-
Annals of the American Thoracic Society Oct 2014Chest wall strapping (CWS) induces breathing at low lung volumes. Mild to moderate obesity can lead to similar changes in lung volumes, due to chest wall and abdominal... (Review)
Review
Chest wall strapping (CWS) induces breathing at low lung volumes. Mild to moderate obesity can lead to similar changes in lung volumes, due to chest wall and abdominal restriction. Chest wall strapping is also conceptually similar to a mismatch between significantly oversized donor lungs transplanted into a recipient with a smaller chest cavity. Chest wall strapping increases lung elastic recoil, reduces pulmonary compliance, and substantially increases maximal expiratory flows. The interactions between elastic properties of the lung parenchyma and small airways are critical for pulmonary function. Chest wall strapping lowers residual volume and closing volume, likely from the interdependence between increased elastic recoil and airways, leading to greater radial distending forces on small airways and small airway dilation. Chronic obstructive pulmonary disease (COPD) and chronic rejection of the transplanted lung, bronchiolitis obliterans syndrome (BOS), are primarily diseases of the small airways, and are characterized by progressive obstruction and subsequent loss of small airways. In COPD, higher body mass index (BMI) (conceptually like being more tightly strapped) is associated with lower lung volumes, increased airway conductance, and lower risk of progression to emphysema or death. Likewise, in lung transplantation, oversized donor lungs have been linked to higher expiratory airflows, lower risk of bronchiolitis obliterans syndrome, and improved survival. This article reviews the physiology of chest wall strapping and explores how it could enhance the understanding or even the treatment of small airway diseases, such as COPD and bronchiolitis obliterans syndrome.
Topics: Airway Resistance; Bronchiolitis Obliterans; Humans; Lung Volume Measurements; Pulmonary Disease, Chronic Obstructive; Pulmonary Ventilation
PubMed: 25172621
DOI: 10.1513/AnnalsATS.201312-465OI -
Indian Journal of Dental Research :... 2009Obstructive sleep apnea (OSA) is an increasingly common disorder. It is characterized by frequent episodes of airway obstruction associated with a reduced caliber of the... (Review)
Review
Obstructive sleep apnea (OSA) is an increasingly common disorder. It is characterized by frequent episodes of airway obstruction associated with a reduced caliber of the upper airway and is vulnerable to further narrowing and collapse. Acute and repetitive effects of apnea and hypopnea include oxygen desaturation, reduction in intrathoracic pressure, excessive daytime sleepiness, impaired executive function and central nervous system arousals. The apnea-hypopnea index and respiratory distress index help quantify the severity of the condition. The condition is associated with several clinical symptoms of which daytime sleepiness is considered the cardinal symptom. Obesity is one of the major predisposing factors. Three types of apneas have been recognized -obstructive, central and mixed; OSA is the commonest. This review will cover aspects of their radiologic features, diagnosis and management.
Topics: Airway Resistance; Diagnostic Imaging; Humans; Oximetry; Physical Examination; Polysomnography; Sleep Apnea, Obstructive; Sleep Stages
PubMed: 20139577
DOI: 10.4103/0970-9290.59457 -
American Journal of Physiology. Lung... Sep 2021Store-operated calcium entry (SOCE) is involved in the pathogenesis of airway inflammation and remodeling in asthma. Store-operated calcium entry-associated regulatory...
Store-operated calcium entry (SOCE) is involved in the pathogenesis of airway inflammation and remodeling in asthma. Store-operated calcium entry-associated regulatory factor (SARAF) can downregulate SOCE. We sought to investigate the role of SARAF in the regulation of airway inflammation and remodeling in asthma mice models, as well as in the functional regulation of human airway smooth muscle cells (hASMCs). Balb/c mice were sensitized and challenged with ovalbumin to establish the asthma mice models. Mice were transfected with lentivirus, which expressed the gene + GFP (green fluorescence protein) or the negative control gene + GFP. Airway resistance was measured with the animal pulmonary function system. Airway inflammation and remodeling were evaluated via histological staining. In vitro cultured hASMCs were transfected with scrambled small interfering RNA (siRNA) or SARAF-specific siRNA, respectively. The proliferation, migration rate, hypertrophy, and SOCE activity of hASMCs were examined with Cell Counting Kit-8, wound healing test, bright field imaging, and Ca fluorescence imaging, respectively. SARAF expression was measured by quantitative real-time PCR. Asthma mice models showed decreased SARAF mRNA expression in the lungs. SARAF overexpression attenuated airway inflammation, resistance, and also remodeling. Downregulation of SARAF expression with siRNA promoted the proliferation, migration, hypertrophy, and SOCE activity in hASMCs. SARAF plays a protective role against airway inflammation and remodeling in asthma mice models by blunting SOCE; SARAF may also be a functional regulating factor of hASMCs.
Topics: Airway Remodeling; Airway Resistance; Animals; Asthma; Calcium-Binding Proteins; Female; Gene Expression Regulation; Humans; Inflammation; Lung; Membrane Proteins; Mice; Mice, Inbred BALB C; Mice, Transgenic; Myocytes, Smooth Muscle
PubMed: 34231388
DOI: 10.1152/ajplung.00079.2020 -
Journal of Applied Physiology... Feb 1998To determine the relationship between upper airway muscle activity and upper airway resistance in nonsnoring and snoring young adults, 17 subjects were studied during... (Comparative Study)
Comparative Study
To determine the relationship between upper airway muscle activity and upper airway resistance in nonsnoring and snoring young adults, 17 subjects were studied during sleep. Genioglossus and alae nasi electromyogram activity were recorded. Inspiratory and expiratory supraglottic resistance (Rinsp and Rexp, respectively) were measured at peak flow, and the coefficients of resistance (Kinsp and Kexp, respectively) were calculated. Data were recorded during control, with continuous positive airway pressure (CPAP), and on the breath immediately after termination of CPAP. Rinsp during control averaged 7 +/- 1 and 10 +/- 2 cmH2O.l-1.s and Kinsp averaged 26 +/- 5 and 80 +/- 27 cmH2O.l-1.s-2 in the nonsnorers and snorers, respectively (P = not significant). On the breath immediately after CPAP, Kinsp did not increase over control in snorers (80 +/- 27 for control vs. 46 +/- 6 cmH2O.l-1.s-2 for the breath after CPAP) or nonsnorers (26 +/- 5 vs. 29 +/- 6 cmH2O.l-1.s-2). These findings held true for Rinsp. Kexp did not increase in either group on the breath immediately after termination of CPAP. Therefore, 1) increases in upper airway resistance do not occur, despite reductions in electromyogram activity in young snorers and nonsnorers, and 2) increases in Rexp and expiratory flow limitation are not observed in young snorers.
Topics: Adult; Airway Resistance; Electromyography; Female; Humans; Inhalation; Male; Nose; Respiratory Muscles; Sleep; Snoring; Tongue
PubMed: 9475857
DOI: 10.1152/jappl.1998.84.2.486 -
American Journal of Physiology. Lung... Mar 2011
Topics: Airway Resistance; Bronchial Hyperreactivity; Humans; Plethysmography; Respiratory Function Tests
PubMed: 21368020
DOI: 10.1152/ajplung.00410.2010 -
Journal of Applied Physiology... Oct 1999The interrupter technique is used to determine airway and tissue resistance. Their accuracy is influenced by the technical properties of the interrupter device and the...
The interrupter technique is used to determine airway and tissue resistance. Their accuracy is influenced by the technical properties of the interrupter device and the compliance of the respiratory system. We investigated the influence of valve characteristics and respiratory system compliance on the accuracy of determining airway and tissue resistance by means of a computer simulation. With decreasing compliance we found increasing errors in both airway and tissue resistance determination of up to 34 and 71%, respectively. On this basis we developed a new occlusion valve, with special emphasis on rapid closing time and tightness in the closed state to improve the accuracy of resistance determination. The newly developed occlusion device greatly improves the accuracy of airway and tissue resistance determination. We conclude that respiratory system compliance is a limiting factor for the accuracy of the interrupter technique. To apply the interrupter technique in patients with extremely low respiratory system compliances, we need sophisticated technical devices.
Topics: Airway Resistance; Compliance; Equipment Design; Equipment and Supplies; Humans; Models, Biological; Respiratory Physiological Phenomena
PubMed: 10517790
DOI: 10.1152/jappl.1999.87.4.1546 -
British Journal of Anaesthesia Sep 2000We compared the airflow resistance of 7.5 and 8.5 mm internal diameter (i.d.) endotracheal tubes (ETTs) with that of a size 4 laryngeal mask airway (LMA). We thought... (Comparative Study)
Comparative Study
We compared the airflow resistance of 7.5 and 8.5 mm internal diameter (i.d.) endotracheal tubes (ETTs) with that of a size 4 laryngeal mask airway (LMA). We thought that any difference in the resistance of the devices alone might be offset by the resistance of the larynx. Sixteen adult ASA physical status I and II patients (14 males, two females) undergoing general anaesthesia were anaesthetized and paralysed with intravenous propofol, ketamine and vecuronium. After insertion of the LMA, controlled ventilation (tidal volume 10 ml kg-1, frequency 12 min-1) was established with three different settings for inspiratory flow (5.5, 7.5 and 12.5 ml kg-1 s-1). Ventilation with the same settings was used after orotracheal intubation with an ETT of i.d. 7.5 mm (females) or 8.5 mm (males). The position of the LMA mask and the tip of the ETT were checked through a fibrescope. The resistance of the devices and, in case of the LMA, of the larynx, was derived by relating proximal and distal pressures (measured via catheters) to inspiratory flow. Four patients--young, tall men--had to be excluded from further study because of a leak around the LMA. In the remaining 10 males and two females, resistance of the LMA (mean (SD) at high flow, 1.19 (0.22) mbar.s litre-1 in males) was less than that of the 8.5 mm i.d. ETT (3.34 (0.52) mbar.s litre-1) (P < 0.01). However, the structures between the LMA and the trachea added another, highly variable, resistance component, so that the mean resistance of the LMA and larynx together was similar (in males: 3.20 (2.71) mbar.s litre-1) to that of the 8.5 mm ETT. In eight patients the epiglottis projected on to one-tenth to two-thirds of the distal opening of the LMA; this was in no case associated with greater resistance. Greater resistance occurred in two patients with a central LMA position and unobstructed view of the glottis and in one patient with marked lateral deviation. In conclusion, there is no clinically relevant difference between the resistance of a size 4 LMA plus that of the larynx and that of an 8.5 mm i.d. ETT.
Topics: Adult; Aged; Airway Resistance; Anesthesia, General; Equipment Design; Female; Humans; Intubation, Intratracheal; Laryngeal Masks; Male; Middle Aged; Respiration, Artificial; Statistics, Nonparametric
PubMed: 11103183
DOI: 10.1093/bja/85.3.410 -
Journal of Speech, Language, and... Jun 2015The larynx has a dual role in the regulation of gas flow into and out of the lungs while also establishing resistance required for vocal fold vibration. This study...
PURPOSE
The larynx has a dual role in the regulation of gas flow into and out of the lungs while also establishing resistance required for vocal fold vibration. This study assessed reciprocal relations between phonatory functions-specifically, phonatory laryngeal airway resistance (Rlaw)-and respiratory homeostasis during states of ventilatory gas perturbations.
METHOD
Twenty-four healthy women performed phonatory tasks while exposed to induced hypercapnia (high CO2), hypocapnia (low CO2), and normal breathing (eupnea). Effects of gas perturbations on Rlaw were investigated as were the reciprocal effects of Rlaw modulations on respiratory homeostasis.
RESULTS
Rlaw remained stable despite manipulations of inspired gas concentrations. In contrast, end-tidal CO2 levels increased significantly during all phonatory tasks. Thus, for the conditions tested, Rlaw did not adjust to accommodate ventilatory needs as predicted. Rather, stable Rlaw was spontaneously accomplished at the cost of those needs.
CONCLUSIONS
Findings provide support for a theory of regulation wherein Rlaw may be a control parameter in phonation. Results also provide insight into the influence of phonation on respiration. The work sets the foundation for future studies on laryngeal function during phonation in individuals with lower airway disease and other patient populations.
Topics: Adolescent; Adult; Airway Resistance; Female; Homeostasis; Humans; Hypocapnia; Larynx; Middle Aged; Phonation; Respiration; Young Adult
PubMed: 25764093
DOI: 10.1044/2015_JSLHR-S-13-0270 -
Journal of Physiological Anthropology Jan 2021Body composition (BC) influences respiratory system mechanics, provoking air flow limitation (AFL). The objective of this study was to determine the relationship of AFL...
BACKGROUND
Body composition (BC) influences respiratory system mechanics, provoking air flow limitation (AFL). The objective of this study was to determine the relationship of AFL in small- and medium-caliber airways with BC in young adults.
METHODS
Eighty-three individuals were recruited (40 men and 43 women). To determine AFL, the following measurements were taken: forced expiratory volume in the first second (FEV), forced expiratory flow between 25 and 75% (FEF), airway resistance (Raw), and specific airway resistance (sRaw). The measured BC variables were body mass index (BMI), body fat percentage (%BF), and fat-free mass (FFM). Binary logistical regression analysis was used to estimate the association between the AFL variables and %BF, BMI, and %FFM, adjusting for weight and gender.
RESULTS
Among men, a relationship was observed between Raw and %BF (r = 0.728; p < 0.0001) and sRaw and BMI (r = 0.617; p < 0.0001). Among women, significant relationships were reported between Raw and BMI (r = 0.615; p < 0.0001) and sRaw and BMI (r = 0.556; p < 0.0001). Among participants with a BMI over 30 kg/m, higher risks of increased Raw (OR = 26.8; p = 0.009) and sRaw (OR = 9.3; p = 0.002) were observed. Furthermore, higher %BF was associated with greater risks for increased Raw (OR = 14.04; p = 0.030) and sRaw (OR = 4.14; p = 0.028). In contrast, increased %FFM (OR = 0.14; p = 0.025) was a protective factor for lung function.
CONCLUSION
Increased %BF is associated with increased AFL in small-caliber airways. Furthermore, increased %FFM is associated with decreased risk for Raw and sRaw in women. Therefore, evidence indicates that increased %FFM is a protective factor for adequate lung function.
Topics: Adult; Airway Resistance; Body Composition; Body Mass Index; Cross-Sectional Studies; Female; Forced Expiratory Volume; Humans; Male; Obesity; Young Adult
PubMed: 33468239
DOI: 10.1186/s40101-021-00252-2 -
Journal of Applied Physiology... Oct 1997We present a dog lung model to predict the relation between inhomogeneous changes in airway morphometry and lung resistance (RL) and elastance (EL) for frequencies...
We present a dog lung model to predict the relation between inhomogeneous changes in airway morphometry and lung resistance (RL) and elastance (EL) for frequencies surrounding typical breathing rates. The RL and EL were sensitive in distinct ways to two forms of peripheral constriction. First, when there is a large and homogeneous constriction, the RL increases uniformly over the frequency range. The EL is rather unaffected below 1 Hz but then increases with frequencies up to 5 Hz. This increase is caused by central airway wall shunting. Second, the RL and EL are extremely sensitive to mild inhomogeneous constriction in which a few highly constricted or nearly closed airways occur randomly throughout the periphery. This results in extreme increases in the levels and frequency dependence of RL and EL but predominantly at typical breathing rates (<1 Hz). Conversely, the RL and EL are insensitive to highly inhomogeneous airway constriction that does not produce any nearly closed airways. Similarly, alterations in the RL and EL due to central airway wall shunting are not likely until the preponderance of the periphery constricts substantially. The RL and EL spectra are far more sensitive to these two forms of peripheral constriction than to constriction conditions known to occur in the central airways. On the basis of these simulations, we derived a set of qualitative criteria to infer airway constriction conditions from RL and EL spectra.
Topics: Airway Resistance; Animals; Bronchi; Dogs; Elasticity; Functional Residual Capacity; Lung; Models, Anatomic; Respiratory Physiological Phenomena; Respiratory System; Total Lung Capacity; Trachea
PubMed: 9338428
DOI: 10.1152/jappl.1997.83.4.1192