Responses to negative pressure surrounding the neck in anesthetized animals

1990 ◽  
Vol 68 (1) ◽  
pp. 154-160 ◽  
Author(s):  
A. D. Wolin ◽  
K. P. Strohl ◽  
B. N. Acree ◽  
J. M. Fouke
Keyword(s):  
Negative Pressure ◽  
Airway Resistance ◽  
Upper Airway ◽  
Transmural Pressure ◽  
Positive Pressure ◽  
Respiratory Drive ◽  
Airway Wall ◽  
Airway Patency ◽  
Upper Airway Resistance ◽  
Continuous Positive Pressure

Continuous positive pressure applied at the nose has been shown to cause a decrease in upper airway resistance. The present study was designed to determine whether a similar positive transmural pressure gradient, generated by applying a negative pressure at the body surface around the neck, altered upper airway patency. Studies were performed in nine spontaneously breathing anesthetized supine dogs. Airflow was measured with a pneumotachograph mounted on an airtight muzzle placed over the nose and mouth of each animal. Upper airway pressure was measured as the differential pressure between the extrathoracic trachea and the inside of the muzzle. Upper airway resistance was monitored as an index of airway patency. Negative pressure (-2 to -20 cmH2O) was applied around the neck by using a cuirass extending from the jaw to the thorax. In each animal, increasingly negative pressures were transmitted to the airway wall in a progressive, although not linear, fashion. Decreasing the pressure produced a progressive fall in upper airway resistance, without causing a significant change in respiratory drive or respiratory timing. At -5 cmH2O pressure, there occurred a significant fall in upper airway resistance, comparable with the response of a single, intravenous injection of sodium cyanide (0.5-3.0 mg), a respiratory stimulant that produces substantial increases in respiratory drive. We conclude that upper airway resistance is influenced by the transmural pressure across the airway wall and that such a gradient can be accomplished by making the extraluminal pressure more negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Motor responses to positive-pressure breathing in the developing opossum

1985 ◽  
Vol 58 (5) ◽  
pp. 1489-1495 ◽  
Author(s):  
J. P. Farber
Keyword(s):  
Airway Resistance ◽  
Upper Airway ◽  
Abdominal Muscle ◽  
Positive Pressure ◽  
Postnatal Life ◽  
Abdominal Muscles ◽  
Upper Airways ◽  
Motor Responses ◽  
Upper Airway Resistance ◽  
Upper Airway Muscles

The suckling opossum exhibits an expiration-phased discharge in abdominal muscles during positive-pressure breathing (PPB); the response becomes apparent, however, only after the 3rd-5th wk of postnatal life. The purpose of this study was to determine whether the early lack of activation represented a deficiency of segmental outflow to abdominal muscles or whether comparable effects were observed in cranial outflows to muscles of the upper airways due to immaturity of afferent and/or supraspinal pathways. Anesthetized suckling opossums between 15 and 50 days of age were exposed to PPB; electromyogram (EMG) responses in diaphragm and abdominal muscles were measured, along with EMG of larynx dilator muscles and/or upper airway resistance. In animals older than approximately 30 days of age, the onset of PPB was associated with a prolonged expiration-phased EMG activation of larynx dilator muscles and/or decreased upper airway resistance, along with expiratory recruitment of the abdominal muscle EMG. These effects persisted as long as the load was maintained. Younger animals showed only those responses related to the upper airway; in fact, activation of upper airway muscles during PPB could be associated with suppression of the abdominal motor outflow. After unilateral vagotomy, abdominal and upper airway motor responses to PPB were reduced. The balance between PPB-induced excitatory and inhibitory or disfacilitory influences from the supraspinal level on abdominal motoneurons and/or spinal processing of information from higher centers may shift toward net excitation as the opossum matures.

Effect of geniohyoid and sternohyoid muscle contraction on upper airway resistance in the cat

1991 ◽  
Vol 71 (4) ◽  
pp. 1346-1354 ◽  
Author(s):  
D. A. Wiegand ◽  
B. Latz
Keyword(s):  
Electrical Stimulation ◽  
Muscle Contraction ◽  
Airway Resistance ◽  
Upper Airway ◽  
Muscle Stimulation ◽  
Nasal Airflow ◽  
Airway Patency ◽  
Upper Airway Resistance ◽  
Wide Range ◽  
Consistent Change

Previous investigators (van Lunteren et al. J. Appl. Physiol. 62: 582–590, 1987) have suggested that the geniohyoid and sternohyoid muscles may act as upper airway dilators in the cat. To investigate the effect of geniohyoid and sternohyoid contraction on inspiratory upper airway resistance (UAR), we studied five adult male cats anesthetized with ketamine and xylazine during spontaneous room-air breathing. Inspiratory nasal airflow was measured by sealing the lips and constructing a nose mask. Supraglottic pressure was measured using a transpharyngeal catheter placed above the larynx. Mask pressure was measured using a separate catheter. Geniohyoid and sternohyoid lengths were determined by sonomicrometry. Geniohyoid and sternohyoid contraction was stimulated by direct muscle electrical stimulation with implanted wire electrodes. Mean inspiratory UAR was determined for spontaneous breaths under three conditions: 1) baseline (no muscle stimulation), 2) geniohyoid contraction alone, and 3) sternohyoid contraction alone. Geniohyoid contraction alone produced no significant reduction in inspiratory UAR [unstimulated, 17.75 +/- 0.86 (SE) cmH2O.l-1.s; geniohyoid contraction, 19.24 +/- 1.10]. Sternohyoid contraction alone also produced no significant reduction in inspiratory UAR (unstimulated, 15.74 +/- 0.92 cmH2O.l-1.s; sternohyoid contraction, 14.78 +/- 0.78). Simultaneous contraction of the geniohyoid and sternohyoid muscles over a wide range of muscle lengths produced no consistent change in inspiratory UAR. The geniohyoid and sternohyoid muscles do not appear to function consistently as upper airway dilator muscles when UAR is used as an index of upper airway patency in the cat.

scholarly journals Sciatic nerve stimulation and its effects on upper airway resistance in the anesthetized rabbit model relevant to sleep apnea

2018 ◽  
Vol 125 (3) ◽  
pp. 763-769 ◽  
Author(s):  
Matthew Schiefer ◽  
Jenniffer Gamble ◽  
Kingman P. Strohl
Keyword(s):  
Sleep Apnea ◽  
Sciatic Nerve ◽  
Nerve Stimulation ◽  
Airway Resistance ◽  
Rabbit Model ◽  
Upper Airway ◽  
Respiratory Drive ◽  
Upper Airway Resistance ◽  
Ventilatory Drive ◽  
Sciatic Nerve Stimulation

Obstructive sleep apnea (OSA) is a disorder characterized by collapse of the velopharynx and/or oropharynx during sleep when drive to the upper airway is reduced. Here, we explore an indirect approach for activation of upper airway muscles that might affect airway dynamics, namely, unilateral electrical stimulation of the afferent fibers of the sciatic nerve, in an anesthetized rabbit model. A nerve cuff electrode was placed around the sciatic and hypoglossal nerves to deliver stimulus while airflow, air pressure, and alae nasi electromyogram (EMG) were monitored both before and after sciatic transection. Sciatic nerve stimulation increased respiratory effort, rate, and alae nasi EMG, which persisted for seconds after stimulation; however, upper airway resistance was unchanged. Hypoglossal stimulation reduced resistance without altering drive. Although sciatic nerve stimulation is not ideal for treating OSA, it remains a target for altering respiratory drive. NEW & NOTEWORTHY Previously, sciatic nerve stimulation has been shown to activate upper airway and chest wall muscles. The supposition that resistance through the upper airway would be reduced with this afferent reflex was disproven. Findings were in contrast with the effect of hypoglossal nerve stimulation, which was shown to decrease resistance without changing muscle activation or ventilatory drive.

Reflex changes in tracheal smooth muscle tone during high-frequency oscillation

1990 ◽  
Vol 68 (2) ◽  
pp. 714-719
Author(s):  
G. C. Man ◽  
K. K. Teo ◽  
C. T. Kappagoda ◽  
S. F. Man
Keyword(s):  
Smooth Muscle ◽  
High Frequency ◽  
Airway Resistance ◽  
Muscle Tone ◽  
Muscle Tension ◽  
Upper Airway ◽  
Tracheal Smooth Muscle ◽  
High Frequency Oscillation ◽  
Positive Pressure ◽  
Upper Airway Resistance

We examined the effect of high-frequency oscillatory ventilation (HFOV) on tracheal smooth muscle tension and upper airway resistance in anesthetized dogs. The animals were ventilated via a low tracheostomy by HFOV or conventional intermittent positive pressure ventilation (IPPV) with and without added positive end-expiratory pressure (PEEP). The transverse muscle tension of the trachea above the tracheostomy was measured and found to be lower during HFOV when compared with IPPV or IPPV with PEEP. When both vagi were cooled to 8 degrees C to interrupt afferent traffic from the lungs, there was no longer any difference between the modes of ventilation. In a second series of experiments, the airflow resistance of the upper airway above the tracheostomy was measured (Ruaw). During HFOV, Ruaw was significantly lower than during either IPPV or IPPV with PEEP. We conclude that HFOV induces a relaxation of tracheal smooth muscle and a reduction of upper airway resistance through a vagally mediated mechanism.

Laryngeal-receptor responses to phasic CO2 in anesthetized cats

1998 ◽  
Vol 85 (3) ◽  
pp. 1135-1141 ◽  
Author(s):  
A. Bradford ◽  
D. McKeogh ◽  
R. G. O’Regan
Keyword(s):  
Negative Pressure ◽  
Muscle Activity ◽  
Upper Airway ◽  
Respiratory Cycle ◽  
Positive Pressure ◽  
Receptor Stimulation ◽  
Airway Patency ◽  
Cold Receptors ◽  
Regulation Of Breathing ◽  
Spontaneously Breathing

We compared the effects of CO2 applied continuously and during expiration on laryngeal-receptor activity in paralyzed, artificially ventilated and nonparalyzed, spontaneously breathing cats by using an isolated larynx, artificially ventilated to approximate a normal respiratory cycle. The majority of quiescent negative-pressure and all cold receptors were excited by 5 and 9% CO2 applied both continuously and during expiration. In general, quiescent positive-pressure, tonic negative-pressure, and tonic positive-pressure receptors were inhibited by 5 and 9% CO2 applied continuously and during expiration. There were no significant differences between responses to 5 and 9% CO2 or to continuous and expired CO2 or between paralyzed and nonparalyzed preparations. In conclusion, laryngeal receptors respond to changes in CO2 concentration occurring during a normal respiratory cycle. Because laryngeal-receptor stimulation exerts reflex effects on ventilation and upper airway muscle activity, these results suggest that airway CO2 plays a role in reflex regulation of breathing and upper airway patency.

Influence of respiratory drive on upper airway resistance in normal men

1989 ◽  
Vol 66 (3) ◽  
pp. 1242-1249 ◽  
Author(s):  
F. Series ◽  
Y. Cormier ◽  
M. Desmeules ◽  
J. La Forge
Keyword(s):  
Airway Resistance ◽  
Upper Airway ◽  
Base Line ◽  
Respiratory Drive ◽  
Upper Airway Resistance ◽  
Co2 Rebreathing ◽  
Bias Flow ◽  
Measured Flow ◽  
The Mean ◽  
Normal Men

The variations in nasal and pharyngeal resistance induced by changes in the central inspiratory drive were studied in 10 normal men. To calculate resistances we measured upper airway pressures with two low-bias flow catheters; one was placed at the tip of the epiglottis and the other in the posterior nasopharynx, and we measured flow with a Fleisch no. 3 pneumotachograph connected to a tightly fitting mask. Both resistances were obtained continuously during CO2 rebreathing (Read's method) and during the 2 min after a 1-min voluntary maximal hyperventilation. The inspiratory drive was estimated by measurements of inspiratory pressure generated at 0.1 s after the onset of inspiration (P0.1) and by the mean inspiratory flow (VT/TI). In each subject both resistances decreased during CO2 rebreathing; these decreases were correlated with the increase in P0.1. During the posthyperventilation period, ventilation fell below base line in seven subjects; this was accompanied by an increase in both nasal and pharyngeal resistances. These resistances increased exponentially as VT/TI decreased. Parallel changes in nasal and pharyngeal resistances were seen during CO2 stimulus and during the period after the hyperventilation. We conclude that 1) the indexes quantifying the inspiratory drive reflect the activation of nasopharyngeal dilator muscles (as assessed by the changes in upper airway resistance) and 2) both nasal and pharyngeal resistances are similarly influenced by changes in the respiratory drive.

Upper airway muscle activity and the thoracic volume dependence of upper airway resistance

1991 ◽  
Vol 70 (1) ◽  
pp. 430-438 ◽  
Author(s):  
R. M. Aronson ◽  
D. W. Carley ◽  
E. Onal ◽  
J. Wilborn ◽  
M. Lopata
Keyword(s):  
Lung Volume ◽  
Airway Resistance ◽  
Linear Regression Analysis ◽  
Control Period ◽  
Upper Airway ◽  
Multiple Linear Regression Analysis ◽  
Respiratory Pattern ◽  
Airway Patency ◽  
Upper Airway Resistance ◽  
Volume Dependence

Although a thoracic volume dependence of upper airway resistance and caliber is known to exist in seated subjects, the mechanisms mediating this phenomenon are unknown. To test the hypothesis that actively altered end-expiratory lung volume (EELV) affects upper airway resistance in the supine position and to explore the mechanisms of any EELV-induced resistance changes, we studied five normal males during wakefulness. Supraglottic upper airway resistance (Ruaw) was calculated at an inspiratory flow of 0.1 l/s. The genioglossal electromyogram was obtained with indwelling wire electrodes and processed as moving time average. End-tidal CO2 was monitored by infrared analyzer. Observations were made during four 20-breath voluntary maneuvers: two at high and two at low EELV in each subject. Each maneuver was preceded by a control period at functional residual capacity. At high lung volume the EELV was increased by 2.23 +/- 0.54 (SD) liters; Ruaw decreased to 67.8 +/- 35.1% of control, while tonic and phasic genioglossal activities declined to 79.0 +/- 23.1 and 72.4 +/- 29.8%, respectively. At low lung volume the EELV was decreased by 0.86 +/- 0.23 liters. Ruaw increased to 178.2 +/- 186.8%, while tonic and phasic genioglossal activities increased to 243.0 +/- 139.3 and 249.1 +/- 146.3%, respectively (P less than 0.0001 for all). The findings were not explained by CO2 perturbations or respiratory pattern. Multiple linear regression analysis indicated that the genioglossal responses blunted the EELV-induced changes in upper airway patency.(ABSTRACT TRUNCATED AT 250 WORDS)

Susceptibility to Upper Airway Obstruction during Partial Neuromuscular Block 

1998 ◽  
Vol 88 (2) ◽  
pp. 371-378 ◽  
Author(s):  
Gilles D'Honneur ◽  
Frederic Lofaso ◽  
Gordon B. Drummond ◽  
Jean-Marc Rimaniol ◽  
Jean V. Aubineau ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Airway Obstruction ◽  
Airway Resistance ◽  
Neuromuscular Block ◽  
Work Of Breathing ◽  
Upper Airway ◽  
Residual Effects ◽  
Airway Patency ◽  
Upper Airway Resistance ◽  
Residual Neuromuscular Block

Background Airway obstruction after anesthesia may be caused or exaggerated by residual neuromuscular block, with loss of muscle support for collapsible upper airway structures. Methods Six male volunteers were studied before treatment, during stable partial neuromuscular block with vecuronium at a mean train-of-four (TOF) ratio of 50% (95% CI, 36-61%), and after reversal by neostigmine. Catheter-mounted transducers were placed in the pharynx and esophagus to estimate, respectively, the upper airway resistance, and the work of breathing (calculated as the time integral of the inspiratory pressure developed by the respiratory muscles, esophageal pressure time product) during quiet breathing, during breathing 5% carbon dioxide, and while breathing with an inspiratory resistor. Breathing with pressure at the airway opening held at pressures from -5 to 40 cm H2O were also tested to assess airway collapsibility. Results Although breathing through a resistor increased upper airway resistance from 1.2 (0.67, 1.72) cm H2O x l(-1) x s to 2.5 (1.32, 3.38) cm H2O x l(-1) x s, and carbon dioxide stimulation reduced resistance to 0.8 (0.46, 1.33) cm H2O x l(-1) x s, no effect of partial neuromuscular block (mean TOF ratio, 52%) on upper airway properties could be shown. Conclusions Neuromuscular block with a TOF ratio of 50% can be present yet clinically difficult to detect in patients recovering from anesthesia. This degree of block has no effect on airway patency in volunteers, even during challenge. Airway obstruction during recovery from anesthesia thus is more likely to be caused by residual effects of general anesthetic agents or centrally acting analgesics, either alone or perhaps in concert with residual neuromuscular block.

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