scholarly journals The Effects of Hyper- and Hypocapnia on Phonatory Laryngeal Airway Resistance in Women

2015 ◽  
Vol 58 (3) ◽  
pp. 638-652 ◽  
Author(s):  
Amanda I. Gillespie ◽  
William Slivka ◽  
Charles W. Atwood ◽  
Katherine Verdolini Abbott
Keyword(s):  
Gas Flow ◽  
Airway Resistance ◽  
Airway Disease ◽  
Lower Airway ◽  
Laryngeal Function ◽  
Vocal Fold Vibration ◽  
Respiratory Homeostasis ◽  
End Tidal ◽  
The Cost ◽  
Laryngeal Airway

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 (R law )—and respiratory homeostasis during states of ventilatory gas perturbations. Method Twenty-four healthy women performed phonatory tasks while exposed to induced hypercapnia (high CO 2 ), hypocapnia (low CO 2 ), and normal breathing (eupnea). Effects of gas perturbations on R law were investigated as were the reciprocal effects of R law modulations on respiratory homeostasis. Results R law remained stable despite manipulations of inspired gas concentrations. In contrast, end-tidal CO 2 levels increased significantly during all phonatory tasks. Thus, for the conditions tested, R law did not adjust to accommodate ventilatory needs as predicted. Rather, stable R law was spontaneously accomplished at the cost of those needs. Conclusions Findings provide support for a theory of regulation wherein R law 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.

Age and Laryngeal Airway Resistance During Vowel Production in Women

1992 ◽  
Vol 35 (2) ◽  
pp. 309-313 ◽  
Author(s):  
Jeannette D. Hoit ◽  
Thomas J. Hixon
Keyword(s):  
Speech Production ◽  
Airway Resistance ◽  
Clinical Implications ◽  
Vowel Production ◽  
Laryngeal Function ◽  
Healthy Women ◽  
Laryngeal Airway

An investigation was conducted to determine if laryngeal valving economy, as reflected in measures of laryngeal airway resistance during vowel production, differs with age in women. Seventy healthy women were studied, 10 each at age 25, 35, 45, 55, 65, 75, and 85 years. Results indicated that laryngeal airway resistance did not differ significantly with age, although it was noted that the 45-year-old women generally had lower laryngeal airway resistance values. This pattern of function differs from that observed in men (Melcon, Hoit, & Hixon, 1989). Discussion of findings includes consideration of factors that might influence laryngeal function during speech production in women. Clinical implications are offered.

Modulations in Respiratory and Laryngeal Activity Associated With Changes in Vocal Intensity During Speech

2000 ◽  
Vol 43 (4) ◽  
pp. 934-950 ◽  
Author(s):  
Eileen M. Finnegan ◽  
Erich S. Luschei ◽  
Henry T. Hoffman
Keyword(s):  
Muscle Activity ◽  
Airway Resistance ◽  
Sudden Change ◽  
Lower Airway ◽  
Emg Activity ◽  
Primary Role ◽  
Respiratory Drive ◽  
Tracheal Pressure ◽  
Vocal Intensity ◽  
Laryngeal Airway

We tested the hypothesis that different strategies are used to alter tracheal pressure (P t ) during sustained and transient increases in intensity. It has been suggested that the respiratory system plays the primary role in P t changes associated with alteration in overall intensity, whereas laryngeal adjustment is primary for transient change in P t related to emphasis. Tracheal pressure, obtained via tracheal puncture, airflow (U), and laryngeal electromyography from the thyroarytenoid muscle (TA EMG) were collected from 6 subjects during sentence production at different intensity levels and with various stress patterns. Using a technique described in a previous study, we computed lower airway resistance (R law ) from measures of P t and U obtained during a sudden change in upper airway resistance. We used this resistance value, together with direct measures of P t and U during speech, to derive a time-varying measure of alveolar pressure (P a ), the pressure created by respiratory muscle activity and elastic recoil of the lungs. P a provided a measure of respiratory drive that was unaffected by laryngeal activity. Laryngeal airway resistance (R lx ) and TA EMG provided measures of laryngeal activity. The results of this study indicated that, contrary to the outcome predicted by the hypothesis, there was no difference in the strategies used to alter P t during sustained and transient increases in intensity. Although changes in both P a and R lx contributed to increase in P t , the contribution of P a was substantially greater. On average, P a contributed to 94% and R lx to 6% of the increase in P t associated with vocal intensity. A secondary purpose of the study was to determine the extent to which laryngeal muscle activity was related to R lx during speech. We found TA EMG activity increased with intensity but was not well correlated with R lx , suggesting that when it contracts, the TA muscle may affect intensity by loosening the cover, which allows for greater amplitude of vocal fold vibration, without necessarily increasing laryngeal airway resistance.

UTILITY OF END TIDAL CO2 MEASUREMENTS IN THE PEDIATRIC POPULATION WITH UPPER AND LOWER AIRWAY DISEASE

1993 ◽  
Vol 9 (5) ◽  
pp. 318
Author(s):  
S. Scott ◽  
T. Abramo ◽  
P. Primm ◽  
M. Cowan ◽  
R. Wiebe
Keyword(s):  
Pediatric Population ◽  
Airway Disease ◽  
Lower Airway ◽  
End Tidal ◽  
End Tidal Co2

Effect of hypercapnia on laryngeal airway resistance in normal adult humans

1994 ◽  
Vol 77 (6) ◽  
pp. 2797-2803 ◽  
Author(s):  
S. T. Kuna ◽  
C. R. Vanoye ◽  
J. R. Griffin ◽  
J. D. Updegrove
Keyword(s):  
Airway Resistance ◽  
Face Mask ◽  
Gas Mixtures ◽  
Normal Adult ◽  
Pressure Flow ◽  
Adult Humans ◽  
Series Of Experiments ◽  
End Tidal ◽  
End Tidal Co2 ◽  
Laryngeal Airway

Laryngeal airway resistance (Rlar) was measured in eight normal adult humans during progressive hyperoxic hypercapnia. In most subjects, the translaryngeal pressure-flow relationship appeared linear under normocapnic conditions. During hypercapnia, the pressure-flow relationship on inspiration and expiration was curvilinear with increasing translaryngeal pressure associated with progressively smaller increments in flow. Translaryngeal pressure-flow relationships at different CO2 levels were compared over their common flow ranges by performing a least-squares linear regression on data throughout inspiration and expiration. During normocapnia, the mean slope, i.e., mean Rlar, was 0.50 +/- 0.21 (SD) cmH2O.l-1.s. A moderately significant decrease in Rlar was present at 9% end-tidal CO2 (P = 0.08). In a separate series of experiments, subjects breathed oxygen- and helium-based gas mixtures through a face mask attached to a pneumotachograph. Data analysis over the flow range present during normocapnia revealed no difference in Rlar between nose and mouth breathing and similar decreases in Rlar under hypercapnic conditions with the oxygen- and helium-based gas mixtures. The decrease in Rlar from normocapnic to hypercapnic conditions found over common, but relatively low, ranges of flow predicts that even greater increases in Rlar would occur at high flow rates in the absence of increasing glottic aperture.

scholarly journals Phonation Demonstrates Goal Dependence Under Unique Vocal Intensity and Aerobic Workload Conditions

2019 ◽  
Vol 62 (8) ◽  
pp. 2584-2600
Author(s):  
Aaron Ziegler ◽  
Jessie VanSwearingen ◽  
John M. Jakicic ◽  
Katherine Verdolini Abbott
Keyword(s):  
Motor Control ◽  
Repeated Measures ◽  
Airway Resistance ◽  
Minute Ventilation ◽  
Theory Of Action ◽  
System Response ◽  
Concentration Data ◽  
Repeated Measures Design ◽  
End Tidal ◽  
Laryngeal Airway

Purpose This study investigated whether metabolic respiratory requirements (treadmill workload) affected glottal valving in phonation, based on aerodynamic measures, when a sound pressure level (vocal SPL) is dictated as a target goal. Consistent with a theory of action, we hypothesized that adjustments in glottal valving as measured by laryngeal airway resistance would be dependent upon vocal SPL level, even as workload increased, and loud vocal SPL would interfere more with respiratory homeostasis than spontaneous vocal SPL. Method Thirty-two women enrolled who were ages 18–35 years. A repeated-measures design was used with random assignment of workload and vocal SPL conditions. Aerodynamic and acoustic data were collected during phonation, as were gas volume and concentration data. Analyses were performed with generalized estimating equations. Results Laryngeal airway resistance at a low workload significantly increased when vocal SPL changed from spontaneous to loud. At a loud vocal SPL, laryngeal airway resistance decreased when workload changed from rest to either low or high. Regarding the respiratory system response, minute ventilation increased at a loud vocal SPL when workload changed from rest to either low or high. End-tidal CO 2 increased under low and high workloads relative to rest at loud and spontaneous vocal SPLs. Conclusions Mostly consistent with a theory of action, in which motor control is goal dependent (i.e., vocal SPL targets), speakers can achieve a loud vocal SPL despite increases in workload requirements. In contrast, laryngeal airway resistance stays relatively low when vocal SPL occurs spontaneously, suggesting glottal adjustments are made to improve gas exchange as metabolic respiratory requirements become prioritized. Metabolic respiratory requirements appear to be overcome by the overlay of motor control for voicing when a loud vocal SPL is targeted. The implication of goal-dependent phonation for clinicians is that real-world conditions (i.e., loud vocal SPL) matter in vocal testing and voice therapy.

Age and Laryngeal Airway Resistance during Vowel Production

1989 ◽  
Vol 54 (2) ◽  
pp. 282-286 ◽  
Author(s):  
Matthew C. Melcon ◽  
Jeannette D. Hoit ◽  
Thomas J. Hixon
Keyword(s):  
Airway Resistance ◽  
Age Groups ◽  
Vowel Production ◽  
Laryngeal Function ◽  
Age Related ◽  
Younger Men ◽  
Old Men ◽  
The Impact ◽  
Insight Into ◽  
Laryngeal Airway

An investigation was conducted to determine if laryngeal valving economy, as reflected in measures of laryngeal airway resistance during vowel production, varies across adulthood. Sixty healthy men were studied, 10 from each of six age groups–25, 35, 45, 55, 65, and 75 years (± 2 years). Results indicated that there are age-related differences in laryngeal airway resistance during vowel production and that these differences are characterized by a lower mean resistance in 75-year-old men than in younger men of the ages studied. This finding provides insight into the impact of age on laryngeal function and has important implications for the evaluation and management of men with voice disorders.

Characterisation of Static Strip Seal Flow

2007 ◽  
Author(s):  
Arash Farahani ◽  
Peter Childs
Keyword(s):  
Gas Flow ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Main Stream ◽  
Cfd Modelling ◽  
Height Range ◽  
And Performance ◽  
Nozzle Guide ◽  
The Cost ◽  
Cooling Air

Strip seals are used in gas turbine engines between two static elements or between components which do not move relative to each other, such as Nozzle Guide Vanes (NGVs). The key role of a strip seal between NGV segments is sealing between the flow through the main stream annulus and the internal air system, a further purpose is to limit the inter-segmental movements. In general the shape of the strip seal is a rectangular strip that fits into two slots in adjacent components. The minimum clearance required for static strip seals must be found by accounting for thermal expansion, misalignment, and application, to allow correct fitment of the strip seals. Any increase in leakage raises the cost due to an increase in the cooling air use, which is linked to specific fuel consumption, and it can also alter gas flow paths and performance. The narrow path within the seal assembly, especially the height has the most significant affect on leakage. The height range of the narrow path studied in this paper is 0.01–0.06 mm. The behaviour of the flow passing through the narrow path has been studied using CFD modelling and measurements in a bespoke rig. The CFD and experimental results show that normalized leakage flow increases with pressure ratio before reaching a maximum. The main aim of this paper is to provide new experimental data to verify the CFD modelling for static strip seals. The typical flow characteristics validated by CFD modelling and experiments can be used to predict the flow behaviour for future static strip seal designs.

Effect of sleep on nocturnal bronchoconstriction and ventilatory patterns in asthmatics

1989 ◽  
Vol 67 (1) ◽  
pp. 243-249 ◽  
Author(s):  
R. D. Ballard ◽  
M. C. Saathoff ◽  
D. K. Patel ◽  
P. L. Kelly ◽  
R. J. Martin
Keyword(s):  
Airway Resistance ◽  
Minute Ventilation ◽  
The Other ◽  
Lower Airway ◽  
Sleep Laboratory ◽  
Sleep State ◽  
Asthmatic Patients ◽  
Ventilatory Responses ◽  
Rate Of Increase ◽  
Normal Controls

To assess the effect of sleep on airflow resistance and patterns of ventilation in asthmatic patients with nocturnal worsening, 10 adult subjects (6 asthmatic patients with nocturnal worsening, 4 normal controls) were monitored overnight in the sleep laboratory on two separate occasions. During 1 night, subjects were allowed to sleep normally, whereas during the other night all sleep was prevented. The six asthmatic patients demonstrated progressive increases in lower airway resistance (Rla) on both nights, but the rate of increase was twofold greater (P less than 0.0001) during the sleep night compared with the sleep prevention night. However, overnight decrements in forced expired volume in 1 s (FEV1) were similar over the 2 nights. The asthmatic patients maintained their minute ventilation as Rla increased during sleep, demonstrating a stable tidal volume with a mild increase in respiratory frequency. We conclude that in asthmatic patients with nocturnal worsening 1) Rla increases and FEV1 falls overnight regardless of sleep state, 2) sleep enhances the observed overnight increases in Rla, and 3) sleep does not abolish compensatory ventilatory responses to spontaneously occurring bronchoconstriction.

Effects of the Water Content of Soda Lime on Compound A Concentration in the Anesthesia Circuit in Sevoflurane Anesthesia 

1998 ◽  
Vol 88 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Hiromichi Bito ◽  
Yukako Ikeuchi ◽  
Kazuyuki Ikeda
Keyword(s):  
Gas Flow ◽  
Soda Lime ◽  
Absorption Capacity ◽  
Low Flow ◽  
Co2 Absorption ◽  
Sevoflurane Anesthesia ◽  
Compound A ◽  
Carbon Dioxide Co2 ◽  
End Tidal ◽  
Co2 Elimination

Background Sevoflurane anesthesia is usually performed with fresh gas flow rates greater than 2 l/min due to the toxicity of compound A in rats and limited clinical experience with sevoflurane in low-flow systems. However, to reduce costs, it would be useful to identify ways to reduce compound A concentrations in low-flow sevoflurane anesthesia. This goal of this study was to determine if compound A concentrations can be reduced by using soda lime with water added. Methods Low-flow sevoflurane anesthesia (fresh gas flow of 1 l/min) was performed in 37 patients using soda lime with water added (perhydrated soda lime) or standard soda lime as the carbon dioxide (CO2) absorbent. The soda lime was not changed between patients, but rather was used until CO2 rebreathing occurred. The perhydrated soda lime was prepared by spraying 100 ml distilled water onto 1 kg fresh soda lime, and water was added only when a new bag of soda lime was placed into the canister. Compound A concentrations in the circle system, soda lime temperatures, inspired and end-tidal CO2 and end-tidal sevoflurane concentrations, and CO2 elimination by the patient were measured during anesthesia. Results Compound A concentrations were significantly lower for the perhydrated soda lime (1.9 +/- 1.8 ppm; means +/- SD) than for the standard soda lime (13.9 +/- 8.2 ppm). No differences were seen between the two types of soda lime with regard to the temperature of the soda lime, end-tidal sevoflurane concentrations, or CO2 elimination. Compound A concentration decreased with the total time of soda lime use for both types of soda lime. The CO2 absorption capacity was significantly less for perhydrated soda lime than for standard soda lime. Conclusions Compound A concentrations in the circuit can be reduced by using soda lime with water added. The CO2 absorption capacity of the soda lime is reduced by adding water to it, but this should not be clinically significant.

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