Evaluation and management of injuries from conductive energy devices (eg, TASERs)

INTRODUCTION — Conductive energy devices (CEDs) are less-lethal weapons used worldwide. Significant injuries are rare and usually from associated trauma. Embedded darts are typically removed by law enforcement without medical assistance. The vast majority of individuals exposed to a CED will not seek medical care.

The range of potential injuries from CEDs as well as the recommended emergency evaluation and management of patients who have been subject to a CED discharge will be reviewed here. The evaluation and management of other electrical injuries, general aspects of trauma and wound management, and issues pertaining to agitated adults are discussed separately.

●(See "Electrical injuries and lightning strikes: Evaluation and management".)

●(See "Initial management of trauma in adults".)

●(See "Basic principles of wound management".)

●(See "Treatment of minor thermal burns".)

●(See "Assessment and emergency management of the acutely agitated or violent adult".)

●(See "Restraint-related cardiac arrest: Pathogenesis, strategies for prevention, and management for hospital clinicians".)

TERMINOLOGY — The following definitions apply to CEDs:

●TASER – The brand name of the most commonly used CED, which stands for "Thomas A Swift Electric Rifle."

●Dart (probe) mode – A mode in the most commonly used CEDs in which two darts are propelled from a distance into the victim's skin, causing muscular incapacitation.

●Stun drive mode – A mode in which electrodes on the front of the weapon make direct contact with the victim's skin, causing only pain.

●Barb – The end of the darts (picture 1 and picture 2) that are propelled by the CED.

●Discharge – This refers to the delivery of a current to the victim. There is no discharge if current is not delivered, which can occur for several reasons. (See 'Mechanics' below.)

●Full cycle – This refers to the duration of current flow from a single trigger pull, which typically lasts five seconds and can be extended by continuing to hold down the trigger.

●Stun gun – A CED with only one mode, delivering electrical charge through direct physical contact of the weapon with the skin, causing pain.

●Shock prod – A stun gun with electrodes at the end of an elongated device, used most commonly with livestock and allowing the user to remain at a distance from the recipient of the discharge.

EPIDEMIOLOGY — CEDs were developed in the 1970s as a less-lethal weapon for use by law enforcement and have been adopted worldwide.

As of 2017, nearly one million CEDs had been sold in the United States, more than 90 percent of United States law enforcement officers had been issued a CED, and law enforcement worldwide had used CEDs more than three million times (average of 900 uses per day) [1]. Although CEDs are predominantly used by law enforcement, they are also marketed to and used by civilians [2].

There are no available comprehensive data on United States emergency department visits for CED injury. A literature review included 948 CED discharges and found that 17 percent resulted in an emergency department visit, but most injuries were mild, with only three hospital admissions [3]. CEDs were less likely to cause injury (both to subject and law enforcement) compared with police dogs, batons, irritant sprays, or physical restraints. The reported injuries are most commonly from falls while incapacitated or barb penetration of particularly vulnerable anatomic structures [3,4]. However, evidence is limited by inconsistent reporting, bias, and difficulty collecting data about at-risk subjects on whom the CED is more likely to be used.

CED TYPES, MECHANICS, AND PHYSIOLOGIC EFFECTS

Types — TASER is the CED overwhelmingly used by law enforcement worldwide (picture 3 and figure 1). All TASERs rely on the same primary technology, while various other types of CEDs have been developed and produced, including stun guns and shock prods. Several companies market personal-use (ie, civilian) CEDs, the majority of which are designed for direct contact only and cannot be shot from a distance. There are no reports of any specific CED models or types having a higher risk profile to cause greater injury. The TASER 7, which became available in 2018, uses a differently designed dart (picture 2) that is removed with a separate plastic tool (figure 2), unlike previous models that do not come with a tool for dart removal.

Mechanics — A TASER delivers pulsed, high-voltage, low-amperage, direct current at 45- to 110-microsecond durations. Voltages range from 1400 to 2600 V delivered to the body. A separate open-circuit voltage of up to 50,000 V is generated to arc through air or thick clothing but does not reach the body. Average currents range from 2 to 4 mA. The device is powered by two 3-volt batteries [5].

CEDs are only effective while a circuit is complete. The CED is ineffective if one or both of the barbs never make contact or are caught in thick clothing. If a barb falls out of the skin at any point or if the CED does not maintain contact in stun drive mode, current delivery ceases. Although barbs embedded in light clothing can complete a circuit due to the high voltages involved, clothing frequently inhibits circuit completion.

The most commonly used CEDs discharge in a five-second cycle, after which the trigger must be pulled again to initiate a subsequent firing and cycle. Holding down the trigger during firing can extend the cycle beyond five seconds.

A TASER can be operated via the following two modes:

●Dart (probe) mode – Darts (picture 1 and picture 2) with 9- to 13-mm barbs are fired by compressed nitrogen and can reach a 6.4- to 11-meter range. Darts are projected at up to 55 meters per second, which is similar to the velocity of a BB gun. The fired barbs typically do not have enough kinetic energy to penetrate thick clothing or deeper than 6 mm through tissue [6]. The darts have a fishhook barb designed to keep them embedded. When a circuit is complete and while it remains intact, pulsed current is discharged for one cycle. Law enforcement and emergency medical services personnel are trained in dart removal, and most are removed in the field [7].

●Stun drive mode – The front of the weapon is pushed directly against the body. The electrodes make contact with the skin, passing current across a much shallower and shorter distance as compared with dart mode.

Physiologic effects — CEDs are designed to induce incapacitation, either by causing involuntary muscle contraction or pain. The specific pulse and current captures alpha motor neurons, causing muscle contraction if the darts are sufficiently separated (ie, dart mode) or pain if they are close to each other (ie, stun drive mode).

In healthy persons, measured physiologic changes following CED discharge are not clinically significant [8,9]. The systemic effects of involuntary muscle stimulation and pain from CED discharge can include catecholamine release, tachycardia, hypotension, decreases in minute ventilation, acidemia, and increased lactate and creatinine kinase concentrations [8,9]. However, studies have found that these physiologic effects when caused solely by CED exposure are relatively mild and unlikely to cause significant acidemia, electrolyte disturbance, myocardial injury, or rhabdomyolysis [8,9]. For example, volunteers at rest who received a 10-second exposure from a TASER 7 had a median lactate increase of 3 mmol/L and median pH decrease of 0.07, which both normalized within one hour of exposure [8]. Median creatine kinase (CK) concentrations did not change within the first hour but were mildly elevated to 142 U/L after 24 hours, which is consistent with results of prior studies in healthy volunteers at rest. There was no rise in troponin or potassium. The adrenergic effects induced by a CED discharge have been found to be similar to the stress response from physical exertion and other incapacitating measures during the law enforcement restraining process [10].

The specific current deployed by CEDs is insufficient to generate a significant degree of electrothermal heat and does not affect the central nervous system. Although animal studies suggest potential arrhythmogenic risk when darts are placed close to the heart, this risk is considered to be very low in humans [11]. The physiology of electrical injury is discussed elsewhere. (See "Electrical injuries and lightning strikes: Evaluation and management".)

MECHANISM AND CLINICAL FEATURES OF INJURY

Overview — Systematic and comprehensive reviews of CED-related injury have found low risk of adverse events when used on a healthy person [4,7,11]. Primary injuries from CEDs are mostly due to barb penetration when darts embed in certain vulnerable anatomic locations, thus injuring the underlying structures. Once incapacitated by the CED discharge, the patient may fall and sustain a secondary injury. Significant injury from the electrical current itself or directly from muscle contraction is unlikely. CED use has been mentioned in high-profile, restraint-related sudden death cases; however, the CED itself does not appear to be the direct cause since current-induced arrhythmias and metabolic acidosis in the absence of other etiologies are not reported [11].

Secondary injury from fall — Secondary injuries can occur from falls after muscle incapacitation. Intracranial hemorrhage and cervical spine fractures may be more likely since these falls occur without the typical reflexive protective mechanisms (eg, outstretched hands) [12]. Long bone fractures from CED-related falls have not been reported.

Injury from dart penetration — Dart-related injuries are rare, but there are reports of penetration in anatomic locations without thick overlying tissue such as the skull, facial bones, eye, throat, chest wall, scrotum, and fingers [3,13]. Newer models have darts (picture 2) with higher mass and kinetic energy, which could lead to an increase in depth and extent of penetrative injuries [14]. There are no reports of infections secondary to dart punctures [15].

●Skull and face – A study on polyurethane mannequin heads found that skull penetration (as much as 6 mm) is possible and more likely to occur at shorter firing distances (<2 meters) [13,16]. Rare frontal and facial bone penetrations without neurologic sequelae have been reported [13].

●Eyes – The eye and surrounding structures are particularly vulnerable to injury from dart penetration. In a study of 17 CED-related eye injuries, 71 percent had a globe rupture, 59 percent had retinal detachment, and 88 percent required operative management [17]. Damage to the lacrimal structure has also been reported [16].

●Throat – There is one report of tracheal penetration with associated pneumomediastinum [18].

●Chest – There is one report of pneumothorax related to possible chest penetration [19].

●Scrotum – Testicular penetrations have been rarely reported without significant immediate injury [20].

●Fingers – Finger penetrations causing fracture and tendon injuries have been rarely reported [21].

Impact of muscle contraction

●Injury to surrounding structures – There are isolated case reports of vertebral body compression fractures without direct trauma in volunteers modeling for CED demonstration, postulated to be secondary to muscular contraction [22].

●Rhabdomyolysis – CED use has been associated with rhabdomyolysis, but the circumstances leading to the need for CED use (eg, agitation, intoxication, prolonged restraint, isometric muscle contraction) likely contribute more to the muscle breakdown compared with the contractions induced by the CED current itself, which causes only a small increase in creatine kinase (CK) in physiologic studies. (See 'Physiologic effects' above.)

●Metabolic acidosis – It is possible that in certain circumstances, the relatively limited physiologic changes from CED discharge could increase the risk of metabolic acidosis (and ultimately sudden cardiac death if allowed to progress untreated) during restraint. Hyperadrenergic individuals undergoing prolonged restraint may not have enough reserve to tolerate these changes [10]. (See "Restraint-related cardiac arrest: Pathogenesis, strategies for prevention, and management for hospital clinicians".)

Electrical and thermal injuries are unlikely — Significant primary electrical injury and electrothermal burns are extremely unlikely because the electrical energy produced by CEDs penetrates only superficially, targeting localized skeletal muscle motor neurons and having little effect elsewhere [11]. Deep electrothermal injuries, such as from high-voltage exposure, have not been reported to occur with CED electrical currents. There is no risk of electrical injury to someone touching a person who receives a CED discharge.

●Arrythmias – Although cardiac arrest and stable arrhythmias have been reported to occur after CED exposure, there is insufficient evidence that CED electrical discharge directly leads to the arrhythmia. Many human studies have found no direct effect on the heart. The potential for arrhythmogenicity has been demonstrated under certain circumstances in swine models, but extrapolation of these findings is limited by differences in physiology and anatomy [11]. Continuous cardiac monitoring during CED discharge in volunteers has demonstrated only sinus tachycardia, and an analysis of the reported cases of associated ventricular fibrillation suggested the CED was not directly causative [10,11].

CED discharge is unlikely to interfere with a pacemaker or implantable cardioverter defibrillator (ICD). These devices have built-in shielding protecting them from electrical noise. In order to trigger a shock, an ICD requires longer than the five-second duration of a CED cycle. Case reports exist of ICDs reading CED activity as ventricular fibrillation and charging but not delivering a shock because repeat sensing after the CED cycle ended recognized the native heart rhythm. Theoretically, firing of repeated CED cycles could lead to an inappropriately delivered shock [11].

●Burns – Minor superficial burns can occur from electrical arcing during stun drive use (picture 4). Reports of deep electrical burns from CED discharge do not exist, although there are rare instances of fatal and non-fatal burns from CED electrical arcing igniting fuel vapor or fuel-soaked clothing [23].

HISTORY AND PHYSICAL EXAMINATION

History — If a patient presents in custody, ask law enforcement the following questions (the responses may be influenced by situational stress or legal concerns):

●Why was the patient brought for medical care (which is typically unusual after an isolated CED discharge)?

●How many five-second cycles of CED exposure were there?

●Was the CED used in dart or stun mode (or both)?

●Where did the barbs penetrate, and were they all removed?

●Was the CED effective (indicating a circuit was completed)?

●How extensive was the patient's physical resistance and how long was the physical restraint process?

●Were other weapons or incapacitating agents used?

Patients are infrequently brought for medical evaluation of only the CED exposure. CEDs are employed in the process of restraint, and the details of the restraining process can be important in interpreting any physiologic effects that may be attributed to the CED. For example, otherwise benign CED-induced physiologic changes may be more significant in a patent who had a prolonged period of struggling against physical restraints.

Any reported loss of consciousness or pain lasting more than 15 minutes needs to be investigated further since a CED discharge should not affect sensorium and pain should resolve quickly.

Whenever possible, maintain the patient's medical privacy while obtaining history. When gathering information from the arresting officers, care should be taken not to disclose history the patient provided when not in the presence of the officer [24].

Physical examination — Perform a thorough skin examination to identify the location of the barb entry points (picture 5), any retained barbs, or superficial burns. Further examination is based on the context of the overall presentation and patient's complaints. Examine the patient for injuries since falls are common after CED-induced incapacitation. Closely examine any areas where the patient has persistent pain. Approach the examination of other complaints (eg, chest pain) in a similar manner as a patient without CED exposure.

LABORATORY AND IMAGING STUDIES

Patient with brief exposure (<15 seconds) — No specific studies are indicated in a patient with isolated total CED exposures of short duration (<15 seconds).

Patient with prolonged exposure — In a patient with prolonged exposures (>15 seconds total), we obtain the following studies because physiologic effects are less understood and such exposures imply a longer overall struggle against restraint [7,25]:

●Electrocardiogram (ECG)

●Blood gas (specifically for pH)

●Serum lactate

●Serum electrolytes, blood urea nitrogen, creatinine

●Troponin

●Creatine kinase (CK; especially if the patient was struggling against restraints for prolonged period)

Secondary injury evaluation — Imaging to evaluate blunt injuries follows standard trauma principles and is discussed separately. (See "Initial management of trauma in adults" and "Management of acute moderate and severe traumatic brain injury" and "Cervical spinal column injuries in adults: Evaluation and initial management" and "Initial evaluation and management of blunt thoracic trauma in adults" and "Initial evaluation and management of blunt abdominal trauma in adults" and "Pediatric blunt abdominal trauma: Initial evaluation and stabilization".)

Dart-related injury evaluation — If reported that the darts (picture 1 and picture 2) were easily removed, imaging is not needed since retained fragments are extremely unlikely. If there was difficulty in removing the dart or the dart appears embedded in bone, obtain a radiograph of the area to make sure there are no retained fragments or to evaluate location of the barb, respectively.

Imaging to evaluate penetrating barb injuries is based on location and expected depth of penetration given the barb length (typically 9 to 13 mm) and propulsion kinetics, with attention to vulnerable locations such as the following (see 'Mechanics' above):

●Skull – Obtain a computed tomography (CT) scan of head if barb is not easily removable or the patient has persistent pain after removal. If the barb could not be removed in the prehospital setting, it is reasonable to obtain a CT scan prior to attempting removal.

●Face and eyes – Obtain maxillofacial CT if the barb is not easily removable or the patient has persistent pain. A CT of the orbits may be needed if the patient has ocular complaints or an abnormal eye exam (picture 6). (See "Initial evaluation and management of facial trauma in adults" and "Overview of eye injuries in the emergency department" and "Approach to diagnosis and initial treatment of eye injuries in the emergency department", section on 'Diagnostic imaging'.)

●Neck – Given the relatively thin skin over the neck, it is reasonable to approach CED dart injuries based on the neck zones as presented in the algorithm and discussed separately (figure 3 and algorithm 1). (See "Penetrating neck injuries: Initial evaluation and management".)

●Chest and abdomen – It is unlikely that a barb will penetrate beyond the chest or abdominal walls of an adult. Therefore, specific imaging (eg, chest radiograph, abdominal CT scan) is unnecessary unless the patient is very thin (eg, child) or has persistent chest or abdominal pain, abnormal breath sounds, abdominal tenderness, hypoxia, or other concerning findings. (See 'Pediatric' below and "Initial evaluation and management of penetrating thoracic trauma in adults" and "Initial evaluation and management of abdominal stab wounds in adults" and "Approach to the initially stable child with blunt or penetrating injury".)

●Spine – Obtain spinal imaging in a patient with persistent pain and midline tenderness. (See "Spinal column injuries in adults: Types, classification, and mechanisms".)

●Hand – Obtain plain radiographs in any patient with barb penetration of the hand or fingers. (See "Overview of finger, hand, and wrist fractures".)

●Scrotum – Obtain a scrotal ultrasound in any patient with penetrating scrotal injury. (See "Penetrating trauma of the upper and lower genitourinary tract: Initial evaluation and management" and "Scrotal trauma in children and adolescents".)

MANAGEMENT

Initial and trauma care — Management of the patient with CED exposure starts with assessing and stabilizing airway, breathing, and circulation. A patient presenting in cardiac arrest should be resuscitated with standard advanced cardiac life support (ACLS) and advanced trauma life support (ATLS) principles; resuscitation practices do not change based on CED use. Because blunt trauma from falls or from the physical restraining process are common, it is reasonable to approach the patient using trauma principles (ie, primary survey followed by secondary survey), especially when the CED was used in dart mode [7]. (See "Advanced cardiac life support (ACLS) in adults" and "Pediatric advanced life support (PALS)" and "Initial management of trauma in adults".)

Isolated CED exposure in a hemodynamically stable patient does not require continuous cardiac monitoring [7].

Embedded dart removal — Even though CED darts have a fishhook barb (picture 1 and picture 2), they are generally easily removed. Cut the wires prior to removal. After removal, inspect the darts for evidence of fragmentation and discard in an appropriate biohazard sharps container. The following are various removal techniques [26]:

●Grasp the dart with a gloved hand or a needle driver and pull with in-line traction (this technique is the easiest and generally effective).

●Infiltrate locally with lidocaine, cut down to the barb with a scalpel, and remove the barb through the incision.

●Disengage the barb by threading a 16-gauge needle over the barb and then gently backing the barb out of the skin.

Darts from the TASER 7 model (picture 2) may require different removal techniques. The probes in this model are attached to a removeable baseplate rather than part of a single solid unit. The model comes with a plastic tool for barb removal that is superior to axial traction by hand or with a needle driver (figure 2 and picture 7). The probe tips in this model bend when hitting bone, which can further complicate removal [14].

●Barbs embedded in bone or sensitive tissue – Barbs can rarely embed in bone and be resistant to standard removal techniques. A case report described using a vice grip to grasp the barb and a large syringe as a fulcrum to remove a barb embedded in a clavicle (picture 8) [27].

Barbs embedded in or near the scrotum, eye (picture 6), face, trachea, finger, or skull may need removal by the appropriate specialist depending on potential for injury to the underlying structure. It is reasonable to have a discussion with the specialist prior to attempting removal.

Skin wounds and burns — Standard wound and burn care, such as cleaning, application of a topical antibiotic ointment, and dressing, is sufficient. Darts typically only produce puncture wounds (picture 5). Prophylactic systemic antibiotics are not needed since these wounds are not at high risk of infection [15]. (See "Basic principles of wound management" and "Treatment of minor thermal burns".)

Patient with ECG changes or abnormal laboratory results — The following summarizes management in a patient who had ancillary studies obtained that have abnormalities:

●Electrocardiogram (ECG) changes or troponin elevation – Since CED discharge does not directly cause an arrhythmia (with the exception of sinus tachycardia), any noted abnormal rhythm should be managed with the standard approach discussed elsewhere. (See "Overview of the acute management of tachyarrhythmias".)

A patient with ischemic ECG changes or troponin elevation should be managed with the standard approach discussed elsewhere, with the understanding that either the CED or the circumstances that resulted in CED use likely contributed to a catecholamine surge and demand myocardial ischemia. (See "Initial evaluation and management of suspected acute coronary syndrome (myocardial infarction, unstable angina) in the emergency department".)

●Creatine kinase (CK) elevation – A CK elevation suggests the presence of rhabdomyolysis. Management starts with ensuring the patient is calm and not continuing to struggle against restraints since CED current itself causes only a small CK increase. Further evaluation and management depend on the extent of CK elevation, often involve serial CK measurement and intravenous (IV) crystalloid administration, and are discussed in detail elsewhere. (See "Rhabdomyolysis: Clinical manifestations and diagnosis" and "Prevention and treatment of heme pigment-induced acute kidney injury (including rhabdomyolysis)".)

●Acidosis or serum lactate elevation – A patient with a metabolic acidosis and/or hyperlactatemia may have suffered prolonged isometric muscle contractions against physical restraints. Once the patient is calm (eg, after chemical sedation), the blood gas and serum lactate should be rechecked to ensure improvement. Evaluation and treatment of lactic acidosis is discussed elsewhere. (See "Causes of lactic acidosis" and "Approach to the adult with metabolic acidosis", section on 'Overview of therapy'.)

●Abnormal serum electrolytes, blood urea nitrogen, or creatinine – Electrolyte abnormalities should be approached with standard principles. If acute kidney injury is present, it is likely from hypovolemia, and initial management should start with administration of IV crystalloid. Further management is discussed elsewhere. (See "General principles of disorders of water balance (hyponatremia and hypernatremia) and sodium balance (hypovolemia and edema)" and "Causes and evaluation of hyperkalemia in adults" and "Overview of the management of acute kidney injury (AKI) in adults".)

DISPOSITION — A patient with an isolated CED exposure who has normal vital signs and normal electrocardiogram (ECG) and laboratory studies, if obtained, does not require admission or a predetermined period of emergency department observation [7]. The vast majority of patients admitted after CED exposure are for medical conditions or trauma not directly related to the CED use [28].

SPECIAL POPULATIONS

CED discharge within the hospital — Clinicians may need to manage a situation during or after hospital security personnel discharge a CED into an agitated or violent patient. CED use by hospital security programs is increasing, and as of 2014, nearly one-half of United States hospitals use CEDs [29]. Protection of hospital staff, the patient, other patients, and visitors is the primary objective. The following general principles should be applied:

●Instruct security personnel to minimize the number of discharges utilized as the safety profile of longer exposures is not established.

●Establish physical restraints as soon as possible since the patient will regain muscle use quickly following the discharge. Touching the patient during CED discharge will not harm those trying to apply restraints.

●If the patient fell during CED exposure, maintain cervical spine immobilization and be aware of possible injuries from the fall while applying physical restraints.

●Once mechanical restraint is established, administer chemical restraints if not already given. Even though there is no continued effect of CED discharge after the current ends, the pain and fear caused by the CED will have various effects on a patient's cooperation or agitation.

●Once restraint has been established, the darts should be removed and evaluation performed as discussed above, including a post-restraint medical evaluation. (See 'History and Physical examination' above and "Assessment and emergency management of the acutely agitated or violent adult", section on 'Post-restraint medical evaluation'.)

Pregnancy — Effects of CED discharge on the fetus are unknown. There is a case report of a subject in custody estimated to be at 8 to 10 weeks of gestation who began spotting one day after CED exposure with darts penetrating the abdomen and the leg progressing to heavy bleeding and cramping at seven days [30]. Incomplete abortion was diagnosed after seven more days.

Pediatric — Very little is known about the effects of CED use on children. No studies have been done, and children are infrequently victims of CED exposure. Since children are more likely to have less soft tissue protection, penetration of a barb into thoracoabdominal or other vulnerable anatomic structures may be more likely to occur. Based on animal models, the theoretical risk of cardiac arrhythmia is also greater in a small, thin individual [11]. As examples, the only reported pneumothorax from possible chest penetration and a case of otherwise unexplained new-onset atrial fibrillation both occurred in 16-year-olds [19,31].

FOLLOW UP CARE — No routine follow-up care is needed.

If a patient presents for routine outpatient care days to weeks after a CED discharge, no CED-specific evaluation is necessary. A patient could present with an infection from the puncture or an unrecognized injury, but these should be managed based on presenting signs and symptoms without CED-specific considerations.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Care of the patient with burn injury" and "Society guideline links: Adult with altered mental status in the emergency department".)

SUMMARY AND RECOMMENDATIONS

●Epidemiology – Approximately 90 percent of law enforcement officers in the United States have been issued conductive energy devices (CEDs), which are less-lethal weapons designed to incapacitate subjects. Significant injuries are rare and usually from associated trauma. Embedded darts are typically removed by law enforcement, and most individuals exposed to a CED will not seek medical care. (See 'Epidemiology' above.)

●Types, mechanics, and physiologic effects of CEDs – TASER (picture 3 and figure 1) is the trade name of the most commonly used CED, which can fire darts (picture 1 and picture 2) from a distance (dart mode) or be pushed against the subject's skin (stun drive mode). Personal-use (ie, civilian) CEDs are designed for stun drive mode only and cannot be shot from a distance. CED darts deliver pulsed, high-voltage, low-amperage, direct current that causes involuntary muscle contraction and pain by capturing alpha motor neurons. Muscle stimulation can cause catecholamine release, acidemia, and creatine kinase (CK) release that is not clinically significant in healthy subjects. (See 'CED types, mechanics, and physiologic effects' above.)

●Clinical features of potential injuries – The CED electrical current itself or muscle contraction is unlikely to directly injure a healthy person. Primary injuries from CEDs are mostly due to barb penetration when darts embed in certain vulnerable anatomic locations such as the skull, face, eyes, throat, scrotum, and fingers. Once incapacitated by the CED discharge, the patient may fall and sustain a secondary injury. CED use has been associated with rhabdomyolysis, but the circumstances leading to the need for CED use (eg, agitation, intoxication, prolonged restraint, isometric muscle contraction) likely contribute to most of the muscle breakdown. It is also possible that in certain circumstances, the relatively limited physiologic changes from CED discharge could increase the risk of metabolic acidosis (and ultimately sudden cardiac death) during restraint. (See 'Mechanism and Clinical Features of Injury' above.)

●History and examination – Ask law enforcement why the patient was brought for medical care, where the barbs penetrated and if they were all removed, the number of five-second cycles, and the details of the restraining process. Examine the barb entry points and for signs of injury (picture 5 and picture 4). (See 'History and Physical examination' above.)

●Laboratory and imaging studies – In a patient with a brief exposure (<15-second discharge), no specific studies are indicated for the CED exposure itself other than imaging for any potential blunt trauma. In a patient with a prolonged (>15-second) exposure, obtain an electrocardiogram (ECG), blood gas, lactate, electrolytes, troponin, and CK. If there was difficulty in removing the dart or the dart appears embedded in bone, obtain a radiograph of the area to make sure there are no retained fragments or to evaluate the location of the barb, respectively. (See 'Laboratory and imaging studies' above.)

●Management – Assess and stabilize airway, breathing, and circulation. Resuscitation practices do not change based on CED use; follow standard advanced cardiac life support (ACLS) and advanced trauma life support (ATLS) principles (ie, primary survey followed by secondary survey) since blunt trauma from falls or from the physical restraining process can occur. Isolated CED exposure in a hemodynamically stable patient does not require continuous cardiac monitoring. (See 'Initial and trauma care' above.)

●Embedded dart removal – Even though CED darts have a fishhook barb, they are generally easily removed by grasping the dart and pulling with in-line traction. Barbs embedded in or near the scrotum, eyes, trachea, fingers, or skull may need removal by the appropriate specialist depending on potential for injury to the underlying structure. (See 'Embedded dart removal' above.)

●Skin wounds – Standard wound and burn care, such as cleaning, application of a topical antibiotic ointment, and dressing, is sufficient. Prophylactic systemic antibiotics are not needed. (See 'Skin wounds and burns' above.)

●ECG changes or lab abnormalities – These are unlikely but are managed based on standard principles after ensuring the patient is calm and not struggling against restraints. (See 'Patient with ECG changes or abnormal laboratory results' above.)

●Patient disposition – A patient with an isolated CED exposure who has normal vital signs and normal ECG and laboratory studies, if obtained, does not require admission or a predetermined period of emergency department observation. (See 'Disposition' above.)