scholarly journals Differential Effects of Isoflurane and Propofol on Upper Airway Dilator Muscle Activity and Breathing

2008 ◽  
Vol 108 (5) ◽  
pp. 897-906 ◽  
Author(s):  
Matthias Eikermann ◽  
Atul Malhotra ◽  
Philipp Fassbender ◽  
Sebastian Zaremba ◽  
Amy S. Jordan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Flow Rate ◽  
Muscle Activity ◽  
Upper Airway ◽  
Respiratory Drive ◽  
Apparent Paradox ◽  
Arterial Blood ◽  
Dilator Muscle ◽  
Spontaneously Breathing ◽  
Intact Rats

Background Anesthesia impairs upper airway integrity, but recent data suggest that low doses of some anesthetics increase upper airway dilator muscle activity, an apparent paradox. The authors sought to understand which anesthetics increase or decrease upper airway dilator muscle activity and to study the mechanisms mediating the effect. Methods The authors recorded genioglossus electromyogram, breathing, arterial blood pressure, and expiratory carbon dioxide in 58 spontaneously breathing rats at an estimated ED50 (median effective dose) of isoflurane or propofol. The authors further evaluated the dose-response relations of isoflurane under different study conditions: (1) normalization of mean arterial pressure, or end-expiratory carbon dioxide; (2) bilateral lesion of the Kölliker-Fuse nucleus; and (3) vagotomy. To evaluate whether the markedly lower inspiratory genioglossus activity during propofol could be recovered by increasing flow rate, a measure of respiratory drive, the authors performed an additional set of experiments during hypoxia or hypercapnia. Results In vagally intact rats, tonic and phasic genioglossus activity were markedly higher with isoflurane compared with propofol. Both anesthetics abolished the genioglossus negative pressure reflex. Inspiratory flow rate and anesthetic agent predicted independently phasic genioglossus activity. Isoflurane dose-dependently decreased tonic and increased phasic genioglossus activity, and increased flow rate, and its increasing effects were abolished after vagotomy. Impairment of phasic genioglossus activity during propofol anesthesia was reversed during evoked increase in respiratory drive. Conclusion Isoflurane compared with propofol anesthesia yields higher tonic and phasic genioglossus muscle activity. The level of respiratory depression rather than the level of effective anesthesia correlates closely with the airway dilator muscle function during anesthesia.

scholarly journals Ketamine Activates Breathing and Abolishes the Coupling between Loss of Consciousness and Upper Airway Dilator Muscle Dysfunction

2012 ◽  
Vol 116 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Matthias Eikermann ◽  
Martina Grosse-Sundrup ◽  
Sebastian Zaremba ◽  
Mark E. Henry ◽  
Edward A. Bittner ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Eye Movement ◽  
Upper Airway ◽  
Muscle Dysfunction ◽  
High Dose ◽  
Loss Of Consciousness ◽  
Respiratory Drive ◽  
Airway Patency ◽  
Dilator Muscle ◽  
Ketamine Anesthesia

Background Procedural sedation is frequently performed in spontaneously breathing patients, but hypnotics and opioids decrease respiratory drive and place the upper airway at risk for collapse. Methods In a randomized, controlled, cross-over, pharmaco-physiologic study in 12 rats, we conducted acute experiments to compare breathing and genioglossus electromyogram activity at equianesthetic concentrations of ketamine, a noncompetitive N-methyl-D-aspartate receptor antagonist that combines potent analgesic with hypnotic action effects, versus propofol. In 10 chronically instrumented rats resting in a plethysmograph, we measured these variables as well as electroencephalography during five conditions: quiet wakefulness, nonrapid-eye-movement sleep, rapid eye movement sleep, and low-dose (60 mg/kg intraperitoneally) and high-dose ketamine anesthesia (125 mg/kg intraperitoneally). Results Ketamine anesthesia was associated with markedly increased genioglossus activity (1.5 to fivefold higher values of genioglossus electromyogram) compared with sleep- and propofol-induced unconsciousness. Plethysmography revealed a respiratory stimulating effect: higher values of flow rate, respiratory rate, and duty-cycle (effective inspiratory time, 1.5-to-2-fold higher values). During wakefulness and normal sleep, the δ (f = 6.51, P = 0.04) electroencephalogram power spectrum was an independent predictor of genioglossus activity, indicating an association between electroencephalographic determinants of consciousness and genioglossus activity. Following ketamine administration, electroencephalogram power spectrum and genioglossus electroencephalogram was dissociated (P = 0.9 for the relationship between δ/θ power spectrum and genioglossus electromyogram). Conclusions Ketamine is a respiratory stimulant that abolishes the coupling between loss-of-consciousness and upper airway dilator muscle dysfunction in a wide dose-range. Ketamine compared with propofol might help stabilize airway patency during sedation and anesthesia.

scholarly journals Upper airway muscle activity in normal women: influence of hormonal status

1998 ◽  
Vol 84 (3) ◽  
pp. 1055-1062 ◽  
Author(s):  
Rainer M. Popovic ◽  
David P. White
Keyword(s):  
Postmenopausal Women ◽  
Muscle Activity ◽  
Airway Resistance ◽  
Upper Airway ◽  
Resistive Load ◽  
Substantial Impact ◽  
Upper Airway Resistance ◽  
Female Hormones ◽  
Dilator Muscle ◽  
Obstructive Sleep

Obstructive sleep apnea is a disorder with a strong male predominance. One possible explanation could be an effect of female hormones on pharyngeal dilator muscle activity. Therefore, we determined the level of awake genioglossus electromyogram (EMGgg) and upper airway resistance in 12 pre- and 12 postmenopausal women under basal conditions and during the application of an inspiratory resistive load (25 cmH2O ⋅ l−1 ⋅ s). In addition, a subgroup of eight postmenopausal women were studied a second time after 2 wk of combined estrogen and progesterone replacement in standard doses. Peak phasic and tonic genioglossus activity, expressed as a percentage of maximum, were highest in the luteal phase of the menstrual cycle (phasic 23.9 ± 3.8%, tonic 10.2 ± 1.0%), followed by the follicular phase (phasic 15.5 ± 2.2%, tonic 7.3 ± 0.8%), and were lowest in the postmenopausal group (phasic 11.3 ± 1.6%, tonic of 5.0 ± 0.6), whereas upper airway resistance did not differ. There was a weak but significant positive correlation between progesterone levels and both peak phasic ( P < 0.05) and tonic ( P < 0.01) EMGgg. Finally, there was a significant increase in EMGgg in the postmenopausal group restudied after hormone therapy. In conclusion, female hormones (possibly progesterone) have a substantial impact on upper airway dilator muscle activity.

Effects of almitrine on genioglossal and diaphragmatic electromyograms

1986 ◽  
Vol 61 (6) ◽  
pp. 2122-2128 ◽  
Author(s):  
D. E. Weese-Mayer ◽  
R. T. Brouillette ◽  
L. M. Klemka ◽  
C. E. Hunt
Keyword(s):  
Slow Wave Sleep ◽  
Minute Ventilation ◽  
Upper Airway ◽  
Respiratory Drive ◽  
Peripheral Chemoreceptor ◽  
Obstructive Sleep ◽  
Adult Cats ◽  
Alpha Chloralose ◽  
Spontaneously Breathing ◽  
Dose Dependent

We previously demonstrated dose-dependent increases in both hypoglossal and phrenic electroneurograms after almitrine in anesthetized, paralyzed, and vagotomized cats. We have now investigated the effect of this peripheral chemoreceptor stimulant on diaphragmatic and genioglossal (GG, an upper airway-maintaining muscle) electromyograms in five unanesthetized, chronically instrumented, spontaneously breathing adult cats during slow-wave sleep. In 12 studies almitrine doses of 1.0–6.0 mg/kg increased inspired minute ventilation (VI), frequency (f), and tidal volume (VT) and decreased expiratory time (TE). However, almitrine doses as high as 6.0 mg/kg failed to augment phasic inspiratory GG activity. To determine why almitrine induced phasic inspiratory upper airway activity in anesthetized, vagotomized cats but not in sleeping cats, additional studies were performed. In four dose-response studies in three pentobarbital-anesthetized cats, almitrine, 1.0–6.0 mg/kg, did not produce phasic inspiratory GG activity. Almitrine did induce phasic inspiratory GG activity in two of three studies in three vagotomized, tracheostomized, alpha-chloralose-urethan-anesthetized cats. These results suggest that almitrine would not be useful in obstructive sleep apnea, yet because almitrine markedly increased VI, f, and VT and decreased TE in unanesthetized sleeping cats the drug may be effective in patients who lack normal central neural respiratory drive, such as the preterm infant.

Thoracic influence on upper airway patency

1988 ◽  
Vol 65 (5) ◽  
pp. 2124-2131 ◽  
Author(s):  
W. B. Van de Graaff
Keyword(s):  
Muscle Activity ◽  
Upper Airway ◽  
Constant Flow ◽  
Airway Patency ◽  
Anesthetized Dogs ◽  
Measured Resistance ◽  
Flow Through ◽  
Phrenic Nerves ◽  
Tracheostomy Tubes ◽  
Spontaneously Breathing

Patency of the upper airway (UA) is usually considered to be maintained by the activity of muscles in the head and neck. These include cervical muscles that provide caudal traction on the UA. The thorax also applies caudal traction to the UA. To observe whether this thoracic traction can also improve UA patency, we measured resistance of the UA (RUA) during breathing in the presence and absence of UA muscle activity. Fifteen anesthetized dogs breathed through tracheostomy tubes. RUA was calculated from the pressure drop of a constant flow through the isolated UA. RUA decreased 31 +/- 5% (SEM) during inspiration. After hyperventilating seven of these dogs to apnea, we maximally stimulated the phrenic nerves to produce paced diaphragmatic breathing. Despite absence of UA muscle activity, RUA fell 51 +/- 11% during inspiration. Graded changes were produced by reduced stimulation. In six other dogs we denervated all UA muscles. RUA still fell 25 +/- 7% with inspiration in these spontaneously breathing animals. When all caudal ventrolateral cervical structures mechanically linking the thorax to the UA were severed, RUA increased and respiratory fluctuations ceased. These findings indicate that tonic and phasic forces generated by the thorax can improve UA patency. Inspiratory increases in UA patency cannot be attributed solely to activity of UA muscles.

Reduced genioglossal activity with upper airway anesthesia in awake patients with OSA

2000 ◽  
Vol 88 (4) ◽  
pp. 1346-1354 ◽  
Author(s):  
Robert B. Fogel ◽  
Atul Malhotra ◽  
Steven A. Shea ◽  
Jill K. Edwards ◽  
David P. White
Keyword(s):  
Muscle Activity ◽  
Upper Airway ◽  
Significant Rise ◽  
Tidal Breathing ◽  
Airflow Resistance ◽  
Dilator Muscle ◽  
Obstructive Sleep ◽  
Airway Mechanics ◽  
Airway Collapsibility ◽  
Negative Airway Pressure

We examined whether topical upper airway anesthesia leads to a reduction in genioglossal (GG) electromyogram (EMG) in patients with obstructive sleep apnea (OSA). Airway mechanics were also evaluated. In 13 patients with OSA, we monitored GG EMG during tidal breathing and during the application of pulses of negative airway pressure (−10 to −12 cmH2O). Airflow resistance and airway collapsibility were determined. All measurements were performed with and without topical anesthesia (lidocaine). Anesthesia led to a significant fall in the peak GG EMG response to negative pressure from 36.1 ± 4.7 to 24.8 ± 5.3% (SE) of maximum ( P < 0.01). This was associated with a fall in phasic and tonic EMG during tidal breathing (phasic from 24.4 ± 4.1 to 16.4 ± 3.4% of maximum and tonic from 10.9 ± 1.6 to 8.0 ± 1.3% of maximum, P < 0.01). A significant rise in pharyngeal airflow resistance was also observed. Our results demonstrate that topical receptor mechanisms in the nasopharynx importantly influence dilator muscle activity and are likely important in driving the augmented dilator muscle activity seen in the apnea patient.

scholarly journals Modulation of laryngeal and respiratory pump muscle activities with upper airway pressure and flow

2001 ◽  
Vol 91 (2) ◽  
pp. 897-904 ◽  
Author(s):  
M. H. Stella ◽  
S. J. England
Keyword(s):  
Negative Pressure ◽  
Muscle Activity ◽  
Upper Airway ◽  
Abdominal Muscle ◽  
Positive Pressure ◽  
Emg Activity ◽  
Posterior Cricoarytenoid ◽  
Spontaneously Breathing ◽  
Respiratory Muscle Activity ◽  
Stimulation Of

The hypothesis that upper airway (UA) pressure and flow modulate respiratory muscle activity in a respiratory phase-specific fashion was assessed in anesthetized, tracheotomized, spontaneously breathing piglets. We generated negative pressure and inspiratory flow in phase with tracheal inspiration or positive pressure and expiratory flow in phase with tracheal expiration in the isolated UA. Stimulation of UA negative pressure receptors with body temperature air resulted in a 10–15% enhancement of phasic moving-time-averaged posterior cricoarytenoid electromyographic (EMG) activity above tonic levels obtained without pressure and flow in the UA (baseline). Stimulation of UA positive pressure receptors increased phasic moving-time-averaged thyroarytenoid EMG activity above tonic levels by 45% from baseline. The same enhancement of posterior cricoarytenoid or thyroarytenoid EMG activity was observed with the addition of flow receptor stimulation with room temperature air. Tidal volume and diaphragmatic and abdominal muscle activity were unaffected by UA flow and/or pressure, whereas respiratory timing was minimally affected. We conclude that laryngeal afferents, mainly from pressure receptors, are important in modulating the respiratory activity of laryngeal muscles.

A threshold lung volume for optimal mechanical effects on upper airway airflow dynamics: studies in an anesthetized rabbit model

2012 ◽  
Vol 112 (7) ◽  
pp. 1197-1205 ◽  
Author(s):  
Kristina Kairaitis ◽  
Manisha Verma ◽  
Jason Amatoury ◽  
John R. Wheatley ◽  
David P. White ◽  
...  
Keyword(s):  
Lung Volume ◽  
Muscle Activity ◽  
Rabbit Model ◽  
Upper Airway ◽  
Flow Limitation ◽  
Volume Increase ◽  
Mechanical Effects ◽  
Pharyngeal Pressure ◽  
Volume Resistance ◽  
Spontaneously Breathing

Increasing lung volume improves upper airway airflow dynamics via passive mechanisms such as reducing upper airway extraluminal tissue pressures (ETP) and increasing longitudinal tension via tracheal displacement. We hypothesized a threshold lung volume for optimal mechanical effects on upper airway airflow dynamics. Seven supine, anesthetized, spontaneously breathing New Zealand White rabbits were studied. Extrathoracic pressure was altered, and lung volume change, airflow, pharyngeal pressure, ETP laterally (ETPlat) and anteriorly (ETPant), tracheal displacement, and sternohyoid muscle activity (EMG%max) monitored. Airflow dynamics were quantified via peak inspiratory airflow, flow limitation upper airway resistance, and conductance. Every 10-ml lung volume increase resulted in caudal tracheal displacement of 2.1 ± 0.4 mm (mean ± SE), decreased ETPlat by 0.7 ± 0.3 cmH2O, increased peak inspiratory airflow of 22.8 ± 2.6% baseline (all P < 0.02), and no significant change in ETPant or EMG%max. Flow limitation was present in most rabbits at baseline, and abolished 15.7 ± 10.5 ml above baseline. Every 10-ml lung volume decrease resulted in cranial tracheal displacement of 2.6 ± 0.4 mm, increased ETPant by 0.9 ± 0.2 cmH2O, ETPlat was unchanged, increased EMG%max of 11.1 ± 0.3%, and a reduction in peak inspiratory airflow of 10.8 ± 1.0%baseline (all P < 0.01). Lung volume, resistance, and conductance relationships were described by exponential functions. In conclusion, increasing lung volume displaced the trachea caudally, reduced ETP, abolished flow limitation, but had little effect on resistance or conductance, whereas decreasing lung volume resulted in cranial tracheal displacement, increased ETP and increased resistance, and reduced conductance, and flow limitation persisted despite increased muscle activity. We conclude that there is a threshold for lung volume influences on upper airway airflow dynamics.

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