Relevance: One of the leading causes of prolonged infection in perivascular gunshot wounds and vascular reconstruction areas is “forgotten” fragments in the wound canal. While metal is usually easy to detect, non-radioactive elements are quite difficult to identify during primary surgical treatment. Typically, detection methods are aimed at interaction through human tissues, using the properties of fragments such as: ferromagnetism, radiopacity, etc. But fragments that do not have the appropriate properties are difficult to detect, because the wound may contain glass, plastic, composites, etc., and these materials are not radiopaque.

The purpose of the work: to develop a method for diagnosing foreign debris in a patient's wound, including non-X-ray contrast agents of direct contact based on the corresponding innovative noise emission technology.

Materials and methods: The noise emission effect was used to detect debris. Acoustic emission is the process of recording acoustic waves that occur in a material (or tissue) as a result of mechanical stress, stretching, or damage. In the context of searching for foreign bodies in a wound, this method allows the detection of foreign objects due to their acoustic properties. Foreign bodies may have a different acoustic response (frequency or signal intensity) compared to biological tissues. An experiment was conducted on biomimetics, where the dependence of the change in the oscillogram on the location of the fragment and its density was revealed. Due to this difference in noise, we were able to tactilely diagnose both metallic and non-metallic fragments. Accordingly, our device consists of 2 main parts: 1) a sterile disposable replaceable part that is inserted into the wound channel; 2) a reusable device with a microphone for recording noise and appropriate software for its processing. Thus, according to the position of the entrance hole, we can determine the starting point, and using the angle of inclination - the further movement of the fragment. Considering the place where we identified the fragments and made marks on the sterile disposable probe, like a ruler, we can determine the location of the fragment quite accurately. 

Results: Using the 3D model of the simulator, the angle and length of the probe entry were previously able to clearly determine the location of the fragment in the body. As the probe moves in the wound canal, a significant noise effect is observed on the oscilloscope screen, which is leveled by special algorithmic support, which improved the signal quality and its informativeness. So far, it has been possible to record the dependence of the amplitude and basic frequency of oscillations depending on the position of the fragment and its size in the wound channel. Thus, using the methods of spectral analysis of noise emission from mechanical contact of a flexible probe with a foreign body in the wound, which allows manipulations through the wound channel and signal processing with special signal amplification filters, as well as means of constructing noise emission spectra based on Fourier series expansion (built into the oscilloscope), we were able to conclude about the presence of a foreign body, its type and position in the wound channel.

Conclusions: 

1. It was determined that non-radioactive fragments are quite difficult to detect in a perivascular gunshot wound during PHO.

2. It was found that the radiation obtained when the probe with mechanical excitation comes into contact with a foreign body is much more informative and allows an indirect assessment of the size of the fragment, even if it is located in a fairly dense tissue, and the signal/noise ratio is informative up to a sensor immersion depth of 380 mm. 

3. The results obtained created the prerequisites for the development, manufacture and testing of an innovative tool for checking wound channels in order to detect fragments, including non-radioactive ones.