Whole body plethysmography

A little-known type of diagnostics - plethysmography - is a way of fixing changes in the volume of internal organs or individual parts of the trunk, which are accompanied by a change in their blood circulation. This method is often used to assess the quality of the vascular tone.

To implement the method of plethysmography, special devices are used - plethysmographs, of various modifications - electrical, water, photographic, mechanical.

Indications for the procedure

In what situations does the doctor refer to diagnostic plethysmography? This direction can get patients with multiple vascular pathologies, with a blood flow disorder in different organs, with chronic cardiac problems. Thus, indications for plethysmography often become:

• prolonged vascular spasm of unexplained etiology;
• vasospastic angiotrophoneurosis, Raynaud's disease;
• varicose disease;
• deep thrombosis;
• circulatory disorders in the brain;
• diseases of the respiratory tract - in particular, the lungs and bronchial tree.

It is possible to conduct plethysmography to fix and evaluate the effectiveness of the treatment. In addition, this diagnostic method helps to clearly identify the quality of conditioned reflexes of blood vessels.

The direction for plethysmography is given by general practitioners, as well as phlebologists, neuropathologists, and vascular surgeons.

[1], [2]

Preparation

Before embarking on plethysmography, it is necessary to prepare the patient - in the first place, the doctor should explain to the patient what the procedure is used for, which it is able to clarify.

• A week before the plethysmography study, the patient is not allowed to consume alcohol, and to take any medications not prescribed by the doctor.
• The patient must visit the latrine before the examination, wear overalls offered by the health worker.
• It is better to come to the plethysmography procedure in advance to sit, relax and calm down. The patient's breathing should be smooth, calm.

[3]

Technique of the plethysmography

The plethysmography procedure is performed on a specific part of the body, depending on which organ or limb is to be examined. For example, if the doctor needs to check the lower limbs, then the electrodes are attached to the legs. A special device records any changes in electrical resistance, depending on the function of breathing and on changes in blood flow inside venous vessels.

Plethysmography consists of the following stages:

• Initially, the patient lies straight, while the lower extremities should be on the elevation, at an angle of not more than 35 degrees. Ankle joints should be above the heart level, which will improve blood flow in the legs.
• The patient bends the limb in the region of the knee and turns it in the hip joint, transferring the body weight to the examined leg.
• The doctor fixes the electrodes from the plethysmograph on the skin of the ankles. Electrodes should be placed in isolation, the distance between them should be approximately 8 cm. The cuff is fixed on the thigh, slightly above the knee joint.
• The doctor uses the device to inflate the cuff to 50-60 cm of water. Post. At the same time venous vessels are squeezed, and the arterial blood supply is not disturbed. The cuff is left in inflated condition for a few seconds (up to one minute), until the curve stabilizes on the apparatus.
• The plethysmograph captures information: the state of the curve shows the degree of venous filling with blood, and the change in this fullness when the cuff is blown off. Standard research is also conducted on another limb. If the doctor has doubts, then the procedure is allowed to re-run.
• To evaluate the results of plethysmography, the doctor uses a curve with the utmost fullness of blood vessels and with the strongest blood flow.

Normally, with a short compression of venous vessels, there is an increase in the filling of their blood. And when the squeezing stops, a sharp outflow is observed.

With thrombotic complications, the blood flow is disrupted: the outflow is inhibited when the cuff is deflated, the blood vessels are filled with blood.

Impedance plethysmography

The essence of impedance plethysmography consists in recording the overall electrical resistance of tissues to the intermittent action of high-frequency currents. Since liquid biological media have a higher coefficient of electrical conductivity, this method allows you to quickly determine the dynamics of blood flow and the type of capillary circulation in the areas of the body.

The conductance of impedance plethysmography leads to an objective assessment of the fullness of any of the departments of the vascular venous network, both in a calm and excited state of the circulation. The main difference between the method and standard rheovasography is that with impedance plethysmography, currents with higher frequencies are used.

Plethysmography is recognized as an absolutely safe and painless technique, with a high coefficient of informativeness.

Occlusion plethysmography

Venous occlusal plethysmography is assigned to assess the volume and speed of blood flow in the legs and hands. During the procedure, any fluctuations in body volume are recorded against the background of a clogged outflow of blood through the venous vessels. Normally, the values of the volume flow of blood in a calm state should be in the range of 2.9 ± 0.37 ml per minute per 100 cubic centimeters of tissues.

In the area of pathology, the volume flow of blood can be permissible to exceed the degree of blood flow in the same sections of a healthy limb 5 to 10 times.

The installation of special electrodes during plethysmography helps to assess not only the state of the blood flow, but also to know the degree of elasticity of the veins on the legs, and also to determine the quality of the outflow of blood to the right heart chambers. The abnormalities found in the study indicate that there is thrombosis, or dysfunction of valves of venous vessels, or worsening of venous blood flow from the abdominal organs.

Plethysmography of the lungs

The general method of plethysmography allows one to directly measure the magnitude of bronchial resistance against a background of calm, measured breathing. The essence of the study is a synchronous measurement of the speed of air flow and differences in pressure in the enclosed cabin space in which the patient is located.

The pressure indices inside the cabin are measured in relation to fluctuations in alveolar pressure - this pressure is measured, taking into account the proportional ratio between the volumes inside the cabin and the volumes of gas in the pulmonary system.

Plethysmography well reveals even small patches of bronchial constriction, in contrast to spirography, in which it is possible to trace the deterioration of bronchial patency caused by the decrease in their lumen during exhalation.

Contraindications to the procedure

Plethysmography has practically no contraindications: the procedure is considered completely safe. However, the study does not conduct in such situations:

• if the patient suffers from claustrophobia or severe mental disorders;
• if the patient is in an excited state, his breathing is restless;
• if the room where the procedure is performed is cold - the cooling of the extremities may distort the results of the study;
• if the patient is under the influence of alcohol, chemical or medicinal products;
• If a patient has severe pains that do not allow him to relax to the fullest.

[4], [5], [6], [7], [8]

Complications after the procedure

Plethysmography refers to modern non-invasive diagnostic methods. This type of research is completely safe and does not cause any unpleasant sensations and consequences. Physicians rule out the development of complications after plethysmography.

[9], [10], [11], [12]

Care after the procedure

No special care for the patient after plethysmography is required. The patient after the diagnostic examination can go home and lead a habitual way of life for him.

[13], [14], [15], [16], [17]

Reviews

It is quite difficult to give a clear assessment of the state of the blood circulation in a certain zone, therefore plethysmography in some cases is simply irreplaceable. For many patients, this type of research helps to establish the correct diagnosis if there is a need to differentiate the vascular pathology of functional and organic etiology.

No other type of diagnostics will be able to identify a damaged and healthy vascular network in a sick person in a short time.

If the doctor needs to determine the presence of severe pathologies of regional blood flow, then plethysmography with high accuracy will be able to establish the typical and pathogenetic features of the dystonic state.

In narrow medical circles, plethysmography is used to study vasoactive drugs, or more precisely, to track their pharmaceutical effects on blood vessels. It was plethysmography in its time that allowed to prove that some substances - for example, caffeine, positively affect cerebral vascular dystonia not because they cause vasodilation, but because they perfectly tone up.

According to medical experts, plethysmography is unique and can not be replaced by any other diagnostic method.