Site of phrenic nerve stimulation-induced upper airway collapse: influence of expiratory time

2002 ◽  
Vol 92 (2) ◽  
pp. 665-671 ◽  
Author(s):  
F. Sériès ◽  
G. Éthier
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Respiratory Muscles ◽  
Upper Airway ◽  
Esophageal Pressure ◽  
Emg Activity ◽  
Phrenic Nerve Stimulation ◽  
Nasal Breathing ◽  
Expiratory Time ◽  
Airway Collapse

Electrical phrenic nerve stimulation (EPNS) applied at end expiration during exclusive nasal breathing can be used to characterize upper airway (UA) dynamics during wakefulness by dissociating phasic activation of UA and respiratory muscles. The UA level responsible for the EPNS-induced increase in UA resistance is unknown. The influence of the twitch expiratory timing (200 ms and 2 s) on UA resistance was studied in nine normal awake subjects by looking at instantaneous flow, esophageal and pharyngeal pressures, and genioglossal electromyogram (EMG) activity during EPNS at baseline and at −10 cmH2O. The majority of twitches had a flow-limited pattern. Twitches realized at 200 ms and 2 s did not differ in their maximum inspiratory flows, but esophageal pressure measured at maximum inspiratory flow was significantly less negative with late twitches (−6.6 ± 2.7 and −5.0 ± 3.0 cmH2O respectively, P = 0.04). Pharyngeal resistance was higher when twitches were realized at 2 s than at 200 ms (6.4 ± 2.4 and 2.7 ± 1.1 cmH2O · l−1 · s, respectively). EMG activity significant rose at peak esophageal pressure with a greater increase for late twitches. We conclude that twitch-induced UA collapse predominantly occurs at the pharyngeal level and that UA stability assessed by EPNS depends on the expiratory time at which twitches are performed.

Selected Contribution: Influence of genioglossus tonic activity on upper airway dynamics assessed by phrenic nerve stimulation

2002 ◽  
Vol 92 (1) ◽  
pp. 418-423 ◽  
Author(s):  
F. Sériès ◽  
I. Marc
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Upper Airway ◽  
Emg Activity ◽  
Flow Limitation ◽  
Tonic Activity ◽  
Phrenic Nerve Stimulation ◽  
Nasal Breathing ◽  
Airway Dynamics ◽  
Phasic Activation

Upper airway (UA) dynamics can be evaluated during wakefulness by using electrical phrenic nerve stimulation (EPNS) applied at end-expiration during exclusive nasal breathing by dissociating twitch flow and phasic activation of UA muscles. This technique can be used to quantify the influence of nonphasic electromyographic (EMG) activity on UA dynamics. UA dynamics was characterized by using EPNS when increasing tonic EMG activity with CO2 stimulation in six normal awake subjects. Instantaneous flow, esophageal and nasopharyngeal pressures, and genioglossal EMG activity were recorded during EPNS at baseline and during CO2 ventilatory stimulation. The proportion of twitches presenting an inspiratory-flow limitation pattern decreased from 100% at baseline to 78.7 ± 21.4% ( P = 10−4) during CO2rebreathing. During CO2 stimuli, maximal inspiratory twitch flow (V˙i max) of flow-limited twitches significantly rose, with the driving pressure at which flow limitation occurred being more negative. For the group as a whole, the increase inV˙i max and the decrease in pressure were significantly correlated with the rise in end-expiratory EMG activity. UA stability assessed by EPNS is dramatically modified during CO2 ventilatory stimulation. Changes in tonic genioglossus EMG activity significantly contribute to the improvement in UA stability.

Control of respiratory activity of the genioglossus muscle in micrognathic infants

1986 ◽  
Vol 61 (4) ◽  
pp. 1523-1533 ◽  
Author(s):  
J. L. Roberts ◽  
W. R. Reed ◽  
O. P. Mathew ◽  
B. T. Thach
Keyword(s):  
Upper Airway ◽  
Esophageal Pressure ◽  
Progressive Increase ◽  
Emg Activity ◽  
Nasal Breathing ◽  
Airway Patency ◽  
Tongue Muscle ◽  
Airway Occlusion ◽  
Pharyngeal Airway ◽  
Obstructive Sleep

The genioglossus (GG) muscle activity of four infants with micrognathia and obstructive sleep apnea was recorded to assess the role of this tongue muscle in upper airway maintenance. Respiratory air flow, esophageal pressure, and intramuscular GG electromyograms (EMG) were recorded during wakefulness and sleep. Both tonic and phasic inspiratory GG-EMG activity was recorded in each of the infants. On occasion, no phasic GG activity could be recorded; these silent periods were unassociated with respiratory embarrassment. GG activity increased during sigh breaths. GG activity also increased when the infants spontaneously changed from oral to nasal breathing and, in two infants, with neck flexion associated with complete upper airway obstruction, suggesting that GG-EMG activity is influenced by sudden changes in upper airway resistance. During sleep, the GG-EMG activity significantly increased with 5% CO2 breathing (P less than or equal to 0.001). With nasal airway occlusion during sleep, the GG-EMG activity increased with the first occluded breath and progressively increased during the subsequent occluded breaths, indicating mechanoreceptor and suggesting chemoreceptor modulation. During nasal occlusion trials, there was a progressive increase in phasic inspiratory activity of the GG-EMG that was greater than that of the diaphragm activity (as reflected by esophageal pressure excursions). When pharyngeal airway closure occurred during a nasal occlusion trial, the negative pressure at which the pharyngeal airway closed (upper airway closing pressure) correlated with the GG-EMG activity at the time of closure, suggesting that the GG muscle contributes to maintaining pharyngeal airway patency in the micrognathic infant.

The effect of diaphragm contraction on upper airway collapsibility

2013 ◽  
Vol 115 (3) ◽  
pp. 337-345 ◽  
Author(s):  
David R. Hillman ◽  
Jennifer H. Walsh ◽  
Kathleen J. Maddison ◽  
Peter R. Platt ◽  
Alan R. Schwartz ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Lung Volume ◽  
Phrenic Nerve ◽  
Upper Airway ◽  
Dependent Manner ◽  
Phrenic Nerve Stimulation ◽  
Airway Patency ◽  
Airway Collapsibility ◽  
The Difference ◽  
Upper Airway Collapsibility

Increasing lung volume increases upper airway patency and decreases airway resistance and collapsibility. The role of diaphragm contraction in producing these changes remains unclear. This study was undertaken to determine the effect of selective diaphragm contraction, induced by phrenic nerve stimulation, on upper airway collapsibility and the extent to which any observed change was attributable to lung volume-related changes in pressure gradients or to diaphragm descent-related mediastinal traction. Continuous bilateral transcutaneous cervical phrenic nerve stimulation (30 Hz) was applied to nine supine, anesthetized human subjects during transient decreases in airway pressure to levels sufficient to produce flow limitation when unstimulated. Stimulation was applied at two intensities (low and high) and its effects on lung volume and airflow quantified relative to unstimulated conditions. Lung volume increased by 386 ± 269 ml (means ± SD) and 761 ± 556 ml during low and high stimulation, respectively ( P < 0.05 for the difference between these values), which was associated with peak inspiratory flow increases of 69 ± 57 and 137 ± 108 ml/s, respectively ( P < 0.05 for the difference). Stimulation-induced change in lung volume correlated with change in peak flow ( r = 0.65, P < 0.01). Diaphragm descent-related outward displacement of the abdominal wall produced no change in airflow unless accompanied by lung volume change. We conclude that phrenic nerve stimulation-induced diaphragm contraction increases lung volume and reduces airway collapsibility in a dose-dependent manner. The effect appears primarily mediated by changes in lung volume rather than mediastinal traction from diaphragm descent. The study provides a rationale for use of continuous phrenic stimulation to treat obstructive sleep apnea.

Negative intrathoracic pressure decreases independently left ventricular filling and emptying

1989 ◽  
Vol 257 (1) ◽  
pp. H120-H131 ◽  
Author(s):  
J. Peters ◽  
C. Fraser ◽  
R. S. Stuart ◽  
W. Baumgartner ◽  
J. L. Robotham
Keyword(s):  
Stroke Volume ◽  
Nerve Stimulation ◽  
Lung Volume ◽  
Phrenic Nerve ◽  
Intrathoracic Pressure ◽  
Esophageal Pressure ◽  
Left Ventricular ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Phrenic Nerve Stimulation

The mechanism for the fall in left ventricular (LV) stroke volume with normal and obstructed inspiration is controversial with changes proposed in LV preload and afterload. During respiration extending over several cardiac cycles, changes in both LV filling and emptying could occur, rendering demonstration of any responsible mechanism difficult. To evaluate the independent effects of negative intrathoracic pressure (NITP) on LV filling and emptying, we have analyzed the effects of NITP confined to either diastole or systole using electrocardiogram (ECG)-triggered phrenic nerve stimulation in six anesthetized closed-chest dogs. Lung volume was either maintained by completely obstructing the airway or allowed to increase during NITP. With diastolic NITP and the airway obstructed during phrenic nerve stimulation, LV filling volume (integrated mitral flow) significantly decreased (-37 +/- 6.1% SE) associated with increases in LV and right atrial filling pressures at end diastole relative to both atmospheric and esophageal pressures. Right atrial pressure relative to either atmospheric or esophageal pressure increased significantly more than left atrial pressure. The ensuing LV stroke volume (integrated ascending aortic flow) decreased significantly (-30.8 +/- 5.9%). With NITP confined to systole and at constant LV preload, LV stroke volume also decreased (-12.9 +/- 2.5%) associated with an increase in LV systolic pressure relative to esophageal pressure. Similar significant changes were observed despite a smaller fall in esophageal pressure when lung volume was allowed to increase during either diastolic or systolic NITP. We conclude that 1) NITP confined to diastole decreases LV filling and the ensuing LV stroke volume, most likely by ventricular interdependence; 2) NITP confined to systole also decreases LV stroke volume, presumptively by imposing an increased afterload on the LV; 3) both diastolic and systolic mechanisms should contribute to a decreased LV stroke volume during normal and obstructed inspiration; and 4) if the effects of intrathoracic pressure changes were to extend over several cardiac cycles, mechanisms exist to account for either increases or decreases in LV volumes.

Effects of neck flexion and mouth opening on inspiratory flow dynamics in awake humans

2002 ◽  
Vol 92 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Eric Verin ◽  
Frédéric Sériès ◽  
Chrystèle Locher ◽  
Christian Straus ◽  
Marc Zelter ◽  
...  
Keyword(s):  
Flow Behavior ◽  
Mouth Opening ◽  
Upper Airway ◽  
Esophageal Pressure ◽  
Flow Dynamics ◽  
Neutral Position ◽  
Neck Flexion ◽  
Phrenic Nerve Stimulation ◽  
Nasal Breathing ◽  
The Impact

Phrenic nerve stimulation (PNS) can assess airflow dynamics of the upper airway (UA) during wakefulness in man. Using PNS, we aimed to assess the impact of neck flexion and mouth opening in promoting UA unstability. Measurements were made during nasal breathing in seven healthy subjects (ages = 23–39 yr; one woman). Surface diaphragm electromyogram, esophageal pressure referenced to mask pressure, and flow were recorded during diaphragm twitches with neck in neutral position and mouth closed and then with neck flexion and/or mouth opening. Twitches always exhibited a flow-limited pattern. Flow-limiting driving pressure (Pd) and peak Pd were increased by neck flexion ( P < 0.01) without significant change in the corresponding flows. UA resistances at these flow values were higher with the neck flexed ( P < 0.05). Mouth opening alone did not exert any significant influence. We conclude that the position of the neck has a discernible impact on the flow behavior through the nonphasically active UA faced with a negative Pd.

Inspiratory Flow Dynamics During Phrenic Nerve Stimulation in Awake Normals During Nasal Breathing

1999 ◽  
Vol 160 (2) ◽  
pp. 614-620 ◽  
Author(s):  
FRÉDÉRIC SÉRIÈS ◽  
ALEXANDRE DEMOULE ◽  
ISABELLE MARC ◽  
CATHIE SANFAÇON ◽  
JEAN PHILIPPE DERENNE ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Inspiratory Flow ◽  
Flow Dynamics ◽  
Phrenic Nerve Stimulation ◽  
Nasal Breathing

Assessment of upper airway stabilizing forces with the use of phrenic nerve stimulation in conscious humans

2003 ◽  
Vol 94 (6) ◽  
pp. 2289-2295 ◽  
Author(s):  
Frédéric Sériès ◽  
Germain Éthier
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Dynamic Properties ◽  
Mouth Opening ◽  
Upper Airway ◽  
Inspiratory Flow ◽  
Dynamic Responses ◽  
Phrenic Nerve Stimulation ◽  
The Stability

Phrenic nerve stimulation (PNS) applied at end-expiration allows the investigation of passive upper airway (UA) dynamic during wakefulness. Assuming that phasic UA dilating/stabilizing forces should modify the UA properties when twitches are applied during inspiration, we compared the UA dynamic responses to expiratory and inspiratory twitches (2 s and 200 ms after expiratory and inspiratory onset, respectively) in nine men (mean age 28 yr). This procedure was repeated with a 2-cm mouth opening provided with a closed mouthpiece. The percentage of flow-limited (FL) twitches was significantly higher when PNS was realized during expiration than during inspiration. Maximal inspiratory flow (V˙i max) of FL twitches was significantly higher for inspiratory twitches (1,383 ± 42 and 1,185 ± 40 ml/s). With mouth aperture,V˙i max decreased with an increase in the corresponding pharyngeal resistance values, and the percentage of twitch with a FL regimen increased but only for inspiratory twitches. We conclude that 1) UA dynamics are significantly influenced by the inspiratory/expiratory timing at which PNS is applied, 2) the improvement in UA dynamic properties observed from expiratory to inspiratory PNS characterizes the overall inspiratory stabilizing effects, and 3) mouth aperture alters the stability of UA structures during inspiration.

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