Ultrasound in lung surgery

Today, the use of ultrasound (ultrasonic inspection) in medicine has received a solid scientific basis and allows the best way to solve many questions of diagnostics and therapy.
In MVTU named after N. E. Bauman and at the Department of traumatology Calibrate, A. Nikolaev, V. I. Loshilova, C. A. Polyakov and gg Semenovym for the first time in 1964, started the development of a method of ultrasonic cutting of bone and soft tissue, and then welding bone tissues. After experimental studies (more than 500 experiments) C. A. Polyakov in 1967 successfully applied in the clinic ultrasonic cutting of bone and soft tissue, and made several successful operations of osteosynthesis.
To date, the ultrasonic method is widely used in Orthopaedics and traumatology at different bone-plastic operations. Soviet specialists use ultrasound in thoracic surgery at the dissection of the scar-sclerotic tissue, decortication and pneumoniae, as well as by sawing of a bone fabric. Surgery ultrasound is also used in the treatment of infected wounds.
Of particular interest experimental research of ultrasonic welding of bronchus stump after lung resection, and also introduction in the Arsenal of surgeons flexible and long waveguides for intramuralnah manipulation of the trachea and bronchi (, A. Nikolaev, V. P. Borisov and others). Previously, such work has been carried out neither in the USSR nor abroad. Of considerable interest for science and practice are the studies on ultrasonic connection lung tissue.
Deserve attention and prospective studies on the local impacts of low-frequency ultrasonic waves on tuberculosis microbacteria directly in a cavern (ultrasonic "irrigation" and sanitation lung cavities).
Ultrasound and lung disease... ten Years ago, these physical and medical concepts wasn't in touch. Now ultrasound is becoming an indispensable diagnostician and a healer of the majority of lung diseases.

The ultrasound. Brief characteristics. Ultrasound - elastic mechanical fluctuations of the environment, the frequency of which exceeds the upper limit of hearing ear of man (about 18 kHz). They are in the frequency range from 18 kHz to 15 MHz. Fluctuations in these distributed in the form of waves, which are periodically alternating areas of tension and compression. The speed of propagation of elastic waves is determined by the properties of the environment and does not depend on the frequency or intensity of ultrasound. Features of ultrasonic oscillations is their focus and the ability to focus energy in a small area of the working tool.
The main feature of the spreading of elastic wave is the distance that it takes place for one period. This value - wavelength dependent on the velocity of sound propagation in the material, and also the frequency.
Sound wave propagating in an environment that has a specific energy, which is periodically transferred from potential to kinetic and back.
To estimate the energy of the sound field is defined value, called the intensity of the sound. Intensity - the amount of energy transferred by a sound wave per second across the platform 1 cm2, perpendicular to the direction of propagation.
When distributing the flat of ultrasonic waves in environment is part of the energy expended to overcome the irreversible loss: for example, the viscosity of the material). This process is called "the absorption of ultrasound", when energy is converted into heat, warming the environment.
If the propagating wave hits the boundary between two media, part of the ultrasonic energy is held on the second Wednesday and the other is reflected back. The distribution of power between the past and the reflected energy depends on the ratio of the acoustic impedance of two media.
Specific properties of ultrasonic oscillations for the influence on biological tissues are as follows:
- high energy intensity with maximum amplitude of oscillations.
- acoustic radiation pressure is displayed in the longitudinal sound waves of finite amplitude displacement. The pressure is always directed from the environment with a higher density to the environment with the lowest;
- cavitation occurs: the process of rupture of the liquid under the action of a stretch stresses with the formation of the gas chambers;
- there is heating of the tissue under the action of ultrasound.
The main parameter of ultrasonic oscillations, which defines biological effects, - intensity ultrasound. Intensity determines the degree of destruction of biological structures.
Time of influence of ultrasound may also play a role.
With increasing exposure time of more than 10 minutes at a moderate intensity ultrasound can cause irreversible abnormal changes in the cells and the destruction of living tissues. Impulsive mode of operation of the source of oscillations allows to extend the exposure time (up to 20 min without significant morphological changes in biological tissues.
The magnitude of the absorption of ultrasonic energy depends on histological structure of tissues. Absorption in fatty tissues, for example, less than usual. Significant absorption is observed in atelectasia lungs, and cartilage and muscles have higher values of the coefficient of attenuation than parenchymal tissue. The coefficient of absorption of ultrasonic energy depends on the direction of the introduction of ultrasound in relation to the direction of the collagen fibers. Bone has a maximum coefficient of absorption and consequently the ultrasonic cutting it stands out the most heat.
When a high-frequency ultrasonic waves more heat is formed on the surface of section soft fabric - bone. Approximately 40% of ultrasonic energy reflected in the tissues.
Cavitation in the soft tissues extremely difficult because of the high viscosity tissue fluids and greater concentration of cells in them. Cavitation in the blood vessels occurs easier than in other tissues.
To explain the mechanism of action of ultrasonic waves recently appeared new hypotheses, theoretical bases of which are associated with the acoustic currents. For physicians and biologists interested in the appearance of acoustic streaming in the fluid layer, bordering ultrasonic oscillating tool. Cytological and functional changes in cells caused by ultrasonic waves caused by microscopic appearance of currents at the cell - liquid and inside cells. The nature and form of microscopic currents depend not only on the ultrasound intensity, but also from viscosity of cytoplasm and a number of other physical parameters of such a complex system as a living cell.
When using ultrasonic oscillations for influence on the soft tissues and implementation process dissection must be considered as biological properties of the fabric itself and the physical parameters of ultrasound.