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American Journal of Physiology. Lung... Jun 2022Lung resistance () is determined by airway and parenchymal tissue resistance, as well as the degree of heterogeneity in airway constriction. Deep inspirations (DIs) are...
Lung resistance () is determined by airway and parenchymal tissue resistance, as well as the degree of heterogeneity in airway constriction. Deep inspirations (DIs) are known to reverse experimentally induced increase in , but the mechanism is not entirely clear. The first step toward understanding the effect of DI is to determine how each of the resistance components is affected by DI. In the present study, we measured and apparent airway resistance (, which combines the effects of airway resistance and airway heterogeneity) simultaneously before and after a DI in acetylcholine (ACh)-challenged ex vivo sheep lungs. We found that at normal breathing frequency (0.25 Hz) ACh-challenge led to a doubling of , 80.3% of that increase was caused by an increase in ; the increase in apparent tissue resistance () was insignificant. 57.7% of the increase in was abolished by a single DI. After subtracting from , the remaining was mostly independent of ACh-challenge and its reduction after a DI came mostly from the change in the mechanical properties of lung parenchyma. We conclude that at normal breathing frequency, in an unchallenged lung is mostly composed of , and the increase in due to ACh-challenge stems mostly from the increase in and that both and can be greatly reduced by a DI, likely due to a reduction in true airway resistance and heterogeneity, as well as parenchymal tissue hysteresis post DI.
Topics: Airway Resistance; Animals; Inhalation; Lung; Parenchymal Tissue; Respiratory Function Tests; Sheep
PubMed: 35537098
DOI: 10.1152/ajplung.00033.2022 -
Respiratory Care Mar 2021A 20% reduction in the FEV is routinely used as an end point for methacholine challenge testing (MCT). Measurement of FEV is effort dependent, and some patients are not...
BACKGROUND
A 20% reduction in the FEV is routinely used as an end point for methacholine challenge testing (MCT). Measurement of FEV is effort dependent, and some patients are not able to perform acceptable and repeatable forced expiration maneuvers. The goal of the present study was to investigate the diagnostic value of airway resistance measurement by forced oscillation technique (FOT), body plethysmography, and interrupter technique compared with the traditionally accepted standard FEV measurement in evaluating the responsiveness to methacholine during MCT.
METHODS
We included in the study adult subjects referred for MCT because of asthma-like symptoms and with normal baseline spirometry. We modified routine MCT protocol by adding the assessment of airway resistance to the measurement of FEV at each step of MCT.
RESULTS
We observed, in the subjects with airway hyper-responsiveness versus those with normal airway responsiveness, a significantly greater percentage change in median (interquartile range) FOT resistance at 10 Hz (25.9% [13.7%-35.4%] vs 16% [15.7%-27.2%]), plethysmographic resistance (70.2% [39.5%-116.3%] vs 37.1% [23.9%-81.9%]), and mean ± SD conductance (-41.3 ± 15.4% vs -29.6 ± 15.9%); and a significantly greater change in mean ± SD FOT reactance at 10 Hz (-0.41 ± 0.48 cm HO/L/s vs -0.09 ± 0.32 cm HO/L/s) and at 15 Hz (-0.29 ± 0.2 cm HO/L/s vs -0.1 ± 0.19 cm HO/L/s). We also recorded significant differences in airway resistance parameters (FOT resistance at 10 Hz, FOT reactance at 15 Hz, plethysmographic airway resistance, and conductance indices as well as interrupter resistance) in FEV non-responders at the onset of respiratory symptoms during MCT compared with baseline.
CONCLUSIONS
Measurements of airway resistance could possibly be used as an alternative method to spirometry in airway challenge. Significant changes in airway mechanics during MCT are detectable by airway resistance measurement in FEV non-responders with methacholine-induced asthma-like symptoms. (ClinicalTrials.gov registration NCT02343419.).
Topics: Adult; Airway Resistance; Bronchial Provocation Tests; Forced Expiratory Volume; Humans; Methacholine Chloride; Spirometry
PubMed: 33203723
DOI: 10.4187/respcare.08331 -
Clinical Physiology and Functional... Sep 2021The forced oscillation technique (FOT) provides detailed information about the mechanics of the respiratory system, while requiring minimal co-operation by the patient....
BACKGROUND
The forced oscillation technique (FOT) provides detailed information about the mechanics of the respiratory system, while requiring minimal co-operation by the patient. FOT may be abnormal in subjects with normal spirometry and appears to be more closely related to airway symptoms. It is, therefore, attractive in epidemiological studies, where a large number of different examinations are made in each subjects in a short period of time. Current technical standards recommend the mean of three consecutive measurements to be used, but there is limited information regarding within-session variability of FOT measurements.
OBJECTIVE
The purpose of this study was to examine the within-session variability in FOT measurements in a large, population-based sample.
METHODS
We performed three consecutive FOT measurements in 700 subjects using the impulse oscillometry system. The first measurement was compared to the mean of three measurements for resistance at 5 and 20 Hz (R5 and R20, respectively), R5-R20, reactance at 5 Hz (X5) and resonant frequency (f ).
RESULTS
The differences between the first and the mean of three measurements (median, interquartile range) were minimal, for example 0.002, -0.008 to 0.014 kPa L s for R5 and -0.001, -0.008 to 0.005 kPa L s for X5. Findings were numerically similar for men and women as well as for subjects with and without airflow obstruction at spirometry.
CONCLUSIONS
We conclude that, whereas in clinical situations, three FOT measurements are to be preferred, a single measurement may suffice in epidemiological studies.
Topics: Airway Resistance; Female; Forced Expiratory Volume; Humans; Male; Oscillometry; Pulmonary Disease, Chronic Obstructive; Reproducibility of Results; Spirometry
PubMed: 33914403
DOI: 10.1111/cpf.12706 -
Journal of Applied Physiology... Aug 2021Obesity alters chest wall mechanics, reduces lung volumes, and increases airway resistance. In addition, the luminal area of the larger conducting airways is smaller in...
Obesity alters chest wall mechanics, reduces lung volumes, and increases airway resistance. In addition, the luminal area of the larger conducting airways is smaller in women than in men when matched for lung size. We examined whether differences in pulmonary mechanics with obesity and sex were associated with the dysanapsis ratio (DR), an estimate of airway size when the expiratory flow is maximal, in men and women with and without obesity. In addition, we examined the ability to estimate DR using predicted versus measured static recoil pressure at 50% forced vital capacity (FVC; Pst). Participants completed pulmonary function testing and measurements of pulmonary mechanics. Flow, volume, and transpulmonary pressure were recorded while completing forced vital capacity (FVC) maneuvers in a body plethysmograph. Static compliance curves were collected using the occlusion technique. DR was calculated using measured values of forced midexpiratory flow and Pst. DR was also calculated using Pst predicted from previously reported data. There was no significant group (lean vs. obese) by sex interaction or main effect of group on DR. However, women displayed significantly larger DR compared with men. Predicted Pst was significantly greater than measured Pst. DR calculated from measured Pst was significantly greater than when using predicted Pst. In conclusion, although obesity does not appear to alter airway size, women may have larger airways compared with men when midexpiratory flow is maximal. In addition, DR estimated using predicted Pst should be used with caution. It is unclear whether obesity in combination with sex influences the dysanapsis ratio (DR). These data indicate that DR is unaltered in adults with obesity and is greater in women than in men but similar between sexes when matched for lung volume. We also report a significant difference between predicted and measured static recoil pressure. Thus, we caution against predicting static recoil pressure in the calculation of DR.
Topics: Adult; Airway Resistance; Female; Forced Expiratory Volume; Humans; Lung; Lung Volume Measurements; Male; Obesity; Vital Capacity
PubMed: 34166096
DOI: 10.1152/japplphysiol.00133.2021 -
Journal of Clinical Sleep Medicine :... May 2022To evaluate the health-related quality of life (HRQoL) in patients with upper airway respiratory syndrome (UARS) and obstructive sleep apnea (OSA) compared to the...
STUDY OBJECTIVES
To evaluate the health-related quality of life (HRQoL) in patients with upper airway respiratory syndrome (UARS) and obstructive sleep apnea (OSA) compared to the general population (GP) in Lima, Peru, and to explore the variables associated with differences in HRQoL in patients with UARS.
METHODS
This was a retrospective study of medical and polysomnography records from 2009-2014 in a referral sleep medicine center for patients aged 18-64 years. UARS was defined by polysomnography as follows: apnea-hypopnea index < 5 events/h, oxygen saturation ≥ 92%, respiratory effort-related arousal index ≥ 5. HRQoL was assessed using the 36-Item Short Form Survey (version 1) questionnaire validated in Peru. The GP HRQoL was obtained from a population-based survey. Linear and logistic regression analyses were conducted.
RESULTS
We reviewed 1,329 polysomnograms and selected 888. UARS and OSA were diagnosed in 93 and 795 participants, respectively. The GP cohort consisted of 641 participants. Total HRQoL mean scores (95% confidence interval) in patients with UARS, patients with OSA, and the GP were 67.4 (63.7-71.1), 66.9 (65.4-68.4), and 82.9 (81.6-84.3), respectively. Patients with UARS and patients with OSA had a 5.5 times (95% confidence interval, 3.3-9.2) and 6.2 times (95% confidence interval, 4.6-8.4) greater probability of having a low total HRQoL score compared to patients in the GP, respectively. In patients with UARS, muscle pain, use of psychotropic medication, obesity, and depression were negatively correlated with the total HRQoL score.
CONCLUSIONS
The impact of OSA and UARS on HRQoL is similar between disease groups and markedly worse when compared to the impact in the GP. In patients with UARS, the presence of muscle pain, obesity, female sex, depression, and use of psychotropic medication negatively impacted HRQoL.
CITATION
Vizcarra-Escobar D, Duque KR, Barbagelata-Agüero F, Vizcarra JA. Quality of life in upper airway resistance syndrome. 2022;18(5):1263-1270.
Topics: Airway Resistance; Female; Humans; Myalgia; Obesity; Quality of Life; Retrospective Studies; Sleep Apnea, Obstructive; Syndrome
PubMed: 34931609
DOI: 10.5664/jcsm.9838 -
Seminars in Respiratory and Critical... Aug 2014Chronic obstructive pulmonary disease (COPD) is characterized by expiratory flow limitation (EFL) due to progressive airflow obstruction. The various mechanisms that... (Review)
Review
Chronic obstructive pulmonary disease (COPD) is characterized by expiratory flow limitation (EFL) due to progressive airflow obstruction. The various mechanisms that cause EFL are central to understanding the physiopathology of COPD. At the end of expiration, dynamic inflation may occur due to incomplete emptying the lungs. This "extra" volume increases the alveolar pressure at the end of the expiration, resulting in auto-positive end-expiratory pressure (PEEP) or PEEPi. Acute exacerbations of COPD may result in increased airway resistance and inspiratory effort, further leading to dynamic hyperinflation. COPD exacerbations may be triggered by environmental exposures, infections (viral and bacterial), or bronchial inflammation, and may result in worsening respiratory failure requiring mechanical ventilation (MV). Acute exacerbations of COPD need to be distinguished from other events such as cardiac failure or pulmonary emboli. Strategies to treat acute respiratory failure (ARF) in COPD patients include noninvasive ventilation (NIV), pressure support ventilation, and tracheal intubation with MV. In this review, we discuss invasive and noninvasive techniques to address ARF in this patient population. When invasive MV is used, settings should be adjusted in a way that minimizes hyperinflation, while providing reasonable gas exchange, respiratory muscle rest, and proper patient-ventilator interaction. Further, weaning from MV may be difficult in these patients, and factors amenable to pharmacological correction (such as increased bronchial resistance, tracheobronchial infections, and heart failure) are to be systematically searched and treated. In selected patients, early use of NIV may hasten the process of weaning from MV and improve outcomes.
Topics: Airway Resistance; Humans; Intubation, Intratracheal; Positive-Pressure Respiration; Pulmonary Disease, Chronic Obstructive; Respiration, Artificial; Respiratory Insufficiency; Severity of Illness Index
PubMed: 25111641
DOI: 10.1055/s-0034-1382155 -
Medicine Oct 2022There are different results on the effect of endotracheal tube (ETT) size on respiratory mechanics in patients undergoing mechanical ventilation, and there are few...
There are different results on the effect of endotracheal tube (ETT) size on respiratory mechanics in patients undergoing mechanical ventilation, and there are few reports in adult laparoscopic surgery. The aim of this study was to investigate the effect of ETT size on airway resistance (RAW) and dynamic lung compliance (COMPL) in patients undergoing laparoscopic colorectal surgery. Seventy-two patients undergoing laparoscopic radical surgery for colorectal cancer under general anesthesia with endotracheal intubation were selected and divided into 3 groups (n = 24) using the random number table method Group A (ETT ID 7.0), Group B (ETT ID 7.5), and Group C (ETT ID 8.0). After mechanical ventilation, intraoperative RAW and COMPL were monitored in each of the 3 groups. In the non-pneumoperitoneal state, RAW in group ID7.0 is significantly higher than this in group ID7.5 and group ID8.0 (P < .05); the RAW between the 2 groups with ID7.5 and ID8.0 was not statistically significant (P > .05). The difference of COMPL between the 3 groups was statistically significant (P < .05); the COMPL of Group ID7.0 is lower than Group ID7.5, and Group ID7.5 is lower than Group ID8.0. In the pneumoperitoneal state, the RAW between ID7.0 group and ID8.0 group was statistically significant, the RAW difference between ID7.0 group and ID7.5 group, ID7.5 group and ID8.0 group not statistically significant (P > .05);the COMPL between the 3 groups was not statistically significant (P > .05). In the non-pneumoperitoneal state, the smaller the ETT internal diameter within a certain range, the higher RAW and the lower COMPL; in the pneumoperitoneal state, the RAW with the ID7.0 ETT was higher than that with the ID8.0 ETT, and the ETT size within a certain range had no effect on COMPL.
Topics: Adult; Humans; Airway Resistance; Lung Compliance; Intubation, Intratracheal; Respiration, Artificial; Respiratory Mechanics
PubMed: 36316839
DOI: 10.1097/MD.0000000000031410 -
The Journal of the Association of... Mar 2020Allergic rhinitis (AR) and asthma are closely linked atopic conditions, often termed as one airway one disease. Nasal airflow obstruction is a cardinal symptom of AR and...
INTRODUCTION
Allergic rhinitis (AR) and asthma are closely linked atopic conditions, often termed as one airway one disease. Nasal airflow obstruction is a cardinal symptom of AR and objective assessment of resistance to nasal airflow in rhinitis can be measured by active anterior rhinomanometry. This study was aimed at correlating the degree of resistance to nasal airflow (NAR) with the clinical severity of allergic rhinitis. In addition, it aimed at determining the proportion of patients with latent lower airway involvement in AR and studying the impact of ARIA severity grade and NAR on this value.
MATERIALS AND METHODS
A prospective prevalence study was conducted wherein 32 patients diagnosed with allergic rhinitis underwent determination of nasal airway resistance by active anterior rhinomanometry and lung function evaluation by spirometry. If spirometry was normal; histamine challenge test was performed to check for bronchial hyper-reactivity.
RESULTS
94% of patients with moderate- severe allergic rhinitis had significantly elevated nasal airway resistance compared to 56% of patients with mild rhinitis. (p=0.014). 71.9% of patients with allergic rhinitis but no symptoms of asthma had bronchial hyper-reactivity with a positive histamine challenge or airflow obstruction on lung functions. 87.5% patients with significantly elevated nasal airway resistance compared to 25% with lower values had lower airway involvement. (p=0.001). 94% of patients with moderate - severe rhinitis and 83% of patients with persistent rhinitis compared to 50% patients with mild and 44% with intermittent symptoms had lower airways involved. (p<0.05).
CONCLUSION
Significantly greater proportion of patients with moderate-severe and persistent allergic rhinitis had elevated nasal airway resistance values. 72% patients with allergic rhinitis had lower airway involvement despite having no symptoms of asthma, prevalence being greater in patients with severe and persistent disease. Proportion of patients with lower airway hyper-responsiveness is significantly higher among patients with raised nasal airway resistance as determined by rhinomanometry. This study thus concludes that measurement of nasal airway resistance determined by active anterior rhinomanometry is a good objective tool to measure severity of nasal obstruction in allergic rhinitis with good correlation with the ARIA clinical severity grade .It may also be a promising tool to identify allergic rhinitis patients who are at a higher risk of having latent lower airway involvement.
Topics: Airway Resistance; Humans; Nasal Obstruction; Prospective Studies; Rhinitis; Rhinitis, Allergic; Rhinomanometry
PubMed: 32138483
DOI: No ID Found -
Facial Plastic Surgery : FPS Jun 2024Assessing patients with complaints of nasal obstruction has traditionally been done by evaluation of the nasal airway looking for fixed or dynamic obstructive locations...
Assessing patients with complaints of nasal obstruction has traditionally been done by evaluation of the nasal airway looking for fixed or dynamic obstructive locations that could impair nasal airflow. Not infrequently, however, symptoms of nasal obstruction do not match the clinical examination of the nasal airway. Addressing this subset of patients may be a challenge to the surgeon. Evaluation of patients with symptoms of nasal obstruction should include a combination of a patient-reported assessment of nasal breathing and at least one objective method for measuring nasal airflow or nasal airway resistance or dimensions. This will allow distinction between patients with symptoms of nasal obstruction and low airflow or high nasal airway resistance and patients with similar symptoms but whose objective evaluation demonstrates normal nasal airflow or normal airway dimensions or resistance. Patients with low nasal airflow or high nasal airway resistance will require treatment to increase nasal airflow as a necessary step to improve symptoms, whereas patients with normal nasal airflow or nasal airway resistance will require a multidimensional assessment looking for less obvious causes of impaired nasal breathing sensation.
Topics: Humans; Nasal Obstruction; Airway Resistance; Algorithms; Rhinomanometry
PubMed: 38301716
DOI: 10.1055/s-0044-1779483 -
The Laryngoscope Jan 2016Drug-induced sleep endoscopy (DISE) is used to determine surgical therapy for obstructive sleep apnea (OSA); however, the effects of anesthesia on the upper airway are... (Review)
Review
OBJECTIVES/HYPOTHESIS
Drug-induced sleep endoscopy (DISE) is used to determine surgical therapy for obstructive sleep apnea (OSA); however, the effects of anesthesia on the upper airway are poorly understood. Our aim was to systematically review existing literature on the effects of anesthetic agents on the upper airway.
DATA SOURCES
PubMed, CINAHL, EBM reviews and Scopus (all indexed years).
REVIEW METHODS
Inclusion criteria included English language articles containing original human data. Two investigators independently reviewed all articles for outcomes related to upper airway morphology, dynamics, neuromuscular response, and respiratory control.
RESULTS
The initial search yielded 180 abstracts; 56 articles were ultimately included (total population = 8,540). The anesthetic agents studied were: topical lidocaine, propofol, dexmedetomidine, midazolam, pentobarbital, sevoflurane, desflurane, ketamine, and opioids. Outcome measures were diverse and included imaging studies, genioglossus electromyography, endoscopic airway assessment, polysomnography, upper airway closing pressure, and clinical evidence of obstruction. All agents caused some degrees of airway collapse. Dexmedetomidine did not have dose-dependent effects when evaluated using cine magnetic resonance imaging, unlike sevoflurane, isoflurane, and propofol, and caused less dynamic collapse than propofol.
CONCLUSIONS
Studies assessing the effect of anesthesia on the upper airway in patients with and without OSA are limited, and few compare effects between agents. Medications with minimal effect on respiratory control (e.g., dexmedetomidine) may work best for DISE.
Topics: Airway Resistance; Analgesics, Opioid; Anesthetics; Humans; Larynx; Pharynx; Sleep Apnea, Obstructive
PubMed: 26198715
DOI: 10.1002/lary.25399