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Journal of Applied Physiology... Aug 2008An acoustic whole body plethysmograph was developed to estimate specific airway resistance (sRaw) in unrestrained mice. The plethysmograph uses acoustic principles to...
An acoustic whole body plethysmograph was developed to estimate specific airway resistance (sRaw) in unrestrained mice. The plethysmograph uses acoustic principles to measure the thoracic breathing pattern and simultaneously measures the airflow entering and/or leaving the plethysmograph. Similarly to traditional methods utilizing a double-chamber plethysmograph, these measurements were combined to estimate sRaw. To evaluate the new system, we placed six conscious A/J mice individually in a whole body plethysmograph (Buxco System) for a 2-min exposure to aerosolized methacholine chloride dissolved in saline (0, 5, 10, and 20 mg/ml), which is known to increase sRaw in mice. Three minutes after exposure, the mice were transferred to the acoustic plethysmograph for 2 min for data collection. The mean baseline value of sRaw was 0.93+/-0.10 cmH2O.s. A dose-dependent increase in sRaw was shown, with an approximate tripling of sRaw at the highest dose. These results demonstrate the ability of the system to estimate sRaw based on plethysmograph airflow and acoustic amplitude.
Topics: Acoustic Stimulation; Airway Resistance; Animals; Electronics; Mice; Plethysmography; Plethysmography, Whole Body; Respiratory Mechanics
PubMed: 18450981
DOI: 10.1152/japplphysiol.00949.2007 -
Journal of Applied Physiology... Jun 1991We propose that a sleep-induced decrement in the activity of the tensor palatini (TP) muscle could induce airway narrowing in the area posterior to the soft palate and...
We propose that a sleep-induced decrement in the activity of the tensor palatini (TP) muscle could induce airway narrowing in the area posterior to the soft palate and therefore lead to an increase in upper airway resistance in normal subjects. We investigated the TP to determine the influence of sleep on TP muscle activity and the relationship between changing TP activity and upper airway resistance over the entire night and during short sleep-awake transitions. Seven normal male subjects were studied on a single night with wire electrodes placed in both TP muscles. Sleep stage, inspiratory airflow, transpalatal pressure, and TP moving time average electromyogram (EMG) were continuously recorded. In addition, in two of the seven subjects the activity (EMG) of both the TP and the genioglossus muscle simultaneously was recorded throughout the night. Upper airway resistance increased progressively from wakefulness through the various non-rapid-eye-movement sleep stages, as has been previously described. The TP EMG did not commonly demonstrate phasic activity during wakefulness or sleep. However, the tonic EMG decreased progressively and significantly (P less than 0.05) from wakefulness through the non-rapid-eye-movement sleep stages [awake, 4.6 +/- 0.3 (SE) arbitrary units; stage 1, 2.6 +/- 0.3; stage 2, 1.7 +/- 0.5; stage 3/4, 1.5 +/- 0.8]. The mean correlation coefficient between TP EMG and upper airway resistance across all sleep states was (-0.46). This mean correlation improved over discrete sleep-awake transitions (-0.76). No sleep-induced decrement in the genioglossus activity was observed in the two subjects studied.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Adult; Airway Resistance; Electromyography; Humans; Male; Muscle Contraction; Palatal Muscles; Sleep; Wakefulness
PubMed: 1885452
DOI: 10.1152/jappl.1991.70.6.2574 -
Archives of Otolaryngology--head & Neck... Aug 1991In the surgical treatment of the paralyzed larynx, a compromise often needs to be made between an orifice size needed to preserve voice and that needed for adequate...
In the surgical treatment of the paralyzed larynx, a compromise often needs to be made between an orifice size needed to preserve voice and that needed for adequate inspiratory airflow rates. To assess the negative pressures needed to generate normal airflows across a narrowed vocal cord aperture, we measured pressure and flow changes across cadaveric larynges while altering aperture size. Best-fit quadratic equations for each aperture area selected were derived and showed that if the aperture were 0.5 cm2 or less, the resistance to normal breathing would be significantly increased. Aperture sizes of 0.67 cm2 or greater are not associated with such an increase in resistance.
Topics: Airway Resistance; Calibration; Humans; In Vitro Techniques; Laryngostenosis; Pressure; Reference Values
PubMed: 1892616
DOI: 10.1001/archotol.1991.01870200061008 -
Journal of Applied Physiology... Jun 1996It has been reported that both the elasticity of the cartilage and airway-parenchymal interdependence can modify shortening of the airway smooth muscle and airway...
It has been reported that both the elasticity of the cartilage and airway-parenchymal interdependence can modify shortening of the airway smooth muscle and airway narrowing during induced constriction. We hypothesized that induced softening of the cartilage could alter airway compliance and/or the forces of mechanical interdependence, resulting in an increased degree of airway narrowing in response to a contractile stimulus. To test this hypothesis, we compared the effects of changing lung volume on airway resistance (Raw) under baseline conditions and during methacholine (MCh)-induced constriction in papain-treated (n = 6) and control rabbits (n = 6). With use of the alveolar capsule technique, Raw was directly measured under baseline conditions at different levels of end-expiratory transpulmonary pressure (Ptp = 4-12 cmH2O). Then aerosolized MCh was delivered (0.2-25 mg/ml) and measurements were performed at different levels of Ptp (4 and 12 cmH2O). From measured tracheal flow and tracheal and alveolar pressure in open-chest animals during mechanical ventilation (tidal volume = 6 ml/kg, breathing frequency = 1 Hz), we calculated Raw by subtracting tissue resistance from lung resistance. Papain treatment significantly increased Raw both under baseline conditions and after induced constriction. We found that increasing Ptp decreased Raw before and after MCh in both groups; however, the effects of changing Ptp on Raw were less in papain-treated animals. These observations suggest that both cartilage elasticity and mechanical interdependence are important determinants of airway smooth muscle shortening. The observation that volume dependence of Raw was less in papain-treated animals is consistent with the hypothesis that papain effects significant changes in the parenchymal attachments.
Topics: Airway Resistance; Animals; Lung; Male; Papain; Rabbits; Respiration
PubMed: 8806889
DOI: 10.1152/jappl.1996.80.6.1872 -
The European Respiratory Journal May 2000The upper airway (UA) of adult animals is known to contain carbon dioxide-sensitive receptors and UA CO2 reflexly affects breathing, UA dilator muscle activity and UA...
The upper airway (UA) of adult animals is known to contain carbon dioxide-sensitive receptors and UA CO2 reflexly affects breathing, UA dilator muscle activity and UA resistance. These effects may function in the control of UA patency. There is evidence that some UA reflexes are stronger in young than in adult animals, but it is not known whether CO2-sensitive receptors are present in the UA of young animals, and the effects of UA CO2 on UA resistance and on UA dilator muscle activity have not been investigated in young animals. The responses of ventilation, UA resistance and geniohyoid muscle electromyographic activity to warm air containing 10% CO2 applied to the isolated UA were measured in anaesthetized, vagotomized young guinea-pigs breathing spontaneously through a low-cervical tracheostomy. Upper airway carbon dioxide caused an increase in ventilation (46.7+/-16.3 to 49.9+/-16.8 mL x min(-1) x 100 g body weight(-1)) and upper airway resistance (56.8+/-14.8 to 63.7+/-17.7 cmH2O x L(-1) x s(-1) x kg body weight(-1)). Similar effects were obtained following vagotomy. Geniohyoid activity became apparent following vagotomy and this activity was reduced by upper airway carbon dioxide. These responses were abolished by topical anaesthesia of the upper airway. This suggests that the reflexes seen are due to carbon dioxide-sensitive receptors in the upper airway.
Topics: Age Factors; Airway Resistance; Animals; Carbon Dioxide; Electromyography; Guinea Pigs; Respiratory Muscles
PubMed: 10853856
DOI: 10.1034/j.1399-3003.2000.15e15.x -
Clinical Science (London, England :... Mar 19801. Airway resistance was measured close to functional residual capacity before and after a full inhalation of total lung capacity, as well as before and after a full...
1. Airway resistance was measured close to functional residual capacity before and after a full inhalation of total lung capacity, as well as before and after a full exhalation to residual volume. 2. The effects of these volume manoeuvres upon airway resistance (and associated lung volume) were determined in four resting normal male subjects and in six normal men during experimentally induced bronchoconstriction after breathing an air/histamine mist from a Wright's nebulizer. 3. In four men the duration of the effect of a full inhalation upon airway resistance after induced bronchoconstriction was assessed separately. 4. Neither a full inhalation nor a full exhalation altered airway resistance under normal conditions. However, a full inhalation reduced airway resistance in the presence of bronchoconstriction and this effect lasted for a period of 45 s. Even with bronchoconstriction, a full exhalation had no effect on airway resistance. 5. Account must therefore be taken of the potential reduction in airway resistance which may result from a full inhalation, particularly when indirect measurements of airway function which involve a full inhalation, such as forced spirometry, are used to assess airway obstruction.
Topics: Airway Resistance; Bronchi; Histamine; Humans; Lung Volume Measurements; Respiration
PubMed: 7363566
DOI: 10.1042/cs0580249 -
Acta Oto-laryngologica 1990The relationship between nasal airway resistance and nasalance in healthy volunteers and in subjects suffering from symptoms of acute rhinitis was investigated. A... (Comparative Study)
Comparative Study
The relationship between nasal airway resistance and nasalance in healthy volunteers and in subjects suffering from symptoms of acute rhinitis was investigated. A non-invasive objective measure of nasalance using the Nasometer (Kay Electronics) was used and an inverse correlation between airway resistance and nasalance was found (r = 0.67, r2 = 0.46, p less than 0.0001). The effect of a topical nasal decongestant on nasal airway resistance and nasalance was investigated, and significant changes were seen both in resistance and nasalance (p less than 0.0001) with a correlation in the changes seen in both parameters (r = 0.82, r2 = 0.66, p less than 0.0001). The measure of nasalance may be useful in assessing various forms of nasal treatment including nasal, adenoidal and palatal surgery. The measurement of nasalance is well tolerated by subjects of all ages and is particularly useful in subjects with high nasal resistance where rhinomanometry tends to be unstable.
Topics: Acute Disease; Adolescent; Adult; Airway Resistance; Female; Humans; Imidazoles; Male; Manometry; Middle Aged; Nasal Decongestants; Rhinitis; Voice Quality
PubMed: 1704676
DOI: 10.3109/00016489009107467 -
The Journal of Laryngology and Otology Nov 2006To identify any prospective, controlled trials providing objective evidence of a reduction in nasal airway resistance following nasal septal surgery, and to undertake a... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To identify any prospective, controlled trials providing objective evidence of a reduction in nasal airway resistance following nasal septal surgery, and to undertake a meta-analysis of available data.
METHODS
A systematic review with meta-analysis of data was undertaken. A systematic review of the literature using a defined search strategy was conducted to identify papers that used objective methods of airway assessment to evaluate the benefit of septal surgery. Accepted techniques for objective airway assessment included acoustic rhinometry, active anterior rhinomanometry and peak nasal inspiratory airflow. Papers were included based on pre-defined criteria, which included standardization of techniques as outlined in the guidelines of the 1984 committee report on the standardization of rhinomanometry.
RESULTS
We identified 942 articles, of which 13 were prospective studies evaluating the objective benefit of nasal septal surgery. Only three of these studies conformed to the inclusion criteria. A meta-analysis on these papers was performed using the Mantel-Haenszel method, and this demonstrated an overall reduction in nasal airway resistance following septal surgery for nasal obstruction (p=0.018).
CONCLUSIONS
The majority of studies evaluating the objective benefit of septal surgery did not conform to the recommendations of the committee report on the standardization of rhinomanometry. Only three prospective controlled trials, with pooled data from 141 cases, were identified for meta-analysis. The conclusions that can be drawn concerning objective improvement in airway function following nasal septal surgery are therefore limited. More long-term studies, adhering to standardized techniques, are needed to provide more convincing data.
Topics: Airway Resistance; Humans; Nasal Obstruction; Nasal Septum; Rhinomanometry; Rhinometry, Acoustic
PubMed: 17040608
DOI: 10.1017/S0022215106003410 -
Research in Veterinary Science 1998Impulse oscillometry (IOS) was compared with conventional pulmonary function techniques (using oesophageal balloon and airflow measurements). Healthy Friesian (FR) and...
Impulse oscillometry (IOS) was compared with conventional pulmonary function techniques (using oesophageal balloon and airflow measurements). Healthy Friesian (FR) and Blue Belgian (BB) calves were examined in different conditions of extrathoracic airway resistance (physiological and vertical head position). Higher resistance values were detected in BB calves compared with FR calves with both conventional and forced oscillation techniques in both head positions. Upper airway narrowing was characterised by increasing resistance values without changes in frequency dependence. Measuring input impedance in animals using a face mask, a considerable capacitive shunt of the upper airways (including the capacitive components of the mask) has to be taken into account. Even if the absolute value of this capacitive component is constant, its influence on the measurement results increases with growing frequency and with an increase in upper airway resistance. In conclusion, (1) impulse oscillometry is sensitive to upper airway resistance changes and (2) face mask capacitance is important and has frequency dependent effects on the respiratory impedance.
Topics: Airway Resistance; Animals; Cattle; Cross-Over Studies; Male; Oscillometry; Posture; Reproducibility of Results; Respiratory Function Tests; Species Specificity
PubMed: 9839885
DOI: 10.1016/s0034-5288(98)90158-8 -
Respiration Physiology Jan 1989The upper airway (UAW) is intrinsically unstable and susceptible to collapse when the negative inspiratory intraluminal pressure exceeds the stabilizing forces which...
The upper airway (UAW) is intrinsically unstable and susceptible to collapse when the negative inspiratory intraluminal pressure exceeds the stabilizing forces which prevent obstruction. In the present study we evaluated mechanisms by which UAW patency is maintained in the presence of increased inspiratory flows when respiration is stimulated. In seven anesthetized dogs breathing spontaneously through a low tracheostomy, the UAW was isolated by a second tracheostomy directed rostrally. UAW pressure-flow relationship and stability against collapse were evaluated during steady flow in the inspiratory direction while the animals were breathing 100% O2 or a hypercapnic gas mixture. The pressure-flow curves of the isolated UAW demonstrated the characteristic pattern of collapsible tubes. Steady state hypercapnia resulted in lower UAW resistance during both inspiration and expiration. UAW resistance decreased linearly as PCO2 and ventilation increased over the course of CO2 rebreathing. In addition, during hypercapnia the critical negative intraluminal pressure required to induce UAW collapse and obstruction increased from -4.3 +/- 0.9 to -8.5 +/- 1.5 SE cm H2O (p less than 0.01), indicating increased stability of the UAW. Since hypercapnia is known to stimulate UAW muscles, our findings suggest that increased UAW muscle activity improves UAW patency both by decreasing their resistance to airflow, and by increasing UAW walls rigidity and stability against collapse.
Topics: Airway Resistance; Animals; Carbon Dioxide; Dogs; Hypercapnia; Trachea
PubMed: 2497502
DOI: 10.1016/0034-5687(89)90084-4