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Respiratory Medicine Jun 2018Impulse oscillometry (IOS) is the most commonly used type of forced oscillation technique in clinical practice, although relatively little is known about its application... (Review)
Review
Impulse oscillometry (IOS) is the most commonly used type of forced oscillation technique in clinical practice, although relatively little is known about its application in COPD. Resistance at 20 Hz (R20) is unrelated to COPD severity and does not improve with bronchodilatation or bronchoconstriction, inferring a lack of large airway involvement in COPD. Peripheral airway resistance expressed as frequency dependent heterogeneity between 5 Hz and 20 Hz (R5-R20), and peripheral airway compliance as area under the reactance curve (AX), are both closely related to COPD severity and exacerbations. Both R5-R20 and AX markedly improve in response to long acting bronchodilators, while AX appears to be more sensitive than R5-R20 in response to bronchoconstriction. Future studies may be directed to assess if IOS in combination with spirometry is more sensitive at predicting future exacerbations. Perhaps AX might also be useful as a screening tool in early stage disease or to monitor long term decline in COPD.
Topics: Airway Resistance; Female; Humans; Male; Oscillometry; Pulmonary Disease, Chronic Obstructive; Respiratory Function Tests; Severity of Illness Index
PubMed: 29857993
DOI: 10.1016/j.rmed.2018.05.004 -
Advances in Experimental Medicine and... 2022Hypoglossal nerve stimulation (HNS) has been shown to be a safe alternative in the treatment of moderate-to-severe obstructive sleep apnea (OSA). A recent meta-analysis...
Hypoglossal nerve stimulation (HNS) has been shown to be a safe alternative in the treatment of moderate-to-severe obstructive sleep apnea (OSA). A recent meta-analysis of 12 studies by Costantino et al. indicated the surgical success rates at 55-75%, a reduction of the apnea hypopnea index (AHI) of 18 events/h, and a reduction of the Epworth Sleepiness Scale (ESS) of 2.9-5.3. After animal studies in the 1970s, the first trial on humans to decrease upper airway resistance by transcutaneous electrical stimulation of the genioglossus was reported in 1989. A separate stimulation of protruding and retracting muscles was realized in 1995 by fine-wire electrodes that were placed into the tongue transoral. Over the next years, several companies developed implantable devices for hypoglossal stimulation in OSA. Initially, devices were developed that used unilateral stimulation of the hypoglossal nerve. In 2014, a device for unilateral respiratory frequency-controlled hypoglossal stimulation finally received FDA approval after a successful phase III trial. In recent years, a device for bilateral breath rate-independent stimulation of the hypoglossal nerve has been added to these approaches as a new development. Accordingly, hypoglossal nerve stimulation, on the one hand, is now an established tool for patients with OSA when standard treatments are not satisfactory. Beyond that, hypoglossal stimulation is undergoing a continuous and impressive development like hardly any other field of surgical therapy for OSA.
Topics: Airway Resistance; Animals; Clinical Trials, Phase III as Topic; Electric Stimulation Therapy; Humans; Hypoglossal Nerve; Sleep Apnea, Obstructive; Tongue; Treatment Outcome
PubMed: 36217095
DOI: 10.1007/978-3-031-06413-5_21 -
Respiratory Physiology & Neurobiology Nov 2021Cystic fibrosis (CF) is characterized by small airway disease; but central airways may also be affected. We hypothesized that airway resistance estimated from...
Cystic fibrosis (CF) is characterized by small airway disease; but central airways may also be affected. We hypothesized that airway resistance estimated from computational fluid dynamic (CFD) methodology in infants with CF was higher than controls and that early airway inflammation in infants with CF is associated with airway resistance. Central airway models with a median of 51 bronchial outlets per model (interquartile range 46,56) were created from chest computed tomography scans of 18 infants with CF and 7 controls. Steady state airflow into the trachea was simulated to estimate central airway resistance in each model. Airway resistance was increased in the full airway models of infants with CF versus controls and in models trimmed to 33 bronchi. Airway resistance was associated with markers of inflammation in bronchoalveolar lavage fluid obtained approximately 8 months earlier but not with markers obtained at the same time. In conclusion, airway resistance estimated by CFD modeling is increased in infants with CF compared to controls and may be related to early airway inflammation.
Topics: Airway Resistance; Computer Simulation; Cystic Fibrosis; Humans; Hydrodynamics; Infant; Models, Biological; Pneumonia; Tomography, X-Ray Computed
PubMed: 34157384
DOI: 10.1016/j.resp.2021.103722 -
Intensive Care Medicine Sep 2018
Topics: Airway Obstruction; Airway Resistance; Humans; Inhalation; Monitoring, Physiologic; Pressure; Respiration, Artificial; Respiratory Muscles; Work of Breathing
PubMed: 29350241
DOI: 10.1007/s00134-018-5045-8 -
Respiratory Physiology & Neurobiology Oct 2023Oscillometry has been around for almost 70 years, but there are still many unknowns. The test is performed during tidal breathing and is therefore free from... (Review)
Review
Oscillometry has been around for almost 70 years, but there are still many unknowns. The test is performed during tidal breathing and is therefore free from patient-dependent factors that could influence the results. The Forced Oscillation Technique (FOT), which requires minimal patient cooperation, is gaining ground, particularly with elderly patients and children. In pulmonology, it is a valuable tool for assessing obstructive conditions (with a distinction between central and peripheral obstruction) and restrictive disorders (intrapulmonary and extrapulmonary). Its sensitivity allows the assessment of bronchodilator and bronchoconstrictor responses. Different lung diseases show different patterns of changes in FOT, especially studied in asthma and chronic obstructive pulmonary disease. Because of these differences, many studies have analysed the usefulness of this technique in different areas of medicine. In this paper, the authors would like to present the basics of oscillometry with the areas of its most recent clinical applications.
Topics: Child; Humans; Aged; Airway Resistance; Oscillometry; Asthma; Pulmonary Disease, Chronic Obstructive; Respiratory Function Tests; Spirometry; Forced Expiratory Volume
PubMed: 37536553
DOI: 10.1016/j.resp.2023.104135 -
The Laryngoscope Oct 2023Obstructive upper airway pathologies are a great clinical challenge for the airway surgeon. Protection against acute obstruction is critical, but avoidance of...
BACKGROUND
Obstructive upper airway pathologies are a great clinical challenge for the airway surgeon. Protection against acute obstruction is critical, but avoidance of unnecessary tracheostomy must also be considered. Decision-making regarding airway, although supported by some objective findings, is largely guided by subjective experience and training. This investigation aims to study the relationship between clinical respiratory distress and objective measures of airway resistance in laryngeal cancer as determined by computational fluid dynamic (CFD) and morphometric analysis.
METHODS
Retrospective CT and clinical data were obtained for series of 20 cases, defined as newly diagnosed laryngeal cancer patients who required admission or urgent airway surgery, and 20 controls. Cases and controls were matched based on T-staging. Image segmentation and morphometric analysis were first performed. Computational models based on the lattice Boltzmann method were then created and used to quantify the continuous mass flow, rigid wall, and constant static pressure inlet boundary conditions.
RESULTS
The analysis demonstrated a significant relationship between airway resistance and acute obstruction (OR 1.018, 95% CI 1.001-1.045). Morphometric analysis similarly demonstrated a significant relationship when relating measurements based on the minimum cross-section, but not on length of stenosis. Morphometric measurements also showed significance in predicting CFD results, and their relationship demonstrated that airway pressures increase exponentially below 2.5 mm. Tumor subsite did not show a significant difference, although the glottic subgroup tended to have higher resistances.
CONCLUSION
Airway resistance analysis from CFD computation correlated with presence of acute distress requiring emergent management. Morphometric analysis showed a similar correlation, demonstrating a radiologic airway assessment technique on which future risk estimation could be performed.
LEVEL OF EVIDENCE
4 (case-control study) Laryngoscope, 133:2734-2741, 2023.
Topics: Humans; Airway Resistance; Laryngeal Neoplasms; Hydrodynamics; Case-Control Studies; Retrospective Studies; Lung; Dyspnea; Airway Obstruction; Respiratory Distress Syndrome; Computer Simulation
PubMed: 36951521
DOI: 10.1002/lary.30649 -
Expert Review of Respiratory Medicine Apr 2019Upper airway resistance syndrome (UARS) as obstructive sleep apnea syndrome (OSAS) has been described as abnormal breathing during sleep, based on the recording... (Review)
Review
Upper airway resistance syndrome (UARS) as obstructive sleep apnea syndrome (OSAS) has been described as abnormal breathing during sleep, based on the recording technologies and knowledge of the time. These terms have advanced the field, but are they still useful? Area Covered: Historically, the definition of UARS syndrome was aimed at recognizing pathology not covered by 'OSAS' and to prompt specialists to go further than the obvious. It aimed at pushing specialists to recognize pathologies earlier and to elicit research in the developmental features of sleep-disordered-breathing (SDB). The technology used to monitor SDB changed over-time, allowing recognition of SDB differently but not necessarily better. Expert Commentary: Currently, we have a better understanding of the development of SDB, and its evolution with aging, leading to co-morbid-OSA. However, the real issue is to recognize the problems much earlier, and to understand what can be done to prevent its development. The notions of OSA, UARS, apnea hypopnea index are only historical. There is enough knowledge to date to go beyond these definitions, to recognize problems differently and to lead to the prevention of the factors leading to SDB. The recognition of non-hypoxic sleep-disordered breathing is a step in this direction.
Topics: Airway Resistance; Female; Humans; Male; Sleep Apnea Syndromes; Sleep Apnea, Obstructive
PubMed: 30689957
DOI: 10.1080/17476348.2019.1575731 -
Experimental Physiology Apr 2020What is the central question of this study? Are sex difference in the central airways present in healthy paediatric patients? What is the main finding and its...
NEW FINDINGS
What is the central question of this study? Are sex difference in the central airways present in healthy paediatric patients? What is the main finding and its importance? In patients ≤12 years we found no sex differences in central airway luminal area. After 14 years, the males had significantly larger central airway luminal areas than the females. The sex differences were minimized, but preserved when correcting for height. Luminal area is the main determinant of airway resistance and our finding could help explain sex differences in pulmonary system limitations to exercise in paediatric patients.
ABSTRACT
Cross-sectional airway area is the main determinant of resistance to airflow in the respiratory system. In paediatric patients (<18 years), previous evidence for sex differences in cross-sectional airway area was limited to patients with history of pulmonary disease or cadaveric studies with small numbers of subjects. These studies either only report tracheal data and do not include a range of ages or correct for height. Therefore, we sought to assess sex differences in airway luminal area utilizing paediatric patients of varying ages and no history of respiratory disease. Using three-dimensional reconstructions from high-resolution computed tomography scans, we retrospectively assessed the cross-sectional airway area in healthy paediatric females (n = 97) and males (n = 128) over a range of ages (1-17 years). The areas of the trachea, left main bronchus, left upper lobe, left lower lobe, right main bronchus, intermediate bronchus and right upper lobe were measured at three discrete points by a blinded investigator. No differences between the sexes were noted in the cross-sectional areas of the youngest (ages 1-12 years) patients (P > 0.05). However, in patients ≥14 years the cross-sectional areas were larger in the males compared to females in most airway sites. For instance, the cross-sectional size of the trachea was 25% (218 ± 44 vs. 163 ± 24 mm , P < 0.01) larger in males vs. females among ages 13-17 years. When accounting for height, these sex differences in airway areas were attenuated, but persisted. Our results indicate that sex differences in paediatric airway cross-sectional area manifest after age ≥14 years and are independent of height.
Topics: Airway Resistance; Bronchi; Child; Child, Preschool; Female; Humans; Inhalation; Lung; Male; Retrospective Studies; Sex Characteristics; Tomography, X-Ray Computed; Trachea
PubMed: 32003484
DOI: 10.1113/EP088370 -
Immunology and Allergy Clinics of North... Feb 2023Physiologic changes during pregnancy have implications for both upper and lower airway function. Upper airway resistance increases, and total lung capacity decreases.... (Review)
Review
Physiologic changes during pregnancy have implications for both upper and lower airway function. Upper airway resistance increases, and total lung capacity decreases. Upper airway symptoms increase; some women develop pregnancy-induced rhinitis and there is an increased prevalence of sleep-disordered breathing compared to prepregnancy. Longitudinal studies examining changes in upper and lower airway function parameters are limited, particularly in women with asthma. Some studies have observed reduced lung function with advancing gestation; however, changes are small and unlikely to be of major clinical significance. Spirometry is therefore a useful tool for clinical assessment of women with asthma during pregnancy.
Topics: Pregnancy; Female; Humans; Asthma; Airway Resistance; Sleep Apnea Syndromes
PubMed: 36411003
DOI: 10.1016/j.iac.2022.07.005 -
Paediatric Respiratory Reviews Mar 2016The Forced Oscillation Technique (FOT) is a lung function modality based on the application of an external oscillatory signal in order to determine the mechanical... (Review)
Review
The Forced Oscillation Technique (FOT) is a lung function modality based on the application of an external oscillatory signal in order to determine the mechanical response of the respiratory system. The method is in principal noninvasive and requires minimal patient cooperation, which makes it suitable for use in young paediatric patients. The FOT has been successfully applied in various paediatric respiratory disorders, such as asthma, cystic fibrosis, and chronic lung disease of prematurity, in order to assess airway obstruction, bronchodilator response, and airway responsiveness after bronchoprovocation challenge. This technique may be more sensitive than spirometry in identifying disturbances of peripheral airways and assessing the level of asthma control or the effectiveness of therapy at the long term. Further research is required to determine the exact role of the FOT in paediatric lung function testing and to incorporate the method in specific diagnostic and management algorithms.
Topics: Airway Resistance; Asthma; Child; Cystic Fibrosis; Forced Expiratory Volume; Humans; Respiratory Function Tests
PubMed: 26777151
DOI: 10.1016/j.prrv.2015.11.001