Superior laryngeal nerve blockade and inspiratory resistive load detection in normal subjects

1995 ◽  
Vol 79 (5) ◽  
pp. 1567-1570 ◽  
Author(s):  
M. F. Fitzpatrick ◽  
T. Zintel ◽  
M. Stockwell ◽  
J. Mink ◽  
C. G. Gallagher
Keyword(s):  
Superior Laryngeal Nerve ◽  
Normal Subjects ◽  
Laryngeal Nerve ◽  
Controlled Study ◽  
Resistive Load ◽  
Detection Thresholds ◽  
Nerve Blockade ◽  
Load Detection ◽  
Significant Difference ◽  
Resistive Loads

The site for detection of added inspiratory resistive loads is unknown, but recent evidence suggests that the airways may play an important role. The aim of this study was to discern whether the larynx has an important independent role in conscious detection of added inspiratory resistive loads. A randomized double-blind placebo-controlled study of the effect of superior laryngeal nerve blockade on inspiratory resistive load-detection threshold was carried out in 12 normal subjects (7 women; mean age 27.5 yr; range 18–45 yr). Baseline (preinjection) detection thresholds were similar on the lidocaine [0.58 +/- 0.16 (SE) cmH2O.l-1.s] and saline (0.53 +/- 0.12 cmH2O.l-1.s; P = 0.28) days. There was no significant difference in load-detection thresholds after injection between lidocaine (0.60 +/- 0.15 cmH2O.l-1.s) and saline (0.55 +/- 0.10 cmH2O.l-1.s; P = 0.68). Thus, the larynx does not appear to be an important independent airway site for conscious inspiratory resistive load detection.

scholarly journals Repeatability of the Evaluation of Perception of Dyspnea in Normal Subjects Assessed Through Inspiratory Resistive Loads

2014 ◽  
Vol 8 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Andréia K Fernandes ◽  
Bruna Ziegler ◽  
Glauco L Konzen ◽  
Paulo R.S Sanches ◽  
André F Müller ◽  
...  
Keyword(s):  
Normal Subjects ◽  
Cross Sectional Study ◽  
Resistive Load ◽  
Cross Sectional ◽  
Intra Class Correlation ◽  
Significant Difference ◽  
Loading System ◽  
Resistive Loads ◽  
The Brain ◽  
Intra Class Correlation Coefficient

Purpose: Study the repeatability of the evaluation of the perception of dyspnea using an inspiratory resistive loading system in healthy subjects. Methods: We designed a cross sectional study conducted in individuals aged 18 years and older. Perception of dyspnea was assessed using an inspiratory resistive load system. Dyspnea was assessed during ventilation at rest and at increasing resistive loads (0.6, 6.7, 15, 25, 46.7, 67, 78 and returning to 0.6 cm H2O/L/s). After breathing in at each level of resistive load for two minutes, the subject rated the dyspnea using the Borg scale. Subjects were tested twice (intervals from 2 to 7 days). Results: Testing included 16 Caucasian individuals (8 male and 8 female, mean age: 36 years). The median scores for dyspnea rating in the first test were 0 at resting ventilation and 0, 2, 3, 4, 5, 7, 7 and 1 point, respectively, with increasing loads. The median scores in the second test were 0 at resting and 0, 0, 2, 2, 3, 4, 4 and 0.5 points, respectively. The intra-class correlation coefficient was 0.57, 0.80, 0.74, 0.80, 0.83, 0.86, 0.91, and 0.92 for each resistive load, respectively. In a generalized linear model analysis, there was a statistically significant difference between the levels of resistive loads (p<0.001) and between tests (p=0.003). Dyspnea scores were significantly lower in the second test. Conclusion: The agreement between the two tests of the perception of dyspnea was only moderate and dyspnea scores were lower in the second test. These findings suggest a learning effect or an effect that could be at least partly attributed to desensitization of dyspnea sensation in the brain.

Mechanism of detection of resistive loads in conscious humans

1992 ◽  
Vol 72 (6) ◽  
pp. 2267-2270 ◽  
Author(s):  
A. Puddy ◽  
G. Giesbrecht ◽  
R. Sanii ◽  
M. Younes
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Primary Source ◽  
Intrathoracic Pressure ◽  
Normal Subjects ◽  
Resistive Load ◽  
Load Detection ◽  
Elastic Load ◽  
Resistive Loads ◽  
Source Of Information

Conscious humans easily detect loads applied to the respiratory system. Resistive loads as small as 0.5 cmH2O.l-1.s can be detected. Previous work suggested that afferent information from the chest wall served as the primary source of information for load detection, but the evidence for this was not convincing, and we recently reported that the chest wall was a relatively poor detector for applied elastic loads. Using the same setup of a loading device and body cast, we sought resistive load detection thresholds under three conditions: 1) loading of the total respiratory system, 2) loading such that the chest wall was protected from the load but airway and intrathoracic pressures experienced negative pressure in proportion to inspiratory flow, and 3) loading of the chest wall alone with no alteration of airway or intrathoracic pressure. The threshold for detection for the three types of load application in seven normal subjects was 1.17 +/- 0.33, 1.68 +/- 0.45, and 6.3 +/- 1.38 (SE) cmH2O.l-1.s for total respiratory system, chest wall protected, and chest wall alone, respectively. We conclude that the active chest wall is a less potent source of information for detection of applied resistive loads than structures affected by negative airway and intrathoracic pressure, a finding similar to that previously reported for elastic load detection.

Resistive Load Detection during Passive Ventilation

1980 ◽  
Vol 59 (6) ◽  
pp. 493-495 ◽  
Author(s):  
K. J. Killian ◽  
C. K. Mahutte ◽  
E. J. M. Campbell
Keyword(s):  
Muscle Contraction ◽  
Spontaneous Breathing ◽  
Respiratory Muscle ◽  
Essential Role ◽  
Normal Subjects ◽  
Assisted Ventilation ◽  
Resistive Load ◽  
Load Detection ◽  
Resistive Loads

1. By using standard psychophysical techniques resistive load detection was estimated in five normal subjects during spontaneous breathing and during passive ventilation in a Drinker respirator. 2. During assisted ventilation a gross deterioration in resistive load detection occurred. 3. The findings imply that active respiratory muscle contraction plays an essential role in the detection of added resistive loads.

A Signal Detection Theory Analysis of the Effect of Chest Cage Restriction upon the Detection of Inspiratory Resistive Loads

1983 ◽  
Vol 64 (4) ◽  
pp. 417-421
Author(s):  
P. G. Narbed ◽  
D. Marcer ◽  
J. B. L. Howell ◽  
E. Spencer
Keyword(s):  
Signal Detection ◽  
Signal Detection Theory ◽  
Normal Subjects ◽  
Detection Theory ◽  
Detection Sensitivity ◽  
Resistive Load ◽  
Load Detection ◽  
Resistive Loads ◽  
Willingness To Report ◽  
And Control

1. By the use of Signal Detection Theory techniques, resistive load detection sensitivity was estimated in six normal subjects, and compared with detection when the chest cage was strapped in the position of full expiration. 2. With chest cage restriction there was both a decrease in detection sensitivity and an increase in the willingness to report the presence of an added load to breathing. 3. This suggests that the similarity of detection in chest clamping and control previously reported was due partly to increased detection bias with chest clamping. 4. These results have implications concerning the dependence of detection on afferent information from the chest wall.

Inspiratory resistive load detection in conscious dogs

1991 ◽  
Vol 70 (3) ◽  
pp. 1284-1289 ◽  
Author(s):  
P. W. Davenport ◽  
D. J. Dalziel ◽  
B. Webb ◽  
J. R. Bellah ◽  
C. J. Vierck
Keyword(s):  
Training Stimulus ◽  
Detection Threshold ◽  
Resistive Load ◽  
Initial Training ◽  
Breathing Patterns ◽  
Physiological Mechanisms ◽  
Mechanical Loads ◽  
Load Detection ◽  
Resistive Loads ◽  
Tracheal Stoma

The physiological mechanisms mediating the detection of mechanical loads are unknown. This is, in part, due to the lack of an animal model of load detection that could be used to investigate specific sensory systems. We used American Foxhounds with tracheal stomata to behaviorally condition the detection of inspiratory occlusion and graded resistive loads. The resistive loads were presented with a loading manifold connected to the inspiratory port of a non-rebreathing valve. The dogs signaled detection of the load by lifting their front paw off a lever. Inspiratory occlusion was used as the initial training stimulus, and the dogs could reliably respond within the first or second inspiratory effort to 100% of the occlusion presentations after 13 trials. Graded resistances that spanned the 50% detection threshold were then presented. The detection threshold resistances (delta R50) were 0.96 and 1.70 cmH2O.l-1.s. Ratios of delta R50 to background resistance were 0.15 and 0.30. The near-threshold resistive loads did not significantly change expired PCO2 or breathing patterns. These results demonstrate that dogs can be conditioned to reliably and specifically signal the detection of graded inspiratory mechanical loads. Inspiration through the tracheal stoma excludes afferents in the upper extrathoracic trachea, larynx, pharynx, nasal passages, and mouth from mediating load detection in these dogs. It is unknown which remaining afferents (vagal or respiratory muscle) are responsible for load detection.

Effect of ventilatory drive on the perceived magnitude of added loads to breathing

1982 ◽  
Vol 53 (4) ◽  
pp. 901-907 ◽  
Author(s):  
J. G. Burdon ◽  
K. J. Killian ◽  
E. J. Campbell
Keyword(s):  
Power Function ◽  
Muscle Force ◽  
Peak Inspiratory Pressure ◽  
Normal Subjects ◽  
Inspiratory Pressure ◽  
Resistive Load ◽  
Sensory Magnitude ◽  
Magnitude Scaling ◽  
Ventilatory Drive ◽  
Resistive Loads

Using open-magnitude scaling we studied the importance of ventilatory drive on the perceived magnitude of respiratory loads by applying a range of externally added resistances (2.1–77.1 cmH2O X l-1 X s) to normal subjects at rest and at three increasing levels of ventilatory drive induced by exercise, CO2-stimulated breathing, and hypoxia. Under all conditions studied the perceived magnitude of the added loads increased with the magnitude of the resistive load and as the underlying level of ventilatory drive increased. When the results were expressed in terms of peak inspiratory pressure, the perceived magnitude was related to the magnitude of the peak inspiratory pressure by a power function (mean r = 0.97). These results suggest that the perceived magnitude of added resistive loads increased with increasing ventilatory drive, in such a manner that the increase in sensory magnitude is proportional to the increase in the inspiratory muscle force developed and suggests that something dependent on this force mediates the sensation.

Effect of ethanol and naloxone on control of ventilation and load perception

1983 ◽  
Vol 55 (3) ◽  
pp. 929-934 ◽  
Author(s):  
T. M. Michiels ◽  
R. W. Light ◽  
C. K. Mahutte
Keyword(s):  
Normal Subjects ◽  
Ethanol Ingestion ◽  
Resistive Load ◽  
Load Compensation ◽  
Ventilatory Responses ◽  
Resistive Loading ◽  
Resistive Loads ◽  
Mouth Occlusion Pressure ◽  
Load Perception ◽  
Respiratory Depressant

The respiratory depressant effects of ethanol and their potential reversibility by naloxone were studied in 10 normal subjects. Ventilatory and mouth occlusion pressure (P0.1) responses to hypercapnia and hypoxia without and with an inspiratory resistive load (13 cmH2O X 1(-1) X S) were measured. The resistive load detected with 50% probability (delta R50) and the exponent (n) in Stevens' psychophysical law for magnitude estimation of resistive loads were studied using standard psychophysical techniques. Each of these studies was performed before ethanol ingestion, after ethanol ingestion (1.5 ml/kg, by mouth), and then again after naloxone (0.8 mg iv). Ethanol increased delta R50 (P less than 0.05) and decreased n (P less than 0.05). Naloxone caused no further change in these parameters. The load compensation (Lc), defined as the ratio of loaded to unloaded response slopes, was not significantly changed after ethanol and naloxone. No correlation was found between the Lc and delta R50 or n. The ventilatory and P0.1 responses to hypercapnia and hypoxia with and without inspiratory resistive loading decreased after ethanol (P less than 0.05, hypercapnia; NS, hypoxia). After naloxone the hypercapnic ventilatory responses increased (P less than 0.05). This suggests that the respiratory depressant effects of ethanol may be mediated via endorphins.

An anatomical study of the myelination of human laryngeal nerves

2011 ◽  
Vol 125 (12) ◽  
pp. 1263-1267 ◽  
Author(s):  
J C Fleming ◽  
N Gibbins ◽  
P J Ingram ◽  
M Harries
Keyword(s):  
Recurrent Laryngeal Nerve ◽  
Cross Sections ◽  
Recovery Of Function ◽  
Superior Laryngeal Nerve ◽  
Anatomical Study ◽  
Laryngeal Nerve ◽  
Clinical Consequence ◽  
Laryngeal Nerves ◽  
Significant Difference ◽  
Myelinated Fibres

AbstractObjective:To determine the differences in myelination between the human recurrent laryngeal nerve and superior laryngeal nerve.Methods:Fifteen confirmed laryngeal nerve specimens were harvested from five cadavers. Cross-sections were examined under a photomicroscope and morphometric analysis performed.Results:There was a significantly greater number of myelinated fibres than unmyelinated fibres, in both the recurrent laryngeal nerve (p = 0.018) and the superior laryngeal nerve (p = 0.012). There was a significantly greater number of myelinated fibres in the superior laryngeal nerve, compared with the recurrent laryngeal nerve (p = 0.028). However, there was no significant difference in the number of unmyelinated fibres, comparing the two nerves (p = 0.116).Conclusion:These findings support those of previous studies, and provide further evidence against the historical plexus theory of laryngeal nerve morphology. The differences in the degree of myelination, both within and between the human laryngeal nerves, may have clinical consequence regarding recovery of function following nerve injury.

Fatigue-induced alterations in Ca2+ and caffeine sensitivities of skinned muscle fibers

1993 ◽  
Vol 75 (2) ◽  
pp. 586-593 ◽  
Author(s):  
J. H. Williams ◽  
C. W. Ward ◽  
G. A. Klug
Keyword(s):  
Citric Acid ◽  
Nerve Block ◽  
Superior Laryngeal Nerve ◽  
Laryngeal Nerve ◽  
Rank Test ◽  
Cough Reflex ◽  
Skinned Muscle ◽  
Signed Rank ◽  
Significant Difference ◽  
Signed Rank Test

The relative importance of laryngeal afferents in the cough reflex in humans is unknown. This study was designed to investigate the importance of superior laryngeal nerve afferents in the cough reflex induced by inhaled nebulized citric acid in awake humans. Nine healthy volunteers had their cough thresholds to inhaled nebulized citric acid measured after superior laryngeal nerve conduction blockade and after a sham nerve block. Of the nine subjects, four showed no change in cough threshold after superior laryngeal nerve anesthesia, three showed increased cough threshold after nerve block compared with no block, and two showed decreased cough threshold after nerve block. The geometric means of the cough thresholds for the nerve block vs. sham block tests were 16 +/- 13 (SD) and 15 +/- 8% citric acid, respectively. There was no statistically significant difference (Wilcoxon signed-rank test) between the cough thresholds with and without superior laryngeal nerve block (P > 0.05). We conclude that, in the awake human, superior laryngeal nerve afferents do not play a necessary role in initiation of citric acid-induced cough.

scholarly journals Assessment of tear secretion and tear film instability in cases with pterygium and normal subjects

2013 ◽  
Vol 5 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Narayani Roka ◽  
SP Shrestha
Keyword(s):  
Dry Eye ◽  
Tear Film ◽  
Strong Relationship ◽  
Normal Subjects ◽  
Controlled Study ◽  
Control Group ◽  
P Value ◽  
Tear Secretion ◽  
Schirmer’S Test ◽  
Significant Difference

Introduction: Dry eye is a common disorder affecting a significant percentage of the population. Materials and methods: This study is a prospective, hospital-based, case-controlled study conducted between January 2009 and May 2010. Seventy-six pterygium cases and 152 age-and- sex matched controls presenting to the OPD of Manipal Teaching Hospital were included. The TBUT Schirmer’s test and basal tear secretion were estimated in all patients. A TBUT of less than 10 seconds and a Schirmer’s test of less than 10 mm were considered abnormal. Results: Pterygium was bilateral in 15 (19.7 % ) and unilateral in 61 (80.3 %) patients. Ninety-two (92.1 %) pterygium patients reported either one or more of the six dry eye symptoms. Redness was the most common (67 %) symptom reported. The mean Schirmer’s test I, mean basal secretion and mean TBUT values were 16.19 mm, 10.01 mm and 10.56 seconds in pterygium cases and 20.22 mm,13.25 mm and 26.25 seconds in the control group respectively. There was a statistically significant difference in the dry eye results between the pterygium cases and the control group (p value < 0.05). The odds ratio between pterygium and dry eye was 3.28. Dry eye was present in 26 % of the normal patients and in 54 % of the pterygium cases. Conclusion: There is a strong relationship between dry eye and pterygium. Nepal J Ophthalmol 2013; 5(9):16-23 DOI: http://dx.doi.org/10.3126/nepjoph.v5i1.7816

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