Rosen & Barkin's 5-Minute Emergency Medicine Consult (698 page)

• 427.0 Paroxysmal supraventricular tachycardia
  
• 427.1 Paroxysmal ventricular tachycardia
  
• 785.0 Tachycardia, unspecified
  

BASICS

• Tasers are part of a class of less lethal weapons referred to as conducted energy weapons (CEWs).
  
• Most common in US are those made by Taser International; these include the M-26, X-26, and X2 although others exist.
  
• These devices use a high-voltage low-amperage current to override the subject’s ability to control the peripheral nervous system; they cause pain so as to induce subject compliance.
  
• Handheld devices such as stun guns require the application of 2 exposed probes to the skin (or close to the skin) to cause a localized response (usually pain).
  
• Other devices, such as the Taser International devices, have barbed probes attached to thin wires that can be shot up to 35 ft to deliver current from a distance.
  
• Needle lengths of CEW barbs are of varied lengths but generally less than or around 0.5 in.
  
• The effects of CEWs vary depending on the type of device being used, location, placement, and distance between the probes on the subject’s body. If probe spread on the body is <5 cm, effectiveness is less.
  
• Skin effects
  
  • May leave marks at site of probe contact, called “signature marks”
    
  • Small puncture wound from barbs
    
• Skeletal effects
  
  • Fractures may result from falls.
    
  • Vertebral compression fractures have been reported as a result of a Taser discharge.
    
  • Barbs may penetrate bone.
    
• Muscle effects
  
  • Strains possible
    
  • Rhabomyolysis possible with repeated prolonged use, though more likely could result from the underlying cause leading to use of the Taser (e.g., excited delirium syndrome [ExDS])
    
• Cardiovascular effects
  
  • Theoretically could cause ventricular fibrillation if a charge was delivered over the heart during a vulnerable part of the cardiac cycle. This risk is not easily quantifiable but estimated to be very low.
    
  • A case of atrial fibrillation has been reported following Taser use.
    
  • No significant effects in otherwise healthy subjects. Does not cause changes in ECG or troponin I.
    
  • Unclear how device would affect pacemakers/automatic internal cardiac defibrillators (AICDs). Energy is low; theoretically should not cause damage. Could cause an AICD to deliver a shock if electrical activity of the CEW is misinterpreted as a dysrhythmia.
    
• Nervous system effects
  
  • There have been case reports of skull penetration and seizure.
    
• Respiratory effects
  
  • Initial concerns that the CEWs would disrupt ventilation proved unfounded. Research has shown that subjects actually increase ventilation during an application.
    

The devices are commonly used in law enforcement but may also be used in the military, self-defense, by those wishing to commit a crime, or an accidental discharge of a weapon on to law enforcement personnel.

DIAGNOSIS

A history of the use of a device is usually obtained. Important factors are:

• The type of device
  
• The mode used (probe or drive stun)
  
• The number of cycles discharged
  
• The duration of cycles applied
  
• Location of contact on the body
  

• Pay particular attention to the location of barb strike. Barbs in the skin, though unlikely, may cause injury to underlying structures:
  
  • Eye
    
  • Face
    
  • Neck
    
  • Groin
    
  • Genitals
    
  • Secondary injuries do occur
    
    • From fall
      
    • From aspiration if device is deployed in the water
      
    • From tetanic muscle contraction
      
    • From barb penetration
      

• All persons who have been exposed to CEW activation should receive a medical evaluation. The scope of that evaluation should depend on the type of use and state of the subject.
  
• For a subject who subsequently becomes compliant, is alert, and is acting appropriately and/or had CEW darts hit areas that are not medically sensitive, the darts may be removed and an evaluation done at intake to a detention facility.
  
• Given the risk to a subject who is in a state of ExDS regardless of CEW use, such a person requires an ED evaluation.
  

The above groups warrant a medical evaluation, given that there are so few data to guide any definitive statements about their use.

Labs should be directed at the underlying reason the person was “tasered.” No labs are required simply because the person was tasered.

If ExDS is present:

• CBC
  
• Chemistry panel
  
• Creatine kinase
  
• UTOX
  
• VBG to check for acidosis
  
• Lactate
  

• Not routine
  
• If altered level of consciousness with no clear cause, then head CT
  
• X-ray if Taser barb penetrated bone; this is most likely if it hit a digit or where bone is close to skin (e.g., tibia, nose).
  
• US if individual is pregnant
  
• Other imaging guided by suspicion of traumatic/secondary injury
  

• Pacemaker interrogation if patient has pacemaker or AICD, since the device may have been damaged or have delivered a shock.
  
• ECG if there is underlying significant heart disease
  
• Women who are pregnant >20 wk should have fetal monitoring.
  

Usually not unclear if device used.

TREATMENT

• If patient is acting normally, has normal vital signs, and AO × 4, appropriate, no special intervention is needed. Depending on jurisdiction, barb may be removed if not in sensitive area (face, eye, groin, neck, genitals). Otherwise, stabilize barb and transport patient to hospital for removal.
  
• If patient is agitated, treatment as per agitation/ExDS.
  
• If cardiac dysrthymia is present, initiate cardiac monitoring, IV access, oxygen, treat if in protocol and scope or practice.
  
• Treat any secondary traumatic injuries.
  

If ExDS, then treat per guidelines, including medications.

Initial treatment is steered toward underlying injuries.

• If patient acting normally, normal vital signs, AO × 4 appropriate, and no complaints of secondary injury, no special intervention needed.
  
• Update tetanus status as needed.
  
• Taser barb removal: Using 2 fingers of nondominant hand, stabilize skin around the barb by holding it down. Use dominant hand to grasp barb shaft and pull barb out.
  
• Treat the puncture wound like any other.
  
• Approach secondary traumatic injuries per trauma protocols.
  
• Treat dysrhthymias per protocol.
  
• Consider and treat ExDS if patient unstable.
  

• Tetanus vaccination, dT or dTaP: 0.5 mL IM
  
• Midazolam (Versed) 5 mg IM/IV for agitation
  
• Haloperidol (Haldol) 5 mg IM/IV for agitation
  

FOLLOW-UP

• Admit for signs of:
  
  • Cardiac instability
    
  • Excited delirium syndrome
    
  • Serious secondary injury
    

Any female who is pregnant should undergo a medical evaluation of the pregnancy; if viable, she should undergo fetal monitoring at an appropriate facility.

Patient acting normally, normal vital signs, AO × 4 appropriate, and no complaints of secondary injury, or secondary injuries treated and stable for discharge

Wound care, injury follow-up

• These patients may be suffering from ExDS, hence law enforcement became involved or Taser was used. Failure to aggressively treat this life-threatening condition will result in untoward outcome.
  
• Always screen for possible secondary injury.
  
• Stable, alert, appropriate subjects do not need much more than simple barb removal (if necessary), a tetanus vaccination update, and wound care.
  

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