A New Method of Negative Expiratory Pressure Test Analysis Detecting Upper Airway Flow Limitation To Reveal Obstructive Sleep Apnea

The upper airway (UA) in humans is commonly modeled as a Starling resistor. However, negative effort dependence (NED) observed in some patients with obstructive sleep apnea (OSA) contradicts predictions based on the Starling resistor model in which inspiratory flow is independent of inspiratory driving pressure when flow is limited. In a respiratory bench model consisting of a collapsible tube and an active lung model (ASL5000), inspiratory flow characteristics were investigated in relation to upstream, downstream, and extra-luminal pressures (denoted as Pus, Pds, and Pout, respectively) by varying inspiratory effort (muscle pressure) from −1 to −20 cmH2O in the active lung. Pus was provided by a constant airway pressure device and varied from 4 to 20 cmH2O, and Pout was set at 10 and 15 cmH2O. Upstream resistance at onset of flow limitation and critical transmural pressure (Ptm) corresponding to opening of the UA were found to be independent of Pus, Pds, and Pout. With fixed Ptm, when Pds fell below a specific value (Pds′), inspiratory peak flow became constant and independent of Pds. NED plateau flow patterns at mid-inspiration (V̇n) were produced within the current bench setting when Pds fell below Pds′. V̇n was proportional to Pds, and the slope (ΔV̇n/ΔPds) increased linearly with Ptm. Ptm and Pds were the two final independent determinants of inspiratory flow. Our bench model closely mimics a flow-limited human UA, and the findings have implications for OSA treatment and research, especially for bench-testing auto-titrating devices in a more physiological way. NEW & NOTEWORTHY A respiratory model consisting of a collapsible tube was used to mimic a flow-limited human upper airway. Flow-limited breathing patterns including negative effort dependence were produced. Transmural and downstream pressures acting on the tube are the two independent determinants of the resulting inspiratory flow during flow limitation. The findings have implications for obstructive sleep apnea treatment and research, especially for bench-testing auto-titrating devices in a more physiological way.

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Upper airway collapsibility evaluated by a negative expiratory pressure test in severe obstructive sleep apnea

Clinics ◽

10.1590/s1807-59322011000400008 ◽

2011 ◽

Vol 66 (4) ◽

pp. 567-572 ◽

Cited By ~ 6

Author(s):

Salvatore Romano ◽

Adriana Salvaggio ◽

Raquel Pastrello Hirata ◽

Anna Lo Bue ◽

Stefano Picciolo ◽

...

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Upper Airway ◽

Severe Obstructive Sleep Apnea ◽

Obstructive Sleep ◽

Airway Collapsibility ◽

Pressure Test ◽

Upper Airway Collapsibility

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Asynchrony of lingual muscle recruitment during sleep in obstructive sleep apnea

Journal of Applied Physiology ◽

10.1152/japplphysiol.00937.2014 ◽

2015 ◽

Vol 118 (12) ◽

pp. 1516-1524 ◽

Cited By ~ 23

Author(s):

Yaniv Dotan ◽

Giora Pillar ◽

Alan R. Schwartz ◽

Arie Oliven

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Upper Airway ◽

Esophageal Pressure ◽

Emg Activity ◽

Muscle Coordination ◽

Flow Limitation ◽

Tongue Muscle ◽

Dilator Muscle ◽

Obstructive Sleep

Pharyngeal collapsibility during sleep increases primarily due to decline in dilator muscle activity. However, genioglossus EMG is known to increase during apneas and hypopneas, usually without reversing upper airway obstruction or inspiratory flow limitation. The present study was undertaken to test the hypothesis that intense activation of the genioglossus fails to prevent pharyngeal obstruction during sleep, and to evaluate if sleep-induced changes in tongue muscle coordination may be responsible for this phenomenon. We compared genioglossus and tongue retractors EMG activity in 13 obstructive sleep apnea (OSA) patients during wakefulness, while breathing through inspiratory resistors, to the activity observed at the end of apneas and hypopneas after 25 mg of brotizolam, before arousal, at equal esophageal pressure. During wakefulness, resistive breathing triggered increases in both genioglossus and retractor EMG. Activation of agonist tongue muscles differed considerably from that of the arm, as both genioglossus and retractors were activated similarly during all tongue movements. During sleep, flow limitation triggered increases in genioglossal EMG that could reach more than twofold the level observed while awake. In contrast, EMGs of the retractors reached less than half the wakefulness level. In sleeping OSA patients, genioglossal activity may increase during obstructed breathing to levels that exceed substantially those required to prevent pharyngeal collapse during wakefulness. In contrast, coactivation of retractors is deficient during sleep. These findings suggest that sleep-induced alteration in tongue muscle coordination may be responsible for the failure of high genioglossal EMG activity to alleviate flow limitation.

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Long-term facilitation in obstructive sleep apnea patients during NREM sleep

Journal of Applied Physiology ◽

10.1152/jappl.2001.91.6.2751 ◽

2001 ◽

Vol 91 (6) ◽

pp. 2751-2757 ◽

Cited By ~ 59

Author(s):

Salah E. Aboubakr ◽

Amy Taylor ◽

Reason Ford ◽

Sarosh Siddiqi ◽

M. Safwan Badr

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Recovery Period ◽

Upper Airway ◽

Flow Limitation ◽

Inspiratory Time ◽

Nasal Cpap ◽

Obstructive Sleep ◽

Long Term Facilitation

Repetitive hypoxia followed by persistently increased ventilatory motor output is referred to as long-term facilitation (LTF). LTF is activated during sleep after repetitive hypoxia in snorers. We hypothesized that LTF is activated in obstructive sleep apnea (OSA) patients. Eleven subjects with OSA (apnea/hypopnea index = 43.6 ± 18.7/h) were included. Every subject had a baseline polysomnographic study on the appropriate continuous positive airway pressure (CPAP). CPAP was retitrated to eliminate apnea/hypopnea but to maintain inspiratory flow limitation (sham night). Each subject was studied on 2 separate nights. These two studies are separated by 1 mo of optimal nasal CPAP treatment for a minimum of 4–6 h/night. The device was capable of covert pressure monitoring. During night 1 (N1), study subjects used nasal CPAP at suboptimal pressure to have significant air flow limitation (>60% breaths) without apneas/hypopneas. After stable sleep was reached, we induced brief isocapnic hypoxia [inspired O2 fraction (Fi O2 ) = 8%] (3 min) followed by 5 min of room air. This sequence was repeated 10 times. Measurements were obtained during control, hypoxia, and at 5, 20, and 40 min of recovery for ventilation, timing ( n = 11), and supraglottic pressure ( n = 6). Upper airway resistance (Rua) was calculated at peak inspiratory flow. During the recovery period, there was no change in minute ventilation (99 ± 8% of control), despite decreased Rua to 58 ± 24% of control ( P < 0.05). There was a reduction in the ratio of inspiratory time to total time for a breath (duty cycle) (0.5 to 0.45, P < 0.05) but no effect on inspiratory time. During night 2 (N2), the protocol of N1 was repeated. N2 revealed no changes compared with N1 during the recovery period. In conclusion, 1) reduced Rua in the recovery period indicates LTF of upper airway dilators; 2) lack of hyperpnea in the recovery period suggests that thoracic pump muscles do not demonstrate LTF; 3) we speculate that LTF may temporarily stabilize respiration in OSA patients after repeated apneas/hypopneas; and 4) nasal CPAP did not alter the ability of OSA patients to elicit LTF at the thoracic pump muscle.

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Alteration in upper airway dilator muscle coactivation during sleep: comparison of patients with obstructive sleep apnea and healthy subjects

Journal of Applied Physiology ◽

10.1152/japplphysiol.01067.2016 ◽

2018 ◽

Vol 124 (2) ◽

pp. 421-429 ◽

Cited By ~ 12

Author(s):

Ron Oliven ◽

Guy Cohen ◽

Yaniv Dotan ◽

Mostafa Somri ◽

Alan R. Schwartz ◽

...

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Healthy Subjects ◽

Upper Airway ◽

Retractor Muscle ◽

Emg Activity ◽

Muscle Coordination ◽

Flow Limitation ◽

Dilator Muscle ◽

Obstructive Sleep

In patients with obstructive sleep apnea (OSA), substantial increases in genioglossus (GG) activity during hypopneas/apneas usually fail to restore normal airflow. We have previously suggested that sleep-induced alteration in tongue muscle coordination may explain this finding, as retractor muscle coactivation was reduced during sleep compared with wakefulness. The present study was undertaken to evaluate whether these alterations in dilator muscle activation during sleep play a role in the pathogenesis of OSA and whether coactivation of additional peripharyngeal muscles (non-GG muscles: styloglossus, geniohyoid, sternohyoid, and sternocleidomastoid) is also impaired during sleep. We compared GG and non-GG muscle electromyographic (EMG) activity in 8 patients with OSA and 12 healthy subjects during wakefulness while breathing through inspiratory resistors with the activity observed during sleep toward the end of flow limitation, before arousal, at equivalent esophageal pressures. During wakefulness, resistive breathing triggered increases in both GG and non-GG muscle activity. During sleep, flow limitation was associated with increases in GG-EMG that reached, on average, >2-fold the level observed while awake. In contrast, EMGs of the non-GG muscles, recorded simultaneously, reached, on average, only ~2/3 the wakefulness level. We conclude that during sleep GG activity may increase to levels that substantially exceed those sufficient to prevent pharyngeal collapse during wakefulness, whereas other peripharyngeal muscles do not coactivate during sleep in both patients with OSA and healthy subjects. We speculate that upper airway muscle dyssynchrony during sleep may explain why GG-EMG activation fails to alleviate flow limitation and stabilize airway patency during sleep. NEW & NOTEWORTHY Pharyngeal obstruction during sleep may trigger genioglossus activity to levels substantially exceeding those observed during wakefulness, without ameliorating flow limitation. In contrast, other peripharyngeal muscles exhibit a much lower activity during sleep in both patients with obstructive sleep apnea and healthy subjects. Coordinated muscular synergy stabilizes the pharynx despite relatively low activity while awake, yet even higher genioglossal activity allows the pharynx to obstruct when simultaneous activity of other dilator muscles is inadequate during sleep.

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Contemporary Methods of Upper Airway Evaluation in Obstructive Sleep Apnea Patients

Korean Journal of Otorhinolaryngology - Head and Neck Surgery ◽

10.3342/kjorl-hns.2013.56.1.7 ◽

2013 ◽

Vol 56 (1) ◽

pp. 7 ◽

Cited By ~ 4

Author(s):

Tae-Bin Won

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Upper Airway ◽

Obstructive Sleep

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Dynamic upper airway narrowing in patients with obstructive sleep apnea

American Journal of Roentgenology ◽

10.2214/ajr.147.6.1330 ◽

1986 ◽

Vol 147 (6) ◽

pp. 1330-1331

Author(s):

I Rubinstein ◽

N Zamel ◽

V Hoffstein

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Upper Airway ◽

Airway Narrowing ◽

Obstructive Sleep

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Aerodynamics Analysis of the Impact of Nasal Surgery on Patients with Obstructive Sleep Apnea and Nasal Obstruction

ORL ◽

10.1159/000516243 ◽

2021 ◽

pp. 1-8

Author(s):

Lifeng Li ◽

Demin Han ◽

Hongrui Zang ◽

Nyall R. London

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Nasal Obstruction ◽

Upper Airway ◽

Apnea Hypopnea Index ◽

Nasal Surgery ◽

Subjective Sleep Quality ◽

Obstructive Sleep ◽

Significant Difference ◽

The Impact

Objective: The purpose of this study was to evaluate the effects of nasal surgery on airflow characteristics in patients with obstructive sleep apnea (OSA) by comparing the alterations of airflow characteristics within the nasal and palatopharyngeal cavities. Methods: Thirty patients with OSA and nasal obstruction who underwent nasal surgery were enrolled. A pre- and postoperative 3-dimensional model was constructed, and alterations of airflow characteristics were assessed using the method of computational fluid dynamics. The other subjective and objective clinical indices were also assessed. Results: By comparison with the preoperative value, all postoperative subjective symptoms statistically improved (p < 0.05), while the Apnea-Hypopnea Index (AHI) changed little (p = 0.492); the postoperative airflow velocity and pressure in both nasal and palatopharyngeal cavities, nasal and palatopharyngeal pressure differences, and total upper airway resistance statistically decreased (all p < 0.01). A significant difference was derived for correlation between the alteration of simulation metrics with subjective improvements (p < 0.05), except with the AHI (p > 0.05). Conclusion: Nasal surgery can decrease the total resistance of the upper airway and increase the nasal airflow volume and subjective sleep quality in patients with OSA and nasal obstruction. The altered airflow characteristics might contribute to the postoperative reduction of pharyngeal collapse in a subset of OSA patients.

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