Effect Of Nasal Expiratory Positive Airway Pressure On Functional Residual Capacity And Upper Airway Dimensions By MRI

2011 ◽  
Author(s):  
Carla W. Braga ◽  
Qun Chen ◽  
David M. Rapoport ◽  
Indu A. Ayappa
Keyword(s):  
Functional Residual Capacity ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Upper Airway ◽  
Residual Capacity ◽  
Expiratory Positive Airway Pressure ◽  
Airway Dimensions

Effects of continuous positive airway pressure on upper airway and respiratory muscle activity

1987 ◽  
Vol 62 (5) ◽  
pp. 2026-2030 ◽  
Author(s):  
C. G. Alex ◽  
R. M. Aronson ◽  
E. Onal ◽  
M. Lopata
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Respiratory System ◽  
Muscle Activity ◽  
Airway Pressure ◽  
Respiratory Muscle ◽  
Positive Airway Pressure ◽  
Upper Airway ◽  
Afferent Input ◽  
Residual Capacity ◽  
Respiratory Muscle Activity

To study the effects of continuous positive airway pressure (CPAP) on lung volume, and upper airway and respiratory muscle activity, we quantitated the CPAP-induced changes in diaphragmatic and genioglossal electromyograms, esophageal and transdiaphragmatic pressures (Pes and Pdi), and functional residual capacity (FRC) in six normal awake subjects in the supine position. CPAP resulted in increased FRC, increased peak and rate of rise of diaphragmatic activity (EMGdi and EMGdi/TI), decreased peak genioglossal activity (EMGge), decreased inspiratory time and inspiratory duty cycle (P less than 0.001 for all comparisons). Inspiratory changes in Pes and Pdi, as well as Pes/EMGdi and Pdi/EMGdi also decreased (P less than 0.001 for all comparisons), but mean inspiratory airflow for a given Pes increased (P less than 0.001) on CPAP. The increase in mean inspiratory airflow for a given Pes despite the decrease in upper airway muscle activity suggests that CPAP mechanically splints the upper airway. The changes in EMGge and EMGdi after CPAP application most likely reflect the effects of CPAP and the associated changes in respiratory system mechanics on the afferent input from receptors distributed throughout the intact respiratory system.

Changes in upper airway resistance with lung inflation and positive airway pressure

1990 ◽  
Vol 68 (3) ◽  
pp. 1075-1079 ◽  
Author(s):  
F. Series ◽  
Y. Cormier ◽  
J. Couture ◽  
M. Desmeules
Keyword(s):  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Upper Airway ◽  
Normal Subjects ◽  
Base Line ◽  
Upper Airways ◽  
Airway Patency ◽  
Lung Inflation ◽  
Bias Flow ◽  
Expiratory Positive Airway Pressure

The influence of pulmonary inflation and positive airway pressure on nasal and pharyngeal resistance were studied in 10 normal subjects lying in an iron lung. Upper airway pressures were measured with two low-bias flow catheters while the subjects breathed by the nose through a Fleish no. 3 pneumotachograph into a spirometer. Resistances were calculated at isoflow rates in four different conditions: exclusive pulmonary inflation, achieved by applying a negative extra-thoracic pressure (NEP); expiratory positive airway pressure (EPAP), which was created by immersion of the expiratory line; continuous positive airway pressure (CPAP), realized by loading the bell of the spirometer; and CPAP without pulmonary inflation by simultaneously applying the same positive extrathoracic pressure (CPAP + PEP). Resistance measurements were obtained at 5- and 10-cmH2O pressure levels. Pharyngeal resistance (Rph) significantly decreased during each measurement; the decreases in nasal resistance were only significant with CPAP and CPAP + PEP; the deepest fall in Rph occurred with CPAP. It reached 70.8 +/- 5.5 and 54.8 +/- 6.5% (SE) of base-line values at 5 and 10 cmH2O, respectively. The changes in lung volume recorded with CPAP + PEP ranged from -180 to 120 ml at 5 cmH2O and from -240 to 120 ml at 10 cmH2O. Resistances tended to increase with CPAP + PEP compared with CPAP values, but these changes were not significant (Rph = 75.9 +/- 6.1 and 59.9 +/- 6.6% at 5 and 10 cmH2O of CPAP + PEP). We conclude that 1) the upper airway patency increases during pulmonary inflation, 2) the main effect of CPAP is related to pneumatic splinting, and 3) pulmonary inflation contributes little to the decrease in upper airways resistance observed with CPAP.

Effects of positive airway pressure on upper airway dilator muscle activity and ventilatory timing

1996 ◽  
Vol 81 (1) ◽  
pp. 470-479 ◽  
Author(s):  
P. C. Deegan ◽  
P. Nolan ◽  
M. Carey ◽  
W. T. McNicholas
Keyword(s):  
Muscle Activity ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Upper Airway ◽  
Normal Subjects ◽  
Emg Activity ◽  
Ventilatory Responses ◽  
Dilator Muscle ◽  
Before And After ◽  
Expiratory Positive Airway Pressure

To determine upper airway (UA) and ventilatory responses to nasal continuous positive airway pressure (CPAP) and expiratory positive airway pressure (EPAP), we quantitated changes in alae nasi (AN) and genioglossus (GG) electromyographic (EMG) activity, ventilatory timing, and end-expiratory lung volume (EELV) at various levels of CPAP and EPAP in six normal subjects during wakefulness and in seven during sleep. The same measurements were also made before and after UA anesthesia in six normal subjects during wakefulness. During both wakefulness and sleep, CPAP application significantly increased EELV and decreased AN and GG EMG activities. In contrast, EPAP significantly increased EMG activities of both muscles while also increasing EELV during wakefulness. The EMG responses were less marked during sleep. Anesthesia of the UA abolished the EMG responses to CPAP but not to EPAP. These results suggest that, in normal subjects, CPAP application causes a reflex reduction in UA dilator muscle activity mediated by UA sensory receptors. In contrast, EPAP increases UA dilator muscle activity, with the response mediated by conscious influences or reflexes arising outside of the UA.

Changes in lung volume and upper airway using MRI during application of nasal expiratory positive airway pressure in patients with sleep-disordered breathing

2011 ◽  
Vol 111 (5) ◽  
pp. 1400-1409 ◽  
Author(s):  
C. W. Braga ◽  
Q. Chen ◽  
O. E. Burschtin ◽  
D. M. Rapoport ◽  
I. Ayappa
Keyword(s):  
Lung Volume ◽  
Airway Pressure ◽  
Sleep Disordered Breathing ◽  
Positive Airway Pressure ◽  
Upper Airway ◽  
Mechanisms Of Action ◽  
Cross Sectional ◽  
Expiratory Positive Airway Pressure ◽  
End Tidal ◽  
Disordered Breathing

Nasal expiratory positive airway pressure (nEPAP) delivered with a disposable device (Provent, Ventus Medical) has been shown to improve sleep-disordered breathing (SDB) in some subjects. Possible mechanisms of action are 1) increased functional residual capacity (FRC), producing tracheal traction and reducing upper airway (UA) collapsibility, and 2) passive dilatation of the airway by the expiratory pressure, carrying over into inspiration. Using MRI, we estimated change in FRC and ventilation, as well as UA cross-sectional area (CSA), in awake patients breathing on and off the nEPAP device. Ten patients with SDB underwent nocturnal polysomnography and MRI with and without nEPAP. Simultaneous images of the lung and UA were obtained at 6 images/s. Image sequences were obtained during mouth and nose breathing with and without the nEPAP device. The nEPAP device produced an end-expiratory pressure of 4–17 cmH2O. End-tidal Pco2rose from 39.7 ± 5.3 to 47.1 ± 6.0 Torr ( P < 0.01). Lung volume changes were estimated from sagittal MRI of the right lung. Changes in UA CSA were calculated from transverse MRI at the level of the pharynx above the epiglottis. FRC determined by MRI was well correlated to FRC determined by N2washout ( r = 0.76, P = 0.03). nEPAP resulted in a consistent increase in FRC (46 ± 29%, P < 0.001) and decrease in ventilation (50 ± 15%, P < 0.001), with no change in respiratory frequency. UA CSA at end expiration showed a trend to increase. During wakefulness, nEPAP caused significant hyperinflation, consistent with an increase in tracheal traction and a decrease in UA collapsibility. Direct imaging effects on the UA were less consistent, but there was a trend to dilatation. Finally, we showed significant hypoventilation and rise in Pco2during use of the nEPAP device during wakefulness and sleep. Thus, at least three mechanisms of action have the potential to contribute to the therapeutic effect of nEPAP on SDB.

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