Exploring classical machine learning for identification of pathological lung auscultations.

The use of machine learning in biomedical research has surged in recent years thanks to advances in devices and artificial intelligence. Our aim is to expand this body of knowledge by applying machine learning to pulmonary auscultation signals. Despite improvements in digital stethoscopes and attempts to find synergy between them and artificial intelligence, solutions for their use in clinical settings remain scarce. Physicians continue to infer initial diagnoses with less sophisticated means, resulting in low accuracy, leading to suboptimal patient care. To arrive at a correct preliminary diagnosis, the auscultation diagnostics need to be of high accuracy. Due to the large number of auscultations performed, data availability opens up opportunities for more effective sound analysis. In this study, digital 6-channel auscultations of 45 patients were used in various machine learning scenarios, with the aim of distinguishing between normal and abnormal pulmonary sounds. Audio features (such as fundamental frequencies F0-4, loudness, HNR, DFA, as well as descriptive statistics of log energy, RMS and MFCC) were extracted using the Python library Surfboard. Windowing, feature aggregation, and concatenation strategies were used to prepare data for machine learning algorithms in unsupervised (fair-cut forest, outlier forest) and supervised (random forest, regularized logistic regression) settings. The evaluation was carried out using 9-fold stratified cross-validation repeated 30 times. Decision fusion by averaging the outputs for a subject was also tested and found to be helpful. Supervised models showed a consistent advantage over unsupervised ones, with random forest achieving a mean AUC ROC of 0.691 (accuracy 71.11%, Kappa 0.416, F1-score 0.675) in side-based detection and a mean AUC ROC of 0.721 (accuracy 68.89%, Kappa 0.371, F1-score 0.650) in patient-based detection.

Early repolarization pattern on ECG predicts worse outcomes in patients hospitalized due to chronic heart failure decompensation.

BACKGROUND: To improve the outcomes of patients with chronic heart failure (CHF), it is important to identify reliable prognostic tools. Early repolarization pattern (ER) on 12­lead electrocardiogram (ECG) is a predictor of worse outcomes, which has been widely researched in the general population but not in the CHF population. OBJECTIVE: To evaluate the incidence and prognostic value of ER and compare its prognostic significance with other non-invasive diagnostic methods for CHF outcomes and hospital readmissions. METHODS: The study included 301 patients (166 men and 135 women) hospitalized for CHF decompensation. CHF diagnosis was confirmed according to the current guidelines. The patients underwent standard tests and impedance cardiography (ICG) at enrollment and on the day of discharge. RESULTS: Thirty-one confirmed ER cases (10.3%) were enrolled. During a median follow-up period of 18 months, 128 cardiac-related deaths were observed (42.5%), with 23 (74.2%) and 105 (38.9%) patients in the ER and non-ER groups, respectively (p < 0.001). The ER group had more readmissions than the non-ER group did at 6-months (2 [1, 2] vs. 1 [1, 2]; p=0.04) and 12-months (3 [2-4] vs. 2 [1-3]; p<0.001). ER on ECG (hazard ratio [HR] 2.59; 95% confidence interval [CI] 1.64-4.07; p<0.001), N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels ≥425.5 pmoL/L (HR 5.1; 95% CI 3.33-7.83; p < 0.001), thoracic fluid content (TFC) ≥36.9 1/kΩ (HR 4.6; 95% CI 2.7-7.85, p < 0.001), and left ventricular ejection fraction (LVEF) ≤40% (HR 4.94; 95% CI 2.83-8.65; p < 0.001) were independently and significantly associated with cardiac death. CONCLUSIONS: The combination of ER, LVEF ≤40%, NT-proBNP, or TFC provides an incremental prognostic value for cardiac-related death in patients with CHF.

Single-Center Study in Lithuania to Evaluate the Role of Transthoracic Impedance Cardiography in the Diagnosis and Outcome Evaluation of 301 Patients with Chronic Heart Failure Exacerbation.

BACKGROUND Scientific data regarding transthoracic impedance cardiography (ICG) parameters and its utility in patients with heart failure (HF) remains controversial. This study from a single center in Lithuania aimed to evaluate the role of ICG in the diagnosis and outcome evaluation of patients who were admitted to the hospital due to HF exacerbation. MATERIAL AND METHODS The sample consisted of 301 consecutive patients with a previous chronic HF diagnosis (166 men, 135 women) hospitalized for HF flare-ups. ICG data were compared to other noninvasive HF diagnostic tests. Data about patient outcomes were gathered from the Lithuanian Medical Record Database. RESULTS A weak correlation of amino-terminal pro-brain natriuretic peptide (NT-proBNP) with thoracic fluid content (TFC) and thoracic fluid content index (TFCI) was found (r=0.204, P<0.001 and r=0.207, P<0.001, respectively). There was weak to moderate correlation of 6-min walk distance with main ICG data. There was weak correlation between left ventricular ejection fraction (LVEF) with TFCI (r=-0.163, P=0.005), systolic index (r=-0.137, P=0.017), and systolic time ratio (r=0.236, P<0.001). By multivariate Cox proportional analysis, the following parameters were independently associated with cardiac death (P<0.001): NT-proBNP ≥425.5 pmoL/L (hazard ratio (HR), 5.104, 95% confidence interval (CI) 3.326-7.832), TFC ≥36.9 1/kOhm (HR, 4.604, 95% CI 2.701-7.849), LVEF ≤40% (HR, 4.942, 95% CI 2.8256-8.647). CONCLUSIONS The combination of non-invasively measured TFC, LVEF, and NT-proBNP showed great prognostic value for predicting readmissions and cardiac death in patients with HF.

SARS-CoV-2 Seroprevalence in Healthcare Workers of Kaunas Hospitals during the First Wave of the COVID-19 Pandemic.

Background and objective: Serologic testing is a useful additional method for the diagnosis of COVID-19. It is also used for population-based seroepidemiological studies. The objective of the study was to determine SARS-CoV-2 seroprevalence in healthcare workers of Kaunas hospitals and to compare two methods for specific SARS-CoV-2 antibody testing. Materials and Methods: A total of 432 healthcare workers in Kaunas hospitals were enrolled in this study. Each participant filled a questionnaire including questions about their demographics, contact with suspected or confirmed COVID-19, acute respiratory symptoms, and whether they contacted their general practitioner, could not come to work, or had to be hospitalized. Capillary blood was used to test for SARS-CoV-2 specific immunoglobulin G (IgG) and immunoglobulin M (IgM) a lateral flow immunoassay. Serum samples were used to test for specific IgG and IgA class immunoglobulins using semiquantitative enzyme-linked immunosorbent assay (ELISA) method. Results: 24.77% of study participants had direct contact with a suspected or confirmed case of COVID-19. A total of 64.81% of studied individuals had at least one symptom representing acute respiratory infection, compatible with COVID-19. Lateral flow immunoassay detected SARS-CoV-2 specific IgG class immunoglobulins in 1.16% of the tested group. Fever, cough, dyspnea, nausea, diarrhea, headache, conjunctivitis, muscle pain, and loss of smell and taste predominated in the anti-SARS-CoV-2 IgG-positive group. Using ELISA, specific IgG were detected in 1.32% of the tested samples. Diarrhea, loss of appetite, and loss of smell and taste sensations were the most predominant symptoms in anti-SARS-CoV-2 IgG-positive group. The positive percent agreement of the two testing methods was 50%, and negative percent agreement was 99.66%. Conclusions: 1.16% of tested healthcare workers of Kaunas hospitals were anti-SARS-CoV-2 IgG-positive. The negative percent agreement of the lateral flow immunoassay and ELISA exceeded 99%.

Role of Multimodal Analgesia in the Evolving Enhanced Recovery after Surgery Pathways.

Enhanced recovery after surgery (ERAS) are specially designed multimodal perioperative care pathways which are intended to attain and improve rapid recovery after surgical interventions by supporting preoperative organ function and attenuating the stress response caused by surgical trauma, allowing patients to get back to normal activities as soon as possible. Evidence-based protocols are prepared and published to implement the conception of ERAS. Although they vary amongst health care institutions, the main three elements (preoperative, perioperative, and postoperative components) remain the cornerstones. Postoperative pain influences the quality and length of the postoperative recovery period, and later, the quality of life. Therefore, the optimal postoperative pain management (PPM) applying multimodal analgesia (MA) is one of the most important components of ERAS. The main purpose of this article is to discuss the concept of MA in PPM, particularly reviewing the use of opioid-sparing measures such as paracetamol, nonsteroid anti-inflammatory drugs (NSAIDs), other adjuvants, and regional techniques.

Diagnostic and Outcome Prediction Value of Transthoracic Impedance Cardiography in Heart Failure Patients During Heart Failure Flare-Ups.

BACKGROUND This study aimed at evaluating the diagnostic and outcome prediction value of transthoracic impedance cardiography (ICG) in heart failure (HF) patients admitted for in-hospital treatment due to flare-ups of their condition. MATERIAL AND METHODS In total, 120 patients of intensive care units who were admitted due to HF flare-ups were involved to the study. The findings of ICG were compared to data obtained by other methods used for diagnosing HF. RESULTS Statistically significant (p<0.001) results were obtained when evaluating differences in ICG data between admission and discharge from the intensive care unit. In addition, a correlation was detected between brain natriuretic peptide (BNP) and thoracic fluid content index (r=0.4, p<0.001). Differences in ICG values, and BNP data emerged after the participants were grouped according to NYHA classes (p<0.05). The evaluation of lethal outcome during 6 months after the discharge yielded statistically significant results: BNP ≥350 pg/mL (Odds Ratio (OR) 4.4), thoracic fluid content ≥34 1/kOhm (OR 4.3), and systolic time ratio ≥0.55 (OR 2.9), p<0.05. CONCLUSIONS ICG data might be applied for the diagnosis and prognosis of HF, although the links between ICG and HF need further evaluation.

Applicability of Impedance Cardiography During Heart Failure Flare-Ups.

BACKGROUND Heart failure (HF) accounts for about 5% of all causes of urgent hospital admissions, and the overall mortality of HF patients within 1 year after hospitalization is 17-45%. Transthoracic impedance cardiography (ICG) is a safe, non-invasive diagnostic technique that helps to detect various parameters that define different cardiac functions. The aim of this study was to investigate the value of ICG parameters in patients hospitalized due to HF flare-ups. MATERIAL AND METHODS The study included 60 patients (24 women and 36 men) who were admitted to intensive care units because of an acute episode of HF without signs of myocardial infarction. The diagnosis of HF as the main reason for hospitalization was verified according to the universally accepted techniques. ICG data were compared to those obtained via other HF diagnostic techniques. RESULTS A moderately strong relationship was found between the ejection fraction (EF) and the systolic time ratio (STR) r=-0.4 (p=0.002). Findings for STR and thoracic fluid content index (TFCI) differed after dividing the subjects into groups according to the EF (p<0.05). A moderately strong relationship was found between brain natriuretic peptide and TFCI r=0.425 (p=0.001), left cardiac work index (LCWI) r=-0.414 (p=0.001). Findings for TFCI, LCWI, and cardiac output differed after dividing the subjects into groups according to HF NYHA classes (p<0.05). CONCLUSIONS Transthoracic impedance cardiography parameters could be applied for the diagnostics and monitoring of HF, but further studies are required to evaluate the associations between ICG findings and HF.

Impedance plethysmography as an alternative method for the diagnosis of peripheral arterial disease.

BACKGROUND AND OBJECTIVE: In the diagnosis of peripheral artery disease (PAD), the ankle-brachial index (ABI) is considered as the standard, and other noninvasive methods have received too little attention. Therefore, the aim of the study was to determine the diagnostic accuracy of impedance plethysmography in diagnosing PAD and to compare this method with other methods. MATERIALS AND METHODS: A total of 66 patients with a mean age of 76.1±9.6 years who had been treated for various cardiovascular diseases at Kaunas Clinical Hospital during 2011-2012 were enrolled into the study. All the patients were screened for PAD. Impedance plethysmography was performed with a new-generation Niccomo™ device. The receiver operating characteristic analysis was employed to determine the diagnostic accuracy of 4 parameters of impedance plethysmography: crest time (CT), crest width (CW), pulse amplitude (Pampl), and alternating blood flow (ABF). RESULTS: There were a significant correlation between the ABI and the CT (r=-0.699, P<0.001), between the ABI and the ABF (r=0.552; P<0.001), and between the ABI and the Pampl only among men (r=0.652; P<0001). No correlation was found between the ABI and the CW. Among all the parameters, the CT had the highest sensitivity and specificity (73.2% and 96.0%, respectively). Other parameters had the following sensitivities and specificities: ABF, 61.0% and 96.0%; and Pampl, 90.0% and 20.0%, respectively. CONCLUSIONS: Impedance plethysmography, especially its parameter CT, is an alternative noninvasive method in diagnosing PAD and could be used for the screening of patients with PAD.

[Diagnostic capabilities of impedance cardiography method in pulmonary hypertension]. / Impedanskardiografijos metodo galimybes diagnozuojant plauciu hipertenzija.

UNLABELLED: THE OBJECTIVE OF THIS STUDY was to investigate the associations among clinical, impedance cardiography, echocardiography, and chest roentgenography data in diagnosis of pulmonary hypertension for patients with cardiovascular and pulmonary diseases. MATERIAL AND METHODS: Pulmonary artery pressure was measured by impedance cardiography method in 181 patients: 80 patients with cardiovascular pathology when pulmonary hypertension was determined by echocardiography, 69 patients with cardiovascular pathology when pulmonary hypertension was not observed using echocardiography, 19 patients with pulmonary pathology when pulmonary hypertension was determined by echocardiography, and 13 patients with pulmonary pathology when pulmonary hypertension was not observed using echocardiography. Clinical data, parameters of impedance cardiography, echocardiography, and chest roentgenography were evaluated. RESULTS: Pulmonary hypertension (impedance cardiography) was diagnosed by computed mean blood pressure in pulmonary artery with a sensitivity and specificity of 72% and 90%, respectively, and by systolic blood pressure with a sensitivity and specificity of 96% and 90%, respectively. A mathematical model of binary regression was developed with a 96.7% accuracy to diagnose pulmonary hypertension. The most important parameters of impedance cardiography were systolic blood pressure in pulmonary artery and systolic time index. CONCLUSIONS: Mean and systolic blood pressures in the pulmonary artery, assessed by a computerized impedance cardiogram, are diagnostically valuable parameters. In diagnostic algorithms of pulmonary hypertension, the following features can be used: atrial fibrillation; thrombosis of deep veins; dyspnea; cyanosis; accent of II tone at the auscultation point of the pulmonary valve; systolic murmur at the tricuspid valve area; increased diameter of the pulmonary artery more than ≥ 18 mm on chest x-ray; increased diameter of the right ventricle; systolic blood pressure in the pulmonary artery and systolic time index measured by impedance cardiography method.

[Evaluation of systolic pressure in pulmonary artery by using impedance cardiography method]. / Sistolinio spaudimo plauciu arterijoje vertinimas impedanskardiografijos metodu.

OBJECTIVE: The methods of cardioechoscopy and heart catheterization are commonly used for diagnosis of pulmonary arterial hypertension in clinical practice. The aim of this study was to assess the diagnostic efficacy of impedance cardiography as safe, non-invasive, and cheap method for detection of pulmonary arterial hypertension. MATERIAL AND METHODS: Pulmonary artery systolic pressure was measured by impedance cardiography method in 109 patients: 41 patients with cardiovascular pathology when pulmonary arterial hypertension was determined by cardioechoscopy; 33 patients with cardiovascular pathology when using cardioechoscopy pulmonary arterial hypertension was not observed; 20 patients with pulmonary pathology when pulmonary arterial hypertension was determined by cardioechoscopy; 15 patients with pulmonary pathology when using cardioechoscopy pulmonary arterial hypertension was not observed. Cardioechoscopy results were compared with the results of impedance cardiography. RESULTS: We found a strong correlation between the data obtained by cardioechoscopy and impedance cardiography methods (r = 0.836, p = 0.0001). There was no statistically significant difference in the distributions of cardioechoscopy and impedance cardiography data (p = 0.915), and statistically significant difference was observed between the data of patients with pulmonary arterial hypertension and patients with normal pulmonary artery systolic pressure (p = 0.0001). CONCLUSIONS: After determining the correlation between cardioechoscopy and impedance cardiography methods (r = 0.836, p = 0.0001), computerized impedance cardiography should be considered as an informative method for diagnosis of pulmonary arterial hypertension.

[Pulmonary hypertension: the issues of diagnosis and treatment]. / Plauciu hipertenzija. Diagnostikos ir gydymo aktualijos.

Pulmonary hypertension is not a rare pathology that is met in a doctor's practice. It has been defined as a mean pulmonary artery pressure >25 mmHg at rest or >30 mmHg at exercise, or by a systolic pulmonary artery pressure >40 mmHg measured by echo-Doppler. The article analyzes pulmonary arterial hypertension, especially primary one, and its classification, diagnosis, and possibilities for medication. The major role in pathogenesis is ascribed for in situ thrombosis, intimal and adventitial proliferation and smooth muscle hypertrophy. Prostacyclin analogues, nitric oxide, calcium channel blockers and endothelin-1 receptor blockers are the most important medicines, which decrease pressure in the pulmonary artery. The clinical case of the 63-year-old woman, who was ill with severe primary pulmonary arterial hypertension, is described in the article.