Using a Taser to control agitated suspects in police custody is standard operating procedure for many law enforcement agencies. In some circles, however, the idea that using a Taser could lead to a suspect's death has caused controversy.

Now, the final results of a study conducted by emergency medicine physicians at the University of California, San Diego (UCSD) Medical Center showed no lasting effects of the Taser on healthy test subjects.

"Evaluating in-custody deaths following use of a Taser is a process that requires looking at the totality of the event. It is like putting a puzzle together. The data from this study helped shape another piece of the puzzle by looking at the physiological effects of a single Taser activation in human subjects," said study director Gary Vilke, M.D., professor of clinical medicine and director of Clinical Research for Emergency Medicine at UC San Diego. Vilke presented his findings at the 2007 Society for Academic Emergency Medicine (SAEM) Annual Meeting, May 16-19, 2007, Chicago, IL.

Taser subdues a person by delivering an electrical current that interferes with the body's neuromuscular system, temporarily incapacitating the recipient.

"I have been Tazed," said Vilke. "The experience is painful while it's happening but afterward, you only feel sore, like you might after a tough workout. Our goal was to find out how, in the absence of alcohol, drugs or other stimulants, humans are affected physiologically."

Vilke monitored the reactions of 32 healthy volunteers from the San Diego County Sheriff's Department who agreed to receive a single, five-second exposure from a Taser X26, the model reportedly used by more than 30 percent of police agencies in the United States. The standard issue law enforcement Taser is set to administer an electric shock in five-second intervals.

Study coordinators measured cardiovascular and blood parameters before the exposure and for one hour after the exposure. Blood pressure and heart rate as well as calcium, sodium, potassium, bicarbonate and lactate levels, and blood pH were measured. Systolic blood pressure decreased after the Taser, likely due to a heightened anxiety before the test. Other measures changed slightly, but there were no clinically significant or lasting changes in the subjects.

This study was funded by the National Institute of Justice. Phase two of the two-year study is already underway, testing the affects of Taser use on subjects who are under additional stress.

"In this phase, the sheriff department volunteers will be exercising to raise their heart rates prior to being exposed to the Taser. Most suspects are being pursued: running, driving fast, excited in some way. This study will monitor participant vital signs while looking at that piece of the puzzle," said Vilke.