Sphygmography

Sphygmography dates back to the invention of the sphygmograph in 1854 by the German physician Carl von Fierordt (1818-1884). The first pulse recording devices (there were several varieties of them) were completely mechanical.

Some Russian scientific medical schools still use the term “sphygmography”, extending it to different ways of recording pulse waves in blood vessels, while in other countries the use of this term ceased with the disappearance of mechanical sphygmographs (the term is used only in historical aspect) and research methods are called on the principle of recording, for example, aplanation tonometry of the carotid and femoral arteries, echo tracking, etc. Probably, the Russian traditions are supported by the outdated GOST ^[3] adopted in the USSR in the early 70s of the XIX century, in which, however, there is no definition of “sphygmograph”, but separate definitions of “sphygmoarteriograph” and “sphygmophlebographer” are given.

Main article: Sphygmograph

A sphygmograph is a device for obtaining a sphygmogram, a graphic display of the properties of a pulse. A sphygmograph consists of a receiver for mechanical oscillations of an artery, a transducer, and a recording device. The sensing element of the sphygmograph is a sensor (receiver) in the form of a pelot with a lever in the role of a transducer (as in the Mare sphygmograph). At the beginning and the middle of the 20th century, photoelectric, electromagnetic, piezocrystalline, or strain gauge sensors were used to convert mechanical signals, and an electrocardiograph with ink recording was used as a recording device.

Sphygmography allows to determine:

• Peripheral vascular patency;
• Properties of the pulse: frequency, rhythm, filling, voltage, height;
• Increase or decrease in blood pressure , relative to normal levels;
• Decrease in vascular resistance;
• The speed of propagation of a pulse wave is an indicator of the stiffness of the arteries ^[4] and their possible damage by atherosclerosis .
• Aortic heart disease ^[5] .
• Stroke volume of the heart according to the Wetzler – Beger or Bremzel-Ranke method.

The sphygmography proper registers the vessel oscillations in the body area with the help of a receiver, which is strictly fixed above the artery, without exerting significant pressure on its walls. Such a study is possible only where the arteries are located superficially, and at those points where pulse palpation is usually performed.

The so-called volumetric sphygmography determines the total volumetric changes in the neck (or limbs) of the patient, who are wearing a compression (for the neck — narrow, with a chamber no larger than half the circumference) a pneumatic cuff (according to the above GOST, a device for measuring the dependence of the volume of an organ or area body with blood from time to time is called "plethysmography" ^[3] ). In the middle of the 20th century, it was believed that volume sphygmography occupies an intermediate position between sphygmography and plethysmography ^[6] . In modern literature, the term “volume sphygmography” or “volume sphygmography” can be found only in a small number of publications by Russian authors, and this term is not currently used in the global research community ^[7] .

At the same time, in 2016, by Order of the Ministry of Health of the Russian Federation 997-n of 12/26/2016 Appendix 15, point 10, devices for volumetric sphygmography were included in the standard of equipment for functional diagnostics departments in modern clinics. ^[eight]

You can also find the term volume segmental sphygmography , that is, the registration of volume changes of any part of the body that is available for the imposition of the cuff. The most important indicator when performing OSFG is the measurement of the speed of propagation of a pulse wave in the arteries of the elastic and muscular types. Elastic arteries include the aorta, subclavian, carotid, and pulmonary arteries, and muscular-type arteries — the brachial, radial, femoral, and arteries of the lower leg ^[9] .

Compression cuff methods can be multichannel when using several cuffs for different extremities (usually in laboratory conditions) or single-channel , as in devices combining oscillometric sphygmomanometry and obtaining peripheral and central sphygmograms (used for both ambulatory monitoring of pulse waves , and for their analysis in the office of the doctor).

There is a sphygmogram of the central and peripheral pulses . A sphygmogram of the central pulse is produced on the subclavian and carotid arteries, or it is restored with the help of special transformations from the curve of the peripheral pulse. Peripheral pulse is examined on the femoral , radial, arteries of the foot and with a volume sphygmography.

Carotid sphygmogram can be recorded synchronously with an electrocardiogram and phonocardiogram (polycardiography).

The rules of preparation for sphygmography are similar to the rules of preparation for blood pressure measurement (sphygmomanometry). For some time before the sphygmography it is necessary to exclude factors affecting the patient’s pulse and blood pressure: mental stress (also during the study), food intake (for 1 hour), exercise, use of tonic drinks (tea, coffee, cocoa), taking drugs from the sympathomimetic group, smoking (1.5–2 hours), drinking alcohol.

The main position of the patient's body - lying on his back. Hands slightly apart, head slightly raised (located on the pillow).

In the study of the carotid artery, the head is slightly set aside, the neck muscles are relaxed. The pilot or funnel is set at the level of the upper edge of the thyroid cartilage or higher under the lower jaw, depending on the location of the best pulsation determined by palpation . Sphygmography of the femoral artery is determined in the upper third of the front surface of the thigh (Scarpa triangle).

To obtain a sphygmogram of the extremities, it is more convenient to use a cuff that is put on the patient’s shoulder, forearm, thigh, or lower leg; in the case of ambulatory monitoring, the preparation and recommendations to the patient are the same as for the daily monitoring of blood pressure .

The speed of pulse wave propagation (PWV) is determined either by simultaneous recording of sphygmograms of two or more arteries, or by separating the pulse wave contour in one artery (using special algorithms) into direct and reflected waves. Various pulse wave analysis techniques also allow the central blood pressure and augmentation index to be obtained ^[10] .

A sphygmogram is the result of a sphygmography in the form of a pulse curve, which is used to determine the properties of the pulse and the diagnosis of the state of the cardiovascular system.

Elements of the sphygmogram:

Anakrot - the rise interval of the pulse wave . During the systole of the left ventricle of the heart, a portion of blood (50-90 ml) is abruptly thrown into the aorta and diverges further along the arteries. At the peak of the anacrot (in the figure at point b) systolic blood pressure is recorded.

Katakrota - the interval of the fall of the wave. Occurs during the outflow of blood from the arteries to the capillaries. The diastolic blood pressure is recorded at the lowest point of the catacrot (point a).

Dicrotic rise (prong) - secondary rise on the catacrot. During the aortic valve closure (section cd), the pressure in the arteries begins to drop sharply, as the blood flows briefly in the opposite direction to the heart, but after this valve is completely closed, it rushes back into the aorta (section de). The moment of complete valve closure on the sphygmogram corresponds to the lowest point of incisura (clipping) (point d). After the dicrotic rise, the pressure drops more slowly (section ef).

• Sphygmomanometer - blood pressure monitor

• Pressman L.P. Clinical sphygmography. - M .: Medicine, 1974. - 128 p.
• Functional research methods in the clinic of internal diseases / Ed. I.I. Isakova. - L .: Medicine, 1977. - S. 89-104. - 296 s.
• Diagnostic and therapeutic techniques / Ed. Vs Mayat - M .: Medicine, 1969. - p. 243–246. - 520 s.