ARTICLE IN PRESS

BASIC INVESTIGATIONS

Respiratory Effect of Prolonged Electrical
Weapon Application on Human Volunteers
Jeffrey D. Ho, MD, Donald M. Dawes, MD, Laura L. Bultman, MD, Jenny L. Thacker, MD, Lisa D. Skinner, MD,
Jennifer M. Bahr, MD, Mark A. Johnson, BS, James R. Miner, MD

Abstract
Background: Conducted electrical weapons (CEWs) are used by law enforcement to subdue combative
subjects. Occasionally, subjects will die after a CEW has been used on them. It is theorized that CEWs
may contribute to these deaths by impairing respiration.
Objectives: To examine the respiratory effects of CEWs.
Methods: Human volunteers received a 15-second application of electrical current from a CEW while
wearing a respiratory measurement device. Common respiratory parameters were collected before, during, and after exposure. Health histories and demographic information were also collected.
Results: Fifty-two subjects were analyzed. Thirty-four underwent a 15-second continuous exposure, and 18
underwent three 5-second burst exposures. In the continuous application group, the baseline mean tidal
volume of 1.1 L increased to 1.8 L during application, the baseline end-tidal CO2 level went from 40.5
mm Hg to 37.3 mm Hg after exposure, the baseline end-tidal oxygen level went from 118.7 mm Hg to
121.3 mm Hg after exposure, and the baseline respiratory rate went from 15.9 breaths/min to 16.4
breaths/min after exposure. In the 5-second burst group, the baseline mean tidal volume increased to
1.85 L during application, the baseline end-tidal CO2 level went from 40.9 mm Hg to 39.1 mm Hg after exposure, the baseline end-tidal oxygen level went from 123.1 mm Hg to 127.0 mm Hg after exposure, and the
baseline respiratory rate went from 13.8 breaths/min to 14.6 breaths/min after exposure.
Conclusions: Prolonged CEW application did not impair respiratory parameters in this population of
volunteers. Further study is recommended to validate these findings in other populations.
ACADEMIC EMERGENCY MEDICINE 2007; -:--–-- ª 2007 by the Society for Academic Emergency
Medicine
Keywords: TASER, conducted electrical weapon, electronic control device, in-custody death,
respiratory

he conducted electrical weapon (CEW) is a device
used by law enforcement to subdue violent or
combative subjects. Basic CEW technology has
been available for many years, but its use has become
more popular in recent times. Critics have attempted to
link CEW use to sudden, unexpected in-custody death
(ICD) events.1–3

T

One of the theories for ICD events involves impairment
of respiration by CEW devices. This theory is included in
medical examiner autopsy reports and media sources
as a hypothetical contributor or cause of the custodial
death.4,5 It is not uncommon for these sources to list
shortness of breath or difficulty breathing proximal to
the CEW application as a notable preterminal event.

From the Department of Emergency Medicine, Hennepin
County Medical Center (JDH, LDS, JMB, JRM), Minneapolis,
MN; Department of Emergency Medicine, Lompoc District Hospital (DMD), Lompoc, CA; Department of Emergency Medicine,
Northern California Kaiser Permanente (LLB), Sacramento, CA;
Department of Emergency Medicine, Banner Good Samaritan
Medical Center (JLT), Phoenix, AZ; and Division of Medical
Research, TASER International (MAJ), Scottsdale, AZ.
Received October 26, 2006; revision received November 17,
2006; accepted November 17, 2006.

TASER International provided partial funding for this project;
the total funding contribution was for analysis equipment and
was $1,708.20. Drs. Ho and Dawes currently serve as independent, expert medical consultants to TASER International and
own stock shares of the company. Mr. Johnson is an employee
of TASER International. Dr. Miner has served as a statistics
consultant to TASER International.

ª 2007 by the Society for Academic Emergency Medicine
doi: 10.1197/j.aem.2006.11.016

Contact for correspondence and reprints: Jeffrey D. Ho, MD;
e-mail: hoxxx010@umn.edu.

ISSN 1069-6563
PII ISSN 1069-6563583

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Ho et al.

This leads to the belief that, because CEW technology is
known to cause muscular incapacitation, it might be possible to incapacitate the muscles of respiration, such as
the intercostal muscles and the diaphragm, during its application. If true, this would be especially concerning
during prolonged CEW application (e.g., the trigger of
the CEW is continuously depressed or depressed multiple times during an encounter). To the best of our knowledge, this is the first study to undertake the examination
of the respiratory effect of prolonged CEW application
on human volunteers.
METHODS
Study Design
This was a prospective observational study of resting
adult volunteers recruited at several TASER International training courses between May 2005 and June
2006. The term ‘‘TASER’’ is an acronym for Thomas A.
Swift’s Electric Rifle and is a concept based on a fictional
series of children’s literature involving hi-tech solutions
to problems and conflicts. The institutional review board
of Hennepin County Medical Center approved the study.
Subjects provided informed written consent upon enrollment.
Study Setting and Population
This study was performed in adult (age older than 18
years) volunteer subjects. All volunteers were personnel
involved in various aspects of law enforcement and
were recruited at various training classes held by the
manufacturer of TASER technology (TASER International, Scottsdale, AZ). Volunteers were taken on a
first-come, first-served basis. As a standard part of their
CEW training course, they were to receive a 15-second
CEW application. They did not have to participate in
our study as a requirement for successful course completion, but declining to participate in the study did not absolve them from receiving the standard CEW application
required by the training course. The application consisted of a 15-second burst with applied electrodes powered by the TASER X-26 model CEW (Figure 1). The
exclusion criteria were pregnancy and persons with mental illness diagnoses. Volunteers were given a TASER X26
CEW upon successful completion of the study protocol.
Study Protocol
All subjects completed a questionnaire to determine age,
gender, body mass descriptors, past medical history,

Figure 1. The TASER X26 device.



RESPIRATORY EFFECT OF ELECTRICAL WEAPON APPLICATION

current medications, and history of significant exertion
within the 24 hours before the study.
Upon completion of the medical questionnaire, the volunteer was given a form-fitting neoprene mask to wear
during the study period. The fit of the mask was tested
to ensure no air leakage. The mask was connected to a
CPX Ultima Analyzer (Med Graphics, St. Paul, MN).
This is a breath-by-breath digital analyzer that provides
measurement of multiple functional respiratory parameters and displays the information graphically. Upon ensuring that the analyzer was functioning correctly, a
short period of rest was given to allow for baseline, pretest respiratory data collection. Once the analyzer had
collected baseline data, the volunteer was subjected to
the CEW application. Respiratory data were collected
continuously from the baseline period until after the
CEW application. The end of the data collection was
determined by an investigator observing the subject’s
return to baseline respiratory pattern. The volunteers
were not told in advance what data points were being
collected during CEW exposure. Data points collected
included oxygen and carbon dioxide concentrations of
expired air, respiratory rate, and tidal volume on a breathby-breath basis. The minimum tidal volume to trigger a
measurement was 50 mL, according to the manufacturer.
The graphical data were processed by Breeze Suite
6.2 software (Med Graphics). Data were divided into four
phases for comparison: phase 1, the start of the subjective baseline measurement to the start of the CEW application; phase 2, during the CEW application, either 15
seconds (for the 15-second continuous discharge) from
the start of the application or 17 seconds (for the 5-1-51-5 second discharge) from the start of the application;
phase 3, the first minute after the end of the CEW application; and phase 4, from the end of phase 3 to the return
of baseline tidal volume. All tidal volume data are
reported at body temperature and ambient pressure
saturated with water vapor. The normal quiet-breathing
tidal volume of a 70-kg adult is about 500 mL/breath
(about 7 mL/kg), with a rate of about 12–20 breaths/min
(a rate of 12 means one breath every 5 seconds).6
The CEW application consisted of manually applying
electrodes to the volunteer while he or she was lying
on a padded mat in the supine position. The electrodes
were manually placed on each subject, instead of fired
from the weapon, to ensure exact placement of electrodes from volunteer to volunteer. The electrodes were
placed on the subject’s trunk in positions to span a
majority of the trunk while including transdiaphragmatic
positioning. Common placement included ipsilateral
and contralateral positioning at shoulder and hip, pectoral region and leg, and scapula and buttock. The
electrodes were then connected to a factory-standard
TASER X26 CEW. A programmable logic controller
(PLC) was used to accurately control the duration of current delivered (Allen-Bradley MicroLogix 1500; Maple
Systems, Inc., Everett, WA). The purpose of the PLC
was to enable the CEW current application to be delivered in an objective, reproducible, and controlled fashion. With the exception of this PLC, the CEW was not
altered from the factory standard. The PLC was programmed to deliver the CEW current for a total of 15
seconds in either a 5 seconds on/one second off fashion

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repeated three times in succession or as a 15-second continuous application. The first 18 subjects included in the
study received the 5/1/5/1/5 application protocol. The
remainder of the subjects received the 15-second continuous application protocol. Upon completion of the
application protocol, the electrodes were removed, the
attachment points were disinfected, and adhesive bandages were applied if needed. Immediately following
the CEW application, all subjects were released from the
study area to go back into the classroom to complete
the didactic portion of their TASER training session.
Data Analysis
Data were entered in an Excel (Microsoft Corp., Redmond, WA) database for analysis. Data analysis was performed using Stata 9.0 (Stata Corp., College Station, TX).
Data are described using descriptive statistics and 95%
confidence intervals. The percentage change from baseline values to the three other phases of data collection
is presented with 95% confidence intervals.
RESULTS
Sixty subjects were eligible for study enrollment. One
subject was excluded before the study because of his current medication history (the subject was on an unmonitored anticoagulant). Seven of the tested subjects were
excluded due to either data collection malfunction (CPX
Ultima instrument wires inadvertently touching the
TASER X26 wires during the test [n = 4]) or due to record
keeping (loss of the TASER application time on the timeline [n = 3]).
Data from 52 subjects were therefore analyzed. Their
mean (ÆSD) age was 31.5 (Æ6.4) years (range, 19–49
years), and 92.3% were male. Their mean (ÆSD) weight
was 199.9 (Æ39.8) lb (90.9 kg) (range, 125–325 lb). Their
mean (ÆSD) body mass index was 28.8 (Æ4.76) kg/m2
(range, 21.9–44.1 kg/m2). Past medical histories included
asthma (n = 3), hypertension (n = 2), hypercholesterolemia (n = 2), atrial fibrillation (n = 1), spontaneous pneumothorax (n = 2), a bowel obstruction (n = 1), depression
(n = 2), and hypothyroidism (n = 1). Three subjects reported having a cough at the time of enrollment, and
five of 52 (9.6%) reported a history of dyspnea on light
exertion due to their underlying medical condition. Of
note, nine of 52 subjects (17.3%) used tobacco. Thirtyfour subjects underwent the 15-second CEW exposure,
and 18 underwent three successive 5-second exposures.
Respiratory data for the two exposure groups are shown
in Tables 1 and 2.
DISCUSSION
Conducted electrical weapons are considered to be an intermediate weapon by law enforcement agencies. Intermediate weapons are those devices that generally can
induce subject compliance due to pain or incapacitation,
and examples include aerosolized chemical irritants, impact batons, and projectile beanbags. The CEW is used
frequently, and the manufacturer reports more than
100,000 voluntary training exposures and more than
119,000 field uses by law enforcement (S Tuttle, personal
communication, November 16, 2006). It provides a pain-

3

Table 1
Respiratory Data for Continuous 15-second CEW Exposure
(n = 34)
Parameter
Tidal volume (L)

Heart rate* (beats/min)

End-tidal CO2 (mm Hg)

End-tidal O2 (mm Hg)

Respiratory rate
(breaths/min)

Minute ventilation (L/min)

Phase

Mean Value
over Phase

95% CI

1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1

1.1
1.8
1.7
1.3
104.7
—
116.3
91.9
40.5
37.3
42.1
42.4
118.7
121.3
114.0
122.4
15.9

0.9, 1.3
1.4, 2.2
1.5, 1.9
1.1, 1.4
97.8, 111.6
—
107.3, 125.3
87.2, 102.8
39.2, 41.7
35.5, 39.0
40.4, 43.8
40.9, 43.9
116.4, 121.0
117.8, 124.8
11.2, 116.9
120.3, 124.4
14.4, 17.5

2
3
4
1
2
3
4

16.4
18.3
17.1
16.3
20.9
29.9
21.3

12.2,
16.5,
15.7,
14.7,
18.0,
27.5,
19.1,

20.7
20.1
17.4
17.9
23.8
32.3
23.5

Phase 1 = baseline measurements pre-exposure; phase 2 = measurements during conducted electrical weapon exposure; phase 3 = measurements during first minute postexposure; phase 4 = measurements from
second minute postexposure to return to baseline.
CEW = conducted electrical weapon.
* Heart rate was unobtainable during CEW application.

ful stimulus to encourage compliance, as well as physiologic and neuromuscular incapacitation in many cases.
Currently, TASER International is the dominant manufacturer in the CEW market and represents the majority
of CEWs in use today in this country. The most common
CEW currently used by law enforcement is the TASER
X26, which is why it was chosen as the test model for
this study. It is considered to be a nonlethal weapon,
under the definition set forth by the U.S. Department of
Defense.7
The X26 is programmed to deliver a roughly rectangular pulse of approximately 100-ms duration with about
100 mC of charge at 19 pulses/s for 5 seconds.8 The
peak voltage across the body is approximately 1,200 V,
but the weapon also develops an open circuit arc of
50,000 V to traverse clothing in cases where no direct
contact is made. The average current is approximately
2.1 mA. It uses compressed nitrogen to fire two metallic
darts up to a maximum of 35 ft with a predetermined angled rate of spread. When it makes adequate contact and
the darts are of adequate separation, it causes involuntary contractions of the regional skeletal muscles that
render the subject incapable of voluntary movement. If
the darts are fired at very close range and do not achieve
adequate separation, full muscular incapacitation may
not be achieved, and the device is then used to encourage
certain behavior through pain compliance.

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Ho et al.

Table 2
Respiratory Data for Three 5-second CEW Exposures (n = 18)
Parameter
Tidal volume (L)

Heart rate* (beats/min)

End-tidal CO2 (mm Hg)

End-tidal O2 (mm Hg)

Respiratory rate
(breaths/min)

Minute ventilation (L/min)

Phase

Mean Value
over Phase

95% CI

1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1

1.4
1.5
1.9
1.7
87.1
—
95.8
81.8
40.9
39.1
40.0
41.2
123.1
127.0
124.2
127.6
13.8

1.2, 1.7
1.2, 1.8
1.7, 2.2
1.2, 1.6
75.9, 98.3
—
80.8, 110.8
70.1, 93.5
39.1, 42.7
36.8, 41.4
38.1, 41.9
39.3, 43.0
118.5, 127.7
121.2, 132.8
118.6, 129.7
123.3, 131.8
11.5, 16.0

2
3
4
1
2
3
4

14.6
18.7
17.2
17.7
19.5
30.1
20.8

12.1,
15.1,
14.8,
16.2,
16.9,
30.1,
20.8,

17.2
22.2
19.5
19.3
22.2
36.3
24.0

Phase 1 = baseline measurements pre-exposure; phase 2 = measurements during conducted electrical weapon exposure; phase 3 = measurements during first minute postexposure; phase 4 = measurements from
second minute postexposure to return to baseline.
CEW = conducted electrical weapon.
* Heart rate was unobtainable during CEW application.

Critics of CEWs have attempted to link CEW use with
ICD events. It is important to realize that deaths very similar to modern-day ICD events occurred decades before
CEW technology was invented.9 Previously, it has been
theorized that ICD events proximal to CEW application
were due to electrocution. However, recent work in
this area has not supported this theory.10–13 Because
the majority of CEW research has concentrated on the
cardiac arena and has failed to show a significant association with ICD, attention has recently turned to the possibility that it could impair respiration. This would be
especially concerning in an acidotic subject (it is presumed that the vast majority of ICD subjects are in the
throes of significant metabolic acidosis from excited
delirium type behavior, which has been described in previous studies).14 It would also be concerning in subjects
who receive prolonged CEW application. We found no
evidence of breathing impairment during either type of
CEW exposure, as shown in Tables 1 and 2.
Current law enforcement CEW applications are for 5
seconds each time the trigger is pulled (the operator
has the option to turn it off sooner or to continue to depress the trigger, which results in continuous application
until the trigger is released, or to depress the trigger multiple times, which results in a 5-second cycle each time it
is depressed). Approximately 70% of reported field applications are for 5 seconds or less.8



RESPIRATORY EFFECT OF ELECTRICAL WEAPON APPLICATION

Prior work in humans failed to demonstrate a statistically significant change in electrocardiograms, serum
markers of cardiac damage, hyperkalemia, or induced
acidosis following a 5-second CEW application.12 Because of this, we elected to extend the duration of exposure to 15 seconds, because some field CEW uses are for
longer than 5 seconds, and longer duration exposures
would intuitively yield more impairment if any was to
be found. We used two different exposure patterns (5
on/1 off/5 on/1 off/5 on versus 15 seconds continuous
on) because these represent the only ways that subjects
could receive prolonged CEW application in the field (intermittent, multiple applications vs. continuous application).
It is interesting to note that the volunteers in this study
had high minute ventilations in the range of 15–19 L/min
before the application of the CEW. The expected range
would be about 6–10 L/min based on a 70-kg adult.6
We believe that this is likely due to involuntary hyperventilation after their baseline serum values had been
determined but just before activation of the CEW. We
believe that this represents a period of heightened anxiety associated with the anticipation of the painful stimulus. While this finding is noteworthy, we do not believe it
has much effect on the generalizability of our data, because we believe that most subjects in real-life situations
would also have an involuntary hyperventilatory response due to conditions surrounding their confrontation with law enforcement, such as fighting, fleeing,
and resisting.
LIMITATIONS
A limitation of this study is the small number of volunteers involved. However, in light of the small number of
volunteers willing to endure a prolonged CEW exposure
because of the discomfort involved, it would be difficult
to conduct this same methodology with a larger number
of volunteers. We believe that the number of volunteers
that we have tested is adequate to detect respiratory
impairment due to CEW exposure.
An additional limitation of this study is that it does not
exactly reproduce the conditions found in most ICD
events. In the field, the majority of ICD subjects are using
illicit substances, exhibiting bizarre, agitated behavior,
and are presumably acidotic when law enforcement officials encounter them.15 There has been some work done
in this area on animal models with regard to cardiac effects of CEW application after illicit stimulant administration, but there is no literature available in this area
examining the respiratory effects of these substances
when coupled with CEW application.11 We are unable to
reproduce these field conditions in our volunteers due
to the illegality of the conditions often found in the field
subjects.
Furthermore, our volunteers were almost all law enforcement officers and with the exception of two, none
admitted to mental illness or illicit substance abuse.
However, our study population was also not in pristine
health and likely resembles the normal American population (overweight, with medical issues such as hypertension, coronary artery disease, asthma, and so on). The
mean body mass index of our volunteers placed them

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5

in the ‘‘overweight’’ category per current federal standards.16 Had we obtained volunteers who were young
and fit from the local police academy recruit class, we
may have had a ‘‘healthy’’ population bias issue with
this study. We do not believe this to be the case.
In addition to this, we preplaced our CEW electrodes
on our volunteers and placed our volunteers in a supine
position for data collection. While this also does not
mimic the conditions of CEW use in the field, this was
a more practical study method, and we are doubtful
that this aspect of our protocol is a significant limitation.

www.azcentral.com/specials/special43/articles/1224
taserlist24-ON.html. Accessed Nov 15, 2006.
5. Mitchell K, Marcum K. Jailers cleared in culpability of
suffocation. Denver Post. Oct 17, 2006. Available at:
http://www.denverpost.com/newsheadlines/ci_45083
87. Accessed Nov 15, 2006.
6. Levitsky MG. Pulmonary Physiology. 6th ed. New
York, NY: McGraw Hill, 2003.
7. United States Department of Defense. Jul 9, 1996.
Department of defense directive 3000.3 policy for
nonlethal weapons. Available at: http://www.dtic.mil/
whs/directives/corres/pdf/d30003_070996/d30003p.pdf.
Accessed Sep 23, 2006.
8. TASER training video and information disk, version
13. Scottsdale, AZ: TASER International, Apr 2006.
9. Bell L. On a form of disease resembling some advanced stages of mania and fever, but so contradistinguished from any ordinary observed or described
combination of symptoms as to render it probable
that it may be overlooked and hitherto unrecorded
malady. Am J Insanity. 1849; 6:97–127.
10. McDaniel WC, Stratbucker RA, Nerheim M, Brewer
JE. Cardiac safety of neuromuscular incapacitating
defensive devices. PACE. 2005; 28(Suppl):S284–7.
11. Lakireddy D, Wallick D, Ryschon K, et al. Effects of
cocaine intoxication on the threshold for stun gun induction of ventricular fibrillation. J Am Coll Cardiol.
2006; 48:805–11.
12. Ho JD, Miner JR, Lakireddy DR, Bultman LL, Heegaard WG. Cardiovascular and physiologic effects
of conducted electrical weapon discharge in resting
adults. Acad Emerg Med. 2006; 13:589–95.
13. Levine SD, Sloane C, Chan T, Vilke G, Dunford J. Cardiac monitoring of subjects exposed to the TASER
[abstract]. Acad Emerg Med. 2005; 12(Suppl 1):71.
14. Hick JL, Smith SW, Lynch MT. Metabolic acidosis
in restraint-associated cardiac arrest: a case series.
Acad Emerg Med. 1999; 6:239–43.
15. Ho JD, Reardon RF, Heegaard WG. Deaths in police
custody: an 8 month surveillance study. Ann Emerg
Med. 2005; 46(Suppl):S94.
16. Department of Health and Human Services, National
Institutes of Health. Standard BMI calculator. Available at: http://www.nhlbisupport.com/bmi/. Accessed
Oct 8, 2006.



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CONCLUSIONS
We were unable to detect any respiratory impairment
during either prolonged continuous or prolonged intermittent CEW exposure in this study population. It does
not appear that prolonged CEW exposure causes a decreased tidal volume, hypercapnia, hypoxia, or apnea.
We recommend further study in this area to validate
our results.
The authors thank Matthew Carver and Andrew Hinz for their
diligent help with data collection. This project would not have
been possible without their assistance.

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