Distribution of breath sound images in patients with pneumothoraces compared to healthy subjects. Diagnostic yield of vibration response imaging technology

Body Acoustics for the Non-Invasive Diagnosis of Medical Conditions

In the past few decades, many non-invasive monitoring methods have been developed based on body acoustics to investigate a wide range of medical conditions, including cardiovascular diseases, respiratory problems, nervous system disorders, and gastrointestinal tract diseases. Recent advances in sensing technologies and computational resources have given a further boost to the interest in the development of acoustic-based diagnostic solutions. In these methods, the acoustic signals are usually recorded by acoustic sensors, such as microphones and accelerometers, and are analyzed using various signal processing, machine learning, and computational methods. This paper reviews the advances in these areas to shed light on the state-of-the-art, evaluate the major challenges, and discuss future directions. This review suggests that rigorous data analysis and physiological understandings can eventually convert these acoustic-based research investigations into novel health monitoring and point-of-care solutions.

Acoustic Methods for Pulmonary Diagnosis

Recent developments in sensor technology and computational analysis methods enable new strategies to measure and interpret lung acoustic signals that originate internally, such as breathing or vocal sounds, or are externally introduced, such as in chest percussion or airway insonification. A better understanding of these sounds has resulted in a new instrumentation that allows for highly accurate as well as portable options for measurement in the hospital, in the clinic, and even at home. This review outlines the instrumentation for acoustic stimulation and measurement of the lungs. We first review the fundamentals of acoustic lung signals and the pathophysiology of the diseases that these signals are used to detect. Then, we focus on different methods of measuring and creating signals that have been used in recent research for pulmonary disease diagnosis. These new methods, combined with signal processing and modeling techniques, lead to a reduction in noise and allow improved feature extraction and signal classification. We conclude by presenting the results of human subject studies taking advantage of both the instrumentation and signal processing tools to accurately diagnose common lung diseases. This paper emphasizes the active areas of research within modern lung acoustics and encourages the standardization of future work in this field.

17 Cases of Acupuncture Related Pneumothorax and Factors Influencing Pneumothorax

OBJECTIVES

Acupuncture is increasing in popularity as a complementary and alternative medicine. Pneumothorax is the most common and potentially serious adverse effect after acupuncture. This complication can cause fatality in the absence of rapid treatment. Here, we analyze the clinical presentation and discuss prevention of post-acupuncture pneumothorax and an approach to reducing this complication.

METHODS

Patients presenting with post-acupuncture pneumothorax in our hospital center during 2011-2015 were retrospectively analyzed. Body mass index (BMI), patient's pre-acupuncture chief complaint and disease, and the characteristics associated with pneumothorax were assessed. The diagnosis of pneumothorax was based on clinical presentation and chest radiography. Conservative treatment or thoracostomy was performed.

RESULTS

Seventeen patients (15 women and 2 men) with a mean age of 42 years (range: 18-73 years) were included; three were underweight (BMI < 18.5kg/m2), 11 patients had a healthy weight (BMI= 18.5-22.95kg/m2), one was overweight (BMI = 23- 24.95kg/m2), and two were obese (BMI ≥ 25 kg/m2). All but one case of bilateral pneumothorax had unilateral pneumothorax (right side: 6; left side: 10). Chest pain or dyspnea, or both. were the initial symptoms in all patients. Twelve patients underwent immediate thoracostomy. The patient with bilateral pneumothorax underwent right-side thoracostomy, and subsequently left-side thoracostomy, due to progression of the left-side pneumothorax. Five patients were successfully managed conservatively. All patients had an excellent outcome; all were asymptomatic and exhibited a normal chest X-ray at follow-up.

CONCLUSION

Acupuncturists must be aware that delayed diagnosis and management of pneumothorax are life-threatening, and when symptoms of possible pneumothorax arise, patients should be advised to undergo an appropriate evaluation and intervention, particularly so in those with abnormal BMI.

Evaluation of Vibration Response Imaging (VRI) Technique and Difference in VRI Indices Among Non-Smokers, Active Smokers and Passive Smokers

Background

Vibration response imaging (VRI) is a new technology for lung imaging. Active smokers and non-smokers show differences in VRI findings, but no data are available for passive smokers. The aim of this study was to evaluate the use of VRI and to assess the differences in VRI findings among non-smokers, active smokers, and passive smokers.

Material/Methods

Healthy subjects (n=165: 63 non-smokers, 56 active smokers, and 46 passive smokers) with normal lung function were enrolled. Medical history, physical examination, lung function test, and VRI were performed for all subjects. Correlation between smoking index and VRI scores (VRIS) were performed.

Results

VRI images showed progressive and regressive stages representing the inspiratory and expiratory phases bilaterally in a vertical and synchronized manner in non-smokers. Vibration energy curves with low expiratory phase and plateau were present in 6.35% and 3.17%, respectively, of healthy non-smokers, 41.07% and 28.60% of smokers, and 39.13% and 30.43% of passive smokers, respectively. The massive energy peak in the non-smokers, smokers, and passive-smokers was 1.77±0.27, 1.57±0.29, and 1.66±0.33, respectively (all P<0.001). A weak but positive correlation was observed between VRIS and smoking index.

Conclusions

VRI can intuitively show the differences between non-smokers and smokers. VRI revealed that passive smoking can also harm the lungs. VRI could be used to visually persuade smokers to give up smoking.

Vibration response imaging in healthy Japanese subjects

BACKGROUND

Vibration response imaging (VRI) records the intensity and distribution of lung sounds during the respiration cycle. Our objective was to analyze VRI findings in healthy Japanese adults.

METHODS

VRI images of 106 healthy subjects (33.7±9.6 years, 52 male and 54 female), including 67 nonsmokers and 39 asymptomatic smokers, were recorded. The regional intensity of vibrations was assessed using quantitative lung data (QLD), and VRI dynamic images by rater assessment, left and right lung asynchrony (gap index), and regional lung asynchrony (asynchrony score).

RESULTS

A dominance of total left lung QLD was observed in all subjects, and this phenomenon was more prominent in female subjects. However, there was no significant difference between the total left and total right lung QLD in smokers. Rater assessments showed that 81.1% of all subjects had a normal final assessment. Male subjects had a significantly higher percentage of good or normal assessments for all image scores, except dynamic image scoring. The asynchrony score was significantly higher in female subjects. There were no significant differences in these qualitative assessments between non-smokers and smokers.

CONCLUSIONS

Although our QLD results were similar to those of a previous report, there were discrepancies between sexes for the qualitative assessments. A significantly higher number of female subjects had abnormal images as assessed by the raters. Furthermore, significantly higher asynchrony scores were observed in female subjects. The VRI variability in sex may be considered normal among the Japanese population. This study is registered with UMIN-CTR under registration number UMIN000002355.

Vibration response imaging: a novel noninvasive tool for evaluating the initial therapeutic effect of noninvasive positive pressure ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease

BACKGROUND

The popular methods for evaluating the initial therapeutic effect (ITE) of noninvasive positive pressure ventilation (NPPV) can only roughly reflect the therapeutic outcome of a patient's ventilation because they are subjective, invasive and time-delayed. In contrast, vibration response imaging (VRI) can monitor the function of a patient's ventilation over the NPPV therapy in a non-invasive manner. This study aimed to investigate the value of VRI in evaluating the ITE of NPPV for patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

METHODS

Thirty-six AECOPD patients received VRI at three time points: before NPPV treatment (T1), at 15 min of NPPV treatment (T2), and at 15 min after the end of NPPV treatment (T4). Blood gas analysis was also performed at T1 and at 2 hours of NPPV treatment (T3). Thirty-nine healthy volunteers also received VRI at T1 and T2. VRI examination at the time point T2 in either the patients or volunteers did not require any interruption of the on-going NPPV. The clinical indices at each time point were compared between the two groups. Moreover, correlations between the PaCO2 changes (T3 vs T1) and abnormal VRI scores (AVRIS) changes (T2 vs T1) were analyzed.

RESULTS

No significant AVRIS differences were found between T1 and T2 in the healthy controls (8.51 ± 3.36 vs. 8.53 ± 3.57, P > 0.05). The AVRIS, dynamic score, MEF score and EVP score showed a significant decrease in AECOPD patients at T2 compared with T1 (P < 0.05), but a significant increase at T4 compared with T2 (P < 0.05). We also found a positive correlation (R2 = 0.6399) between the PaCO2 changes (T3 vs T1) and AVRIS changes (T2 vs T1).

CONCLUSIONS

VRI is a promising noninvasive tool for evaluating the initial therapeutic effects of NPPV in AECOPD patients and predicting the success of NPPV in the early stage.

A physical approach to the automated classification of clinical percussion sounds

Chest percussion is a traditional technique used for the physical examination of pulmonary injuries and diseases. It is a method of tapping body parts with fingers or small instruments to evaluate the size, consistency, borders, and presence of fluid/air in the lungs and abdomen. Percussion has been successfully used for the diagnosis of such potentially lethal conditions as traumatic and tension pneumothorax. This technique, however, has certain shortcomings, including limitations of the human ear and the subjectivity of the administrator, that lead to overall low sensitivity. Automation of the method by using a standardized percussion source and computerized classification of digitized signals would remove the subjective factor and other limitations of the technique. It would also enable rapid on-site diagnostics of pulmonary traumas when thorough clinical examination is impossible. This paper lays the groundwork for an objective signal classification approach based on a general physical model of a damped harmonic oscillator. Using this concept, critical parameters that effectively subdivide percussion signals into three main groups, historically known as "tympanic," "resonant," and "dull," are identified, opening the possibility for automated diagnostics of air/liquid inclusions in the thorax and abdomen. The key role of damping in forming the character of the percussion signal is investigated using a 3D thorax phantom. The contribution of the abdominal component into the complex multimode spectrum of chest percussion signals is demonstrated.

Vibration response imaging (VRI) in lung transplant recipients

BACKGROUND

In the first 6 months following lung transplantation, the most frequently occurring complications are infection, acute rejection and anastomotic dysfunction. The utility of vibration response imaging (VRI) lung images in assisting with the detection of these complications was evaluated.

OBJECTIVES

The study aimed to evaluate if VRI is a good, non-invasive method of detecting clinical problems in lung transplant (LTx) recipients during early follow-up.

METHODS

Between 06/2006 and 03/2007 all LTx patients who received transplants during the preceding 6 months at the Hannover Medical School received baseline VRI at enrollment with subsequent reassessment in combination with standard follow-up at 1, 3 and 6 months thereafter. The resulting images were analysed by two blinded reviewers.

RESULTS

Fifty-five lung transplant recipients were enrolled in the study, with 49 patients successfully completing follow-up. Device operability and patient participation occurred without significant problems. High numbers of abnormal scans were detected. According to the clinical diagnosis, 29 patients (59.2 %) were stable at all four visits. Twenty clinical problems occurred (e.g., infections, rejections, obstructions, unknown deterioration). Agreement with clinical interpretation of rejections and infections was poor. Central airway obstruction (CAO) was detected in 80% by both reviewers. Accuracy in detecting obstructions was 89%; positive predicted value and negative predicted value were 80% and 90%, respectively.

CONCLUSION

The VRI system is a non-invasive easy-to-use method with technical success and good image quality. The high number of abnormal scans makes interpretation following LTx difficult. VRI was unable to detect deterioration in graft function with the exception of ventilation disorders like central airway complications.

Effect of airflow rate on vibration response imaging in normal lungs

Background:

Evaluating the effect of airflow rate on amplitude of lung sound energy and regional distribution of lung sounds may assist in the interpretation of computerized acoustic measurements.

Objectives:

The aim of this study was to assess the effect of airflow rate on Vibration Response Imaging (VRI) measurement in healthy lungs.

Methods:

Lung sounds were recorded from 20 healthy adults in the frequency range of 150-250 Hz using 40 piezoelectric sensors positioned on the posterior chest wall. During the recordings, subjects were breathing at airflow rates ranging between 0.3 and 1.7L/s. Online visual feedback was provided using a pneumotach mouthpiece.

Results:

Amplitude of lung sound energy significantly increased with increasing airflow rate (p<0.00001, Friedman test). A strong relationship (R2=0.95) was obtained between amplitude of lung sound energy at peak inspiration and airflow rate raised to the third power. This correlation did not significantly affect normalized lung sound distribution maps at peak inspiration, especially when airflow was higher than 1.0L/s. Acoustic maps obtained at airflow rates below 0.7L/s differed from those recorded above 1.0L/s (p<0.05, Wilcoxon matched-paired signed-ranks test).

Conclusion:

These findings may be of importance when comparing healthy and diseased lungs or when monitoring changes in lung sounds during treatment follow-up.