Ultrasound assessment of the vulnerability of the internal organs to stabbing: determining safety standards for stab-resistant body armour
Introduction
Ideal stab-resistant body armour would prevent edged weapons from penetrating the human body in stab attacks. With current materials, this cannot be guaranteed for all types of knife blades; some penetration into the body may occur before the passage of the knife can be arrested by the armour.
It is assumed that no serious injury to the victim will occur if the internal organs are not breached by the assailant’s weapon. The ‘safe’ distance to which an assailant’s knife can be pushed into the body before breaching the internal organs needs to be determined. A previous CT study has determined this distance for the internal organs in hospital patients lying supine in a scanner, with their arms above the heads [1]. The information from this study provided the basis for determining the new Home Office standard for issuing stab-resistant body armour to the Police [2]. To learn more about the vulnerability of organs to the passage of a blade into the body in different and more natural body postures, and at different stages of the breathing cycle, a dynamic ultrasound study was performed on healthy volunteers.
Section snippets
Methods
Twenty-five healthy volunteers aged between 18 and 50 were recruited. Ultrasound measurements of the minimum skin-to-organ distances were recorded for each subject in three postures: lying supine, standing erect, and leaning forward at 45° (braced against the examination couch). Each subject’s height and weight were recorded.
All subjects were scanned with a Toshiba 3.75 MHz ultrasound curved strip probe measuring 1.75×7.5 cm. The probe was applied with a moderately firm pressure by the same
Minimum skin-to-organ distances
The minimum skin-to-organ distances as a function of posture are presented in Fig. 1. The spleen was the shallowest organ and was only 9 mm deep to the skin in one subject in the supine position. The deepest organ was the right kidney, which was 56 mm deep to the skin in another subject, also in the supine position. There was no demonstrable difference in the skin-to-organ distances between male and female subjects.
The effect of posture on the minimum skin-to-organ distances is seen in Fig. 2.
Discussion
Ideal stab-resistant body armour would prevent edged weapons from penetrating the human body in stab attacks, and would be light enough not to interfere unduly with the wearer’s ability to function. Armour designers need to carefully balance the ‘wearability’ against protection. With current materials, wearable armour cannot be guaranteed to prevent blade penetration into the human body for all types of knife blades; some penetration into the body may occur before the passage of the knife can
References (2)
- et al.
Safety standards for stab-resistant body armour; a computer tomographic assessment of organ to skin distances
Injury
(1998) - Stab-resistant body armour test procedure. Police Scientific Development Branch, Home Office Police Department,...
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