RU2467684C1 - Method for evaluating breathing reserve of lungs - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely pulmonology, and can find application in evaluating individual breathing reserves of human lungs. Substance of the method consists in X-ray examination to determine a shadow area of right and left lungs. Additionally, individual's height, weight and body surface are determined. It is followed by calculating a breathing reserve index by formula: I_BRL=S_{body surface}:(S_{right lung}+S_{left lung})- If the value I_BRL is more than 45, breathing reserve of lungs is considered to be low, the value within the range of 45-40 shows medium reserve, and the value less than 40 - high reserve. The value I_BRL exceeding 45 enables predicting postoperative respiratory failure in cardiosurgical patients.

EFFECT: use of the given invention provides higher accuracy of individual assessment of the anatomic-functional status of lungs, with finding a prognosis criteria of developing postoperative respiratory failure in cardiosurgical patients.

2 cl, 1 tbl, 2 ex

Description

The invention relates to medicine, namely to pulmonology, functional diagnostics, and can be used to determine individual respiratory reserves of the human lungs.

Pulmonary respiration is the gas exchange between the atmosphere and the blood of the pulmonary capillaries, the result is blood arterialization (Struchkov P.V., Vinnitskaya R.S., Lyukevich I.A. Introduction to the functional diagnosis of external respiration. - M., 1996. - 72 from). Violation of the ventilation function of the lungs with the development of respiratory failure is one of the terrible conditions in clinical practice.

Respiratory failure is a condition in which the external respiration system either does not provide adequate blood arterialization, or blood arterialization is provided by the tension of compensatory mechanisms.

The area of gas exchange in the lungs determines the number of alveoli capable of gas exchange, and an adequate increase in their volume during breathing. For each person, the gas exchange area in a healthy person is determined by the individual anatomical volume of the lungs. The lung volume in the skeleton of the chest in an adult is relatively stable (G. Avtandilov. Fundamentals of pathological practice. - 2nd edition. - M., 1998. - S.355-357). At the same time, the body weight of an adult can change and depends on constitutional features, obesity or weight loss and other factors. Therefore, the ratio of the "area of gas exchange of the pulmonary fields" to the "surface area of the body" can change both with increasing body weight, and with its decrease. Naturally, the mismatch of the area of gas exchange of the pulmonary fields to the surface area of the body can be an anatomical component of respiratory failure.

At the same time, the existing methods for examining the lungs do not allow registering this ratio and the parameters of its changes in clinical practice to assess latent or severe respiratory failure.

An X-ray examination is used to study pulmonary fields (Propaedeutics of internal diseases. A. Grebenev M .: Medicine, 2001, p. 94). At the same time, X-ray methods for examining the lungs are narrowly focused and are used to determine the transparency of the lung tissue, the presence of foci of compaction.

To determine the quantitative and qualitative parameters of the ventilation function of the lungs, spirometry is performed (Vorobyeva Z. V. Research of the ventilation function of the lungs. - M., 2008, 190 p.). It allows you to determine the size of the respiratory reserve of the lungs and compensatory capabilities, to identify the presence and degree of respiratory failure in various pathological conditions, to reveal the mechanisms of its development. At the same time, the method of spirometry does not allow determining the correspondence of the available lung area for gas exchange to growth with the body mass of the subject.

There is a method of determining the function of external respiration of the lungs and respiratory system by measuring the parameters of the respiratory movements of the chest, non-contact, using a system of sensors located on the left and right of the screen installed above the front surface of the chest. The patient is placed in a chair equipped with a radiator of electromagnetic waves, the registration of the measured parameters is carried out simultaneously in a personal computer. In this case, the amplitude of chest movements at the level of the upper-middle and lower parts of the chest, the front wall of the abdomen and diaphragm, followed by extrapolation of the obtained data to the total lung volumes and to the volumes of each lung separately, is used as these parameters [patent RU 2113168, 1998] .

The prototype of the invention is a method for assessing the functional abilities of the lungs, which consists in the fact that they carry out chest x-ray in direct projection in the phases of maximum inspiration and expiration. At the same time, it is carried out against the background of a fixed radiopaque grating with subsequent observation of the obtained images on a stereo comparator when they are reversed relative to the vertical position by 90 °. The differences of the horizontal parallaxes between the image of the fifth rib of the anterior part of the rib cage of the left (Δp _l ) and right (Δp _p ) lung and lattice are measured. Then, according to the formula, the functional state of the lungs (k) is evaluated, k = Δp _l / Δp _p . Moreover, at k≈1, the excursion capacity of the left and right lung is equivalent; for k> 1, sclerotic changes in the left lung are 1.5 times less than in the right. At k >> 1, there is no lesion in the left lung; it works in large volume, compensating for the lack of work of the right lung affected by sclerosis. For k <1, sclerotic changes in the right lung are 1.5 times less than in the left. When k << 1, there is no lesion in the right lung, it works in large volume, compensating for the lack of work of the left lung affected by sclerosis [patent RU 2358652, 2009]. The disadvantages of this method are its complexity, the assessment of the functional abilities of the lungs is carried out only in relation to changes in the right and left lungs relative to each other, while not taking into account the patient’s body weight and the correspondence of lung volume to a given body weight.

The task of the invention is to develop a method for obtaining a formalized indicator of the respiratory reserve, due to the size of the lungs and body weight of the subject.

The technical result when using the invention is to simplify the method, increase the accuracy of an individual assessment of the anatomical and functional state of the lungs, obtain a criterion for predicting the development of respiratory failure in the postoperative period in cardiac patients.

The proposed method for assessing the respiratory reserve of the lungs is as follows. On a chest x-ray in a direct projection, the area of the shadows of the right and left lung is determined separately. In this case, the landmarks of the boundaries of the lungs are the edges of their shadows on the radiograph. Summing up the area of the right and left lung, the value of the total area of the pulmonary fields is obtained.

The next step is to determine the surface area of the body of the subject. To do this, with the help of a height meter determine the growth of the test in centimeters (cm). Body weight is determined by weighing on a medical scale, in kilograms (kg). Further, using the “Du Bois Nomograms for Determining the Body Surface by Height and Body Weight”, the body surface area of the subject is determined (Bova A.A., Denshchuk Yu-Ya.S., Gorokhov S.S. Functional diagnostics in the practice of a doctor (manual for doctors) / MIA Moscow, 2007, p.199).

The index of the respiratory reserve of the lungs (AND _DRL ) is calculated as the ratio of the surface area of the body of the investigated to the area of the lungs according to the radiograph according to the following formula:

And _DRL = S _{body surface} : (S of the _{right lung} + S of the _{left lung} ),

Where

And _DRL - an index of the respiratory reserve of the lungs,

S _{body surface} area of the patient’s body surface (m ² )

S of the _{right lung} - the area of the shadow of the right lung on the radiograph (m ² );

S of the _{left lung} - the area of the shadow of the left lung on the radiograph (m ² ).

If the value of And _{DRL is} more than 45, the respiratory reserve of the lungs is estimated as low, 45-40 - as medium and less than 40 - as high.

With a value of And _DRL more than 45, there are manifestations of respiratory failure and a high probability of developing pulmonary complications in the postoperative period. With And _DRL less than 40 a high reserve of ventilation function of the lungs.

We conducted a study of chest radiographs in direct projection and body surface area in 26 patients, aged 35 to 75 years, the average age of 52.3 ± 6.9, who underwent surgical treatment for heart disease in cardiopulmonary bypass. Patients included in this study did not differ significantly from each other in terms of the severity of initial circulatory failure, the duration of surgery, the duration of mechanical ventilation, and the level of hemoglobin after surgery. Among the studied patients in the postoperative period, complications from the respiratory organs were more often observed in the group of patients with the ratios "body surface area / lung area on the radiograph" more than 45 (table).

The invention is illustrated by the following clinical examples.

Example 1. Patient C, 44 years old. Body weight 76 kg. Height 174 cm. Body area 1.90 m ² . The area of the right lung on the radiograph is 0.0292 m ² , the left is 0.0220 m ² . The ratio of body area to lung area is 37.2.

The patient underwent surgical treatment for critical aortic stenosis, aneurysm of the ascending aorta. The postoperative period is smooth, without manifestations of respiratory failure.

Due to the presence of a high pulmonary reserve (37.2) in the postoperative period, complications associated with impaired lung function and the addition of an infection of the respiratory tract were not observed.

Example 2. Patient I., 52 years old. Body weight 110 kg. Height 170 cm. Body area 2.20 m ² . The area of the right lung on the radiograph is 0.0228 m ² , the left 0.0220 m ² . The ratio of body area to lung area is 49.08.

The patient underwent surgical treatment for coronary heart disease with unstable angina pectoris - coronary artery bypass grafting was performed. In the postoperative period, manifestations of respiratory failure (dyspnea at rest) were observed, lower lobar pneumonia and bilateral pleurisy developed. The development of pulmonary complications was due to the initial state of the lungs in the patient, identified by assessing the ratio of the areas “body surface - lungs” and hyperfunction of “reduced” lungs.

This invention can be used both for making a diagnosis and for choosing a method for the prevention of pulmonary complications and therapy. The proposed method is aimed at an individual assessment of the anatomical and functional state of the lungs.

The determination of the respiratory reserve index according to the developed technique contributes to a better understanding of the physiology of the lungs and a more accurate knowledge of the pathophysiology of the development of respiratory failure allows us to judge possible lung complications.

High measurement accuracy during this research method allows to identify respiratory disorders even in cases where clinical and radiological methods did not allow to detect deviations from the norm.

METHOD FOR ASSESSING A LUNG RESPIRATORY RESERVE

Table The indicators of growth, body weight, body surface area, lung area by x-ray and the ratio of body surface to lung area in patients No. Patient age Height (cm) Body weight (kg) Patient's body area (m ² ) The area of the left lung (m ² ) The area of the right lung (m ² ) The sum of the areas of the left and right lungs (m ² ) Respiratory Reserves Index one N., 57 172 93 2.09 0.0288 0,0296 0.0584 35.78 2 K., 40 176 73 1.90 0.0196 0.0232 0.0428 44.4 3 K., 44 178 78 1.95 0.0240 0,0300 0.0540 36.11 four L. 75 167 65 1.73 0.0212 0,0300 0.0512 33.79 5 S., 45 174 76 1.9 0,0252 0,0308 0.0560 33.93 6 I., 64 168 75 1.85 0.0176 0.0184 0.0360 51.39 7 K., 54 176 70 1.85 0,0236 0.0280 0.0516 35.85 8 N., 76 160 55 1.55 0.0152 0.0184 0.0336 46.13 9 V., 43 164 74 1.80 0.0136 0,0204 0.0340 52.92 10 S., 44 172 77 1.9 0.0220 0,0292 0.0512 12/37 eleven I., 52 170 110 2.20 0.0220 0.0228 0.0448 49.08 12 P., 65 175 110 2.25 0,0276 0,0316 0.0592 38.01 13 E., 62 166 70 1.79 0,0268 0,0252 0.0520 34.42 fourteen B. 36 170 77 1.89 0.0160 0.0228 0.0388 48.71 fifteen C., 60 168 87 1.97 0,0268 0,0284 0.0552 35.69 16 M., 55 176 84 2.00 0,0204 0.0260 0.0464 43.10 17 A., 47 163 75 1.80 0.0137 0,0205 0.0342 52.63 eighteen F., 43 165 one hundred 2.05 0.0108 0.0144 0.0252 81.35 19 K., 53 153 63 1,60 0.0120 0.0148 0.0268 59.7 twenty G., 57 172 90 2.25 0.0168 0.0212 0.0380 59.21 21 G., 50 158 70 1.71 0.0108 0.0132 0.0240 71.25 22 X., 54 161 60 1.61 0,0204 0.0240 0.0444 36.26 23 3., 59 168 61 1.78 0,0204 0,0236 0.0440 40.45 24 A., 48 164 82 1.83 0.0196 0,0248 0.0444 41.21 25 M., 60 154 68 1,67 0,0204 0,0248 0.0452 36.95 26 S., 47 162 74 1.80 0.0134 0,0202 0.0336 53.57

Claims (2)

1. A method for assessing the functional ability of the lungs, including x-ray examination, characterized in that it further determines the height and weight of the subject, then determines the surface area of the patient’s body, and the x-ray determines the shadow area of the right and left lung, after which the respiratory reserve index is calculated by the formula:
And _DRL = S _{body surface} : (S of the _{right lung} + S of the _{left lung} ),
where And _DRL - an index of the respiratory reserve of the lungs;
S _{body surface} - the surface area of the patient’s body, m ² ;
S of the _{right lung} - the area of the shadow of the right lung on the radiograph, m ² ;
S of the _{left lung} - the area of the shadow of the left lung on the radiograph, m ² ,
and when the value of I _{DRL is} more than 45, the respiratory reserve of the lungs is estimated as low, 45-40 - as medium and less than 40 - as high. 2. The method according to claim 1, characterized in that with a value of And _DRL more than 45 predict respiratory failure in the postoperative period in cardiac surgery patients.