stopping power

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stopping power2016-12-18T23:04:21+00:00

stopping power 

stopping power image from New Medical Terms

stopping power

FORENSICS

A popular term referring to the alleged ability of one or more bullets to stop an intruder, a charging bull, or any big ass living thing headed your way

The article by Ken Newgard, MD, in The Physiological Effects of Handgun Bullets: The Mechanisms of Wounding and Incapacitation, Wound Ballistics Review, 1(3): 12-17; 1992, should give pause to those beguiled by naive reports in popular (read, unscientific) gun magazines about stopping power, “The only method of reliably stopping a human with a handgun is to decrease the functioning capability of the CNS, and specifically, the brain and cervical spinal cord; there are 2 ways to accomplish this goal: 

(1) direct trauma to the CNS resulting in tissue destruction–which occurs quickly, and

(2) lack of oxygen to the brain caused by bleeding and loss of blood pressure–which is much slower

Adequate blood pressure can be maintained with minimal clinical symptoms up to a 20% blood loss. For an average 70 kg male, the cardiac output is 5.5 L/minute; the total blood volume is 60 ml/kg. Assuming the cardiac output can double under stress–the heart beats faster and with greater force, the aortic blood flow can reach 11 L/min; if one assumes a wound that totally severs the thoracic aorta, it would take 4.6 seconds to lose 20% of his blood volume from one point of injury; this is the minimum time in which a person could lose 20% of his blood volume; this analysis does not account for oxygen contained in the blood already perfusing the brain, that will keep the brain functioning for an even longer period of time; most wounds will not bleed at this rate because: 

• Bullets usually do not completely sever blood vessels, 

• As blood pressure falls, the bleeding slows, 

• Surrounding tissue acts as a barrier to blood loss, 

• The bullet may only penetrate smaller blood vessels, 

• Bullets can disrupt tissue without hitting any major blood vessels, resulting in a slow ooze rather than rapid bleeding, and 

• Compensatory mechanisms that prevent haemorrhagic shock, including venous constriction, increased cardiac output and vascular fluid transfer.

Newgard considered the survival times of persons who had received fatal gunshot wounds to determine if the person who was shot had enough time to shoot back and stated, “Instantaneous incapacitation is not possible with non-CNS wounds and does not always occur with CNS wounds. The intrinsic physiologic compensatory mechanisms of humans makes it difficult to inhibit a determined, aggressive person’s activities until he has lost enough blood to cause haemorrhagic shock.” Newgard’s summary of the data is sobering, “…the body’s compensatory mechanisms designed to save a person’s life after sustaining a bleeding wound, allow a person to continue to be a threat after receiving an eventually fatal wound, thus necessitating more rounds be fired in order to incapacitate or stop the assailant.”

Bottom line: One bullet, no matter how big and how bad it is, is unlikely to give the advancing party “religion” and stop him. Keep shooting!!! 

Synonyms Bullet incapacitation, gunshot incapacitation, projectile incapacitation 

Reference www.firearmstactical.com/wound.htm

IMAGING

The density of a tissue reflected in an image’s whiteness; white tissues–e.g., bone have the greatest stopping power

RADIATION ONCOLOGY

The ability of a material to stop ionising radiation; alpha particles are stopped by a piece of paper, gamma radiation by thick lead shielding

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