Advanced/Novel Stenting for Pediatric Dynamic Airway Collapse.

Background Chronic obstructive pulmonary disease (COPD) is a disease characterized by diffuse airway obstruction affecting small and large airways. Airway collapse is more during expiration. Aim To investigate excessive expiratory airway collapse and its frequency in patients with COPD, with correlation to clinical and functional parameters. Patients and methods The study was carried out at Chest Department, Zagazig University Hospital during the period from August 2017 to August 2018. It included 40 patients with COPD meeting GOLD criteria. All patients underwent pulmonary function tests and low-dose computed tomography scan at three times: at end inspiration, at end expiration, and at dynamic expiration. The degree of dynamic airway collapse is evaluated and correlated with GOLD stage, clinical data, and BODE index. Results There is a negative correlation between forced expiratory volume in 1 s% predicted with the dynamic airway collapse at the arch of the aorta (r=−0.72, P=0.000), at bronchus intermedius (r=−0.06, P=0.000), and with the dynamic airway collapse at carina (r=−0.32, P=0.03). There is a significant difference among different GOLD scale categories regarding dynamic collapse at aortic arch (P=0.000) and dynamic collapse at bronchus intermedius (P=0.000), with no correlation with other physiological parameters or the need of noninvasive positive pressure ventilation or mechanical ventilation. Conclusion Dynamic airway collapse is not infrequent in patients with COPD, and it can affect patients’ pulmonary functional parameters and disease severity but does not affect the overall prognosis.

Simple SummaryAirway collapse consists of the partial/complete narrowing of an airway with subsequent restriction to the airflow. It can occur anywhere along the trachea or bronchial tree in dogs and may be present throughout the respiratory cycle (i.e., static collapse) or it may be associated with a specific phase of respiration (e.g., expiration), hence “dynamic collapse”. In dogs, the clinical signs of an airway collapse may overlap those of other respiratory diseases. This study aimed to determine whether ventilator-assisted computed tomography (CT) with images acquired at inspiration and expiration would detect static and dynamic airway collapse in dogs with spontaneous respiratory disease and to compare the CT results with those obtained with tracheobronchoscopy, a modality which is commonly used to assess the airways in anesthetized dogs. The study found that the variation in the size of the airway was more profound for the trachea, the right mainstem bronchus and the right middle lobar bronchus in dogs with an airway collapse. Static collapse was only seen in the trachea of dogs with an airway collapse. The agreement between the CT and tracheobronchoscopy results was slight to moderate. The study shows that inspiratory and expiratory CT scans can detect static and dynamic airway collapse with it having limited agreement with the tracheobronchoscopy results. Scoring systems that are tailored to the clinical manifestations of function impairments may improve the comparisons in the future.Airway collapse (AC) in dogs includes a tracheal collapse, mainstem and lobar bronchial collapse, and bronchomalacia (i.e., segmental/subsegmental bronchial collapse). The clinical presentation of AC may overlap with non-collapsible airway disease (NCAD) or another non-lower airway respiratory disease (NLARD). This study determined whether paired inspiratory (I)/expiratory (E)-breath-hold computed tomography (I/E-BH CT) can detect a static and dynamic AC in dogs with spontaneous respiratory disease and it compared the CT-derived metrics of the AC to the tracheobronchoscopy metrics. The CT-acquired I and E diameter and cross-sectional area (CSA) for the trachea, mainstem and lobar bronchi in dogs with an AC (n = 16), NCAD (16), and NLARD (19) served for a dynamic percent of the airway narrowing (%AN) calculation. A scoring system assessed the bronchomalacia. The circularity was calculated for each airway. The results were compared to the tracheobronchoscopy collapse grading. In the dogs with an AC, the %AN was larger for the trachea, right mainstem bronchus and right middle lobar bronchus when they were compared to the dogs with NCAD and NLARD. Flattening was only identified for the trachea of the AC dogs. The agreement between the CT and tracheobronchoscopy scores was 20% from trachea to the lobar bronchi and 47% for the segmental/subsegmental bronchi. Paired I/E-BH CT can detect static and dynamic AC with limited agreement with the tracheobronchoscopy metrics. Independent scoring systems that are tailored to the clinical manifestations of functional impairments are needed.

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BackgroundDisproportionate bulging of the pars membranosa into the central airway on expiration, now termed ‘excessive dynamic airway collapse’ (EDAC), has poorly characterised significance. Despite physiological arguments supporting an association between obstructive sleep apnoea (OSA) and dynamic intra-thoracic central airway collapse, this is unproven.MethodsAn audit was conducted of patients having had both a dynamic CT chest and a diagnostic polysomnogram between 2009 and 2018 and within 2 years of one another. Dynamic airway collapse was quantified by the presence of EDAC (≥75% collapse) at any of five sites plus a composite index of mean cross-sectional area (CSA) change. Linear regression models were used to assess associations between pre-defined variables.ResultsA total of 59 patients was included. Median apnoea-hypopnoea index (AHI) was 13 events/hour (IQR: 5–31 events/hour | range 0–153 events/hour). EDAC was not identified. Median composite dynamic airway collapse index was 18% (IQR: 9–30% | range: 0–63%). Unadjusted and adjusted linear regression analyses demonstrated statistically significant associations between degree of dynamic intra-thoracic central airway collapse and multiple OSA indices. In the adjusted model, every 10% worsening in dynamic airway collapse was associated with an increase in apnoea-hypopnoea index (AHI) of 5 events/hour (95% confidence interval: 0.9–10 events/hour | p = 0.019). No association was found between dynamic airway collapse and symptoms or healthcare utilisation.ConclusionsThis study supports an association between dynamic intra-thoracic central airway collapse and OSA, despite the failure to identify EDAC, which was likely due to retrospectively audited CT scans not being performed to research standards.

Evaluation of military personnel for exertional dyspnea can present a diagnostic challenge, given multiple unique factors that include wide variation in military deployment. Initial consideration is given to common disorders such as asthma, exercise-induced bronchospasm, and inducible laryngeal obstruction. Excessive dynamic airway collapse has not been reported previously as a cause of dyspnea in these individuals. To describe the clinical and imaging characteristics of military personnel with exertional dyspnea who were found to have excessive dynamic collapse of large airways during exercise. After deployment to Afghanistan or Iraq, 240 active U.S. military personnel underwent a standardized evaluation to determine the etiology of persistent dyspnea on exertion. Study procedures included full pulmonary function testing, impulse oscillometry, exhaled nitric oxide measurement, methacholine challenge testing, exercise laryngoscopy, cardiopulmonary exercise testing, and fiberoptic bronchoscopy. Imaging included high-resolution computed tomography with inspiratory and expiratory views. Selected individuals underwent further imaging with dynamic computed tomography. A total of five men and one woman were identified as having exercise-associated excessive dynamic airway collapse on the basis of the following criteria: (1) exertional dyspnea without resting symptoms, (2) focal expiratory wheezing during exercise, (3) functional collapse of the large airways during bronchoscopy, (4) expiratory computed tomographic imaging showing narrowing of a large airway, and (5) absence of underlying apparent pathology in small airways or pulmonary parenchyma. Identification of focal expiratory wheezing correlated with bronchoscopic and imaging findings. Among 240 military personnel evaluated after presenting with postdeployment exertional dyspnea, a combination of symptoms, auscultatory findings, imaging, and visualization of the airways by bronchoscopy identified six individuals with excessive dynamic central airway collapse as the sole apparent cause of dyspnea. Exercise-associated excessive dynamic airway collapse should be considered in the differential diagnosis of exertional dyspnea.

ObjectiveThe study aimed to evaluate the utility and safety of drug-induced sleep endoscopy (DISE) in infants with suspected dynamic upper airway collapse.MethodsInfants with suspected dynamic upper airway collapse were enrolled in the study. All subjects developed clinical symptoms within the first year of life. Each subject underwent both awake endoscopy (AE) and DISE. Endoscopic findings and sedation strategies for DISE were recorded. The diagnostic rate of dynamic upper airway collapse was compared between the DISE and AE. Adverse events during DISE were also recorded.Results(1) A total of 21 cases were included. The median age at the time of bronchoscopy was 4.0 months. (2) For the cases beyond neonatal age (n = 18), 16 (88.9%) received midazolam only, and 2 (11.1%) received midazolam combined with dexmedetomidine. For the neonates (n = 3), two (66.7%) received 10% chloral hydrate only, and one (33.3%) received 10% chloral hydrate combined with phenobarbital. (3) Six cases (28.6%) were diagnosed under both AE and DISE, whereas 15 cases (71.4%) were diagnosed under DISE only. The diagnostic rate was significantly higher under DISE than that under AE (100.0% vs. 28.6%, P < 0.01) in the cases with dynamic upper airway collapse. Of the cases with laryngomalacia, 3 cases (18.7%) were diagnosed under both AE and DISE, whereas 13 cases (81.3%) were diagnosed under DISE only. The diagnostic rate was significantly higher under DISE than that under AE (100.0% vs. 18.7%, P < 0.01) in the cases with laryngomalacia. Of the cases with tongue base collapse, all (100.0%) were diagnosed under both AE and DISE. Of the cases with retropalatal and hypopharynx collapse, all (100.0%) were diagnosed under DISE only. (4) One case (4.8%) developed a hypoxic episode during DISE, which was resolved by the pressurized facial mask-assisted ventilation.ConclusionsDISE was found to be a feasible and safe procedure in infants with suspected dynamic upper airway collapse. Compared with AE, DISE significantly improved the diagnostic rate of laryngomalacia and appeared to be a more reliable method to diagnose pharyngeal airway collapse, especially retropalatal and hypopharynx collapse.

Using sleep MRI, we aimed to identify static craniofacial measurements and dynamic upper airway collapse patterns associated with severe obstructive sleep apnoea (OSA) during natural sleep in age and BMI-matched patients. Nested case-control study. Sleep MRI images (3.0 Tesla scanner) and synchronised acoustic recording were used to observe patterns of dynamic airway collapse in subjects with mild and severe OSA. Midsagittal images were also used for static craniofacial measurements. Fifteen male subjects with severe OSA (mean AHI 70.3±23 events/h) were matched by age and BMI to 15 subjects with mild OSA (mean AHI 7.8±1.4 events/h). Subjects were selected from a consecutive sleep MRI study cohort. Static craniofacial measurements selected a priori included measurements that represent maxillomandibular relationships and airway morphology. Axial, sagittal and coronal views of the airway were rated for dynamic collapse at retropalatal, retroglossal and lateral pharyngeal wall regions by blinded reviewers. Bivariate analysis was used to correlate measures associated with severity of OSA using AHI. Statistical significance was set at P<0.01. Lateral pharyngeal wall collapse from dynamic sleep MRI (β=51.8, P<0.001) and upper airway length from static MRI images (β=27.2, P<0.001) positively correlated with severity of OSA. Lateral pharyngeal wall collapse and upper airway length are significantly associated with severe OSA based on sleep MRI. Assessment of these markers can be readily translated to routine clinical practice, and their identification may direct targeted surgical treatment.

Feasibility of Assessing the Abnormal Pediatric Airway using Rotational Optical Coherence Tomography. The OCT Air study.

Many horses demonstrate dynamic collapse of more than one upper respiratory tract (URT) structure during high-speed treadmill videoendoscopy (HSTV). To report the frequency of complex dynamic URT collapse in harness racehorses and determine if an association exists between occurrence of certain disorders. Retrospective study of 99 Standardbreds and Coldblooded trotters that had one or more dynamic URT disorders identified during HSTV between 1998 and 2006. The horses underwent HSTV using a protocol that included periods of free head carriage and poll flexion until fully fatigued. Dynamic abnormalities were classified as: dynamic laryngeal collapse (DLC) associated with poll flexion; axial deviation of the aryepiglottic folds (ADAF); dynamically flaccid epiglottis (FE); caudal palatal instability (PI); intermittent dorsal displacement of the soft palate (iDDSP); pharyngeal collapse (PC); alar fold collapse (AFC) and nasal flutter (NF). Cluster analysis and Fisher's exact test was performed between groups. Significance was set at P<0.05. The overall incidence of complex dynamic URT collapse was 69.7%. Axial deviation of the aryepiglottic folds was significantly associated with PI (P<0.0001) and FE (P<0.0001); iDDSP was significantly associated with PI (P = 0.004) only. Dynamic laryngeal collapse associated with poll flexion was significantly associated with FE (P = 0.002). Cluster analysis confirmed strong associations between the above diagnosis groups and weaker associations between others. Caudal PI seems to result in 2 diagnosis groupings: one that leads to ADAF and the other to iDDSP. Dynamic collapse of the margins of the epiglottis was a common finding in this study strongly associated with DLC, PI and ADAF. The associations between certain dynamic diagnoses identified in this study seems best explained as due to local anatomic and functional weaknesses that influence other structures through the Bernouilli principle, rather than being due to a generalised neurological disorder.

When airway obstruction is due to extraluminal compression and/or dynamic collapse, metal and silicone rubber prosthetic stents may stabilize the affected airway. Through a rigid bronchoscope, we inserted three metal stents in two patients and 18 silicone stents in 15 adult patients with symptomatic tracheobronchial compression and dynamic airway collapse. The underlying cause was malignancy in three patients; benign tracheobronchial malacia in three patients, two of whom refused surgical resection; and tracheobronchial stenosis that developed at the anastomotic site following lung transplantation in 11 patients. Clinical status and lung function studies were analyzed before and after stent insertion. Following stent insertion, airway diameter at least doubled and near normal patency of the affected tracheobronchial tree was achieved in every patient using stents of axial length 4 to 5 cm. The stents were well tolerated clinically, and all patients noted immediate relief of dyspnea. Following stent insertion, the forced vital capacity (FVC) increased from 64 +/- 21% predicted (mean +/- 1 SD) to 73 +/- 19% predicted, p less than 0.1; the forced expiratory volume in 1 s (FEV1) from 49 +/- 25% predicted to 72 +/- 26% predicted, p less than 0.02; the ratio of the FEV1/FVC from 59 +/- 16% to 78 +/- 15%, p less than 0.01; and the maximum flow at 50% expired FVC from 38 +/- 26% predicted to 72 +/- 31% predicted, p less than 0.01.

In neonatal and pediatric patients who require long-term endotracheal intubation, the subglottic mucosa is most susceptible to injury from the endotracheal tube. At present, there is no diagnostic modality to identify early signs of subglottic mucosal pathology. Fourier-domain optical coherence tomography (FD-OCT) is a minimally-invasive imaging modality which acquires high-resolution, 3D cross-sectional images of biological tissue. FD-OCT of the neonatal and pediatric airways was conducted to evaluate subglottic microanatomy and histopathologic changes associated with prolonged intubation. FD-OCT of the larynx, subglottis and proximal trachea was conducted in pediatric and neonatal patients. OCT image sets were analyzed by anatomic categorization (airway level), tissue segmentation and mucosa micrometry in MATLAB. Subsequently, OCT data sets were rendered into digital 3D airway models in Mimics software. We report original methods for subglottic OCT image processing and analysis.

This report describes a case of dynamic inspiratory airway collapse concomitant with subglottic stenosis in a patient who previously underwent tracheostomy that led to repeated post-operative extubation failure. A 43-year-old woman who had undergone tracheostomy 25 years previously was admitted to our intensive-care unit (ICU) after coronary artery bypass graft surgery. On postoperative day (POD) 0, she was extubated, but stridor was observed. We suspected upper airway obstruction and she was therefore reintubated. Before reintubation, urgent laryngotracheoscopy revealed dynamic inspiratory airway collapse and obstruction concomitant with subglottic stenosis. Preoperative computed tomography showed mild subglottic stenosis. Although intravenous corticosteroids were administered to prevent tracheal mucosal edema and a cuff leak test was confirmed to be negative, she developed extubation failure on POD6. On POD12, we performed tracheostomy to reduce mechanical irritation from the endotracheal tube. Mechanical ventilation was withdrawn and she discharged from the ICU. On POD33, her tracheostomy tube was removed and she remained clinically asymptomatic. We should be aware of the history of tracheostomy, especially at high tracheostomy sites, even in the absence of respiratory symptoms as risk factors for dynamic inspiratory airway collapse concomitant with subglottic stenosis contributing to repeated respiratory failure after extubation. J. Med. Invest. 70 : 301-305, February, 2023.

INTRODUCTION:The prevalence of EDAC (Excessive Dynamic Airway Collapse) has not been studied specifically in patients with chronic obstructive pulmonary disease (COPD).OBJECTIVE:The aim of this study was to investigate the prevalence of EDAC in COPD and to determine whether there are clinical factors or functional variables that could influence the degree of expiratory collapse of central airways.METHODS:Prospective observational study of a group of patients with COPD. The degree of tracheobronchial collapse was evaluated by low-dose dynamic airway computed tomography (CT). We recorded clinical and pulmonary function tests data, quality of life and BODE index.RESULTS:This study included 53 patients with COPD, 46 (87%) males, mean age 65 (SD, 9) years.CONCLUSIONS:The prevalence of EDAC observed in a sample of patients with different levels of COPD severity is low. The degree of dynamic central airway collapse was not related to the patient's epidemiological or clinical features, and did not affect lung function, symptoms, capacity for effort, or quality of life.

The paper by Chhajed et al.1 in this issue is a timely update of tracheal and bronchial stenosis, an uncommon and difficult management problem for which there is now a range of therapeutic methods. Although the authors are from one of the more experienced groups dealing with airway stenoses in Australia, they report a total of only eight cases of tracheal stenosis collected over approximately 7 years. The vast majority of proximal tracheobronchial stenoses can now be treated using one or more of the current therapies applied endobronchially. Very rarely persistent, difficult cases may require thoracotomy. In the absence of any randomized control trial evidence, the current approach to patients with airway stenosis remains based on recent larger reported case series2–9 and the local experience of the unit to which the case is referred. We believe the key steps in dealing with tracheobronchial stenoses are to: (i) suspect, (ii) assess, (iii) diagnose, (iv) dilate and (v) maintain airway patency. Suspecting a tracheobronchial stenosis requires an understanding of the various aetiologies and patterns of clinical presentation.6,10,11 Generally, lesions affecting large airway patency can be classified12 as: 1 Intrinsic: (i.e. within the lumen) due to mucosal injury, endobronchial tumour. 2 Intramural: (i.e. within the wall) due to inflammation, scar, oedema or tumour within the mucosa or damage to the cartilaginous airway skeleton. 3 Extrinsic: due to extramural tumour, nodes or compression. 4 A combination of some or all of these. Clinically, intrinsic endobronchial stenosis most commonly occurs post-intubation, post-tracheostomy or due to malignancy. Post-traumatic fibrous stenosis may be thin and membranous, affecting only a very short segment of the airway; it may narrow the lumen over several centimeters of length of trachea; or it may bronchus in an hour-glass shape. Less common causes include anastomotic complications (e.g. lung transplantation). Intrinsic or intramural stenosis may also occur: (i) with benign airway tumours, (ii) post tuberculosis, (iii) with Wegener’s granulomatosis, (iv) with relapsing polychondrititis, and even (v) with deceleration injury (especially injuring the left main bronchus).13 Extrinsic compression may be due to tumour, goitre, vascular or developmental abnormalities. Assessment is usually physiological, using lung function tests of spirometry with flow/volume curve recordings. Both inspiratory and expiratory flow limitation occur with fixed lesions. Inspiratory flow limitation occurs with dynamic collapse of extra-thoracic lesions, and expiratory flow limitation occurs with dynamic collapse of narrowed intrathoracic lesions. Radiology may help clarify the anatomical location and extent of the lesion. Bronchoscopy is more sensitive than radiology and is the key tool for defining the anatomical type, extent, pathology and microbiology of the airway problem. Diagnosis of the extent (calibre and length), functional status and pathology of the stenosis are critical in determining which management option to use. It is critical to know: (i) if the endobronchial component is due to tumour, granulation tissue, granulomatous tissue, true fibrous stricture or a combination of these, (ii) whether dynamic collapse (bronchomalacia) is seen present with loss of integrity of the airway cartilagenous skeleton and (iii) whether there is fixed narrowing due to external compression. The extent and precise combination of the above factors determine the first initial treatment requirements, the subsequent steps in management and the likely outcome and prognosis. Dilatation is usually the next step in treatment and a variety of methods may be used. It is crucial to understand that stents should be used to maintain airway patency once it has been established by other means: they are not a primary method for dilating a tight stricture. Gross intraluminal tissue may be removed (particularly with malignancy, benign tumours or granulation tissue): (i) manually, with forceps, (ii) by shearing along the wall with the tip of the rigid bronchoscope, (iii) using electrocautery, (iv) using laser therapy (Nd: YAG or CO2), (v) using Argon Plasma Coagulation, (vi) using silver nitrate or (vii) using cryotherapy. These treatments may be effective either individually or in combination.14 The procedure used will depend on availability, the likelihood of complications (including haemorrhage) and the development of granulation tissue growth post-procedure. If there is no intraluminal tissue or after such has been removed, dilatation of the narrowed lumen may be achieved using various approaches. These include: (i) dilatation with the rigid bronchoscope, (ii) the use of bougies and, as described in the paper by Chhajed et al.1, (iii) the use of balloon dilatation. Balloon dilatation has some practical advantages, particularly for benign strictures, and may dilate to a larger diameter than a bronchoscope. Like bouginage, it compresses the tissues but without shearing force, and is less likely to result in bleeding. Both debulking (e.g. with laser therapy) and dilatation procedures may need to be repeated at 2–3-month intervals in malignant endobronchial disease but may establish long-lasting or permanent airway patency in benign conditions without any airway stent. Tumour15 and granulation tissue regrowth16 may be reduced or prevented using external beam radiotherapy and intraluminal brachytherapy with an after-loading catheter placed in proximity to intrabronchial tumour at bronchoscopy. After re-establishing the airway lumen, or in situations of focal dynamic airway collapse, stenting may be required to maintain airway patency. Stents are of two types—solid or expandable. It may be clear at the onset that stenting is required (e.g. predominantly airway malacia) or the decision to stent may be made when stenosis recurs despite multiple dilation attempts. Although first described almost 40 years ago, the use of solid (typically silicon) stents only came into routine practice in the late 1980s.11 Solid stents can be used for most indications, but have many problems including: (i) difficulty of placement, (ii) encroachment on the airway lumen, (iii) impairment of mucociliary clearance and (iv) dislodgement. They do, however, have a major advantage in that they can be readily removed. The first generation of expandable metal stents17 allowed greater ease of deployment with less encroachment on the airway lumen, less effect on mucociliary clearance and virtually no risk of dislodgement. However, new problems emerged: (i) incorrect placement was very difficult to correct, (ii) constant shortening/lengthening of the stent with the respiratory cycle led often to exuberant granulation tissue ingrowth6 and, less commonly, (iii) erosion into adjacent blood vessels caused fatal haemorrhage.18 Ingrowth of granulation tissue or tumour can be more difficult to re-treat in the presence of a metal stent. This difficulty was partially ameliorated by adding an impermeable coating to the expandable stent. This prevents tissue or tumour ingrowth. By the mid-1990s, problems with the available stents led to a re-evaluation of the ideal airway stent. Computer-generated weave patterns led to a woven stent which did not expand or contract with the respiratory cycle. Improvements in metal technology led to the development of nickel-titanium alloy (e.g. nitinol) stents which have the unusual property of elasticity at room temperature but plasticity (rigidity) at body temperature.19 Theoretically, this reduces the radial tension on the airway wall, thus reducing the risk of migration through the wall into adjacent blood vessels. It also significantly reduces the risk of granulation tissue formation. Malpositioning of these stents can also be corrected with relative ease. Anchoring of these stents occurs with epithelial ingrowth into the stent and they usually cannot be removed beyond a few days after placement. These stents are now commercially available and experience is increasing. However, the use of any stent for a benign indication requires cautious consideration, especially where there is a possibility that the underlying pathology can be corrected and airway patency restored. Bio-absorbable stents (e.g. poly-k-lactide)20 are presently in development. These will allow temporary stenting with the advantages of expandable stents, but will ‘remove themselves’ by resorption. The anatomical area within which stents can be placed is quite limited with present technology. The proximal limit is about 2 cm below the vocal cords (to preserve voice and airway protection) and the distal limit is within the main bronchi, although Colt and Dumon have reported stenting of the bronchus intermedius and left lower lobe bronchus.11 Stenting of other lobar or segmental bronchi is rarely feasible. Stricture of the airway anastomosis following lung transplantation is not uncommon (6–13% of bronchial anastomoses)9,21 and is difficult to stent as the anastomosis is often within 2–3 mm of the right or left upper lobe orifice. In summary, endobronchial treatment for tracheobronchial stenoses is now readily available for proximal lesions and is described in a number of recent case series reports. The paper by Chhajed et al.1 highlights that these are uncommon and difficult problems which often present a serious therapeutic challenge to the clinician. A systematic approach using the variety of methods now available, however, may lead to gratifying results. Ongoing and future improvements in technology will allow us to do much more to provide lasting symptomatic and functional benefit for these patients.

Standard spirometry fundamentally overlooks the mechanical dynamics of forced expiration. This study derived novel biomechanical parameters to establish functional phenotypes and predict clinical respiratory impairments. Utilizing 16,596 acceptable spirometry records from NHANES (2007 to 2012), parameters reflecting kinetic power, mass constraint, and airway instability were mathematically derived. Principal component analysis, K-means clustering, and a Multilayer Perceptron neural network were sequentially applied. Three distinct biomechanical phenotypes emerged: Load-Constrained (45.4%), Mechanically Efficient (23.5%), and Dynamic Collapse (31.0%). Aging significantly degraded kinetic power, demonstrating a steeper functional decline in males (p < 0.001). The neural network achieved 93.2% testing accuracy in classifying spirometric abnormalities. Crucially, Dynamic Airway Collapse Ratio (100% normalized importance), BMI (89.4%), and kinetic power (86.2%) fundamentally outperformed traditional demographic predictors such as chronological age (20.4%) and biological sex (7.1%). Structural and dynamic kinetic factors drive pulmonary dysfunction far more accurately than conventional demographics. Classifying these mechanical phenotypes facilitates highly targeted precision cardiopulmonary rehabilitation.