The Effects of Pre-Existing Loads Upon Detection of Externally Applied Resistances to Breathing in Man

1973 ◽  
Vol 45 (4) ◽  
pp. 561-564
Author(s):  
D. I. McCloskey
Keyword(s):  
Normal Subjects ◽  
External Resistance ◽  
Airways Resistance

1. It was confirmed that normal subjects can detect an increase in airways resistance of 1.2 cmH2O 1−1 s when this is presented during a sequence of otherwise unresisted breaths. 2. In contrast when such subjects meet the same resistance presented unexpectedly during a sequence of breaths against a larger resistance (2.5 cmH2O 1−1 s), they commonly fail to detect it, indicating that they believe no external resistance remains. 3. Subjects breathing continuously against a given external resistance frequently during the course of the study indicate that they believe that a decrease in resistance has been made.

Reversibility of Airways Obstruction in Chronic Bronchitis

1972 ◽  
Vol 42 (6) ◽  
pp. 725-733 ◽  
Author(s):  
T. W. Astin
Keyword(s):  
Muscle Contraction ◽  
Chronic Bronchitis ◽  
Lung Volume ◽  
Normal Subjects ◽  
Atropine Sulphate ◽  
Airways Obstruction ◽  
Chest Disease ◽  
Before And After ◽  
Airways Resistance ◽  
Intravenous Atropine

1. Airways resistance and lung volume were measured in twenty-five patients with chronic bronchitis and fifteen patients without chest disease before and after the inhalation of isoprenaline. Similar measurements were made on fourteen of these patients with chronic bronchitis and twelve other patients without chest disease before and after the intravenous injection of atropine sulphate. 2. There were significant decreases in airways resistance after isoprenaline inhalation and intravenous atropine both in patients with bronchitis and normal subjects but the decreases were greater in the patients with chronic bronchitis. 3. The decrease in resistance was proportional to the degree of initial airways resistance. 4. The results are considered to indicate that bronchial muscle contraction increases the airways resistance of patients with chronic bronchitis and contributes to the airways obstruction; its contribution increases with increasing severity of the condition. A significant part of the increased airways resistance in these patients is potentially reversible and nervously mediated.

The Effect of Added External Resistance on Regional Pulmonary Filling and Emptying Sequences

1971 ◽  
Vol 49 (5) ◽  
pp. 406-411 ◽  
Author(s):  
R. R. Martin ◽  
J. E. Wilson ◽  
W. R. D. Ross ◽  
N. R. Anthonisen
Keyword(s):  
Flow Rate ◽  
Normal Subjects ◽  
Low Flow ◽  
Maximum Speed ◽  
Respiratory Effort ◽  
External Resistance ◽  
Flow Rates ◽  
Alveolar Plateau ◽  
Minimal Resistance ◽  
Maximal Effort

Using the radioactive 133Xe technique, the effects of external resistances on the distribution of inspired gas and on the expiratory alveolar plateau were examined in four normal subjects. Subjects inhaled 133Xe boli one of three ways: slowly through minimum external resistance, with maximum speed through minimal resistance, and with maximal effort but at very low flow rates through a large external resistance. Also, always after a slow inspiration through low resistance, subjects expired in three different ways: slowly through minimal resistance, with maximum speed through minimal resistance, and finally with maximal effort through an external resistance which sharply limited flow rates. Both regional intrapulmonary 133Xe distribution and the shape of the alveolar plateau appeared to depend entirely on flow rate and to be independent of effort. These results were interpreted as indicating that variations in respiratory effort do not produce variations in dynamic pleural pressure between lung regions.

Effects of cardioselective beta adrenoceptor blockade on specific airways resistance in normal subjects and in patients with bronchial asthma

1976 ◽  
Vol 19 (5part1) ◽  
pp. 493-501 ◽  
Author(s):  
Bramah N. Singh ◽  
Robert M. L. Whitlock ◽  
Russell H. Comber ◽  
Faith H. Williams ◽  
Edward A. Harris
Keyword(s):  
Bronchial Asthma ◽  
Normal Subjects ◽  
Beta Adrenoceptor ◽  
Airways Resistance

Control of larynx during loaded breathing in normal subjects

1986 ◽  
Vol 60 (6) ◽  
pp. 1887-1893 ◽  
Author(s):  
K. Sekizawa ◽  
M. Yanai ◽  
H. Sasaki ◽  
T. Takishima
Keyword(s):  
Low Frequency ◽  
Normal Subjects ◽  
Respiratory Center ◽  
External Resistance ◽  
Frequency Sound ◽  
Tightly Coupled ◽  
Loaded Breathing ◽  
Laryngeal Resistance

We examined laryngeal resistance (Rla) in six normal subjects in control and four kinds of loaded breathing: hypercapnia, chest strapping, added external resistance, and inhaled methacholine. Rla was measured with a low-frequency sound methed (Sekizawa et al., J. Appl. Physiol. 55: 591–597, 1983). In control and the four kinds of loaded breathing, changes in Rla were tightly coupled with ventilation and Rla decreased during inspiration and increased during expiration. Hypercapnia and chest strapping significantly decreased Rla in both inspiration and expiration in all subjects. Added external resistance decreased inspiratory Rla in all subjects, but decreased expiratory Rla in three subjects, did not change it in two subjects, and increased it in one subject. Inhaled methacholine increased Rla in both inspiration and expiration in all subjects. The present study suggests that although laryngeal movement is tightly coupled with ventilation, laryngeal aperture may be determined by the complex competition of dilating and constricting mechanisms associated with the activity of the respiratory center and neural reflexes from the airway.

Bronchial Sympathetic Activity in Chronic Bronchitis

1972 ◽  
Vol 43 (6) ◽  
pp. 881-889 ◽  
Author(s):  
T. W. Astin
Keyword(s):  
Chronic Bronchitis ◽  
Sympathetic Activity ◽  
Normal Subjects ◽  
Control Subjects ◽  
Chest Disease ◽  
Before And After ◽  
Alpha Receptors ◽  
Airways Resistance ◽  
Propranolol Administration ◽  
Made In

1. Measurements of airways resistance and lung volume were made in sixteen patients with chronic bronchitis and ten patients without chest disease before and after intravenous propranolol administration. 2. The airways resistance of the patients with chronic bronchitis increased significantly after propranolol administration but in the control subjects there was no significant increase. 3. In the patients with chronic bronchitis the increases in airways resistance were greater when the initial values were high. 4. In seven of the patients with chronic bronchitis and seven further control subjects airways resistance was measured before and after intravenous thymoxamine administration. 5. The airways resistance of the normal subjects was unchanged by thymoxamine administration, but that of the patients with chronic bronchitis decreased significantly. 6. The results are consistent with the existence of bronchial alpha receptors in man. In patients with chronic bronchitis there are greater degrees of both alpha and beta bronchial sympathetic activity than in normal subjects. The greater the severity of the condition the greater is the degree of beta sympathetic activity. In considering the factors causing airways obstruction in chronic bronchitis sympathetic activity should be taken into account.

Effects of bronchoconstriction and external resistive loading on the sensation of dyspnea

1991 ◽  
Vol 71 (6) ◽  
pp. 2183-2190 ◽  
Author(s):  
O. Taguchi ◽  
Y. Kikuchi ◽  
W. Hida ◽  
N. Iwase ◽  
M. Satoh ◽  
...  
Keyword(s):  
Normal Subjects ◽  
Vagal Afferents ◽  
Vagal Activity ◽  
Resistive Load ◽  
Occlusion Pressure ◽  
Analog Scale ◽  
External Resistance ◽  
Resistive Loading ◽  
Afferent Vagal

To determine whether the intensity of dyspnea at a given level of respiratory motor output differs between bronchoconstriction and the presence of an external resistance, we compared the sensation of difficulty in breathing during isocapnic voluntary hyperventilation in six normal subjects. An external resistance of 1.9 cmH2O.1–1.s was applied during both inspiration and expiration. To induce bronchoconstriction, histamine aerosol (5 mg/ml) was inhaled until airway resistance (Raw) increased to a level approximately equal to the subject's control Raw plus the added external resistance. To clarify the role of vagal afferents on the genesis of dyspnea during both forms of obstruction to airflow, the effect of airway anesthesia by lidocaine aerosol inhalation was also examined after histamine and during external resistive loading. The sensation of difficulty in breathing was rated at 30-s intervals on a visual analog scale during isocapnic voluntary hyperpnea, in which the subjects were asked to copy an oscilloscope volume trace obtained previously during progressive hypercapnia. Histamine inhalation significantly increased the intensity of the dyspneic sensation over the equivalent external resistive load at the same levels of ventilation and occlusion pressure during voluntary hyperpnea. Inhaled lidocaine decreased the sensation of dyspnea during bronchoconstriction with no change in Raw, but it did not significantly change the sensation during external resistive loading. These results suggest that afferent vagal activity plays a role in the genesis of dyspnea during bronchoconstriction.

Phase variation in nasal airways resistance assessed by active anterior rhinomanometry

1987 ◽  
Vol 101 (9) ◽  
pp. 910-916 ◽  
Author(s):  
G. S. Kenyon
Keyword(s):  
Statistical Significance ◽  
Phase Variation ◽  
Normal Subjects ◽  
Nasal Airways ◽  
Nasal Cycle ◽  
Significant Difference ◽  
Airways Resistance ◽  
Respiratory Phases ◽  
Active Anterior Rhinomanometry

AbstractMeasurements of nasal airways resistance in normal subjects have shown a significant difference between values obtained in the two respiratory phases. Higher overall values are found during expiration in both the unprepared and decongested nose but these differences fail to maintain statistical significance after application of a decongestant. This indicates that the phase of respiration in which measurement is made must be routinely recorded especially when measurement is made without decongestant, and comparisons of data made only with recordings from equivalent parts of the nasal cycle.

Auditory Selective Attention in Cerebral-Palsied Individuals

1985 ◽  
Vol 16 (4) ◽  
pp. 260-266 ◽  
Author(s):  
Lee Ann Laraway
Keyword(s):  
Selective Attention ◽  
White Noise ◽  
Normal Subjects ◽  
Auditory Selective Attention ◽  
Normal Individuals ◽  
Significant Difference

The purpose of this study was to determine whether there is a statistically significant difference between the auditory selective attention abilities of normal and cerebral-palsied individuals. Twenty-three cerebral-palsied and 23 normal subjects between the ages of 5 and 21 were asked to repeat a series of 30 items consisting of from 2 to 4 digits in the presence of intermittent white noise. Results of the study indicate that cerebral-palsied individuals perform significantly poorer than normal individuals when the stimulus is accompanied by noise. Noise was not a significant factor in the performance of the normal subjects regardless of age.

The Effect of Stapedectomy on the Loudness of One’s Own Voice

1965 ◽  
Vol 8 (3) ◽  
pp. 223-234 ◽  
Author(s):  
William Melnick
Keyword(s):  
Middle Ear ◽  
Normal Subjects ◽  
Sound Energy ◽  
Loudness Function ◽  
Before And After ◽  
Increased Sensitivity

Five subjects with normal middle ear mechanisms, and otosclerotic patients, before and after stapedectomy, matched the loudness of their voices to the loudness of a 125-cps-sawtooth noise. The results showed loudness matching functions with gradual slopes, less than 1.00, for the normal subjects and the patients prior to stapedectomy. Post-surgically, the loudness function for the patients increased in steepness to considerably more than 1.00. These results are explained, most logically, in terms of increased sensitivity of the altered middle ear to sound energy generated by the listener’s own voice.

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