The characteristics of the pressure waves generated in the soft target by impact and its contribution to indirect bone fractures

When a high-velocity spherical fragment impacts a biological body, it will initiate strong pressure waves spreading throughout the body. A pressure wave, especially a shock wave with a steep front, generated by impact, may cause blood vessel injuries, viscera injuries, and indirect bone fractures. This paper reports research on pressure waves near the wound tracks, generated by spherical fragments, and calculates the zones of indirect bone fractures generated by pressure waves of impact.

The wounding characteristics of spherical steel fragments in live tissues

This paper reports the wounding effectiveness tests of four kinds of spherical steel fragments, striking against live tissues at various velocities. The most pronounced wound characteristic for the spherical fragments was that the entrances were larger than the exits; the higher the striking velocity, the larger the size of the wound. The skin near the entrance tended to be torn away when the striking velocity was above 1,200 m/s. As a general rule, most exits appeared to be circular with a diameter slightly bigger than that of the fragment. Shapes of the wound channels were conic in general. The channel volumes were proportional to the striking velocities of the fragments; in the case of two spheres having the same striking energy, the small one would produce larger volume of wound channel and amount of debrided tissues. The energy release rate for smaller fragments was higher than that for larger ones.

An estimation of the physical characteristics of wounds inflicted by spherical fragments

Based on test results of projecting four different types of spherical fragments, diameters of which were 3.175 mm, 4.763 mm, 5.56 mm, and 6.35 mm, respectively, into the biological soft tissues and the soap blocks used as simulants, an estimation of the physical characteristics of wounds inflicted by spherical fragments was established in this paper. With impact velocities in the range of 450-1,500 m/s, all four types of spherical fragments showed little variation in drag coefficients for each medium. Some specific wound characteristics such as amount of debrided tissue, volume of the wound channel, etc., can be predicted as functions of energy transfer for spherical fragments of less than 1 gram.

An analysis of the wounding factors of four different shapes of fragments

The wounding characteristics to a biological target of four typical shapes of fragments (square, triangular, cylindrical, and spherical) with masses of less than 1 gram and velocities between 460 and 1,500 m/s are studied in this paper. The following conclusions about the effects of the wounding factors, such as energy transfer, velocity, mass, and shape of fragment are presented: 1) For given target characteristics, the important wounding factors of fragments are impact velocity, mass, and shape, and of these velocity is the most important. 2) Besides direct effects, the fragment velocity has great influence on far-reaching, indirect wounding effects. When velocity increases, it not only increases the size of direct wound, but also the rate of indirect bone fracture. 3) The rate of energy transfer is affected by fragment shape, and it is also a decreasing function of mass. 4) Under the same conditions there are differences in wounding effectiveness among the four fragment shapes, the triangular with a comparatively high wounding effectiveness, followed by the square, cylindrical, and spherical. The types of wound channels are also different, the cylindrical and spherical making a "through" type, the square and triangular making a "blind-tube" type.

Wounding properties of steel pellets with different velocities and quality on soft tissue of dogs

The characteristics of the soft-tissue wounds of the hind legs of 155 dogs produced by stainless steel spheres with four different masses and at various impact velocities were observed. It was found that when the mass of the spheres was identical, the velocity became the main factor to determine the severity of the damage; when the mass of the spheres was different but their kinetic energy was similar, then a smaller but faster sphere produced more severe damage than a larger but slower one. Shallow but wide and severe wounds usually resulted. The rate of disability of extremities with such wounds was very high. These wounding properties of steel spheres have caused some new problems in the treatment of war injuries.

Computed tomography of oleothorax

Oleothorax as therapy for pulmonary tuberculosis was discontinued some 35 years ago. An oleothorax may expand and cause respiratory distress. Additional complications include bronchopleural fistula and cutaneous fistula. Computed tomography has not previously been used to evaluate oleothorax. This case report describes the use of computed tomography in a patient with a symptomatic oleothorax.

Balloon dilatation of esophageal strictures

Esophageal dilatation is a safe and effective method for treating most esophageal strictures. Balloon dilatation is primarily used in those strictures in which conventional techniques were initially unsuccessful. We have successfully treated 13 patients with severe esophageal strictures of both benign and malignant etiologies. The patients subjectively felt better and weight gain was uniform. The patients were able to maintain adequate patency of the esophagus with bougie and self-dilatation. The length of follow-up ranged from 2 to 30 months. The various techniques used for balloon dilatation of esophageal strictures are presented. No serious complications were encountered. Dilatation by balloon catheter appears to be a safe method to dilate severe strictures and provides maximum patient benefit with minimal trauma and morbidity.

Mediastinal pancreatic pseudocyst

We have described a case of extension into the mediastinum by a pancreatic pseudocyst. This rare phenomenon should be included in the differential diagnosis of mediastinal mass lesions. We advocate the use of CT in evaluating a mediastinal mass to determine its solid or cystic nature, size, extent, and relationship to adjacent structures.