Biomedical subjects

J A Malinowski

Publications and source records attributed to J A Malinowski.

10 recordsLinked to original sources

PubMed1990

Wounding effects of the AK-47 rifle used by Patrick Purdy in the Stockton, California, schoolyard shooting of January 17, 1989.

The limited disruption produced in tissue simulant by the rifle and bullets used in the Stockton, California, schoolyard shooting is entirely consistent with the autopsy reports on the five children who died of their wounds. It is also entirely consistent with well-documented battlefield studies and with previous tissue-simulant studies from many laboratories. It is inconsistent with many exaggerated accounts of assault-rifle wounding effects described by the media in the aftermath of this incident. This information should be documented for the historical record. However, the critical reason for correcting the misconceptions produced by media reaction to this incident is to prevent inappropriate gunshot-wound treatment.

Aorta↗

PubMed1988

The wound profile: illustration of the missile-tissue interaction.

The wound profile was developed at the Letterman Army Institute of Research in order to measure the amount, type, and location of tissue disruption produced by a given projectile, and to present the data in a standardized, easy to understand picture. The entire missile path is captured in one or more 25 X 25 X 50 cm blocks of 10% ordnance gelatin at 4 degrees C. The penetration depth, projectile deformation and fragmentation pattern, yaw, and temporary cavity of the missile in living anesthetized swine muscle are reproduced by this gelatin. Measurements are taken from cut sections of the blocks after mapping of the fragmentation pattern with biplanar X-rays. These data are then reproduced on a life-sized wound profile which includes a scale to facilitate measurement of tissue disruption dimensions, a drawing of the loaded cartridge case before firing, the bullet weight and morphology before and after firing (and calculated percent of fragmentation), and the striking velocity. This technique allows us to determine the wounding character of the projectile without the need for elaborate and expensive high-speed cine and X-ray equipment, or the need for shooting live animals. The method improves our understanding of the wounding process and should lay the groundwork to assure more rational and effective treatment.

Firearms↗

PubMed1988

A reconsideration of the wounding mechanism of very high velocity projectiles--importance of projectile shape.

In 1976 a paper appeared which forecast "significant increases in velocities of projectiles from guns and fragments from warheads." It was postulated that the higher velocity projectiles would cause shallow wounds with wide tissue destruction on the surface--especially when striking velocity exceeded the speed of sound in tissue (about 1.5 km/sec). Other studies have not dealt with projectiles in this velocity range; the conclusions and assumptions stated in this 1976 paper have been quoted by others and accepted as fact. In a previous study, we shot blunt fragments into gelatin, but our findings did not support the proposed hypothesis that temporary cavity shape in tissue changes at velocities above the sonic speed. The temporary cavity becomes larger with increasing velocity but it does not become shallow unless the projectile fragments on impact. In the present study, we shot a series of blunt projectiles into animal tissue at velocities of 764 to 2,049 m/s. The stellate skin and muscle disruption splits from temporary cavity stretch we observed in this study are not apparent on entrance wounds from individual explosive device fragments in the living wounded. We suggest, therefore, that studies using blunt projectiles at striking velocities above 700 m/s are lacking in clinical relevance. We also compared wounds produced by pointed projectiles with those produced by blunt projectiles. The marked difference in wound morphology showed the fallacy of doing a study with blunt missiles and applying conclusions from that study to tissue disruption caused by all projectiles.

Animals↗

PubMed1988

Internal deformation of the AK-74; a possible cause for its erratic path in tissue.

A series of 20 shots with the AK-74 Russian Assault Rifle, in which the entire course of the bullet was captured in gelatin, showed a change in direction of the bullet track approximating a right angle in every case. Bullets were recovered from the gelatin for ten consecutive shots of this series and examined roentgenographically. In all cases an internal deformation was discovered to have taken place: lead from the bullet's core flowed into the air space inside the bullet's tip. The roentgenograms also showed that this flow of lead resulted in an asymmetrical bullet in every case. We suggest this resulting bullet imbalance as a possible cause of the unusually marked curve in this bullet's path through tissue.

Firearms↗

PubMed1988

Ordnance gelatin for ballistic studies. Detrimental effect of excess heat used in gelatin preparation.

Most users of ordnance gelatin for ballistics studies are apparently unaware of the detrimental effects on this tissue simulant's properties caused by excess heating in reconstitution of the gelatin powder. Material published by the Gelatin Manufacturers Institute of America states that heating gelatin above 40 degrees C can be detrimental to its properties. The manufacturer of type 250 A Ordnance Gelatin does not include directions for preparation with the gelatin powder. Directions that can be obtained by contacting the manufacturer fail to give any recommendations on the amount of heat applied during gelatin preparation and do not mention the detrimental effects of excess heat. These oversights are corrected in the revised set of directions included in this article.

Forensic Medicine↗

PubMed1986

Wounding mechanism of projectiles striking at more than 1.5 km/sec.

In 1976 Charters and Charters (2) described experiments intended to study effects of projectiles with a striking velocity greater than 1 km/sec. They postulated that the projectiles at higher velocity would cause shallow wounds with wide tissue destruction on the surface, especially when striking velocity exceeded the speed of sound in tissue (about 1.5 km/sec). We found no other studies reported dealing with projectiles in this velocity range, the conclusions and assumptions of Charters and Charters have been quoted by others and accepted as fact. We designed and performed experiments to test the hypothesis of Charters and Charters by comparing temporary cavity morphology and penetration in gelatin. We fired two types of blunt projectiles over a velocity range from 650 m/sec (2,137 ft/sec) to 2,016 m/sec (6,614 ft/sec). In these studies we found no evidence to indicate that shape and characteristics of the disruption in ordnance gelatin change significantly when missile striking velocity exceeds sonic speed in the target.

Forensic Medicine↗

PubMed1985

Skin wound healing determined by water loss.

An in vivo method of monitoring healing was tested incorporating an Evaporimeter measuring water evaporation; reepithelialization was detected through reestablishment of the water barrier. In the first study two wounds were created with a 2-mm biopsy punch on each of the backs of 15 rabbits and covered with occlusive and semiocclusive dressings. Water loss increased from a preoperative value of 6 g m-2 hr-1 to 55 g m-2 hr-1 after surgery. Water loss from the occluded site returned to baseline values in 9 days as opposed to 17 days for the semioccluded sites (P less than 0.05). The second study followed the healing of full-thickness 4 X 4-cm wounds in five rabbits treated with fine-mesh gauze and five treated with a human amnion dressing. Wound area and water loss were observed during the repair process. Visually measuring the wound area, the injuries appeared 100% healed on Day 30. The Evaporimeter continued to detect significantly increased water loss up until Day 45 when the original baseline values were reached. No differences were observed between the gauze and amnion groups. The Evaporimeter presents a simple yet accurate, noninvasive tool measuring the wound healing endpoint based on regeneration of the epidermal water barrier.

Animals↗

PubMed1985

The wound profile: a visual method for quantifying gunshot wound components.

A wound profile method is reported for predicting the wounding potential of ordnance in living animal tissue by shooting projectiles into 10% gelatin blocks kept at a temperature of 4 degrees C. Blocks (25 X 25 X 50 cm) were placed end to end so that the entire missile-gelatin interaction was captured. The penetration and fragmentation pattern in these blocks previously was found comparable to wounds in living swine leg muscle. The extent of the radial cracks in the gelatin approximated the temporary cavity size in swine muscle. Measurements from longitudinal sections of the blocks indicated the depth of penetration and the sizes of both the permanent and temporary cavities, and fragmentation patterns were mapped from biplanar X-rays of the blocks. The four wound components, penetration, fragmentation, permanent cavitation, and temporary cavitation, were diagrammed in what was termed a 'wound profile.' This profile should help characterize wounds caused by different missiles.

Gelatin↗

PubMed1984

Wounding potential of the Russian AK-74 assault rifle.

The Russian contribution to the new generation of smaller caliber assault rifles is the AK-74, whose 5.61-mm (diameter), 3.4-gm (weight), 2.5-cm (length) aerodynamically shaped bullet has a muzzle velocity of 900 m/s. Our tests show that in living swine soft tissues and gelatin tissue simulant the AK-74's copper-plated steel jacket resists fragmentation or deformation. Since the bullet does not fragment, the tissue disruption surrounding the bullet pathway is limited to the stretching effect of temporary cavitation. We present evidence indicating that the energy used during temporary cavity formation causes limited permanent tissue disruption in the more elastic soft tissues (muscle, bowel wall, lung); the same insult in the relatively nonelastic liver, however, causes multiple fractures and massive permanent disruption. We conclude that the AK-74, despite its rather high velocity and marked tendency to yaw soon after penetration, causes relatively nondramatic wounds due to its nonfragmenting behavior.

Abdominal Injuries↗

PubMed1984

Bullet fragmentation: a major cause of tissue disruption.

Effects of nonfragmenting solid brass bullets (5.56 mm, 3.1 gm, 1.9 cm long, machine-made at Letterman Army Institute of Research) and fragmenting soft-point bullets (5.56 mm, 3.2 gm, 1.7 cm long, commercially made by Hornady Manufacturing Co., Grand Island, NE) were compared when they were fired through soft tissue of the hind legs of five live swine (50 to 70 kg). The swine were anesthetized endotracheally (0.8% halothane) and placed in the supine position with the hind legs extended. Blocks of tissue simulant (10% gelatin at 4 degrees C, molded in blocks 20 X 22 X 47 cm) were placed against the skin at the predicted point of bullet exit. All shots (a fragmenting bullet through one hind leg and a nonfragmenting bullet through the other hind leg of each swine) were fired at a range of 3 m from a rifle with a bullet tract at 90 degrees to the long axis of the swine's body. Bullet velocities ranged from 930 to 990 m/s. Dissections of the bullet tract (through tissue and gelatin) revealed that tissue disruption from the fragmenting bullets was significantly greater (p less than 0.001) than from nonfragmenting bullets. The recovered bullets were weighed. The results showed that the fragmenting bullet lost 59 to 77% of its original weight and the nonfragmenting bullet was the same weight as originally. Recognition of the amount of tissue disruption and identification of bullet fragments in the wounds resulting from the two different bullets should be a useful guide to operating surgeons in selecting the best approach for treatment of gunshot injuries.

Animals↗