RU2258459C1 - Method for early diagnostics of post-traumatic venous thrombosis in inferior limbs - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: one should study symmetrical segments of sick and healthy limb due to performing electromagneto-resonance impedometry of these segments. While studying one should apply two metal electrodes as pickup units installed at the borders of tested segments in a sick limb. On should measure impedance value, electrodes should be installed onto symmetrical parts of a healthy limb to measure impedance value again. Availability of thrombosis should be stated upon at impedance alteration in the segment of a sick limb by 25% and more.

EFFECT: higher efficiency of early diagnostics.

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Description

The invention relates to medicine and can be used for early diagnosis of post-traumatic vein thrombosis of the lower extremities by a non-invasive method. A possible field of application of the diagnostic method is surgery, traumatology.

A known method for the early diagnosis of thrombosis of the veins of the leg using the ultrasound method, based on the use of the Doppler effect. An ultrasonic signal emanating from a piezoelectric crystal is sent through the skin and subcutaneous tissue to the vessels. Moving red blood cells reflect these waves, changing their frequency. These frequency changes are proportional to the erythrocyte circulation rate and, after appropriate amplification, are translated into an audio signal. It can also be converted to an electrical signal and recorded as a curve of venous current.

An apparatus with a radiation frequency of 5 MHz allows you to examine all available limb veins. When the ultrasound signal is directed to the site of venous occlusion, there is no signal. Therefore, the absence of amplification of the sound signal means the existence of venous occlusion between the measurement sites [Ferstrate M., Fermelen J. Thromboses. - M .: Medicine, 1986 - P.247, 249; Saveliev B.C., Gologorsky V.A. Phlebology: A Guide for Physicians. - M .: Medicine, 2001. - P.73]:

- this method has a large error, its sensitivity is insufficient to diagnose distal thrombosis;

- the method has limited capabilities in the diagnosis of venous thrombosis, gives a large percentage of false-negative results.

A known device for the impedance measurement of living tissues of a biological object, containing a generator, block, transformer, sensor and recorder, metal electrodes, capacitors, a circuit connected to the output of the sensor, the sensor is made in the form of an oscillatory circuit [RF Patent No. 2182814, cl. 7 A 61 B 5/053, published May 27, 2002, Bull. No. 15; RF patent No. 2178985, cl. 7 A 61 B 5/053, published 02/10/2002, Bull. No. 4].

The objective of the invention is to improve the accuracy of early diagnosis of post-traumatic thrombosis of the veins of the leg.

This object is achieved by the fact that in the method of early diagnosis of post-traumatic thrombosis of the leg veins by ultrasound dopplerography, symmetric segments of the diseased and healthy limb are additionally examined by conducting electromagnetic resonance impedanometry of these segments; in the study, 2 metal electrodes are used that are installed at the boundaries of the patient’s studied segment limbs, measure the magnitude of the impedances of these sections, set the electrodes on a symmetrical sections of a healthy limb, again measure the magnitude of the impedance. The presence of thrombosis is established when the impedance of a segment of a diseased limb changes by 25% or more.

After ultrasound dopplerography of the veins of the injured lower limb is carried out, an additional study of the symmetric sections of the diseased and healthy limbs is carried out by means of electromagnetic resonance impedanometry of the ADO brand.

The patient is in a horizontal position, both lower limbs are on the Beller's tire. Two electrodes are alternately placed on the skin of the damaged lower limb, and they are positioned so that the fracture zone is between the electrodes, that is, on the distal and proximal part of the lower leg in the projection of the vascular bundle (respectively, the lower electrode on the posterior surface in the region of the medial ankle, the upper electrode - on the posterior inner surface of the upper third of the leg). The distance between the electrodes should not be more than 25 cm. Having strengthened the electrodes with dielectric tapes, we measure the magnitude of the impedance. Then the electrodes are placed over the area of the healthy limb, which is strictly symmetrical to the measurement section of the diseased limb, and the impedance value is again measured.

Next, the measurement results are compared. In the obtained difference in the measurements of the impedance of the diseased limb compared with the healthy limb, the presence of vein thrombosis of the injured leg is reliably diagnosed.

An impedance difference of 25% or more reliably indicates the presence of venous thrombosis of the damaged limb. The operating frequency range of the generator is 200-500 kHz.

Clinical example:

Patient N., 42 years old, was admitted to the traumatology department in the order of emergency ambulance, with a diagnosis of closed comminuted fracture of both bones of the right lower leg in the middle third, with displacement of the fragments. Upon admission, the patient performed novocaine blockade of the fracture site, skeletal traction for the calcaneus, a load of 6 kg was imposed, with reposition and immobilization purpose in the preoperative period. Symptomatic therapy was performed. Within three days, the patient developed edema of the injured lower leg in difference compared with the healthy limb by 4 cm in the absence of complaints from the patient. A duplex scan of the vessels of the injured lower limb was performed, in which signs of thrombosis of the tibial veins of the right lower leg were revealed. The study was confirmed by impedanometry of the leg segment. In this case, the impedance measurements of a healthy limb — the tibial region — were 110, and the impedance measurement of an injured lower leg was 141. The difference in the impedance measurements of a healthy and diseased limb was 31, which as a percentage of this indicator represents an increase in the impedance of a diseased limb by 28%. According to this result, thrombosis of the injured lower leg in the early stages of the injury was reliably diagnosed in the absence of complaints and specific symptoms in the patient. In accordance with the data obtained, a course of antithrombotic therapy was carried out in the early stages of the formation of thrombosis, and this avoided the development of post-thrombotic complications from the injured limb.

The proposed method allows to identify acute post-traumatic thrombosis of the leg veins in the early stages of injury, as well as monitor the results of the study during treatment. The method is characterized by the speed of issuing information, without burdening the patient with trauma and the duration of the study.

The proposed method for the early diagnosis of post-traumatic vein thrombosis of the lower extremities by ultrasound dopplerography and recording the physical parameters of the affected segment of the limb by electromagnet resonance impedancemetry was tested experimentally in the departments of traumatology and surgery of the Municipal Clinical Hospital BSMP No. 2. Tests confirmed the high information content of the method, ease of implementation. The method is harmless and painless.

Claims (1)

A method for the early diagnosis of post-traumatic vein thrombosis of the lower extremities by ultrasound dopplerography, characterized in that they additionally examine the symmetrical segments of the diseased and healthy limb by conducting electromagnetic resonance impedanometry of these segments, using two metal electrodes that are installed at the boundaries of the studied segment of the diseased limb as sensors measure the magnitude of the impedance, set the electrodes on the symmetrical sections of healthy impurities, the impedance value is measured again, the presence of thrombosis is established when the impedance of the segment of the diseased limb is changed by 25% or more.