Special Feature

Injuries from Less Lethal Weapons: Are You Ready?

By Theodore C. Chan, MD, FACEP, Professor of Clinical Medicine, Medical Director, Department of Emergency Medicine, University of California San Diego Medical Center, San Diego.

Less lethal weapons are becoming increasingly popular amongst law enforcement agencies and the military to apprehend and subdue violent and dangerous persons in the field. Compared with firearms and other lethal force activities, these weapons are designed to be nonlethal to the targeted subject(s). Police agencies have adopted these weapons as a part of their use of force continuum in the face of public scrutiny and criticism regarding the supposed overzealous use of lethal force in many communities.

Less lethal weapons take advantage of a variety of technologies including blunt kinetic energy projectiles, riot control agents such as pepper spray, and electric stun devices such as the TASER. These weapons are designed to incapacitate individuals while minimizing the risk of fatality to the subjects, and reducing the risk of injuries to law enforcement personnel and bystanders. However, these weapons have been reported to cause significant and serious injuries to subjects, often resulting in the need for emergency medical care. Because of the increasing deployment of these technologies, EPs need to be aware of the emerging injury patterns associated with these less lethal weapons.

Blunt Projectiles

Blunt projectiles are designed to deliver blunt force kinetic energy (imparting energies of 100-200 Joules) to induce pain and incapacitation, but not necessarily to deliver lethal injury. In fact, unlike firearms, these projectiles are not designed to penetrate the body. However, because of the force required to incapacitate, significant blunt, as well as penetrating traumatic injuries have been reported with the use of these devices.

Less lethal blunt projectiles are classified into flexible and nonflexible projectiles. Flexible projectiles conform to the target shape and reduce the density of kinetic energy delivered. These projectiles include bean bag rounds, flexible batons, doughnut-shaped projectiles, and web-dispensing shots that immobilize the subject. Nonflexible projectiles are made of plastic, rubber, polyvinylchloride material, or wood, and are single or multiprojectile. These projectiles tend to have higher velocities than flexible projectiles and deliver an increased energy density to the subject.

Important factors include the anatomic area struck by the projectile, the distance range from which the projectile was delivered, and the number of rounds fired at the subject. Although most injuries occur to the extremities, early experiences with blunt projectiles in the 1950s and 1960s identified the head and neck regions as most vulnerable for significant injury. In particular, these weapons were reported to have caused significant closed head and brain injuries, as well as neck trauma in some cases.1 More recent reports have noted significant and even fatal injuries associated with projectiles that struck the chest and abdomen.2,3 Reported injuries have included pneumothorax, lung contusion and laceration, as well as myocardial lacerations.4 In addition, the potential for inducing life-threatening cardiac dysrhythmias from blunt projectiles striking the chest, similar to commotio cordis, has been suggested as a mechanism by which these less lethal weapons can, in fact, become lethal.

Riot Control Agents – Pepper Spray

Riot control agents (e.g., tear gas, mace, and most recently pepper spray) now are used widely to subdue crowds as well as individuals. Pepper, or oleoresin capsicum (OC) spray, can be delivered at a subject via liquid spray, aerosol and powder delivered by a projectile. In fact, OC spray is now available for general public use.5

OC is made up of a mixture of fat soluble phenols, capsinoids, derived from the natural oily extract of the capsicum pepper plant (i.e., hot chili peppers). These agents act as direct irritant and stimulate chemo-nociceptors in primary afferent nerve endings, resulting in immediate pain and burning sensation over exposed areas. In addition, they cause the release of peripheral neuropeptides, including substance P, which can result in neurogenic inflammation, vasodilatation, capillary leakage of plasma fluid, and pain sensation.6

OC exposure can result in burning sensation to the skin, eyes, and mucous membranes. Exposure to the nasal passages can result in irritation, congestion, and rhinorrhea. Airway exposure can cause coughing, gagging, temporary inability to speak, and shortness of breath. Most of these symptoms are short-lived, resolving after 15 to 30 minutes.

More significant injuries have been reported with OC exposure. Because most exposures are directed at the face, ocular injuries have been reported. In two large case series, significant corneal abrasions were found in 7-8.6% of all OC exposures.7,8 Fatalities also have been reported associated with OC spray.9 However, in nearly all of these cases, death was attributed to causes other than the exposure. Only one case reported in the medical literature clearly implicates OC as a cause of death. In that case, Steffee and colleagues reported the death of an asthmatic person sprayed 10-15 times with OC who suffered a sudden cardiorespiratory arrest. Autopsy revealed severe epithelial lung damage and evidence of bronchospasm likely precipitated by pepper spray exposure.10 However, considering the widespread use of OC, and the limited number of fatalities associated with exposure — and even fewer cases in which a causal connection is clear — it is doubtful that OC itself is inherently lethal.

Electric Stun Devices – TASER

Electric stun devices include various guns, belts, and shields, which are designed to deliver an incapacitating electrical shock to subjects on contact. These devices gained notoriety as the weapon used by Los Angeles police to subdue Rodney King in 1992. Most recently, the TASER — an acronym for its inventor, the Thomas A. Swift Electric Rifle — has been deployed widely throughout law enforcement agencies nationwide.11

The TASER consists of two barbed probes connected to a gun by 15- to 20- foot copper wires. The barbed probes are fired at a subject, penetrating the clothing or skin, and the electrical charge is discharged from the gun through the wires to the probes. The newest TASER model can deliver 50,000 volts with rapid fire, low amplitude shocks. The device incapacitates subjects by causing involuntary contraction of skeletal muscle and painful shock-like sensations throughout the muscles of the body. Most shocks are five seconds in duration or fewer. Once the discharge is halted, the subject usually recovers immediately.

Medical concerns regarding the TASER relate to injuries associated with the barb probe, indirect trauma from falls or other injuries associated with loss of voluntary muscle control, and the potential for injuries from the electrical discharge throughout the body. Subjects often present to the ED for care related to barb injury or removal. Barbs can be removed simply by stretching the surrounding the skin and tugging sharply on the probe.12 Because the barb only penetrates to a maximum depth of 4 mm, significant penetrating trauma has not been associated with the TASER. However, minor skin burns, have been reported at these sites.12

Of greater concern have been reports of injuries potentially related to the discharge of electrical current through the body. These reports include a spontaneous miscarriage occurring seven days after TASER shock, and allegations of testicular torsion and sterility associated with exposure.12,13 In addition, the American Civil Liberties Union and Amnesty International have reported a number of deaths associated with TASER shock, though a clear causal connection remains unproven. In particular, concerns have been raised regarding the potential of the TASER electrical discharge to cause cardiac injury and induce life-threatening dysrhythmias (e.g., ventricular fibrillation or asystole), particularly in individuals with preexisting heart disease or pacemakers. Thus far, safety data on TASER use have been limited mainly to animal studies, though industry data suggest a low case fatality rate of 4 in 40,000 TASER shocks in humans.12 Further comprehensive research is needed to ultimately determine the safety of this less lethal technology.

References

1. Millar R, et al. Injuries caused by rubber bullets. A report on 90 patients. Br J Surg 1975;62:480.

2. Ritchie AJ, et al. Life threatening injuries to the chest caused by plastic bullets. BMJ 1990;301:1027.

3. Steele JA, et al. Plastic bullet injuries in Northern Ireland: experiences during a week of civil disturbance. J Trauma 1999;46:711.

4. Chute DJ, et al. Injury patterns in a plast (AR-1) baton fatality. Am J Forensic Med Pathol 1998;19:226.

5. Smith J, et al. The use of chemical incapacitant sprays: a review. J Trauma 2002;52:595.

6. Sanico AM, et al. Dose-dependent effects of capsaicin nasal challenge: in vivo evidence of human airway neurogenic inflammation. J Alergy Clin Immunol 1997;100:632.

7. Brown L, et al. Corneal abrasions associated with pepper spray exposure. Am J Emerg Med 2000;18:271.

8. Watson WA, et al. Oleoresin capsicum (Cap-stun) toxicity from aerosol exposure. Ann Pharmacother 1996; 30:733.

9. Granfield J, et al. Pepper spray and in-custody deaths: International Association of Chiefs of Police Executive Brief. Sci Tech 1994;1.

10. Steffee CH, et al. Oleoresin capsicum (pepper) spray and “in-custody deaths”. Am J Forensic Med Pathol 1995;16:185.

11. Hamilton A. From Zap to Zzzz. Time. March 28, 2005. Online at www.time.com (accessed March 28, 2005).

12. Bleetman A, et al. Introduction of the TASER into British policing. Implications for UK emergency departments: an overview of electronic weaponry. Emerg Med J 2004;21:136.

13. Ordog G, et al. Electronic gun (TASER) injuries. Ann Emerg Med 1987;16:73.