Lung sounds in pneumonia
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Key Lung Sounds in Pneumonia: Crackles, Rhonchi, and Adventitious Sounds
Lung sounds in pneumonia are notably different from those in healthy individuals. The most common abnormal sounds detected in pneumonia patients are inspiratory crackles, expiratory crackles, and rhonchi. Studies have shown that inspiratory crackles are present in about 81% of pneumonia patients compared to only 28% of healthy controls, while expiratory crackles are found in 65% of pneumonia cases versus 9% in controls. Rhonchi are also more frequent in pneumonia patients (19%) and absent in healthy individuals. These adventitious sounds are key indicators for diagnosing pneumonia using lung auscultation .
Automated and AI-Based Lung Sound Analysis for Pneumonia Detection
Recent advances in technology have enabled the use of automated systems and artificial intelligence (AI) to analyze lung sounds for pneumonia diagnosis. Computerized lung sound analyzers can objectively quantify and characterize pneumonia-related sounds, providing an "acoustic pneumonia score" that helps distinguish pneumonia patients from healthy controls with high sensitivity and specificity . Machine learning models, such as support vector machines (SVM) and gradient boosting algorithms, have demonstrated high accuracy (up to 97-99%) in classifying lung sounds and identifying pneumonia, especially when using features like Mel Frequency Cepstral Coefficients (MFCC) and energy parameters 347.
Deep learning approaches, including CNN-LSTM models, have also been used to analyze spectrograms of lung sounds, achieving promising results in distinguishing pneumonia from healthy cases . Additionally, AI models that incorporate both cardiopulmonary and lung sounds, after filtering out environmental noise, have shown improved diagnostic performance .
Digital Auscultation and Machine Learning in Pediatric Pneumonia
Digital auscultation, combined with automated machine learning algorithms, is being explored to improve pneumonia diagnosis in children, particularly in low-resource settings. These systems can classify lung sounds as normal, crackles, wheeze, or both, with moderate sensitivity and specificity compared to expert pediatricians . However, systematic reviews highlight that while digital auscultation shows potential, there is still limited robust evidence for its accuracy in pediatric pneumonia, and more well-designed studies are needed 106.
Special Considerations: COVID-19 and Interstitial Pneumonia
Automated lung sound analysis has also been applied to detect interstitial pneumonia, such as that seen in COVID-19 patients. Algorithms can identify characteristic "velcro-like" lung sounds associated with interstitial changes, achieving diagnostic accuracy rates around 75% when compared to imaging techniques .
Conclusion
Lung sounds in pneumonia are characterized by a high prevalence of adventitious sounds, especially crackles and rhonchi. Automated and AI-based analysis of lung sounds offers objective, accurate, and non-invasive tools for pneumonia diagnosis in both adults and children. While these technologies show high promise, especially in resource-limited settings, further research and standardization are needed to fully establish their clinical utility, particularly in pediatric populations.
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