Sensation of inspired volume in normal subjects and quadriplegic patients

1982 ◽  
Vol 53 (6) ◽  
pp. 1481-1486 ◽  
Author(s):  
A. F. DiMarco ◽  
D. A. Wolfson ◽  
S. B. Gottfried ◽  
M. D. Altose
Keyword(s):  
Magnitude Estimation ◽  
Muscle Tension ◽  
Upper Airway ◽  
Normal Subjects ◽  
Motor Command ◽  
Resistive Load ◽  
Rib Cage ◽  
Lidocaine Solution ◽  
Loaded Breathing ◽  
The Central Nervous System

To investigate the influence of respiratory muscle tension and feedback from rib cage receptors, the sensation of inspired volume was compared in normal subjects and quadriplegic patients during active breathing, with and without the addition of an inspiratory resistive load, and during passive ventilation produced by a tank respirator. In separate trials, volume sensation was assessed using tests of magnitude estimation and volume reproduction. The mean exponents and standard errors for the magnitude estimation of inspired volume in normal subjects were 1.32 +/- 0.08, 1.24 +/- 0.06, and 1.23 +/- 0.09 during passive, active, and loaded breathing, respectively. These values were not significantly different from one another, nor were there any differences between normal subjects and quadriplegics. During volume reproduction trials where the mechanical conditions were different between control and test breaths, the inspired volumes during active unloaded breathing were significantly smaller than during passive ventilation but greater than the inspired volumes during loaded breathing. Errors in volume reproduction were no different in normal subjects and quadriplegics, suggesting that inputs from rib cage receptors are not essential for the sensation of inspired volume. The sensation of inspired volume in both normal subjects and quadriplegics was found to be unaffected by inhalation of a 2% lidocaine solution. This suggests that upper airway receptors are also not essential for volume sensation. The intensity of the sensation of a given inspired volume may depend on the level of the central nervous system motor command and/or on the tension developed by the diaphragm.

Influence of prior ventilatory experience on the estimation of breathlessness during exercise

1990 ◽  
Vol 78 (2) ◽  
pp. 149-153 ◽  
Author(s):  
Rachel C. Wilson ◽  
P. W. Jones
Keyword(s):  
Exercise Test ◽  
Prior Experience ◽  
Minute Ventilation ◽  
Normal Subjects ◽  
Resistive Load ◽  
Inspiratory Time ◽  
Borg Scale ◽  
Exercise Tests ◽  
Loaded Breathing ◽  
Inspiratory Load

1. The intensity of breathlessness was measured during exercise in nine normal subjects using a modified Borg scale to examine the effect of prior experience of breathlessness on subsequent estimates of breathlessness. 2. Each subject performed four exercise tests, each of which consisted of two identical runs of workload incrementation (run 1 and run 2). An inspiratory resistive load of 3.8 cmH2O s−1 l−1 was applied during the appropriate run of the exercise test to examine the effect of (a) prior experience of ‘loaded’ breathing on breathlessness estimation during ‘unloaded’ breathing, and (b) prior experience of ‘unloaded’ breathing on breathlessness estimation during ‘loaded’ breathing. Run 1 was the conditioning run; run 2 was the run in which the effect of conditioning was measured. 3. There was a good correlation between breathlessness and minute ventilation during both unloaded’ breathing (median r = 0.93) and ‘loaded’ breathing (median r = 0.95). 4. The slope of the Borg score/minute ventilation relationship was greater during ‘loaded’ breathing than during ‘unloaded’ breathing (P < 0.01). There was no difference in mean Borg score between ‘unloaded’ and ‘loaded’ breathing. 5. After a period of ‘loaded’ breathing during run 1, estimated breathlessness was significantly reduced during ensuing ‘unloaded’ breathing in run 2 (P < 0.01) compared with the exercise test in which ‘unloaded’ breathing was experienced throughout both run 1 and run 2. 6. After a period of ‘unloaded’ breathing in run 1, estimated breathlessness was significantly increased during ensuing ‘loaded’ breathing in run 2 (P < 0.01) compared with the exercise test in which the inspiratory load had already been experienced in run 1. 7. Changes in the pattern of breathing (inspiratory time, expiratory time, total breath duration, inspiration time/total breath duration ratio and tidal volume) were not consistent with the changes in breathlessness. 8. We suggest that perception of breathlessness may be influenced by a subject's immediate prior experience of an altered relationship between breathlessness and ventilation.

Effect of thoracoabdominal breathing patterns on inspiratory effort sensation

1987 ◽  
Vol 62 (4) ◽  
pp. 1665-1670 ◽  
Author(s):  
J. W. Fitting ◽  
D. A. Chartrand ◽  
T. D. Bradley ◽  
K. J. Killian ◽  
A. Grassino
Keyword(s):  
Normal Subjects ◽  
Motor Command ◽  
Esophageal Pressure ◽  
Inspiratory Effort ◽  
Breathing Patterns ◽  
Borg Scale ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Main Variable ◽  
Unique Relationship

The respiratory sensations evoked by added inspiratory loads are currently thought to be largely mediated by the activity of the inspiratory muscles. Because of the differences in proprioceptors and in afferent and efferent innervations among the inspiratory muscles, we hypothesized that the sensation evoked by a given load would be different when the motor command is directed mainly to rib cage muscles or mainly to the diaphragm. To test this hypothesis, we studied six normal subjects breathing against several inspiratory resistances while emphasizing the use of rib cage muscles, or the diaphragm, or a combination of both. At the end of 10 loaded breaths the subjects rated the perceived magnitude of inspiratory effort on a Borg scale. A linear and unique relationship (r = 0.96 +/- 0.02; P less than 0.001) was found between the sensation and esophageal pressure (Pes) in the three thoracoabdominal breathing patterns. We conclude that the level of Pes, whether generated mainly by the rib cage muscles or the diaphragm, is the main variable related to the sensation of inspiratory effort under external inspiratory loads.

Control of segmental upper airway resistance in patients with obstructive sleep apnea

1993 ◽  
Vol 74 (6) ◽  
pp. 2694-2703 ◽  
Author(s):  
M. J. Wasicko ◽  
J. S. Erlichman ◽  
J. C. Leiter
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Upper Airway ◽  
Normal Subjects ◽  
Emg Activity ◽  
Electromyographic Activity ◽  
Resistive Load ◽  
Airway Collapse ◽  
Upper Airway Collapse ◽  
Obstructive Sleep

We sought to determine if the upper airway response to an added inspiratory resistive load (IRL) during wakefulness could be used to predict the site of upper airway collapse in patients with obstructive sleep apnea (OSA). In 10 awake patients with OSA, we investigated the relationship between resistance in three segments of the upper airway (nasal, nasopharyngeal, and oropharyngeal) and three muscles known to influence these segments (alae nasi, tensor veli palatini, and genioglossus) while the patient breathed with or without a small IRL (2 cmH2O.l–1.s). During IRL, patients with OSA exhibited increased nasopharyngeal resistance and no significant increase in either the genioglossus or tensor veli palatini activities. Neither nasal resistance nor alae nasi EMG activity was affected by IRL. We contrasted this to the response of five normal subjects, in whom we found no change in the resistance of either segment of the airway and no change in the genioglossus EMG but a significant activation of the tensor palatini. In six patients with OSA, we used the waking data to predict the site of upper airway collapse during sleep and we had limited success. The most successful index (correct in 4 of 6 patients) incorporated the greatest relative change in segmental resistance during IRL at the lowest electromyographic activity. We conclude, in patients with OSA, IRL narrows the more collapsible segment of the upper airway, in part due to inadequate activation of upper airway muscles. However, it is difficult to predict the site of upper airway collapse based on the waking measurements where upper airway muscle activity masks the passive airway characteristics.

Steady-state response of normal subjects to inspiratory resistive load

1986 ◽  
Vol 60 (5) ◽  
pp. 1471-1481 ◽  
Author(s):  
V. Im Hof ◽  
P. West ◽  
M. Younes
Keyword(s):  
Steady State ◽  
Normal Subjects ◽  
Driving Pressure ◽  
Resistive Load ◽  
Steady State Response ◽  
Occlusion Pressure ◽  
State Response ◽  
Inspiratory Resistance ◽  
Residual Capacity ◽  
Loaded Breathing

Tidal volume (VT) is usually preserved when conscious humans are made to breathe against an inspiratory resistance. To identify the neural changes responsible for VT compensation we calculated the respiratory driving pressure waveform during steady-state unloaded and loaded breathing (delta R = 8.5 cmH2O X 1(-1) X s) in eight conscious normal subjects. Driving pressure (DP) was calculated according to the method of Younes et al. (J. Appl. Physiol. 51: 963–989, 1981), which provides the equivalent of occlusion pressure at functional residual capacity throughout the breath. VT during resistance breathing was 108% of unloaded VT, as opposed to a predicted value of 82% of control in the absence of neural compensation. Compensation was accomplished through three changes in the DP waveform: 1) peak amplitude increased (+/- 23%), 2) the duration of the rising phase increased (+42%); and 3) the rising phase became more concave to the time axis. There were no changes in the relative decay rate of inspiratory pressure during expiration, in the shape of the declining phase of DP, or in end-expiratory lung volume.

Glutathione metabolic responses to loaded breathing: variation among respiratory muscles

1996 ◽  
Vol 81 (3) ◽  
pp. 1362-1369 ◽  
Author(s):  
G. Supinski ◽  
D. Nethery ◽  
N. Murhez ◽  
R. Ciufo ◽  
A. DiMarco
Keyword(s):  
Respiratory Muscles ◽  
Respiratory Arrest ◽  
Resistive Load ◽  
Control Groups ◽  
Rib Cage ◽  
Loaded Breathing ◽  
Glutathione Oxidation ◽  
Muscle Groups ◽  
And Control ◽  
Gssg Level

Several studies have shown that loaded breathing elicits an oxidation of reduced glutathione (GSH) to oxidized glutathione (GSSG) within the diaphragm, but the effects of loaded breathing on GSH and GSSG levels in other respiratory muscles have not been examined. The present experiment examined this issue by using decerebrate unanesthetized rats in which a large inspiratory resistive load was applied until respiratory arrest. Subsequently, muscle samples from the triangularis sterni, diaphragm (Dia), parasternal intercostal (PI), upper rib cage lateral intercostal, lower rib cage lateral intercostal, and soleus were assayed for GSH and GSSG. Glutathione levels were also measured on samples from unloaded control animals. We found that the Dia from loaded animals had a lower GSH level than did control animals (i.e., 653 +/- 99 and 928 +/- 40 nmol/gm for loaded and control groups, respectively; P < 0.05), higher GSSG level (68 +/- 14 and 32 &/- 7 nmol/gm for loaded and control groups, respectively; P < 0.05), and higher GSSG-to-GSH ratios (GSSG/GSH; 17.0 +/- 6.0 and 3.7 +/- 0.9% for loaded and control groups, respectively; (P <0.05). Of the other muscles examined, only the PI muscles had comparable alterations in glutathione levels in response to loading. Specifically, for the PI muscles of loaded and control groups, GSH was 427 +/- 75 and 618 +/- 40 nmol/g, (P < 0.05), GSSG was 71 +/- 16 and 20 +/- 5 nmol/g (P < 0.01), and GSSG/GSH was 22 +/- 8 and 3.6 +/- 1.2%, respectively (P < 0.05). No other muscle demonstrated a significant increase in GSSG or GSSG/GSH with loading, and only the lower rib cage lateral intercostal had a significant reduction in GSH. These findings indicate variation in the degree of glutathione oxidation elicited by inspiratory loading among the different respiratory muscles. The fact that quantitatively similar glutathione alterations were observed in the Dia and PI muscles suggests that these muscle groups may share a similar propensity to generate free radicals during inspiratory loading.

Oxygen cost of resistive-loaded breathing in quadriplegia

1992 ◽  
Vol 73 (3) ◽  
pp. 825-831 ◽  
Author(s):  
H. Manning ◽  
F. D. McCool ◽  
S. M. Scharf ◽  
E. Garshick ◽  
R. Brown
Keyword(s):  
Chest Wall ◽  
Energy Cost ◽  
Regression Line ◽  
Normal Subjects ◽  
Oxygen Cost ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Residual Capacity ◽  
Loaded Breathing ◽  
The Mean

We hypothesized that, in quadriplegia, chest wall distortion would increase the energy cost of ventilation. To assess this, we measured the oxygen cost of breathing (VO2 resp) and changes in chest wall configuration during inspiratory resistive-loaded breathing tasks in five quadriplegic and five normal subjects. Each subject performed three breathing tasks that spanned a range of work rates (Wtot). Configurational changes of the abdomen and upper, lower, and transverse rib cage were assessed with magnetometers. We found that 1) in both groups, VO2resp increased linearly with Wtot over the range of tasks performed, 2) the mean slope of the regression line of VO2resp vs. Wtot was greater for quadriplegic than for normal subjects (3.7 +/- 0.8 vs. 2.0 +/- 0.7 ml O2/J, P less than 0.01), 3) efficiency of breathing (Wtot/VO2resp) was less for quadriplegic than for normal subjects (1.9 +/- 0.6 vs. 3.5 +/- 1.4%, P less than 0.001), 4) during inhalation, upper and lower rib cages behaved similarly in the two groups, but the quadriplegic subjects had a decrease in transverse rib cage and a much greater increase in abdomen than normal subjects, and 5) functional residual capacity decreased in normal but not in quadriplegic subjects during the breathing tasks. We conclude that the lesser efficiency of breathing in quadriplegia may be related to the elastic work of chest wall distortion, shorter mean operational diaphragm length, and possibly differences between normal and quadriplegic subjects in mechanical advantage of available inspiratory muscles.

Collapsibility of the human upper airway during normal sleep

1989 ◽  
Vol 66 (4) ◽  
pp. 1800-1808 ◽  
Author(s):  
L. Wiegand ◽  
C. W. Zwillich ◽  
D. P. White
Keyword(s):  
Minute Ventilation ◽  
Upper Airway ◽  
Nrem Sleep ◽  
Normal Subjects ◽  
Load Application ◽  
Resistive Load ◽  
Airway Collapsibility ◽  
Upper Airway Collapsibility ◽  
Small Increments ◽  
Normal Men

Upper airway resistance (UAR) increases in normal subjects during the transition from wakefulness to sleep. To examine the influence of sleep on upper airway collapsibility, inspiratory UAR (epiglottis to nares) and genioglossus electromyogram (EMG) were measured in six healthy men before and during inspiratory resistive loading. UAR increased significantly (P less than 0.05) from wakefulness to non-rapid-eye-movement (NREM) sleep [3.1 +/- 0.4 to 11.7 +/- 3.5 (SE) cmH2O.1–1.s]. Resistive load application during wakefulness produced small increments in UAR. However, during NREM sleep, UAR increased dramatically with loading in four subjects although two subjects demonstrated little change. This increment in UAR from wakefulness to sleep correlated closely with the rise in UAR during loading while asleep (e.g., load 12: r = 0.90, P less than 0.05), indicating consistent upper airway behavior during sleep. On the other hand, no measurement of upper airway behavior during wakefulness was predictive of events during sleep. Although the influence of sleep on the EMG was difficult to assess, peak inspiratory genioglossus EMG clearly increased (P less than 0.05) after load application during NREM sleep. Finally, minute ventilation fell significantly from wakefulness values during NREM sleep, with the largest decrement in sleeping minute ventilation occurring in those subjects having the greatest awake-to-sleep increment in UAR (r = -0.88, P less than 0.05). We conclude that there is marked variability among normal men in upper airway collapsibility during sleep.

Effect of [Asu,]eel calcitonin on prolactin release in normal subjects and patients with prolactinoma

1985 ◽  
Vol 108 (3) ◽  
pp. 297-304 ◽  
Author(s):  
Hidesuke Kaji ◽  
Kazuo Chihara ◽  
Naoto Minamitani ◽  
Hitoshi Kodama ◽  
Tetsuya Kita ◽  
...  
Keyword(s):  
Body Weight ◽  
Bolus Injection ◽  
Normal Subjects ◽  
Regular Insulin ◽  
Prolactin Release ◽  
Saline Administration ◽  
The Central Nervous System ◽  
Plasma Prl ◽  
Male Subjects

Abstract. The effect of [Asu]eel calcitonin (ECT), an equipotent analogue of eel CT, on prolactin (Prl) secretion was examined in 12 healthy male subjects and in 6 patients with prolactinoma. In healthy subjects, ECT (0.5 μg/kg body weight · h) or saline was infused for 2 h and TRH was injected iv as a bolus of 500 μg at 1 h of ECT or saline administration. ECT did not affect basal Prl levels during 1 h of infusion. TRH caused a significant increase of plasma Prl with peak values of 75.2 ± 11.6 ng/ml in ECT-infused subjects, which did not differ from those infused with saline (68.5 ± 8.3 ng/ml). Next, an iv bolus injection of regular insulin (0.1 U/kg body weight) was followed by an infusion of ECT or saline alone. Plasma Prl peaks after hypoglycaemic stress were significantly lower in ECT-infused subjects than those in saline-injected controls (ECT, 16.5 ± 3.1 vs 33.5 ± 9.6 ng/ml, P < 0.05). In patients with prolactinoma, basal levels of plasma Prl ranging from 42.0–4130 ng/ml failed to change during iv infusion of ECT. Moreover, ECT (10−9–10−6m) did not affect Prl release from prolactinoma tissues perifused in vitro. These findings suggest that ECT may not act directly on the pituitary to modify Prl release. Rather, peripherally administered ECT appears to suppress Prl release via the central nervous system.

Oronasal partitioning of ventilation during exercise in humans

1991 ◽  
Vol 71 (2) ◽  
pp. 546-551 ◽  
Author(s):  
J. R. Wheatley ◽  
T. C. Amis ◽  
L. A. Engel
Keyword(s):  
Upper Airway ◽  
Normal Subjects ◽  
Face Mask ◽  
Inspiratory Flow ◽  
Mean Flow ◽  
Total Flow ◽  
Progressive Exercise ◽  
Expiratory Flow ◽  
Exercise In Humans

The partitioning of oronasal breathing was studied in five normal subjects during progressive exercise. Subjects performed three to five identical runs, each consisting of four 1-min work periods at increments of 50 W. Nasal and oral airflow were measured simultaneously using a partitioned face mask both during and for 4 min after exercise. Total mean flows were the sum of nasal and oral flows. At a total mean inspiratory flow of 2 l/s, the nasal fraction of total flow was 0.36 +/- 0.04 (SE) and decreased by 6 +/- 3% between total flows of 1.5 and 2.5 l/s. Throughout exercise, the nasal fraction of total mean inspiratory flow did not differ from that of total expiratory flow and was similar to that of total mean inspiratory flow during the postexercise period at a corresponding total mean flow (both P greater than 0.02). The results show that oronasal flow partitioning is not directly due to the exercise itself but is related to the level of ventilation and is uninfluenced by the direction of upper airway flow (i.e., inspiratory vs. expiratory). These findings suggest tightly controlled modulation of the relative resistances of the oral and/or nasal pathways.

scholarly journals Effect of Head Elevation on Passive Upper Airway Collapsibility in Normal Subjects during Propofol Anesthesia

2011 ◽  
Vol 115 (2) ◽  
pp. 273-281 ◽  
Author(s):  
Masato Kobayashi ◽  
Takao Ayuse ◽  
Yuko Hoshino ◽  
Shinji Kurata ◽  
Shunji Moromugi ◽  
...  
Keyword(s):  
Upper Airway ◽  
Normal Subjects ◽  
Target Concentration ◽  
Airway Patency ◽  
Head Elevation ◽  
Jaw Opening ◽  
Airway Collapsibility ◽  
Upper Airway Collapsibility ◽  
Head Flexion ◽  
Male Subjects

Background Head elevation can restore airway patency during anesthesia, although its effect may be offset by concomitant bite opening or accidental neck flexion. The aim of this study is to examine the effect of head elevation on the passive upper airway collapsibility during propofol anesthesia. Method Twenty male subjects were studied, randomized to one of two experimental groups: fixed-jaw or free-jaw. Propofol infusion was used for induction and to maintain blood at a constant target concentration between 1.5 and 2.0 μg/ml. Nasal mask pressure (PN) was intermittently reduced to evaluate the upper airway collapsibility (passive PCRIT) and upstream resistance (RUS) at each level of head elevation (0, 3, 6, and 9 cm). The authors measured the Frankfort plane (head flexion) and the mandible plane (jaw opening) angles at each level of head elevation. Analysis of variance was used to determine the effect of head elevation on PCRIT, head flexion, and jaw opening within each group. Results In both groups the Frankfort plane and mandible plane angles increased with head elevation (P &lt; 0.05), although the mandible plane angle was smaller in the free-jaw group (i.e., increased jaw opening). In the fixed-jaw group, head elevation decreased upper airway collapsibility (PCRIT ~ -7 cm H₂O at greater than 6 cm elevation) compared with the baseline position (PCRIT ~ -3 cm H₂O at 0 cm elevation; P &lt; 0.05). Conclusion : Elevating the head position by 6 cm while ensuring mouth closure (centric occlusion) produces substantial decreases in upper airway collapsibility and maintains upper airway patency during anesthesia.

Sign in / Sign up

Export Citation Format

Share Document