A New Method to Predict Postoperative Lung Function: Quantitative Breath Sound Measurements

Factors affecting prediction accuracy of postoperative FEV1 and DL,CO in patients undergoing lung resection

INTRODUCTION

Despite significant development in systemic therapy and radiotherapy, surgery is still the cornerstone for curative lung cancer treatment. Although predicted postoperative function (ppo) somewhat exactly correlates with actual postoperative function bigger differences may be a cause of serious clinical outcome.

Effects of spinal deformities on lung development in children: a review

Scoliosis before the age of 5 years is referred to as early-onset scoliosis (EOS). While causes may vary, EOS can potentially affect respiratory function and lung development as children grow. Moreover, scoliosis can lead to thoracic insufficiency syndrome when aggravated or left untreated. Therefore, spinal thoracic deformities often require intervention in early childhood, and solving these problems requires new methods that include the means for both deformity correction and growth maintenance. Therapeutic strategies for preserving the growing spine and thorax include growth rods, vertically expandable titanium artificial ribs, MAGEC rods, braces and casts. The goals of any growth-promoting surgical strategy are to alter the natural history of cardiorespiratory development, limit the progression of underlying spondylarthrosis deformities and minimize negative changes in spondylothorax biomechanics due to the instrumental action of the implant. This review further elucidates EOS in terms of its aetiology, pathogenesis, pathology and treatment.

Predicting Pulmonary Function From the Analysis of Voice: A Machine Learning Approach

Introduction

To self-monitor asthma symptoms, existing methods (e.g. peak flow metre, smart spirometer) require special equipment and are not always used by the patients. Voice recording has the potential to generate surrogate measures of lung function and this study aims to apply machine learning approaches to predict lung function and severity of abnormal lung function from recorded voice for asthma patients.

Methods

A threshold-based mechanism was designed to separate speech and breathing from 323 recordings. Features extracted from these were combined with biological factors to predict lung function. Three predictive models were developed using Random Forest (RF), Support Vector Machine (SVM), and linear regression algorithms: (a) regression models to predict lung function, (b) multi-class classification models to predict severity of lung function abnormality, and (c) binary classification models to predict lung function abnormality. Training and test samples were separated (70%:30%, using balanced portioning), features were normalised, 10-fold cross-validation was used and model performances were evaluated on the test samples.

Results

The RF-based regression model performed better with the lowest root mean square error of 10·86. To predict severity of lung function impairment, the SVM-based model performed best in multi-class classification (accuracy = 73.20%), whereas the RF-based model performed best in binary classification models for predicting abnormal lung function (accuracy = 85%).

Conclusion

Our machine learning approaches can predict lung function, from recorded voice files, better than published approaches. This technique could be used to develop future telehealth solutions including smartphone-based applications which have potential to aid decision making and self-monitoring in asthma.

Changes in Forced Expiratory Volume in 1 Second after Anatomical Lung Resection according to the Number of Segments

Background

Although various methods are already used to calculate predicted postoperative forced expiratory volume in 1 second (FEV₁) based on preoperative FEV₁ in lung surgery, the predicted postoperative FEV₁ is not always the same as the actual postoperative FEV₁. Observed postoperative FEV₁ values are usually the same or higher than the predicted postoperative FEV₁. To overcome this issue, we investigated the relationship between the number of resected lung segments and the discordance of preoperative and postoperative FEV₁ values.

Methods

From September 2014 to May 2020, the data of all patients who underwent anatomical lung resection by video-assisted thoracoscopic surgery (VATS) were gathered and analyzed retrospectively. We investigated the association between the number of resected segments and the differential FEV₁ (a measure of the discrepancy between the predicted and observed postoperative FEV₁) using the t-test and linear regression.

Results

Information on 238 patients who underwent VATS anatomical lung resection at Kyung Hee University Hospital at Gangdong and by DH. Kim for benign and malignant disease was collected. After applying the exclusion criteria, 114 patients were included in the final analysis. In the multiple linear regression model, the number of resected segments showed a positive correlation with the differential FEV₁ (Pearson r=0.384, p<0.001). After adjusting for multiple covariates, the differential FEV₁ increased by 0.048 (95% confidence interval, 0.023–0.073) with an increasing number of resected lung segments (R²=0.271, p<0.001).

Conclusion

In this study, after pulmonary resection, the number of resected segments showed a positive correlation with the differential FEV₁.

Predicting Postoperative Lung Function Following Lung Cancer Resection: A Systematic Review and Meta-analysis

BACKGROUND

Lung resection remains the gold standard treatment for early stage lung cancer; prediction of postoperative lung function is a key selection criterion for surgery with the aim of determining risk of postoperative dyspnoea. We aimed to identify the different prediction techniques used, and compare their accuracy.

METHODS

A systematic review and meta-analysis sought to synthesise studies conducted that assess prediction of postoperative lung function up to 18/02/2018 (n = 135). PROBAST was used to assess risk of bias in studies, 17 studies were judged to be at low risk of bias.

FINDINGS

Meta-analysis revealed CT volume and density measurement to be the most accurate (mean difference 71 ml) and precise (standard deviation 207 ml) of the reported techniques used for predicting FEV1; evidence for predicting gas transfer was lacking.

INTERPRETATION

The evidence suggests using CT volume and density is the preferred technique in the prediction of postoperative FEV1. Further studies are required to ensure that the methods and thresholds we propose are linked to patient reported outcomes.

FUNDING

Salary support for NKO, RM, PN, BN, and AMT was provided by University Hospitals Birmingham NHS Foundation Trust.

Predicting Lung Function Following Lobectomy: A New Method to Adjust for Inherent Selection Bias

BACKGROUND

Predictions that overestimate post-lobectomy lung function are more likely than underestimates to lead to lobectomy. Studies of post-lobectomy lung function have included only surgical patients, so overestimates are overrepresented. This selection bias has led to incorrect estimates of prediction bias, which has led to inaccurate threshold values for determining lobectomy eligibility.

OBJECTIVE

The objective of this study was to demonstrate and adjust for this selection bias in order to arrive at correct estimates of prediction bias, the 95% limits of agreement, and adjusted threshold values for determining when exercise testing is warranted.

METHODS

We conducted a retrospective study of patients evaluated for lobectomy. We used multiple imputations to determine postoperative results for patients who did not have surgery because their predicted postoperative values were low. We combined these results with surgical patients to adjust for selection bias. We used the Bland-Altman method and the bivariate normal distribution to determine threshold values for surgical eligibility.

RESULTS

Lobectomy evaluation was performed in 114 patients; 79 had lobectomy while 35 were ineligible based on predicted values. Prediction bias using the Bland-Altman method changed significantly after controlling for selection bias. To achieve a postoperative FEV1 > 30% and DLCO ≥30%, a predicted FEV1 > 46% and DLCO ≥53% were required. Compared to current guidelines, using these thresholds would change management in 17% of cases.

CONCLUSION

The impact of selection bias on estimates of prediction accuracy was significant but can be corrected. Threshold values for determining surgical eligibility should be reassessed.

Predictors of long-term compensatory response of pulmonary function following major lung resection for non-small cell lung cancer

BACKGROUND AND OBJECTIVE

Long-term pulmonary function which might include compensatory response (CR) significantly influences quality of life of long-term survivor after major lung resection. We investigated long-term pulmonary function after major lung resection.

METHODS

A total of 137 patients who had undergone lobar resection for non-small cell lung cancer (NSCLC) from May 2013 to June 2014 had spirometry at 10-14 months after surgery. Actual post-operative forced expiratory volume in 1 s (FEV₁ ) (FEV_1apo )/predicted post-operative FEV₁ (FEV_1ppo ), actual post-operative forced vital capacity (FVC) (FVC_apo )/predicted post-operative FVC (FVC_ppo ), its relationship with clinicopathological factors and immunohistochemistry for pro-surfactant protein C (pro-SPC), thyroid transcription factor-1 (TTF-1) and vascular endothelial growth factor receptor 2 (VEGFR2) were investigated.

RESULTS

FEV_1apo /FEV_1ppo showed strong correlation with FVC_apo /FVC_ppo (r = 0.628; P < 0.001). We defined greater CR as both FEV_1apo /FEV_1ppo and FVC_apo /FVC_ppo were >120%. Greater CR was significantly associated with decreased smoking index (P < 0.001) and greater resected subsegments (P = 0.037). The never-smoker group revealed significantly greater CR compared with the smoker group in both FEV_1apo /FEV_1ppo (119.9 ± 12.5% vs 107.5 ± 14.2%; P = 0.030) and FVC_apo /FVC_ppo (117.9 ± 9.98% vs 107.2 ± 13.1%; P = 0.046) in case-matched comparison. The expression of pro-SPC, TTF-1 and VEGFR2 in the normal lung parenchyma of greater CR group was significantly higher than those of lesser CR group (P < 0.001 for each). In addition, pro-SPC, TTF-1 and VEGFR2 expressions showed a significant correlation to the degree of CR especially in the smoker group (r = 0.631, 0.705 and 0.732, respectively; P < 0.001 for each).

CONCLUSION

Our data suggest that smokers may develop lesser long-term CR after major lung resection. Decreased expression of pro-SPC, TTF-1 and VEGFR2 may indicate decreased capacity of CR, especially in patients who smoke.

Regional Lung Sound Asynchrony in Chronic Obstructive Pulmonary Disease Patients

<b><i>Background:</i></b> Regional lung sound distribution in chronic obstructive pulmonary disease (COPD) is reported to be asynchronous. Mathematical analyses using vibration response imaging (VRI), such as left and right lung asynchrony (gap index; GI) and regional lung asynchrony (asynchrony score; AS), are useful measures to evaluate lung sound asynchrony. <b><i>Objectives:</i></b> The aim of this study was to investigate the association of lung sound asynchrony with pulmonary functions and emphysematous lesions in COPD patients. <b><i>Methods:</i></b> VRI recordings and pulmonary function tests were performed in 46 stable male COPD patients and in 40 healthy male smokers. Lung sound asynchrony was evaluated using GI, AS of the left and right lung (AS L-R), and AS of the upper and lower lung (AS U-L). In 38 patients, computed tomography taken within 6 months was available and analyzed. <b><i>Results:</i></b> AS L-R and AS U-L were significantly higher in COPD patients than in healthy smokers, with no significant difference in GI. There were no significant correlations with either AS and pulmonary functions, excluding a negative correlation between AS U-L and diffusion capacity. Although there were no significant correlations between both AS and severity of emphysema, significant positive correlations were observed between heterogeneity of emphysematous lesions and AS L-R (&#x03C1; = 0.38, p < 0.05) or AS U-L (&#x03C1; = 0.51, p < 0.005). <b><i>Conclusions:</i></b> Regional lung sounds are distributed more asynchronously in COPD patients than in healthy smokers, which correlates with the heterogeneous distribution of emphysematous lesions.

Chaos to randomness: distinguishing between healthy and non-healthy lung sound behaviour

Lung abnormalities and respiratory diseases increase as side effects of urban life and development. Therefore, understanding lung dynamics and its changes during the presence of abnormalities are critical in order to design more reliable tools for the early diagnosis and screening of lung pathology. The goal of this paper is to indicate the chaotic nature of normal lung sound and its transition to randomness in the presence of lung disease. The latter characteristic could serve as an indicator for evaluating the recovery process for patients suffering from lung disease. To verify this idea, we compared group of healthy and non-healthy subjects and also group of non-healthy subjects before and after treatments. Chaotic and randomness indices applied to lung sound signals which captured by multichannel data acquisition system. Results show that the normal lung displays chaotic dynamics. However, with the increase in lung abnormality, moves toward more random behaviour and away from its original chaotic state. Also, chaotic and randomness indices indicate their abilities to classify healthy and non-healthy lung sounds.

The correlation between lung sound distribution and pulmonary function in COPD patients

Background

Regional lung sound intensity in chronic obstructive pulmonary disease (COPD) patients is influenced by the severity and distribution of emphysema, obstructed peripheral airways, and altered ribcage and diaphragm configurations and movements due to hyperinflation. Changes in the lung sound distribution accompanied by pulmonary function improvements in COPD patients were observed after bronchodilator inhalation. We investigated the association of lung sound distribution with pulmonary functions, and the effects of emphysematous lesions on this association. These studies were designed to acquire the basic knowledge necessary for the application of lung sound analysis in the physiological evaluation of COPD patients.

Methods

Pulmonary function tests and the percentage of upper- and lower-lung sound intensity (quantitative lung data [QLD]) were evaluated in 47 stable male COPD patients (54 - 82 years of age). In 39 patients, computed tomography taken within 6 months of the study was available and analyzed.

Results

The ratio of lower QLD to upper QLD showed significant positive correlations with FEV₁ %predicted (%FEV₁; ρ = 0.45, p<0.005) and MEF₅₀ %predicted (%MEF₅₀; ρ = 0.46, p<0.005). These correlations were not observed in COPD patients with dominant emphysema (% low attenuation area >40%, n = 20) and were stronger in less emphysematous patients (n = 19, %FEV₁; ρ = 0.64, p<0.005, %MEF₅₀; ρ = 0.71, p<0.001).

Conclusions

In COPD patients, the ratio of lower- to upper-lung sound intensities decreased according to the severity of obstructive changes, although emphysematous lesions considerably affected lung sound distribution.