BackgroundIn our effort to increase the value and academic standing of teaching, we implemented a... more BackgroundIn our effort to increase the value and academic standing of teaching, we implemented an initiative focused on scholarship in teaching. Our program was narrowly focused, project-based, peer-reviewed, resource-neutral, and open to all faculty. Faculty members are invited annually to submit a description of their educational projects in keeping with Glassick’s criteria. Our purpose was to assess the effects of this award program.MethodWe reviewed the distribution of applications over a 3-year period and determined the academic departments, academic rank of applicants, and focus of projects. A questionnaire assessed applicants’ perceptions of the value of participation, its contribution to promotion and advancement, and its role in subsequent dissemination activities.ResultsSlightly fewer than half (60 of 124, 48%) of the applications submitted during 2016 through 2018 were judged by peer review to meet Glassick’s criteria for scholarship and received the award. Most applicants were junior faculty, and most applications were from the department of medicine though all departments who taught students in core clinical rotations were represented during the years studied. The projects that were awarded were more likely to be disseminated when compared with those who were not awarded.Lessons LearnedOur scholarship in teaching program seemingly advanced educational scholarship among teaching faculty and provided a way of recognizing projects that advanced educational initiatives. Further efforts are required to promote support from departmental leadership, to enhance faculty participation, and to encourage success through mentoring and assistance in project preparation.
Psychophysical studies of the sensations associated with the act of breathing have suggested that... more Psychophysical studies of the sensations associated with the act of breathing have suggested that dyspnea is a function of the sense of the effort of breathing and is based on the magnitude of the centrally generated respiratory motor command signal (El-Manshawi et al., 1986). It is attractive to consider such a unitary mechanism for this important symptom in patients with cardiopulmonary disorders, but it is clear that a variety of other physiological factors contribute to respiratory sensations. This is in part suggested by the observations of Chonan et al (1987a) that at a given level of respiratory drive, the intensity of dyspnea may be modified by sensory feedback from lung and/or chest wall mechanoreceptors.
Recovery from respiratory inhibition produced by the lung inflation reflex was studied in anesthe... more Recovery from respiratory inhibition produced by the lung inflation reflex was studied in anesthetized dogs, paralyzed and ventilated with a respiratory pump. During constant ventilation the lungs were periodically inflated using positive end-expiratory pressure, while the respiratory motor output was monitored in the phrenic nerve. Inhibition of the phrenic discharge was followed by gradual recovery throughout 8-min inflation periods despite constant blood gases. Recording afferent potentials in a vagus nerve indicated that adaptation of pulmonary stretch receptors contributed to the initial recovery of the phrenic discharge, but this recovery continued after the receptor discharge had stabilized. The phrenic discharge also recovered after initial inhibition in two situations which avoided stretch receptor adaptation: a) when the stretch receptor discharge from the separate lungs was alternated in an overlapping manner by asynchronous pulmonary ventilation, and b) during continuous electrical stimulation of a vagus nerve. Phrenic activity was temporarily increased above its control value after periods of lung inflation, asynchronous ventilation and vagal stimulation. It is concluded that the lung inflation reflex gradually attenuates during prolonged stimulation due to both stretch receptor adaptation and changes within the central pathways.
American Journal of Respiratory and Critical Care Medicine, May 1, 1994
The effect of chest wall vibration on dyspnea at rest was investigated in 15 patients with severe... more The effect of chest wall vibration on dyspnea at rest was investigated in 15 patients with severe chronic respiratory diseases. The magnitude of their baseline dyspnea was 17.9 +/- SE 3.3 mm on a 150-mm visual analog scale. One hundred hertz out-of-phase vibration (OPV; inspiratory intercostal muscles vibrated during expiration and expiratory intercostal muscles vibrated during inspiration) increased dyspnea an average of 21.9 +/- SE 7.8 mm (p < 0.05). One hundred hertz in-phase vibration (IPV; inspiratory intercostal muscles vibrated during inspiration and expiratory intercostal muscles vibrated during expiration) decreased dyspnea an average of 6.9 +/- SE 2.8 mm (p < 0.05). Changes in the respiratory pattern and arterial blood gas determinations elicited by 5-min IPV were investigated in eight of the 15 patients. Tidal volume was significantly increased in all eight of these patients. Respiratory frequency was decreased in seven patients and increased in one. Functional residual capacity, measured before and during the application of IPV for a period of about 10 breaths, was increased in one patient and decreased in the remaining seven. PaCO2 decreased by 1.3 +/- 1.0 mm Hg (p < 0.05), from 49.6 +/- 8.4 mm Hg; PaO2 increased by 3.4 +/- 2.3 mm Hg (p < 0.05), from 67.7 +/- 12.7 mm Hg. The results indicate that in-phase chest wall vibration decreased pathologic dyspnea in patients with chronic respiratory disease and suggest that the effects on respiratory sensation are mediated by afferent information from chest wall respiratory muscles to supraspinal centers.
Breathing is controlled automatically (via chemo- and mechanoreceptors strategically located thro... more Breathing is controlled automatically (via chemo- and mechanoreceptors strategically located throughout the body) and can be voluntarily controlled as well. Volitional and automatic mechanisms can drive the respiratory muscles over separate anatomical pathways to the spinal motor neurons (Plum, 1970; Euler, 1986).
An unpleasant sensation of difficulty in breathing is a common complaint in a variety of disease ... more An unpleasant sensation of difficulty in breathing is a common complaint in a variety of disease states. The psychophysical approach to the study of respiratory sensations has contributed greatly to the understanding of the mechanisms of dyspnea. Although dyspnea, in large part, is an expression of the sense of the effort of breathing, the intensity and quality of the subjective experiences during breathing are also dependent on afferent feedback primarily from receptors in the respiratory muscles. These inputs may act either by changing the level and pattern of respiratory motor activity or by a direct effect on higher brain centers. Finally, the expression of the symptoms of dyspnea in patients with cardiopulmonary disease is shaped by individual behavioral styles, personality, and emotional state. All of these factors must be taken into consideration in the management of the dyspneic patient.
Publisher Summary This chapter focuses on respiratory sensation and respiratory muscle activity. ... more Publisher Summary This chapter focuses on respiratory sensation and respiratory muscle activity. In the study described in the chapter, magnitude scaling methods were used to compare, in a group of normal subjects, the sensations produced by ventilatory elastic and resistive loading. In keeping with the psychophysical power law, the relationships between the physical magnitude of the load and the subjective intensity of the sensation were linear when plotted on log-log coordinates. The exponent for the magnitude estimation of elastic loads in the normal subjects was 1.02 ± SE 0.06 while the exponent for the estimation of resistive loads was 0.71 ± 0.05. The exponents for the estimation of elastic and resistive ventilatory loads were closely correlated, suggesting a common basis for the sensation produced by the two types of loads. However, the perceptual acuity for elastic loads was greater than that for resistive loads; a twofold change in elastic load produced the equivalent change in sensation as a 2.7-fold change in resistive load. This difference in perceptual sensitivity was consistent with the observations that the maximum tolerable resistive load greatly exceeds the maximum elastic load and may in part explain the finding that hypercapnic ventilatory responses are better maintained during elastic loading than resistive loading.
The effect of increased FRC on the change in respiratory muscle electrical activity (EMG) and the... more The effect of increased FRC on the change in respiratory muscle electrical activity (EMG) and the duration of inspiration (Ti) and expiration (Te) produced by increases in chemical drive (i.e., progressive hypercapnia and isocapnic hypoxia) was assessed in 15 anesthetized, spontaneously breathing dogs. FRC was raised by applying continuous positive pressure (4 and 8 cmH2O) to the airway. Progressive hypercapnia and hypoxia were produced by rebreathing techniques. At any PCO2 or PO2, increases in FRC decreased diaphragm EMG (D); increased abdominal muscle EMG (AB); and prolonged Te without affecting Ti. The effect of increased FRC on D, AB, and Te diminished as PCO2 increased or PO2 decreased. The effect of sustained increases in lung volume in the absence of phasic changes was assessed by performing airway occlusion for a single inspiration during rebreathing at both control and increased FRC. The effects of increases in FRC were present during airway occlusion but were eliminated by vagotomy. We conclude, therefore, that tonic vagal stimulation produced by increases in FRC modified the change in respiratory muscle electrical activity and timing produced by increasing chemical drive.
BackgroundIn our effort to increase the value and academic standing of teaching, we implemented a... more BackgroundIn our effort to increase the value and academic standing of teaching, we implemented an initiative focused on scholarship in teaching. Our program was narrowly focused, project-based, peer-reviewed, resource-neutral, and open to all faculty. Faculty members are invited annually to submit a description of their educational projects in keeping with Glassick’s criteria. Our purpose was to assess the effects of this award program.MethodWe reviewed the distribution of applications over a 3-year period and determined the academic departments, academic rank of applicants, and focus of projects. A questionnaire assessed applicants’ perceptions of the value of participation, its contribution to promotion and advancement, and its role in subsequent dissemination activities.ResultsSlightly fewer than half (60 of 124, 48%) of the applications submitted during 2016 through 2018 were judged by peer review to meet Glassick’s criteria for scholarship and received the award. Most applicants were junior faculty, and most applications were from the department of medicine though all departments who taught students in core clinical rotations were represented during the years studied. The projects that were awarded were more likely to be disseminated when compared with those who were not awarded.Lessons LearnedOur scholarship in teaching program seemingly advanced educational scholarship among teaching faculty and provided a way of recognizing projects that advanced educational initiatives. Further efforts are required to promote support from departmental leadership, to enhance faculty participation, and to encourage success through mentoring and assistance in project preparation.
Psychophysical studies of the sensations associated with the act of breathing have suggested that... more Psychophysical studies of the sensations associated with the act of breathing have suggested that dyspnea is a function of the sense of the effort of breathing and is based on the magnitude of the centrally generated respiratory motor command signal (El-Manshawi et al., 1986). It is attractive to consider such a unitary mechanism for this important symptom in patients with cardiopulmonary disorders, but it is clear that a variety of other physiological factors contribute to respiratory sensations. This is in part suggested by the observations of Chonan et al (1987a) that at a given level of respiratory drive, the intensity of dyspnea may be modified by sensory feedback from lung and/or chest wall mechanoreceptors.
Recovery from respiratory inhibition produced by the lung inflation reflex was studied in anesthe... more Recovery from respiratory inhibition produced by the lung inflation reflex was studied in anesthetized dogs, paralyzed and ventilated with a respiratory pump. During constant ventilation the lungs were periodically inflated using positive end-expiratory pressure, while the respiratory motor output was monitored in the phrenic nerve. Inhibition of the phrenic discharge was followed by gradual recovery throughout 8-min inflation periods despite constant blood gases. Recording afferent potentials in a vagus nerve indicated that adaptation of pulmonary stretch receptors contributed to the initial recovery of the phrenic discharge, but this recovery continued after the receptor discharge had stabilized. The phrenic discharge also recovered after initial inhibition in two situations which avoided stretch receptor adaptation: a) when the stretch receptor discharge from the separate lungs was alternated in an overlapping manner by asynchronous pulmonary ventilation, and b) during continuous electrical stimulation of a vagus nerve. Phrenic activity was temporarily increased above its control value after periods of lung inflation, asynchronous ventilation and vagal stimulation. It is concluded that the lung inflation reflex gradually attenuates during prolonged stimulation due to both stretch receptor adaptation and changes within the central pathways.
American Journal of Respiratory and Critical Care Medicine, May 1, 1994
The effect of chest wall vibration on dyspnea at rest was investigated in 15 patients with severe... more The effect of chest wall vibration on dyspnea at rest was investigated in 15 patients with severe chronic respiratory diseases. The magnitude of their baseline dyspnea was 17.9 +/- SE 3.3 mm on a 150-mm visual analog scale. One hundred hertz out-of-phase vibration (OPV; inspiratory intercostal muscles vibrated during expiration and expiratory intercostal muscles vibrated during inspiration) increased dyspnea an average of 21.9 +/- SE 7.8 mm (p < 0.05). One hundred hertz in-phase vibration (IPV; inspiratory intercostal muscles vibrated during inspiration and expiratory intercostal muscles vibrated during expiration) decreased dyspnea an average of 6.9 +/- SE 2.8 mm (p < 0.05). Changes in the respiratory pattern and arterial blood gas determinations elicited by 5-min IPV were investigated in eight of the 15 patients. Tidal volume was significantly increased in all eight of these patients. Respiratory frequency was decreased in seven patients and increased in one. Functional residual capacity, measured before and during the application of IPV for a period of about 10 breaths, was increased in one patient and decreased in the remaining seven. PaCO2 decreased by 1.3 +/- 1.0 mm Hg (p < 0.05), from 49.6 +/- 8.4 mm Hg; PaO2 increased by 3.4 +/- 2.3 mm Hg (p < 0.05), from 67.7 +/- 12.7 mm Hg. The results indicate that in-phase chest wall vibration decreased pathologic dyspnea in patients with chronic respiratory disease and suggest that the effects on respiratory sensation are mediated by afferent information from chest wall respiratory muscles to supraspinal centers.
Breathing is controlled automatically (via chemo- and mechanoreceptors strategically located thro... more Breathing is controlled automatically (via chemo- and mechanoreceptors strategically located throughout the body) and can be voluntarily controlled as well. Volitional and automatic mechanisms can drive the respiratory muscles over separate anatomical pathways to the spinal motor neurons (Plum, 1970; Euler, 1986).
An unpleasant sensation of difficulty in breathing is a common complaint in a variety of disease ... more An unpleasant sensation of difficulty in breathing is a common complaint in a variety of disease states. The psychophysical approach to the study of respiratory sensations has contributed greatly to the understanding of the mechanisms of dyspnea. Although dyspnea, in large part, is an expression of the sense of the effort of breathing, the intensity and quality of the subjective experiences during breathing are also dependent on afferent feedback primarily from receptors in the respiratory muscles. These inputs may act either by changing the level and pattern of respiratory motor activity or by a direct effect on higher brain centers. Finally, the expression of the symptoms of dyspnea in patients with cardiopulmonary disease is shaped by individual behavioral styles, personality, and emotional state. All of these factors must be taken into consideration in the management of the dyspneic patient.
Publisher Summary This chapter focuses on respiratory sensation and respiratory muscle activity. ... more Publisher Summary This chapter focuses on respiratory sensation and respiratory muscle activity. In the study described in the chapter, magnitude scaling methods were used to compare, in a group of normal subjects, the sensations produced by ventilatory elastic and resistive loading. In keeping with the psychophysical power law, the relationships between the physical magnitude of the load and the subjective intensity of the sensation were linear when plotted on log-log coordinates. The exponent for the magnitude estimation of elastic loads in the normal subjects was 1.02 ± SE 0.06 while the exponent for the estimation of resistive loads was 0.71 ± 0.05. The exponents for the estimation of elastic and resistive ventilatory loads were closely correlated, suggesting a common basis for the sensation produced by the two types of loads. However, the perceptual acuity for elastic loads was greater than that for resistive loads; a twofold change in elastic load produced the equivalent change in sensation as a 2.7-fold change in resistive load. This difference in perceptual sensitivity was consistent with the observations that the maximum tolerable resistive load greatly exceeds the maximum elastic load and may in part explain the finding that hypercapnic ventilatory responses are better maintained during elastic loading than resistive loading.
The effect of increased FRC on the change in respiratory muscle electrical activity (EMG) and the... more The effect of increased FRC on the change in respiratory muscle electrical activity (EMG) and the duration of inspiration (Ti) and expiration (Te) produced by increases in chemical drive (i.e., progressive hypercapnia and isocapnic hypoxia) was assessed in 15 anesthetized, spontaneously breathing dogs. FRC was raised by applying continuous positive pressure (4 and 8 cmH2O) to the airway. Progressive hypercapnia and hypoxia were produced by rebreathing techniques. At any PCO2 or PO2, increases in FRC decreased diaphragm EMG (D); increased abdominal muscle EMG (AB); and prolonged Te without affecting Ti. The effect of increased FRC on D, AB, and Te diminished as PCO2 increased or PO2 decreased. The effect of sustained increases in lung volume in the absence of phasic changes was assessed by performing airway occlusion for a single inspiration during rebreathing at both control and increased FRC. The effects of increases in FRC were present during airway occlusion but were eliminated by vagotomy. We conclude, therefore, that tonic vagal stimulation produced by increases in FRC modified the change in respiratory muscle electrical activity and timing produced by increasing chemical drive.
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