Diagnosing Aerodynamic Supraglottic Collapse With Rest and Exercise Flexible Laryngoscopy

Adult Laryngomalacia: A Scoping Review

OBJECTIVE

This review sought to determine the characteristics of adults diagnosed with new onset laryngomalacia including airway symptoms, laryngoscopic findings, treatments, and outcomes. Moreover, we wanted to highlight suspected limitations in the literature.

DATA SOURCES

Studies were identified through CINAHL, Cochrane Review, PubMed, and Scopus published between 1966 and 2023.

REVIEW METHODS

The search was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis Extension for Scoping Reviews checklist by 2 independent investigators. A meta-analysis of proportions and continuous measures was conducted.

RESULTS

Of the 1121 abstracts identified, 33 articles pertaining to laryngomalacia in the adult population were included. The most common presenting symptoms were stridor at rest (78.3%, 65.1-88.3) and dyspnea with exertion (83.8%, 64.8-96.3). The most suspected etiology was exercise-induced (86.0%, 69.4-95.5), and the most common description of laryngomalacia on visualization was collapse of supraglottic structures during exercise (93.3%, 79.0-99.1). Nonsurgical options were attempted in 87.0% (54.0-99.1), which included oral appliances, respiratory retraining, breathing techniques, and working with a speech pathologist. Surgical options were ultimately performed in 84.2% (75.0-91.0). Complete resolution of symptoms following therapy was seen in 61.9% (48.0-74.6).

CONCLUSION

Adult onset laryngomalacia is difficult to characterize. It typically presents in patients during exercise, with neurological injury, or idiopathically. Surgical management can lead to improvement or complete resolution of symptoms. The need for a universal nomenclature is highlighted in this review, as it is inconsistently classified.

Value of the Hyomental Distance Measured With Ultrasound in Forecasting Difficult Laryngoscopy in Newborns

PURPOSE

Preoperative evaluations of difficult airways are imperative, especially in newborns. The hyomental distance is a reliable index for predicting difficult airways in adults. However, few studies have evaluated the value of the hyomental distance for predicting difficult airways in newborns. It is unclear whether the hyomental distance forecasts a restricted or difficult view when using direct laryngoscopy. We intended to develop an effective system for predicting difficult tracheal intubation in newborns.

DESIGN

A prospective observational clinical study.

METHODS

Newborns aged 0 to 28 days undergoing oral endotracheal intubation with direct laryngoscopy for elective surgery under general anesthesia were enrolled. The hyomental distance and hyoid level tissue thickness were assessed by ultrasound. Other parameters, such as the mandibular length and sternomental distance, were also evaluated before anesthesia. The glottic structure view under laryngoscopy was graded according to the Cormack-Lehane classification. The patients with Grade 1 and 2 laryngeal views were assigned to Group E. Those with Grade 3 and 4 views were assigned to Group D.

FINDINGS

A total of 123 newborns were recruited for our study. The incidence of poor visualization of the larynx during laryngoscopy in our study was 10.6%. The multifactor logistic regression results showed that the hyomental distance was a powerful predictor of difficult laryngoscopy (OR = 0.16, 95% CI 0.03-0.74, P = .019). The curve with the highest sensitivity and specificity and the maximum area under the curve (AUC) was the hyomental distance. The receiver operating characteristic (ROC) curve for the hyomental distance suggested that the best cut-off value was less than equal to 2.74 cm, with an AUC of 0.80 (95% CI 0.64-0.95).

CONCLUSIONS

It is noninvasive and feasible to accurately measure the hyomental distance with ultrasound in newborns, and the results are reliable. We believe that the hyomental distance measured with ultrasound could be used as a marker for predicting difficult laryngoscopy in newborns.

Hypopharyngeal geometry impact on air-induced loads on the supraglottis

Exercise-induced laryngeal obstruction (EILO) describes paradoxical laryngeal closure during inspiration at high-intensity exercise. It is hypothesised that during intense activity, the air-induced loads on supraglottic walls overcome their internal stiffness, leading to the obstruction. Recent investigations have revealed that the air-induced loads on the supraglottic walls vary nonlinearly with increasing flow rate. It is, however, unclear whether certain geometric configurations of the hypopharynx and larynx may contribute to the predisposition to EILO. This study investigates the influence of hypopharyngeal and laryngeal geometry on upper respiratory tract airflow and air-induced forces. A computational fluid dynamics model is developed to study airflow through larynx. Four real, adult upper respiratory tracts with variable configurations are considered. Two steady, uniform inspiratory flow rates of 60 L/min and 180 L/min are considered. The analysis shows that geometries with a space lateral to the epiglottis (EpiS) and piriform fossae (PF) directs the hypopharyngeal and supraglottic pressure field to remain positive and increase with the flow rate. In geometries with EpiS and PF, pressure differential occurs around the aryepiglottic fold producing a net inward force over the region. The three-fold increase in flow rate induces near ten-fold increases in force over the region which may facilitate the closure. It is concluded that hypopharyngeal anatomy, particularly the piriform fossae, play a significant role in the obstruction of the supraglottic airway and should be considered in research and clinical assessment of EILO.

Exercise Related Respiratory Problems in the Young-Is It Exercise-Induced Bronchoconstriction or Laryngeal Obstruction?

Complaints of breathlessness during heavy exercise is common in children and adolescents, and represent expressions of a subjective feeling that may be difficult to verify and to link with specific diagnoses through objective tests. Exercise-induced asthma and exercise-induced laryngeal obstruction are two common medical causes of breathing difficulities in children and adolescents that can be challenging to distinguish between, based only on the complaints presented by patients. However, by applying a systematic clinical approach that includes rational use of tests, both conditions can usually be diagnosed reliably. In this invited mini-review, we suggest an approach we find feasible in our everyday clinical work.

Is the healthy respiratory system built just right, overbuilt, or underbuilt to meet the demands imposed by exercise?

In the healthy, untrained young adult, a case is made for a respiratory system (airways, pulmonary vasculature, lung parenchyma, respiratory muscles, and neural ventilatory control system) that is near ideally designed to ensure a highly efficient, homeostatic response to exercise of varying intensities and durations. Our aim was then to consider circumstances in which the intra/extrathoracic airways, pulmonary vasculature, respiratory muscles, and/or blood-gas distribution are underbuilt or inadequately regulated relative to the demands imposed by the cardiovascular system. In these instances, the respiratory system presents a significant limitation to O₂ transport and contributes to the occurrence of locomotor muscle fatigue, inhibition of central locomotor output, and exercise performance. Most prominent in these examples of an "underbuilt" respiratory system are highly trained endurance athletes, with additional influences of sex, aging, hypoxic environments, and the highly inbred equine. We summarize by evaluating the relative influences of these respiratory system limitations on exercise performance and their impact on pathophysiology and provide recommendations for future investigation.

Differential diagnosis and management of adult-onset laryngomalacia

OBJECTIVE

Adult-onset laryngomalacia is a rare clinical entity that has been infrequently reported. This study aims to evaluate the clinical presentation, diagnosis, and management of adult-onset laryngomalacia through literature review and report of a case.

METHODS

PubMed and Google Scholar databases were queried for articles published from 1960 to 2019 including only patients aged 18 years and older. Included keywords were: 'laryngomalacia', 'adult laryngomalacia', 'acquired laryngomalacia', 'idiopathic laryngomalacia', 'laryngeal obstruction', 'floppy epiglottis', 'floppy epiglottis', and 'epiglottis prolapse'. Data extracted from literature included clinical presentation, diagnostic workup, surgical management, and follow-up care.

SOURCES

PubMed and Google Scholar.

RESULTS

A total of 21 articles reported 41 cases of adult-onset laryngomalacia. Within these cases, 5 etiologies were identified: neurologic (n = 14), exercise-induced (n = 9), post-operative (n = 7), idiopathic (n = 7), and age-related (n = 4) laryngomalacia. Anterior prolapse of arytenoids and aryepiglottic folds was the most common laryngoscopic finding (n = 21), followed by posterior epiglottic prolapse (n = 20). Management included supraglottoplasty (n = 14), epiglottidectomy (n = 8) or epiglottopexy (n = 2). Neurologic etiology required tracheotomy more often than the other etiologies (n = 5, 36% vs. 15%). Three patients were managed expectantly without surgical intervention and reported symptom resolution.

CONCLUSION

Adult laryngomalacia is a rare diagnosis comprising a spectrum of disease. This diagnosis may be overlooked, but association with neurologic injury or trauma should encourage consideration. In comparison to pediatric laryngomalacia, patients often require surgical intervention. Surgical decision is based on the direction of supraglottic collapse, where supraglottoplasty and partial epiglottidectomy are effective interventions.

LEVEL OF EVIDENCE

N/A.

Surgical intervention for exercise-induced laryngeal obstruction: A UK perspective

OBJECTIVES

Exercise-induced laryngeal obstruction (EILO) is a prevalent cause of exertional breathlessness and wheeze in young individuals. Typically diagnosed using the continuous laryngoscopy during exercise (CLE) test, treatment is largely based on breathing retraining promoting improved laryngeal function. In some cases, these techniques fail to alleviate symptoms, and surgical intervention with supraglottoplasty can be valuable in the supraglottic form of EILO. Globally, there is currently limited experience utilizing a surgical approach to EILO, and data regarding the optimum surgical technique and published outcomes and complication rates are thus limited.

STUDY DESIGN

Retrospective observational case series.

METHODS

In this report, we describe our experience as the only UK center undertaking supraglottoplasty for EILO. We report the surgical outcome of 19 patients (n = 16 female), mean age, 29.6 ± 13.1 years, referred for surgery with moderate to severe supraglottic EILO. Follow-up clinic ± CLE was performed within 4 months (median = 6 weeks), and CLE scores were evaluated before and following surgery.

RESULTS

We found a beneficial effect of surgery on supraglottic CLE scores (median score reducing from 3/3 to 1/3 postoperatively [P < .05] overall) with 79% (n = 15) of patients reporting an improvement in their exercise capacity. One patient developed an apparent increased tendency for glottic-level EILO following surgery; however, no voice- or swallowing-related complications were encountered.

CONCLUSIONS

This study is the first to report the UK experience, surgical technique, and outcome for EILO surgery. The findings indicate that EILO surgery appears to be a safe and effective option for individuals with moderate to severe supraglottic-type EILO who have failed initial conservative treatment.

LEVEL OF EVIDENCE

5 Laryngoscope, 130:E667-E673, 2020.

The Shaking Palsy of the Larynx-Potential Biomarker for Multiple System Atrophy: A Pilot Study and Literature Review

In its early stages multiple system atrophy (MSA), a neurodegenerative movement disorder, can be difficult to differentiate from idiopathic Parkinson's disease (PD), and emphasis has been put on identifying premotor symptoms to allow for its early identification. The occurrence of vegetative symptoms in addition to motor impairment, such as orthostatic hypotension and neurogenic bladder dysfunction, enable the clinical diagnosis in the advanced stages of the disease. Usually with further disease progression, laryngeal abnormalities become clinically evident and can manifest in laryngeal stridor due to impaired vocal fold motion, such as vocal fold abduction restriction, mostly referred to as vocal fold paresis, or paradoxical vocal fold adduction during inspiration. While the pathogenesis of laryngeal stridor is discussed controversially, its occurrence is clearly associated with reduced life expectancy. Before the clinical manifestation of laryngeal dysfunction however, abnormal vocal fold motion can already be seen in patients that might not yet fulfill the diagnostic criteria of MSA. In this article we summarize the current literature on pharyngolaryngeal findings in MSA and report preliminary findings from a pilot study investigating eight consecutive MSA patients. Patients showed varying speech abnormalities. Only 2/8 patients exhibited laryngeal stridor. However, during FEES, all patients presented with irregular arytenoid cartilages movements and vocal fold abduction restriction. 3/8 showed vocal fold fixation and 1/8 paradoxical vocal fold motion. All patients presented with oropharyngeal dysphagia, 5/8 with penetration or aspiration events. We suggest that specific abnormal vocal fold motion can help identifying MSA patients and may allow for delimiting this disorder from idiopathic PD. These findings therefore may serve as a novel clinical biomarker for MSA. Based on the available data and our preliminary clinical experience we developed a standardized easy-to-implement task-protocol to be performed during flexible endoscopic evaluation of swallowing (FEES) for detection of MSA-related pharyngolaryngeal movement disorders. Furthermore, we initiated a prospective study to evaluate the diagnostic utility of this protocol.

A systematic review of surgical treatment for supraglottic exercise-induced laryngeal obstruction

Objectives

Exercise‐induced laryngeal obstruction (EILO) is a condition causing breathing difficulties and stridor during exercise. The condition has in severe cases been treated surgically with supraglottoplasty. The purpose of this systematic review is to assess the evidence and recommendations for surgical intervention in treating patients with EILO.

Methods

A systematic search was performed in PubMed and Embase to identify relevant studies describing surgical treatment of patients diagnosed with severe EILO. According to eligibility criteria, data were independently extracted by two reviewers. To assess the risk of bias of each included study, the Newcastle‐Ottawa scale (NOS) was used.

Results

The screening process identified 11 observational studies with a total of 75 patients. Findings indicated that many beneficial outcomes are to be found in surgical treatment for EILO. These indications were found both on visual verification of improvement of the laryngeal obstruction during exercise and patient self‐reported symptom severity. The average NOS score (4.3) indicated low level of evidence in the included studies.

Conclusion

Studies reporting effects of surgical treatment of EILO have shown promising results in patients with laryngeal obstruction. However, the heterogeneity of study methodologies and the level of evidence precludes definitive recommendations for or against supraglottoplasty at this time; prospective and methodologically robust studies are now needed.

Level of Evidence

4

Dynamic tonsillar prolapse masquerading as paradoxical vocal fold movement dysfunction

INTRODUCTION

Paradoxical vocal fold movement dysfunction (PVFMD) is a disorder in which the vocal folds involuntarily adduct during inspiration resulting in stridor, cough, dysphonia and dyspnea. Diagnosis of PVFMD is difficult given the episodic nature of the disorder and the often-normal laryngeal exam in between episodes. Moreover, additional sources of obstruction have been identified as sources of Periodic Occurrence of Laryngeal Obstruction (POLO). Treatments can vary with site of obstruction.

OBJECTIVE

To evaluate pediatric patients presenting to a Vocal Fold Dysfunction Center for evaluation of exertional, inspiratory, harsh breath sounds and dyspnea suggestive of PVFMD whom were found to have a dynamic obstruction of the upper airway due to adenotonsillar hypertrophy and prolapse.

METHODS

Retrospective chart review of patients diagnosed with exertional dynamic tonsillar prolapse whom have undergone adenotonsillectomy. Clinical characteristics, spirometry, exam findings and response to adenotonsillectomy were recorded.

RESULTS

Seven patients with exercise induced dyspnea and respiratory distress with whom underwent exercise spirometry then subsequent adenotonsillectomy were identified. Symptomatic co-morbidities were common and included: rhinitis (43%), reflux (29%), sleep disordered breathing (29%), asthma (14%), obesity (14%), prematurity (14%) and anxiety/post-traumatic stress disorder (PTSD) (14%). Preoperative use of bronchodilators or reflux medications was common. All patients were noted to have >50% oropharyngeal obstruction secondary to tonsillar hypertrophy and dynamic lateral pharyngeal collapse or tonsillar prolapse with inspiration. No exercise induced paradoxical vocal fold dysfunction was identified. All baseline and most exertion FVC, FEV1, FEV1/FVC and FEF 25-75% were normal. Four patients had flow volume loops suggestive of obstruction. All patients had symptomatic improvement after adenotonsillectomy.

CONCLUSIONS

Dynamic tonsillar prolapse can result in subjective exertional dyspnea and objective upper airway resistance mimicking PVFMD and treatment with adenotonsillectomy can greatly reduce symptoms.

Laryngeal sensitivity testing in youth with exercise-inducible laryngeal obstruction

Exercise-inducible laryngeal obstruction (EILO) has been recognized as a not rare respiratory problem in youth practicing sports. The aim of the study was to test the mechanosensitivity of the larynx, and to identify the factors affecting it in a group of youth with proven EILO. Laryngeal sensory testing was performed in 54 adolescents and young adults with EILO. Laryngeal mucosal alterations were assessed according to the Reflux Finding Score (RFS). The data concerning diseases possibly affecting the upper airway, findings of previously performed flexible videolaryngoscopy during exercise, and RFS score were compared between the participants with laryngeal hyposensitivity and those with normal sensitivity. The participants with isolated vocal folds' adduction during an EILO attack were compared with those who demonstrated supraglottis collapse. Testing revealed an increased threshold for mechanical stimuli in 81.5% of participants. Among participants with hyposensitivity, there were significantly more participants with dysphagia during EILO attacks than among the participants with normal laryngeal sensitivity. The hyposensitivity group had a significantly higher RFS score compared with the other group. Isolated vocal folds' approximation was only observed in 11.9% of participants. These participants were younger and had asthma more frequently compared with the others. Only 16.9% of participants with EILO did not state symptoms related to gastroesophageal reflux. The decreased mechanosensitivity was detected in the majority of participants, suggesting that laryngopharyngeal reflux can be an important etiological factor. The problem of breathing difficulties during sport activities in youth can also be associated with the disproportionate growth of the respiratory tract.

Exercise inducible laryngeal obstruction: diagnostics and management

Obstruction of the central airways is an important cause of exercise-induced inspiratory symptoms (EIIS) in young and otherwise healthy individuals. This is a large, heterogeneous and vastly understudied group of patients. The symptoms are too often confused with those of asthma. Laryngoscopy performed as symptoms evolve during increasing exercise is pivotal, since the larynx plays an important role in symptomatology for the majority. Abnormalities vary between patients, and laryngoscopic findings are important for correct treatment and handling. The simplistic view that all EIIS is due to vocal cord dysfunction [VCD] still hampers science and patient management. Causal mechanisms are poorly understood. Most treatment options are based on weak evidence, but most patients seem to benefit from individualised information and guidance. The place of surgery has not been settled, but supraglottoplasty may cure well-defined severe cases. A systematic clinical approach, more and better research and randomised controlled treatment trials are of utmost importance in this field of respiratory medicine.

Congenital laryngomalacia is related to exercise-induced laryngeal obstruction in adolescence

OBJECTIVES

Congenital laryngomalacia (CLM) is the major cause of stridor in infants. Most cases are expected to resolve before 2 years of age, but long-term respiratory prospects are poorly described. We aimed to investigate if CLM was associated with altered laryngeal structure or function in later life.

METHODS

Twenty of 23 (87%) infants hospitalised at Haukeland University Hospital during 1990-2000 for CLM without comorbidities and matched controls were assessed at mean age 13 years. Past and current respiratory morbidity was recorded in a questionnaire, and spirometry performed according to standard quality criteria. Laryngoscopy was performed at rest and continuously throughout a maximal treadmill exercise test (continuous laryngoscopy exercise test (CLE-test)), and scored and classified in a blinded fashion according to preset criteria.

RESULTS

In the CLM group, laryngeal anatomy supporting CLM in infancy was described at rest in nine (45%) adolescents. Eleven (55%) reported breathing difficulties in relation to exercise, of whom 7 had similarities to CLM at rest and 10 had supraglottic obstruction during CLE-test. Overall, 6/20 had symptoms during exercise and similarities to CLM at rest and obstruction during CLE-test. In the control group, one adolescent reported breathing difficulty during exercise and two had laryngeal obstruction during CLE-test. The two groups differed significantly from each other regarding laryngoscopy scores, obtained at rest and during exercise (p=0.001 or less).

CONCLUSIONS

CLM had left footprints that increased the risk of later exercise-induced symptoms and laryngeal obstruction. The findings underline the heterogeneity of childhood respiratory disease and the importance of considering early life factors.

Larynx during exercise: the unexplored bottleneck of the airways

Exercise-induced shortness of breath is not uncommon in otherwise healthy young people. Based on the presenting symptoms alone, it is challenging to distinguish exercise-induced asthma (EIA) from exercise-induced obstruction of central airways, sometimes leading to diagnostic errors and inadequate treatment. Central airway obstruction usually presents with exercise-induced inspiratory symptoms (EIIS) during ongoing exercise. EIIS tends to peak towards the end of an exercise session or immediately after its completion, contradicting symptoms of EIA typically peaking 3-15 min after the exercise has stopped. EIIS is usually associated with some form of laryngeal obstruction. Transnasal flexible laryngoscopy performed continuously throughout an incremental exercise test from rest to exhaustion or to intolerable symptoms is usually diagnostic, and also provides information that is important for further handling and treatment. Reflecting the complex anatomy and functional features of the larynx, exercise-induced laryngeal obstruction (EILO) appears to be a heterogeneous condition. Contradicting previous beliefs, recent literature suggests that laryngeal adduction in a majority of cases starts in supraglottic structures and that vocal cord adduction (VCD) most often occurs as a secondary phenomenon. However, EILO is poorly understood and more and better research is needed to unravel causal mechanisms. The evidence base for treatment of EILO is weak. Speech therapy, psychotherapy, biofeedback, muscle training, anticholinergic aerosols have all been applied, as has laser supraglottoplasty. Randomized controlled trials with well-defined and verifiable inclusion and success criteria are required to establish evidence-based treatment schemes.

The Effect of Exercise on Respiratory Resistance in Athletes With and Without Paradoxical Vocal Fold Motion Disorder

PURPOSE

An investigational, portable instrument was used to assess inspiratory (R(i)) and expiratory (R(e)) resistances during resting tidal breathing (RTB), postexercise breathing (PEB), and recovery breathing (RB) in athletes with and without paradoxical vocal fold motion disorder (PVFMD).

METHOD

Prospective, controlled, repeated measures within-subject and between-groups design. Twenty-four teenage female athletes, 12 with and 12 without PVFMD, breathed into the Airflow Perturbation Device for baseline measures of respiratory resistance and for two successive 1-min trials after treadmill running for up to 12 min. Exercise duration and dyspnea ratings were collected and compared across groups.

RESULTS

Athletes with PVFMD had lower than control R(i) and R(e) values during RTB that significantly increased at PEB and decreased during RB. Control athletes' R(e) decreased significantly from RTB to PEB but not from PEB to RB, whereas R(i) did not change from RTB to PEB but decreased from PEB to RB. Athletes without PVFMD ran longer, providing lower dyspnea ratings.

CONCLUSION

Immediately following exercise, athletes with PVFMD experienced increased respiratory resistance that affected their exercise performance. The difference in resting respiratory resistances between groups is intriguing and could point to anatomical differences or neural adaptation in teenagers with PVFMD. The Airflow Perturbation Device appears to be a clinically feasible tool that can provide insight into PVFMD and objective data for tracking treatment progress.

Test-retest reliability of respiratory resistance measured with the airflow perturbation device

PURPOSE

In this study, the authors aimed to determine reliability of the airflow perturbation device (APD) to measure respiratory resistance within and across sessions during resting tidal (RTB) and postexercise breathing in healthy athletes, and during RTB across trials within a session in athletes with paradoxical vocal fold motion (PVFM) disorder.

METHOD

Prospective, repeated-measures design. The APD measured respiratory resistance during 3 baseline assessments in 24 teenage female athletes, 12 with and 12 without PVFM. Control athletes provided data at rest and following a customized exercise challenge during each of 3 sessions. Intraclass correlation coefficient (ICC) analysis assessed strength of relationships, and repeated-measures analysis of variance assessed differences across trials and sessions.

RESULTS

ICC analyses confirmed strong correlations across RTB trials for inspiratory, expiratory, and mean respiratory resistance in both groups. Inspiratory resistance decreased ~5% between sessions for control participants; expiratory and mean respiratory resistances were stable. Data from control athletes across sessions and following rigorous exercise were strongly correlated when taken at comparable intervals.

CONCLUSIONS

APD-measured respiratory resistance, including separate assessments for the inspiratory and expiratory phases, has strong test-retest reliability during RTB and after exercising. This suggests that the APD is a useful measurement tool for the assessment of airway function in patients suspected of having PVFM.

Validity of a new respiratory resistance measurement device to detect glottal area change

OBJECTIVE

To determine the correlation between respiratory resistance (Rr) values measured with the Airflow Perturbation Device (APD) to laryngoscopic images of glottal area (GA) in feigned paradoxical vocal fold motion (PVFM), also known as vocal cord dysfunction.

HYPOTHESIS

There is a strong inverse relationship between Rr and GA such that laryngeal constriction can be detected and quantified by APD-measured Rr.

STUDY DESIGN

Prospective, single subject study.

METHODS

A healthy adult feigned breathing that was characteristic of PVFM. Rr and GA were simultaneously recorded, synchronized, and analyzed for three complete breathing cycles with significant glottal constriction occurring during inspiration.

RESULTS

Cross-correlation analysis revealed a strong negative correlation (-0.824) between GA and Rr during feigned PVFM breathing such that Rr increased when GA decreased.

CONCLUSION

APD-measured Rr appears to be a viable noninvasive method for diagnostic screening and monitoring of treatment outcomes for individuals presenting with dyspnea related to PVFM.