Objective: to evaluate the features of pulmonary function in children over two years of age with different phenotypes of bronchial asthma.

   Methods. 261 children aged 3 to 5 years with a confirmed diagnosis of bronchial asthma were examined. The reversibility of bronchial obstruction (ΔRINTexp > 0.21 kPa·l^-1·s) was recorded in all groups. Four asthma phenotypes were identified: isolated bronchial asthma (n = 56), bronchial asthma + atopic dermatitis (n = 81), bronchial asthma + allergic rhinitis (n = 54), and bronchial asthma + atopic dermatitis + allergic rhinitis (n = 70). All patients underwent measurement of airway resistance using the interrupter technique (RINT) on a SuperSpiro spirometer, both initially and after a salbutamol test. Statistical processing included univariate analysis of variance (ANOVA), Student's t-test with correction for inequality of variances, and Pearson's χ² test.

   Results. The initial values of RINTexp are minimal in the group of isolated bronchial asthma (0.9046±0.16496 kPa·l^-1·s) and maximal in the group of bronchial asthma + atopic dermatitis + allergic rhinitis. The differences between all phenotypes are statistically significant (ANOVA, p < 0.001; pairwise comparisons, p from 0.022 to < 0.001). The analysis of the distribution along the centile ranges revealed an extremely significant relationship between the phenotype and the RINTexp level (χ² = 69, p < 0.001).

   Conclusion. The pulmonary function in children aged 3 to 5 years with bronchial asthma significantly depends on the disease phenotype. An increase in comorbidity (a combination of asthma with atopic dermatitis and/or allergic rhinitis) is associated with a progressive increase in airway resistance. The most pronounced impairments of pulmonary function are observed in the phenotype of bronchial asthma + atopic dermatitis + allergic rhinitis.

   Using ROC analysis among 118 COPD patients, depending on the desaturation-distance ratio (DDR), a comparative assessment of three diagnostic approaches to detecting «desaturators» was carried out: (1) by SpO₂ regression ≥ 4 % during the 6-minute walking test (6MWT) from baseline (preload) to the end level of blood oxygenation and/or by SpO₂ regression below 90 % by the end of 6 MWT (∆SpO₂base-end ≥ 4 % and/or up to SpO₂end < 90 %); (2) by regression of SpO₂ ≥ 4 % during 6 MWT from baseline (preload) to the minimum level of blood oxygenation and/or by regression of SpO₂ to the minimum value < 90 % during 6 MWT (∆SpO₂base-min ≥ 4 % and/or to SpO₂min < 90 %); (3) only by regression
of SpO₂ ≥ 4 % (∆SpO₂base-end ≥ 4 %). A comparison of the first two approaches revealed a significant advantage of the diagnostic approach ∆SpO₂base-end ≥ 4 % and/or up to SpO₂end < 90 %: AUC was 0.89 vs 0.84 with the second approach, the sensitivity level was 81 vs 62 % with identical specificity. In addition, in the case of an approach using the formula ∆SpO₂base-min ≥ 4 % and/or to SpO₂min < 90 %, overdiagnosis of exercise-induced desaturation (EID) hemoglobin by oxygen was detected – 61,9 % of «desaturators» vs 30,5 % of «desaturators» with the first diagnostic approach (p < 0.001). Taking into account the maximum values of AUC (0.94) and sensitivity (96 %), the high level of specificity (92 %), and the simplicity of identifying «desaturators» based on only one indicator, the optimal diagnostic approach was to identify «desaturators» according to the formula ∆SpO₂base-end ≥ 4 %. EID was associated with a DDR level ≥ 3.3 % m^-1. DDR ≥ 3.9 % m^-1 was associated with the need for an additional O2 flow during 6MWT to maintain a minimum acceptable SpO₂ value ≥ 88 % during exercise.

   The bronchodilator test (BDT) is a component of spirometry widely used to assess the degree of improvement of lung function in response to bronchodilator administration.

   The aim of the study was to evaluate and systematize modern approaches to performing BDT to determine the reversibility of obstructive disorders, as well as to critically analyze the criteria for interpreting its results and its clinical significance in the diagnosis of obstructive pulmonary diseases.

   An analytical review of international and national clinical guidelines, as well as scientific publications on spirometry, bronchodilator testing, and the diagnosis of chronic obstructive pulmonary disease (COPD) / bronchial asthma (BA) for the period 1974–2025 was conducted. Indications, contraindications, and the methodology for performing BDT were systematized. Various criteria for a positive bronchodilator response were analyzed: from the classic criterion (+12 % and ≥ 200 mL from baseline of Forced Expiratory Volume in 1 second (FEV1) and Forced Vital Capacity (FVC)) to modern approaches using predicted values (+10 % of predicted) and z-scores. It was established that the detection rate of obstructive disorders using post-bronchodilator spirometry values is 11–35% lower compared to pre-bronchodilator data. It has been shown that BDT is not a reliable tool for differentiating between bronchial asthma and COPD; however, a positive response can be considered a modifiable trait. For the diagnosis of COPD, it is advisable to use post-bronchodilator spirometry values. To date, there is no single universal standard for performing the bronchodilator test. The choice of a specific drug, its dose, the method of inhalation, and the criteria for a positive response should be dictated by the specific clinical task. The current variability in methodology indicates the need for further research to standardize BDT.

   Aim. To address the problem of underdiagnosis of sudden cardiac death based on the analysis and successful verification of the cause of syncope in young patients with high-risk syncope without structural heart disease after the first syncope.

   Methods. The study included 128 patients with syncope. Based on inclusion and exclusion criteria, 63 patients were included in the study, aged 18 to 44 years; the average age of the subjects was 25.98 ± 6.69 years. An analysis of the causes of syncope established after the patient's first visit regarding a syncope was performed, and these data were compared with the final clinical diagnosis obtained on the basis of electrophysiological and molecular genetic diagnostic methods. The frequency of recurrence of syncope and SCD episodes from the time of the first syncope was assessed.

   Results. The study found that only 20 patients (31.7 %) sought medical attention after their first syncopal episode. Only 11 patients (17.7 %) were correctly diagnosed with a cardiac cause after their first syncope. Fifty-two patients (82.3 %) were diagnosed with non-cardiogenic syncope or syncope of unknown etiology. Retrospectively, all 52 (82.5 %) patients experienced a recurrence of syncope within 1–2 years, of which 10 patients (15.9 %) had an episode of SCD with successful cardiopulmonary resuscitation. In 14 patients (22.6 %), a diagnosis of syncope against the background of cardiocerebral syndrome was established at the outpatient stage, in 12 (19.4 %) – vegetative-vascular dystonia, somatoform dysfunction of the autonomic nervous system, in 8 (12.9 %) a diagnosis of anxiety disorder with panic attacks, in 4 – obesity (6.5 %), 3 patients had epilepsy (4.8 %) with the prescription of antiepileptic drugs, 2 patients had migraine without aura (3.2 %), 2 had tension headache (3.2 %), 3 patients had a diagnosis of paroxysmal conditions without specification (4.8 %), 1 had osteochondrosis of the cervical spine (1.6 %) and 2 had closed craniocerebral injury (3.2 %). After using methods of molecular genetic analysis and functional diagnostics (including genome/exome sequencing, implantable cardiac monitor, intracardiac electrophysiological study), the following final diagnoses were made: 12 people were diagnosed with rare diseases – channelopathies, 16 people – sinus node arrest and Short's syndrome, 15 patients – atrioventricular block grade 3 and grade 2 Mobitz 2, 15 patients – ventricular tachycardia, 5 patients – Wolff – Parkinson – White syndrome.

   Conclusion. High-risk syncope in young patients without structural heart disease should be considered a potential predictor of life-threatening conditions. Early identification of the risk of recurrent syncope and sudden cardiac death, as well as timely verification of the cause of syncope, can prevent a fatal outcome.

   Background. The position of the electrical heart axis (EHA) can be determined by various methods. In clinical practice, discrepancies often occur between physician-assessed and automated EHA estimates.

   Objective. To evaluate the significance of discrepancies between different EHA determination methods in patients with cardiovascular pathology.

   Materials and methods. We analyzed 12,323 ECGs from 9,794 patients. EHA position was determined using five methods: the Minnesota Code table (αMC), standard formulas using net voltage in leads I/III, I/II, and I/aVF (αI,III, αI,II, αI,aVF), and the mean QRS vector in leads I/II (αm). Amplitude measurements were automated and served as the single data source. Agreement was assessed using Bland – Altman analysis. Cases with maximal discrepancies underwent physician visual ECG review.

   Results. Best agreement was between αMC and αI,III. Discrepancies increased with the angle between lead III and leads aVF, II. The largest differences in number and magnitude were between αMC and αm. Visual analysis of frontal plane QRS loop morphology explained these discrepancies by differences in the angular position of the net cardiac electrical vector corresponding to maximal lead projection.

   Conclusion. Automated EHA calculation using leads I and III ensures comparability with physician assessment. Discrepancies between net voltage-based and mean vector-based EHA may have independent diagnostic value, as they characterize frontal plane QRS loop morphology and may provide information on ventricular myocardial depolarization.

   The Russian (Leningrad) Research Neurosurgical Institute named after Professor A.L. Polenov, established in 1926, has developed into one of the country's largest neurophysiological research schools. The introduction of new methods of electrophysiological research of the nervous system into clinical practice at the turn of the 1940^s and 1950^s posed the challenge of training specialists in clinical neurophysiology. This training was initiated by Academician A. V. Lebedinsky. In the 1960^s and 1990^s, the neurophysiological school was led by such leaders as Academician N. P. Bekhtereva, Professors I. V. Vvedenskaya and Yu. V. Dubikaitis, and Associate Professor T.S. Stepanova. Thanks to the activities of the neurophysiological scientific school, the Institute has been continuously training and educating new generations of neurophysiologists. The achievements of the Institute have greatly contributed to the development of brain sciences in Russia and are widely recognized abroad.

   Background. The high prevalence of thyroid nodules (up to 68% with high-resolution ultrasound) combined with a low malignancy rate (5–6.5 %) creates a risk of overdiagnosis and unnecessary invasive interventions. Risk stratification systems such as TI-RADS are intended to standardize ultrasound assessment; however, their performance in different morphological groups remains insufficiently studied.

   Objective. To evaluate the diagnostic significance of the TI-RADS system in ultrasound examination of focal thyroid pathology with histological verification.

   Materials and methods. A retrospective analysis of ultrasound reports of 284 patients (aged 18–83 years) with a morphologically confirmed diagnosis (based on fine-needle aspiration biopsy or postoperative histology) was performed. Patients were divided into three groups: benign non-neoplastic diseases (n = 141), adenomas (n = 52), and thyroid cancer (n = 91). Ultrasound was performed using a multiparametric protocol (B-mode, color and power Doppler imaging). Each nodule was assigned a TI-RADS category. Statistical analysis included calculation of sensitivity, specificity, and ROC analysis.

   Results. The proportion of nodules classified as TI-RADS 2 was 23.1 %, TI-RADS 3 – 11.2 %, TI-RADS 4 – 25.6 %, and TI-RADS 5 – 40.1 %. Sensitivity and specificity of TI-RADS for detecting thyroid cancer were 91.04 % and 91.41 %, respectively (AUC = 0.963). For adenomas, sensitivity decreased to 61.6 % and specificity to 82.4 %.

   Conclusion. The TI-RADS system has high predictive ability in the diagnosis of thyroid cancer, but its effectiveness in differentiating adenomas is limited, which calls for an individualized approach.