Extrathoracic airway resistance in man

1961 ◽  
Vol 16 (2) ◽  
pp. 326-330 ◽  
Author(s):  
Robert E. Hyatt ◽  
Roger E. Wilcox
Keyword(s):  
Flow Resistance ◽  
Airway Resistance ◽  
Human Subjects ◽  
Upper Airway ◽  
Normal Subjects ◽  
Mouth Breathing ◽  
Human Beings ◽  
Lung Inflation ◽  
Upper Airway Resistance ◽  
Extrathoracic Airway

Simultaneous extrathoracic and intrathoracic flow resistance was measured in 19 unanesthetized subjects during mouth breathing. Lateral intratracheal pressure was recorded from a needle introduced 2 cm below the larynx. The intratracheal-oral pressure gradient was recorded during various respiratory maneuvers. The pressure drop from esophagus to trachea was also recorded. The extrathoracic pressure-flow relationships were alinear. Large inter- and intrasubject variability in upper airway resistance was encountered. Some factors contributing to this variability were defined. The upper airway accounted for approximately 45% of the total airway resistance in nine normal and 20% in 10 emphysematous human subjects. Upper airway resistance decreased with increasing lung inflation in four normal subjects. The magnitude and potential variability of the upper airway resistance must be considered in evaluating maneuvers designed to alter intrathoracic flow resistance, especially in normal human beings. It appears that during mouth breathing the major component of the upper airway resistance is located in the larynx. Submitted on September 14, 1960

Partitioning of respiratory flow resistance in man

1964 ◽  
Vol 19 (4) ◽  
pp. 653-658 ◽  
Author(s):  
B. G. Ferris ◽  
J. Mead ◽  
L. H. Opie
Keyword(s):  
Chest Wall ◽  
Flow Resistance ◽  
Airway Resistance ◽  
Upper Airway ◽  
Mouth Breathing ◽  
Lower Airway ◽  
Nasal Breathing ◽  
Pulmonary Tissue ◽  
Tissue Resistance ◽  
Highly Nonlinear

Measurements of flow resistance of various components of the respiratory system were measured in adult male subjects in the sitting position. Nasal resistance is the largest single component being nearly one-half the total and two-thirds of the airway resistance during nose breathing. It is highly nonlinear, and shows much variability. During mouth breathing upper airway resistance (mouth, pharynx, glottis, larynx and upper trachea) is also markedly nonlinear, and accounts for one-third the total airway resistance. Lower airway resistance is approximately linear up to flows of 2 liters/sec. Pulmonary tissue resistance is low as reported in this study. Chest wall resistance is nearly linear up to flow rates of 2 liters/sec and accounts for slightly less than half the total respiratory resistance during mouth breathing and 10–19% during nasal breathing. larynx; airways; chest wall; nose Submitted on December 16, 1963

Measurement of upper and lower airway resistance and conductance in man

1964 ◽  
Vol 19 (6) ◽  
pp. 1059-1069 ◽  
Author(s):  
Richard W. Blide ◽  
H. David Kerr ◽  
William S. Spicer
Keyword(s):  
Direct Measurement ◽  
Airway Resistance ◽  
Lateral Pressure ◽  
Upper Airway ◽  
Normal Subjects ◽  
Lower Airway ◽  
Upper Airway Resistance ◽  
Human Lungs ◽  
Lower Airways ◽  
Airway Conductance

The resistances to flow in the upper (Ruaw) and lower (Rlaw) airway of human lungs were measured simultaneously with total airway resistance (Raw) and the volume of thoracic gas (Vtg) using the plethysmographic method and lateral pressure taps at the tracheal and oral levels. Ruaw is found to decrease slightly in a curvilinear fashion with increasing Vtg while its reciprocal, Guaw, is linearly related to Vtg with a negative Vtg intercept in normal subjects. Lower airway conductance (Glaw) is linearly related to Vtg with a slope of approximately 1.0 liters/sec per cm H2O per liter. From the partitioned resistances it is deduced that total airway conductance (Gaw) is curvilinear but approximately linear over the majority of the Vtg. A method of calculating resistance and conductance in the upper and lower airways from Raw versus Vtg data is presented using the equation Raw = Vtg/(A @#X002B; B Vtg) where B2/A @#X003D; dGlaw/ dVtg. Three hundred and sixty-two records of Raw versus Vtg data from 22 normal, asthmatic, and bronchitic subjects are then evaluated by this method and the results compared to those obtained by direct measurement. intrathoracic or lower airway conductance; intrathoracic or lower airway resistance; extrathoracic or upper airway conductance; extrathoracic or upper airway resistance Submitted on November 8, 1963

scholarly journals The effect of inhaled menthol on upper airway resistance in humans: A randomized controlled crossover study

2013 ◽  
Vol 20 (1) ◽  
pp. e1-e4 ◽  
Author(s):  
Effie J Pereira ◽  
Lauren Sim ◽  
Helen S Driver ◽  
Chris M Parker ◽  
Michael F Fitzpatrick
Keyword(s):  
Crossover Study ◽  
Receptor Agonist ◽  
Airway Resistance ◽  
Human Subjects ◽  
Minute Ventilation ◽  
Symptomatic Relief ◽  
Upper Airway ◽  
Quiet Breathing ◽  
Upper Airway Resistance ◽  
Cold Receptor

BACKGROUND: Menthol (l-menthol) is a naturally-occurring cold receptor agonist commonly used to provide symptomatic relief for upper airway congestion. Menthol can also reduce the sensation of dyspnea. It is unclear whether the physiological action of menthol in dyspnea reduction is through its cold receptor agonist effect or whether associated mechanical changes occur in the upper airway.OBJECTIVE: To determine whether menthol inhalation alters upper airway resistance in humans.METHODS: A randomized, sham-controlled, single-blinded crossover study of inhaled menthol on upper airway resistance during semirecumbent quiet breathing in healthy subjects was conducted. Ten healthy participants (eight female) with a mean (± SD) age of 21±1.6 years completed the study.RESULTS: Nasal resistance before testing was similar on both occasions. No differences were found in respiratory frequency (mean ± SEM) (menthol 17.0±1.1 cmH2O/L/s; sham 16.9±0.9 cmH2O/L/s), minute ventilation (menthol 7.7±0.5 cmH2O/L/s; sham 7.9±0.5 cmH2O/L/s) or total inspiratory time/total breath time (menthol 0.4±0.1 cmH2O/L/s; sham 0.4±0.1 cmH2O/L/s). The upper airway resistance was similar during menthol (3.47±0.32 cmH2O/L/s) and sham (3.27±0.28 cmH2O/L/s) (P=0.33) inhalation.CONCLUSION: Inhalation of menthol does not alter upper airway resistance in awake human subjects.

Effects of respiratory drive on upper airways in sleep apnea patients and normal subjects

1989 ◽  
Vol 67 (3) ◽  
pp. 973-979 ◽  
Author(s):  
F. Series ◽  
Y. Cormier ◽  
M. Desmeules ◽  
J. La Forge
Keyword(s):  
Sleep Apnea ◽  
Airway Resistance ◽  
Upper Airway ◽  
Normal Subjects ◽  
Base Line ◽  
Respiratory Drive ◽  
Upper Airway Resistance ◽  
Co2 Rebreathing ◽  
Airway Pressures ◽  
Line Level

We compared the changes in nasal and pharyngeal resistance induced by modifications in the central respiratory drive in 8 patients with sleep apnea syndrome (SAS) with the results of 10 normal men. Upper airway pressures were measured with two low-bias flow catheters; one was placed at the tip of the epiglottis and the other above the uvula. Nasal and pharyngeal resistances were calculated at isoflow. During CO2 rebreathing and during the 2 min after maximal voluntary hyperventilation, we continuously recorded upper airway pressures, airflow, end-tidal CO2, and the mean inspiratory flow (VT/TI); inspiratory pressure generated at 0.1 s after the onset of inspiration (P0.1) was measured every 15–20 s. In both groups upper airway resistance decreased as P0.1 increased during CO2 rebreathing. When P0.1 increased by 500%, pharyngeal resistance decreased to 17.8 +/- 3.1% of base-line values in SAS patients and to 34.9 +/- 3.4% in normal subjects (mean +/- SE). During the posthyperventilation period the VT/TI fell below the base-line level in seven SAS patients and in seven normal subjects. The decrease in VT/TI was accompanied by an increase in upper airway resistance. When the VT/TI decreased by 30% of its base-line level, pharyngeal resistance increased to 319.1 +/- 50.9% in SAS and 138.5 +/- 4.7% in normal subjects (P less than 0.05). We conclude that 1) in SAS patients, as in normal subjects, the activation of upper airway dilators is reflected by indexes that quantify the central inspiratory drive and 2) the pharyngeal patency is more sensitive to the decrease of the central respiratory drive in SAS patients than in normal subjects.

Motor responses to positive-pressure breathing in the developing opossum

1985 ◽  
Vol 58 (5) ◽  
pp. 1489-1495 ◽  
Author(s):  
J. P. Farber
Keyword(s):  
Airway Resistance ◽  
Upper Airway ◽  
Abdominal Muscle ◽  
Positive Pressure ◽  
Postnatal Life ◽  
Abdominal Muscles ◽  
Upper Airways ◽  
Motor Responses ◽  
Upper Airway Resistance ◽  
Upper Airway Muscles

The suckling opossum exhibits an expiration-phased discharge in abdominal muscles during positive-pressure breathing (PPB); the response becomes apparent, however, only after the 3rd-5th wk of postnatal life. The purpose of this study was to determine whether the early lack of activation represented a deficiency of segmental outflow to abdominal muscles or whether comparable effects were observed in cranial outflows to muscles of the upper airways due to immaturity of afferent and/or supraspinal pathways. Anesthetized suckling opossums between 15 and 50 days of age were exposed to PPB; electromyogram (EMG) responses in diaphragm and abdominal muscles were measured, along with EMG of larynx dilator muscles and/or upper airway resistance. In animals older than approximately 30 days of age, the onset of PPB was associated with a prolonged expiration-phased EMG activation of larynx dilator muscles and/or decreased upper airway resistance, along with expiratory recruitment of the abdominal muscle EMG. These effects persisted as long as the load was maintained. Younger animals showed only those responses related to the upper airway; in fact, activation of upper airway muscles during PPB could be associated with suppression of the abdominal motor outflow. After unilateral vagotomy, abdominal and upper airway motor responses to PPB were reduced. The balance between PPB-induced excitatory and inhibitory or disfacilitory influences from the supraspinal level on abdominal motoneurons and/or spinal processing of information from higher centers may shift toward net excitation as the opossum matures.

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