent CSF leaks
- Low GCS, fixed/dilated pupils, and bullets that cross midline are associated with very poor outcomes and surgery may not be of benefit
- Neck
- Penetrating in Patients with Overt (Hard) Signs
- Zone II injuries that penetrate the platysma at the discretion of the surgeon
- Zone I, II, or III injuries identified by diagnostic studies
- Chest
- GSW to the chest is an indication to proceed to the OR for exploration and treatment
- In the event that patient does not go to OR immediately, subsequent indications for OR would include
- Hemodynamic instability
- Expanding hematoma
- Surgical finding on CT scan
- Significant chest tube output
- Abdomen/Pelvis
- GSW to the abdomen/pelvis is an indication to proceed to the OR for exploration and treatment
- In the event that patient does not go to OR immediately, subsequent indications for OR would include
- Hemodynamic instability
- Development of peritonitis
- Surgical finding on CT scan
- Complications
- Complications from GSW are extensive and related to the structures injured
- Wounds themselves are subject to bleeding, scarring, infection, and pain
- Prevention
- Federal legislation aimed at reducing gun related deaths has been controversial
- School and community based initiatives have been very successful in certain areas
- Other programs have focused on recognizing domestic violence and suicide prevention
Disposition
- Admission criteria
- All wounds to head, neck, chest, abdomen, pelvis, spine, and genitals
- Extremity GSWs with neurovascular or joint involvement
- Specific social situations and pain management
- Consult(s)
- Trauma surgeon for all wounds (simple extremity flesh wounds would be one possible exception)
- Additional specialists (Neurosurgery, Vascular, Orthopedics) depending on the injury
- Discharge/Follow-up instructions (extremity injuries without NV or joint injury)
- Pain Management
- +/- Antibiotics
- Police report must be filed
- Return precautions: pain, bleeding, signs of infection
- Follow up with trauma surgery in most cases
References
- Fackler ML. FBI 1993 Wound Ballistics Seminar: Efficacy of Heavier Bullets Affirmed. Wound Ballistics Review, 1994;1(4):8-9
- Post AF, Boro T, Ecklund JM, Corvounis PE, et al. Management of Specific Injuries. In: Mattox KL, Moore, EE, Feliciano DV; (eds). Trauma, 7th ed. McGraw-Hill:USA, 2013;Section 2
- Newgard K. The Physiological Effects of Handgun Bullets: The Mechanisms of Wounding and Incapacitation. Wound Ballistics Review, 1992;1(3):12-17
- Fackler ML, Bellamy RF, Malinowski JA. The wound profile: illustration of the missile-tissue interaction. J Trauma. Jan 1988;28(1 Suppl):S21-S29
- Lindsey D. The idolatry of velocity, or lies, damn lies, and ballistics. J Trauma Dec 1980;20(12):1068-1069
- Barach E, Tomlanovich M, Nowak R. Ballistics: A pathophysiologic examination of the wounding mechanisms of firearms, Part I. J Trauma. Mar 1986;26(3):225-235
- Barach E, Tomlanovich M, Nowak R. Ballistics: A pathophysiologic examination of the wounding mechanisms of firearms, Part II. J Trauma. Apr 1986;26(4):374-383
- Smock WS. Forensic Emergency Medicine. In: Marx J, Hockberger R, Walls R, et al; (eds). Rosen's Emergency Medicine: Concepts and Clinical Practice, 5th ed. Mosby:Philadelphia, PA, 2002;pp.829-834
- Fackler ML. Ballistic injury. Ann Emerg Med. Dec 1986;15(12):1451-1455
- Gunshot Wounds Forensic Pathology. StatPearls [Internet]. Available at: https://www.ncbi.nlm.nih.gov/books/NBK556119/. [Accessed April 2022]
Contributor(s)
- Latham, Douglas E., MD
- Singh, Ajaydeep, MD
Updated/Reviewed: April 2022