RU2790920C1 - A method for diagnosing latent respiratory failure in patients with pneumonia - Google Patents

Abstract

FIELD: medicine, namely to therapy, pulmonology, functional diagnostics.

SUBSTANCE: Pulse oximetry and a six-minute step test are performed. The transcutaneous saturation is continuously recorded with a discreteness of 1 every 2 seconds in automatic mode and with data stored in the device's memory simultaneously when performing a six-minute step test. Before the six-minute step test, the patient is instructed that his walking speed should be maximum in order to walk the greatest distance in 6 minutes. The desaturation of ∆SpO₂ with oxygen ≥ 4% of the baseline level during a six-minute step test in patients with pneumonia is a predictor of the development of respiratory failure. A decrease in SpO₂ < 94% is a sign of latent respiratory failure.

EFFECT: The method enables to diagnose latent respiratory failure in patients with pneumonia, timely identify latent hypoxemia in patients, initiate timely therapeutic measures and prevent the unpredictable course of pneumonia with the formation of complications in the form of decompensated respiratory failure.

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Description

The invention relates to medicine, namely to therapy, pulmonology, functional diagnostics, and can be used to diagnose latent (subcompensated) respiratory failure (RD) in patients with pneumonia.

Pneumonia is an acute disease with focal lesions of the structural and functional units of the lungs, manifested by a clinical picture with signs of an intoxication syndrome, cough, the presence of auscultatory phenomena and obligatory radiological patterns. The most common complication of pneumonia leading to poor outcome is DN.

Despite the improvement of methods of prevention, diagnosis and treatment, no significant trends in the reduction of complications of pneumonia in the form of DN have been identified so far [1].

Today, for the diagnosis and evaluation of DN, gasometric indicators are used, according to which it is customary to diagnose and grade DN according to severity. These indicators include: partial tension of oxygen in arterial blood (PaO ₂ ) and SaO ₂ - oxygen saturation of hemoglobin. [2].

For the study of PaO ₂ , an invasive method of arterial puncture is used, which requires certain skills from medical personnel and allows one to evaluate only one-time information about arterial blood oxygenation.

To study SaO ₂ , an indirect hardware method of pulse oximetry is used - a non-invasive measurement of the percentage of oxyhemoglobin in arterial blood. The operation of the pulse oximeter is based on the ability of hemoglobin bound (HbO ₂ ) and not bound (Hb) to oxygen to absorb light of various wavelengths. The method of single-stage pulse oximetry has a number of limitations and errors, depending both on the device itself and on the functional state of the body. Both PaO ₂ and SaO ₂ are dynamic and can change over a short period of time.

A known method for diagnosing respiratory failure in chronic obstructive pulmonary disease, including the identification of the degree of respiratory failure based on determining the level of blood oxygen saturation during pulse oximetry at rest, the minimum level of blood oxygen saturation during the test with a 6-minute walk, the patient filling out a questionnaire in which the severity shortness of breath when filling out the questionnaire is assessed in points on a scale: shortness of breath does not bother, except for a very intense load - 1 point, shortness of breath bothers when walking fast or climbing a slight elevation - 2 points, shortness of breath leads to slower walking compared to other people of the same age or there is a need to make stops when walking at a normal pace on a flat surface - 3 points, shortness of breath makes it impossible to leave the house or appears when dressing and undressing - 4 points, calculate the index of respiratory failure in arbitrary units according to the formula: IDN = (SpO ₂ initial - SpO ₂ minimum) * M, where IDN is the index of respiratory failure (arb. units), SpO ₂ initial - the level of saturation at rest (%), SpO ₂ minimum - the minimum level of saturation recorded during the test with a 6-minute walk (%), Μ - the result of the questionnaire in points, if the value of IDN does not exceed 8 conv. units, the degree of respiratory failure, detected when determining the level of blood oxygen saturation during pulse oximetry at rest, is not corrected, with values of IDN equal to or more than 8 arb. units, increase the detected degree of respiratory failure to the next degree (RF patent No. 2755390, А61В 5/083, publ. 09/15/2021).

The main difference of the proposed solution is that this patent deals with COPD, we have pneumonia, while the authors are considering clarifying the degree of respiratory failure, we are considering the diagnosis of latent respiratory failure. The authors of the patent study 2 points of saturation, which leads to a decrease in the accuracy of diagnosis, and we use continuous monitoring. At the same time, the proposed solution uses only an objective analysis of the saturation indicator during the entire 6MShT.

At present, based on the use of data from one-stage indicators, a classification of respiratory failure has been formed (Table 1).

These parameters are applicable in the diagnosis of DN, when there is already a detailed clinical picture of a complication in the form of DN and the pathogenesis of a violation of the correspondence of minute alveolar ventilation of the structural and functional units of the lungs, their departments and parts, all lungs to the volumetric blood flow rate, that is, disorders of ventilation-perfusion relations. With a hidden (subcompensated) DN, the parameters of one-time indicators will correspond to normal values. Under physiological conditions, there is always a normal variability in the ventilation-perfusion ratio, which does not lead to DN. With DN, physiological variability is always transformed into pathological, as a result of which pulmonary gas exchange is disturbed at the level of the entire external respiratory system.

Methods that make it possible to reliably diagnose DN at the onset, as well as to assess the presence of latent (subcompensated) DN, are not currently described and are not used in routine clinical practice.

The invention is based on the task of creating a method for functional diagnosis of latent (subcompensated) DN precisely at the stage of transformation of the physiological variability of ventilation-perfusion relations into pathological. Objective of the invention: improving diagnosis, simplifying the interpretation of data, improving the accuracy of determining DN in patients with pneumonia of various etiologies.

The solution of this problem is ensured by the fact that in the method for diagnosing latent respiratory failure in patients with pneumonia, including pulse oximetry, continuous registration of transcutaneous saturation is performed with a discreteness of 1 time in 2 seconds in automatic mode and with saving data in the memory of the device simultaneously when performing a six-minute step test, at the same time, before starting the six-minute walking test, the patient is instructed that the speed of his walking should be maximum in order to cover the greatest distance in 6 minutes; oxygen desaturation of ΔSpO ₂ ≥ 4% of baseline during a six-minute walking test in patients with pneumonia is a predictor of respiratory failure; a decrease in SpO ₂ < 94% during a six-minute walk test is a sign of underlying respiratory failure.

EFFECT: possibility of timely diagnosis of latent (subcompensated) DN in patients with pneumonia of various etiologies.

Positive effect: the method is non-invasive, more accurate and objective - allows you to analyze the dynamic parameters of SaO ₂ in the physiological conditions of the body.

The technical result is achieved by the fact that in patients with pneumonia, the saturation and pulse were continuously recorded with a discreteness of 1 time in 2 seconds with the data stored using the MCP during the 6MShT, followed by evaluation of the results.

The introduction of this method in the diagnosis of patients with pneumonia will allow timely detection of latent hypoxemia, risk groups for developing DN, initiating timely therapeutic measures and preventing an unpredictable course of pneumonia with the formation of a complication in the form of decompensated DN.

The invention is illustrated in FIG. 1, which shows the implementation of the registration of SaO ₂ using the MCP allows you to objectively evaluate the indicator characterizing the absence of DN. In FIG. 2 shows a decrease in SpO ₂ ≥ 4% from baseline during 6MShT, which is a predictor of the development of respiratory failure. In FIG. 3 and FIG. 4 shows a decrease in SpO ₂ < 94% during 6MWT, which is a sign of the presence of latent respiratory failure.

For the diagnosis of latent (subcompensated) DN by a non-invasive method, which consists in conducting monitoring computer pulse oximetry (MCP), when performing a six-minute step test (6MShT), continuous registration of saturation with a discreteness of 1 time in 2 seconds is carried out with the data stored in the memory of the device with subsequent evaluation of the results. The use of this method makes it possible to identify signs of latent (subcompensated) DN in patients with pneumonia of various etiologies. The MCP data processing makes it possible to estimate the saturation parameters with high accuracy and to carry out a visual analysis of oximetric trends. At present, MCP is widely used in the somnological service [3]. However, its functional reserves have not been fully utilized.

The essence of the proposed method is as follows: the patient is installed with an MCP device of various modifications, which performs continuous registration of transcutaneous saturation with a discreteness of 1 time in 2 seconds in automatic mode and saves data in the memory of the device (Fig. 1). MCP is carried out simultaneously when performing 6MShT strictly according to the approved generally recognized protocol [4]. Before starting 6MWT, the patient is instructed that his walking speed should be as fast as possible in order to cover the greatest distance in 6 minutes. 6MShT is simple, safe, well tolerated, does not require expensive equipment and participation of highly qualified personnel. Within 6 minutes, the patient walks the distance taken into account in meters on a flat, hard surface. The appearance of shortness of breath with 6MShT without taking into account SaO ₂ can demonstrate not only the subjectivity of complaints, but also low exercise tolerance and the presence of background diseases, as it reflects the general reaction of all body systems, including respiratory, cardiovascular, nervous, etc. Implementation registration of SaO ₂ using the MCP allows you to objectively evaluate the indicator characterizing the absence of DN (Fig. 1). Oxygen desaturation (ΔSpO ₂ ) of ≥ 4% of baseline during 6MWT in patients with pneumonia would be a predictor of DN (Figure 2). A decrease in SpO ₂ < 94% during 6MShT will be a sign of the presence of a latent (subcompensated) DN (Fig. 3).

The essence of the claimed method is illustrated by the following clinical examples:

Example 1. Patient P., 44 years old. Complaints of general weakness, fever up to 38.7°C, dry cough. Sick for 3 days. Lung radiography revealed infiltration in S4, S5 of the right lung. Pneumonia was diagnosed. Organs without features. According to the results of the performed MCP at 6MShT, desaturation (ΔSpO ₂ ) with oxygen ≥ 4% of the initial level (SpO ₂ max. 98% SpO ₂ min. 94%) was revealed, which is a predictor of the development of DN. The patient was included in the risk group for developing DN. Discharged after 17 days of recovery.

Example 2. Patient T., 53 years old. Complaints of general weakness, runny nose, fever up to 37.8°C, cough with yellow-green sputum. Sick for 7 days, treated independently. Asked for medical help in connection with increased cough and persistence of intoxication syndrome. Lung radiography revealed infiltration in S8, S9, S10 of the right lung, S8, S9 of the left lung. Pneumonia was diagnosed. According to the results of the performed MCP at 6MWT, a decrease in SpO ₂ < 94% was revealed, which is a sign of the presence of a latent (subcompensated) DN. The patient was included in the risk group for progression of DN. Subsequently, after 72 hours on the background of treatment, MCP was repeated at 6MWT, where there was no decrease in SpO ₂ , which was regarded as an indicator of the effectiveness of the therapy. Discharged after 18 days of recovery.

Example 3. Patient V., aged 25. Complaints of general weakness, chills against the background of an increase in body temperature up to 39.5 ° C, dry debilitating cough, anosmia, excessive sweating. Sick for 6 days, treated independently. Asked for medical help in connection with the appearance of shortness of breath during physical exertion. When performing lung radiography, an increase in the pulmonary pattern in the lower basal sections of both lungs was revealed, according to the results of computed tomography of the lungs in S4, S5, S6, S8, S9, S10 of the right lung, S8, S9 of the left lung, ground-glass changes were revealed. Pneumonia was diagnosed. On examination, the general condition is satisfactory, the skin is pale, the pulse is rhythmic with a heart rate of 88 per minute, breathing is hard, wheezing is not auscultated, SpO ₂ when breathing atmospheric air at rest is 95%, other organs and systems are without pathology. According to the results of the performed MCP at 6MWT, a decrease in SpO ₂ < 94% was revealed, which is a sign of the presence of a latent (subcompensated) DN. Pathogenetic therapy was corrected (antioxidant therapy was added, oxygen therapy with a flow of 2 l / min), against which a subjective improvement in well-being was noted in dynamics. Subsequently, 72 hours later, MCP was re-performed at 6MWT, where there was no decrease in Sp0 ₂ , which was regarded as an indicator of the effectiveness of the therapy. Discharged after 14 days of recovery.

Thus, the method allows you to reliably determine the signs of latent (subcompensated) DN, which allows you to use it in clinical practice to identify risk groups that require timely correction of therapy. This method is short, easily reproducible, highly sensitive.

Bibliography

1. Tatochenko V.K. Pneumonia in children: diagnosis and treatment. Attending doctor. 2008; (8):5-9.

2. Avdeev S.N. Respiratory failure. Atmosphere. Pulmonology and Allergology. 2004; (1):21-27.

3. Molchanov K.I., Buzunov R.V., Nikonov E.L. Development of a somnological service in medical institutions of the Main Medical Directorate of the Administration of the President of the Russian Federation. Kremlin medicine. Clinical Bulletin. 2012; (1):25-29.

4. Holland AE, Spruit MA, Troosters T, et al. An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease. Eur Respir J. 2014;44(6):1428-1446. doi: 10.1183/09031936.00150314.

Claims (1)

A method for diagnosing latent respiratory failure in patients with pneumonia, including pulse oximetry, characterized in that transcutaneous saturation is continuously recorded with a discreteness of 1 time per 2 seconds in automatic mode and data is stored in the device's memory simultaneously when performing a six-minute step test, while before starting a six-minute walking test, the patient is instructed that his walking speed should be as fast as possible in order to cover the greatest distance in 6 minutes; oxygen desaturation of ΔSpO ₂ ≥ 4% of baseline during a six-minute walking test in patients with pneumonia is a predictor of respiratory failure; a decrease in SpO ₂ < 94% is a sign of the presence of latent respiratory failure.

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