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Effects of aging on sensation of respiratory force and displacement.

The psychophysical technique of magnitude production was used to evaluate the sensation of inspiratory force and inspired volume in young and older subjects. Inspiratory force was generated during a static inspiratory maneuver against a closed airway. The exponent of the power function relationship between airway pressure and sensation intensity during force scaling was not significantly different between young and older subjects. In contrast, the exponents for the magnitude production of inspired volume were significantly greater in the older compared with the young group. We also assessed the effects of age on the relative importance of force and displacement signals on the sensation of inspired volume. Subjects attempted to reproduce a control tidal volume while breathing against a series of inspiratory resistive and elastic loads. In both groups error in tidal volume reproduction increased progressively as the severity of the load increased. During moderate and severe loading the error in the older subjects was significantly greater than in the young group. Correspondingly, the peak inspiratory airway pressures at tidal volume reproduction against these loads were significantly smaller in the older compared with the young subjects. The results suggest that in older subjects cues related to respiratory muscle force are more important than volume in the sensation of lung volume changes. In young subjects the sensation of lung volume changes is based to a greater degree on signals of volume or displacement.

Adult↗

Effects of bronchoconstriction and external resistive loading on the sensation of dyspnea.

To determine whether the intensity of dyspnea at a given level of respiratory motor output differs between bronchoconstriction and the presence of an external resistance, we compared the sensation of difficulty in breathing during isocapnic voluntary hyperventilation in six normal subjects. An external resistance of 1.9 cmH2O.1-1.s was applied during both inspiration and expiration. To induce bronchoconstriction, histamine aerosol (5 mg/ml) was inhaled until airway resistance (Raw) increased to a level approximately equal to the subject's control Raw plus the added external resistance. To clarify the role of vagal afferents on the genesis of dyspnea during both forms of obstruction to airflow, the effect of airway anesthesia by lidocaine aerosol inhalation was also examined after histamine and during external resistive loading. The sensation of difficulty in breathing was rated at 30-s intervals on a visual analog scale during isocapnic voluntary hyperpnea, in which the subjects were asked to copy an oscilloscope volume trace obtained previously during progressive hypercapnia. Histamine inhalation significantly increased the intensity of the dyspneic sensation over the equivalent external resistive load at the same levels of ventilation and occlusion pressure during voluntary hyperpnea. Inhaled lidocaine decreased the sensation of dyspnea during bronchoconstriction with no change in Raw, but it did not significantly change the sensation during external resistive loading. These results suggest that afferent vagal activity plays a role in the genesis of dyspnea during bronchoconstriction.

Adult↗

Distinguishable sensations of breathlessness induced in normal volunteers.

Various theories about the genesis of dyspnea have often assumed that the sensation is similar from patient to patient and is generated by a single underlying mechanism. To investigate whether breathlessness induced in normal volunteers by different stimuli represents one or more than one sensation, we studied 30 subjects in whom breathlessness was induced by each of 8 different stimuli: breath-holding, CO2 inhalation, inhalation of CO2, with ventilation voluntarily targeted below the level dictated by chemical drive, breathing with a resistive load, breathing with an elastic load, voluntary elevation of functional residual capacity, voluntary limitation of tidal volume, and exercise. For each stimulus, subjects were asked to choose description of their sensation(s) of breathlessness from a questionnaire listing 19 descriptors. The responses from this questionnaire were evaluated using cluster analysis to search for relationships among descriptors and to identify natural groupings. We found that distinct groups of descriptors emerged, i.e., subjects could distinguish different sensations of breathlessness. In addition, we found an association between certain descriptor groups and stimuli. We conclude that the term breathlessness may encompass multiple sensations, and, therefore, may not be explainable by a single physiologic mechanism.

Adult↗

Prostaglandin E2 inhalation increases the sensation of dyspnea during exercise.

To clarify the role of vagal afferents from the lung in the sensation of dyspnea, we examined the effects of prostaglandin E2 (PGE2) inhalation on the sensation of dyspnea during exercise in eight normal male subjects. This intervention was chosen because inhaled PGE2 is known to stimulate vagal afferent receptors in the lung, in particular C-fiber endings, without a significant increase in airway resistance. After either physiologic saline or PGE2 aerosol (100 micrograms/ml) inhalation through a Bird nebulizer for 2 min, exercise tests were performed on a bicycle ergometer. The tests consisted of 3 min at rest followed by graded work loads (zero to 150 watts, 50-watt increments). Minute ventilation (VE) and respiratory rate were monitored from an expiratory line through a face mask. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were calculated from samples of mixed expired gas. The sensation of difficulty in breathing (dyspnea) was measured on a modified Borg scale at rest and at the end of each work load. We found that although airway resistance and lung volume did not change significantly between saline and PGE2 inhalations, inhaled PGE2 significantly increased the magnitude of the dyspneic sensation when compared with inhaled saline at the same levels of work load, ventilation, and oxygen consumption. These results suggest that in addition to probable roles of motor command and chemical drive, afferent vagal activity from the lung also contributes to the sensation of dyspnea during exercise.

Adult↗

The sensation of respiratory muscle force.

The sensation of respiratory muscle force was examined in 8 normal subjects using the direct scaling method of magnitude production. At the end of a normal expiration, at functional residual capacity (FRC), subjects generated an inspiratory effort against a closed airway to produce a force that correspond to specific numerical values for sensation magnitude. Thereafter, at lung volumes of 2 L above FRC and 1 L below FRC, subjects attempted to reproduce the same force as that previously generated at FRC. Diaphragm electromyographic activity, recorded with an esophageal electrode, was used as a measure of central respiratory motor output. The difference between the mouth pressure during relaxation against a closed shutter and the peak airway pressure during the static inspiratory maneuver (Pmus) was employed as an index of muscle tension. The exponent for the magnitude production of force during maneuvers at FRC, i.e., the slope of the line relating log airway pressure and log sensation magnitude was 1.60 +/- SE 0.15. The exponent for force scaling was 1.47 +/- SE 0.17 after correcting for differences in inspiratory duration during maneuvers of different force. During inspiratory maneuvers at FRC plus 2 L, diaphragm EMG was 441 +/- SE 70%, but Pmus was 111 +/- SE 11% of the respective values during subjectively equal efforts at FRC. During inspiratory maneuvers at FRC minus 1 L, diaphragm EMG was 54 +/- SE 5%, but Pmus was 94 +/- SE 4% of the respective values during efforts at FRC perceived to be of equal force. These results suggest that the sensation of respiratory muscle force depends primarily on signals related to the tension generated by the contracting muscles rather than on the sensation of innervation associated with the central nervous system motor command.

Adult↗

Different sensations from cones with the same photopigment.

We used adaptive optics to study color fluctuation in the appearance of tiny flashes of light. For five subjects, near threshold, monochromatic stimuli with full widths at half maximum of 1/3 arcmin were delivered throughout a patch of retina near 1 deg in which we also determined the locations of L, M, and S cones. Subjects reported a wide variety of color sensations, even for long-wavelength stimuli, and all subjects reported blue or purple sensations at wavelengths for which S cones are insensitive. Subjects with more L cones reported more red sensations, and those with more M cones tended to report more green sensations. White responses increased linearly with the asymmetry in L to M cone ratio. The diversity in the color response could not be completely explained by combined L and M cone excitation, implying that photoreceptors within the same class can elicit more than one color sensation.

Color Perception↗

Perceived message sensation value (PMSV) and the dimensions and validation of a PMSV scale.

Sensation seeking has been linked to drug abuse and risky behaviors, and is positively associated with preferences for messages high in sensation value (i.e., perceived to be highly novel, arousing, dramatic, or intense). This suggests the utility of valid and reliable measures of perceived message sensation value (PMSV) in research on information processing, persuasion, and reducing risk-related behaviors. Dimensions and construct validity of a 17-item PMSV scale were examined via 2 studies: 1 of 368 high school students' reactions to televised antimarijuana public service announcements (PSAs) and one of 444 college students' responses to televised anticocaine PSAs. Exploratory and confirmatory factor analyses indicated 3-dimensional solutions for the PMSV scale were nearly identical for high sensation seeking (HSS) and low sensation seeking (LSS) respondents in Study 1 and HSS respondents in Study 2. Total scale alphas were .87 for Study 1 and .93 for Study 2. The PMSV scale and its dimensions (Emotional Arousal, Dramatic Impact, Novelty) were positively correlated with affective response measures in both studies for HSS and LSS. Study 1 also examined cognitive, narrative, and sensory PSA processing, which were found to be positively associated with total PMSV and the Arousal and Dramatic Impact dimensions of PSMV for both HSS and LSS.

Adolescent↗

Intraoral sensation in patients with brainstem lesions: role of the rostral spinal trigeminal nuclei in pons.

Two patients with caudal pontine lesions had diminished intraoral sensation for all modalities sparing facial sensation. A third patient with lateral medullary infarction developed diminished facial pain and temperature sensation sparing intraoral structures. This segregation of intraoral sensation within the brainstem is consistent with animal studies which show that the rostral spinal trigeminal nuclei in the caudal half of the pons play an important role in intraoral and dental sensation.

Adult↗

The effects of preceded fatiguing on the relations between monopolar surface electromyogram and fatigue sensation.

Relations between surface electromyogram (EMG) and fatigue sensation was compared between the first fatiguing contraction and the following contractions with insufficient rests. Six male subjects performed static contractions of the elbow flexors at 8 and 13% MVC with the forearm semipronated and at 13% MVC with the forearm supinated. Contractions were repeated 6 (13% MVC) or (8% MVC) times (C1, C2, C3, C4, C5, C6) with rests of 5 min (13% MVC) or 10 min (8% MVC). During the contractions the subjects reported values of rated fatigue sensation (VRFS) whose scale was from 0.0 (no fatigue sensation) to 4.0 (apparent pain and moderate severity) at every 30 sec. C1 ended between 3.5 and 4.0 of VRFS or at 18 min (13% MVC) or 20 min (8% MVC) of contracting time. C2-C5 ended when fatigue sensation became that at the end of C1 or 5 min had passed. Bipolar and monopolar surface EMG was recorded from 6 synergists of elbow flexors. Mean amplitude (AEMG) and relative power below 22Hz (RPWL20) were calculated. Though AEMGs were positively correlated with VRFSs in C1, the correlations were often obscure in C2-C6. Most AEMGs at the same VRFS were larger in C2-C6 than in C1. AEMGs at the start of C2-C6 were sometimes larger than those at the end of C1. RPWL20s of monopolar EMG positively correlated with VRFSs. The RPWL20 correlations were often reserved in all contractions. The increases of AEMGs in C2-C6 at the same VRFS cannot be explained by the migration of the activities among synergists, since the increases in AEMGs were seen in most synergists simultaneously. The compensation of the failure of muscle contractibility were not the only cause of the increases in the AEMGs during fatiguing contractions. The compression of EMG spectrum towards lower frequencies was usable to estimate the change of fatigue sensation.

Adult↗

Motion sickness history, food neophobia, and sensation seeking.

Motion sickness is believed to be caused by conflicting sensory signals, a situation that mimics the effects of ingesting certain toxins. Thus, one might suspect that individuals who have experienced a relatively high frequency of motion sickness may be particularly vigilant about avoiding anything that produces nausea, induding potentially nauseating toxins. Consequently, they may be more resistant to trying new foods, i.e., be more food neophobic, since unfamiliar foods can have unexpected adverse effects due to toxins or allergens. Likewise, many highly stimulating experiences can trigger motion sickness, so individuals who are more susceptible may be more prone to avoid such experiences, i.e., be less sensation seeking. Finally, it was expected that food neophobia would be more frequent in individuals low on sensation seeking tendencies. Self-reported motion sickness history in 308 adults (M= 18.8 yr.; SD = 1.6) was correlated with scores on the Arnett Inventory of Sensation Seeking and the Food Neophobia Scale. As predicted, greater history of motion sickness was associated with lower Sensation Seeking scores. Food Neophobia was not correlated with motion sickness history but, as expected, was negatively correlated (r = -.42) with scores on Sensation Seeking. Further research is recommended that measures actual sensitivity to motion sickness.

Adolescent↗

An exploratory study of the relationship between type A and sensation-seeking behavior.

The focus of the study was the relationship between Type A behavior and sensation-seeking behavior for individuals who had had a first myocardial infarction. Impulsivity, time compulsion, and sensation-seeking behavior were assumed to be risk taking. From 50 subjects with documented first myocardial infarctions were obtained scores on Type A behavior and sensation seeking. Pearson correlations were nonsignificant. Analysis of variance of Type A behavior scores for men aged 38 to 49 yr., 50 to 57 yr., and 58 to 69 yr. showed no significant effects. The group aged 38 to 49 yr. had the highest mean Type A score but these were not extreme. Subjects scored low to moderate on sensation seeking. Being a low sensation seeker apparently had more impact than Type A behavior.

Adult↗

The effects of camphor, eucalyptus and menthol vapour on nasal resistance to airflow and nasal sensation.

The effects of five minutes exposure to camphor, eucalyptus or menthol vapour on nasal resistance to airflow and nasal sensation of airflow were compared with the effects of exercise on the nose. Inhalation of camphor, eucalyptus or menthol had no effect on nasal resistance to airflow but the majority of subjects reported a cold sensation in the nose with the sensation of improved airflow. Exercise caused a decrease in nasal resistance but did not induce any nasal sensation of cold or improved airflow. The results indicate that camphor, eucalyptus and menthol stimulate cold receptors in the nose. The clinical significance of nasal sensation of airflow is discussed.

Adult↗

Recovery of sensation in free flaps.

A clinical study of touch, pain, warm and cold stimuli and two-point discrimination was performed in 27 free flaps four months to four years after the microsurgical procedure. There were 5 free skin flaps (2 with nerve suture), 15 musculocutaneous, 4 muscle-covered with split skin grafts and 3 osteomusculocutaneous flaps transplanted to various sites on the body. The results show full or nearly full recovery of touch and pain sensation in all free skin flaps. The musculocutaneous and osteomusculocutaneous free flaps developed good sensation if firmly grown onto the healthy recipient skin with normal sensation. Muscle flaps covered with split skin grafts and all flaps surrounded by scar tissue had a clinical absence of sensation. This study and our earlier findings of the regeneration of nerves in free skin grafts, in skin flaps and in experimental free flaps, lead us to suggest that the healthy denervated skin of the free flap provides a strong neurotrophic stimulus to the cut cutaneous nerves in the edges of the recipient skin. Cutaneous nerves freely regenerate in the loose subcutaneous tissue of the flap. We therefore conclude that all free flaps with skin islands have a potential for developing sufficient protective touch and pain sensation and even some superficial sensitivity.

Adolescent↗

[Effect of Impletol injection into paratonsillar tissue on abnormal sensation in the throat].

If the abnormal sensation, such as a lump or choking, in the throat was mainly caused by inflammatory changes in the palatine tonsils or their surrounding tissues and conveyed via vagal nerve branches distributing there, the sensation might be reduced by topically injected Impletol (Procaine and caffeine in saline solution), i.e. Impletol test for focal tonsillitis. One hundred patients with abnormal sensation in the throat were injected Impletol (Impletol group), 50 patients were injected saline solution alone (Saline group) and 50 patients had injection needle simply inserted into the peritonsillar tissues (Needle group). The Impletol group showed the best result and was followed by Saline group and then Needle group. Namely, the degree of sensation reduced by 80% or more in 38% of the Impletol group and by 50% or more in 62% of them. Those rates were 26% and 60% for Saline group and 28% and 52% for Needle group, respectively. Though the results were indicative of the effectiveness of the Impletol injection for the abnormal sensation in the throat, the difference among these three groups was not statistically significant.

Adult↗

[Relationship between nasal airflow sensation and nasal patency].

The relationship between nasal airflow sensation and nasal patency was evaluated by means of visual analogue test and anterior rhinomanometry. It was demonstrated that there is no significant correlation between the subjective sensation of nasal airflow and objective assessment of nasal airflow resistance. The site responsible for sensing airflow is located in the nasal vestibule. The volatile agents used in traditional Chinese medicine for nasal obstruction, such as camphor and menthol, could only improve the nasal sensation of airflow without alteration of nasal airway resistance. Our results suggested that the nasal sensation of airflow could not reflect real patency completely. Therefore, assessment of subjective sensation of airflow and measurement of nasal airway resistance combined must be used in the diagnosis and treatment of nasally obstructed patients.

Adult↗

[Effect of hypoxia on the sensation of dyspnea during hypercapnic ventilatory response in normal subjects].

We examined, in 32 normal adults, the effect of hypoxia on the sensation of dyspnea during hypercapnic ventilatory response (HCVR). The tests were conducted under two different levels of inspiratory O2 content, either hyperoxia (PETO2 greater than 150 Torr) or hypoxia (PETO2 50-55 Torr), with simultaneous assessment of dyspnea sensation by visual analogue scaling (VAS). The sensation was evaluated either in relation to VE standardized by predicted MVV (the slope of VAS-VE regression line or VAS at VE 40%) or in relation to PETCO2 (the slope of VAS-PETCO2 line or VAS at PETCO2 55 Torr). Concomitant hypoxia significantly enhanced both the mean value of delta VE/delta PETCO2 and that of delta P0.1/delta PETCO2. The sensation of dyspnea did not differ between the two conditions when it was evaluated in relation to ventilation, whereas it was markedly greater during hypoxic HCVR when it was evaluated in relation to PETCO2. The hypoxic augmentation of the sensation, compared at PETCO2 55 Torr, could be explained by increase of the motor output from the respiratory center, since it was positively correlated with the relative change of VE, VTTI, and delta P0.1/delta PETCO2 (r = 0.70, p less than 0.0001; r = 0.63, p less than 0.0001; r = 0.40, p less than 0.05, respectively). From these findings, we conclude that hypoxia does not have a direct dyspnogenic effect, at least in normal subjects.

Adult↗

Falling sensation in patients who undergo the Epley maneuver: a retrospective study.

The author conducted a retrospective study to determine the prevalence of a falling sensation in patients who underwent the Epley canalith repositioning maneuver for the treatment of benign paroxysmal positional vertigo. The author studied a total of 436 maneuvers performed on 412 patients and observed 58 episodes (13%) of a strong falling sensation, some very severe. In almost every case, the sensation occurred when the patient was moved to the final (sitting) position; in 1 case, the sensation occurred nearly 30 minutes later. The author recommends that physicians who perform the Epley maneuver warn patients of the risk of a falling sensation, take steps to prevent its consequences, and monitor their patients for at least 30 minutes after the completion of the procedure.

Adolescent↗

[In vivo confocal microscopy observation and evaluation of sensation in diabetic corneas].

OBJECTIVE: To test the changes of corneal sensation in diabetic patients and to observe the diabetic corneas using confocal microscopy. METHODS: One hundred and thirty-two diabetic patients were enrolled in this study. The diabetic history and medication were recorded. The FBG and HbA(1c) were checked for every patient. The patient's eye was systemically checked, including the IOP, visual acuity, cornea sensation, lenses, and the fundus. Two hundred patients of other diseases were enrolled as controls. The cornea of 85 patients and 56 controls were checked by the confocal microscopy. The right eyes of both patients and controls were used for analysis. RESULTS: The cornea sensation of diabetic patients was significantly depressed as compared to that of the controls (P < 0.01). The depression of cornea sensation was related to the course of the disease, the presence of diabetic retinopathy and the degree of the diabetic retinopathy (P < 0.05). The confocal microscopy revealed that there was a higher corneal epithelium edema rate (11.76%) in diabetic patients than that of the controls (1.79%) (P < 0.05). The nerve fiber density of the diabetic patients was decreased and there were some morphological changes in the nerve fiber of diabetic patients, such as sparse, slim, less branches, less long fibers, edema and zigzag of the fibers. CONCLUSION: The depression of the corneal sensation in diabetic patients is probably caused by the reduction and the degeneration of the corneal nerve fibers.

Adolescent↗