Dianna S. Dodd

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We studied the dynamic mechanical properties of the chest wall in 7 patients with severe chronic air-flow obstruction (CAO). Measurements were made during quiet breathing at rest and during exercise on a bicycle ergometer at work rates equivalent to 50 and 100% of their maximal work rate (Wmax). The peak inspiratory pleural pressure relative to the chest(More)
We examined the respiratory activity of the posterior cricoarytenoid muscle (PCA) simultaneously with the movements of the vocal cords during tidal breathing and panting in four normal seated subjects. A bipolar electrode was constructed to record the surface electromyogram (EMG) of the PCA. The glottis was visualized with a fiberoptic bronchoscope, and the(More)
We measured the relative changes in upper and lower rib cage volume (delta RCU and delta RCL, respectively) using an induction coil plethysmograph (Respitrace) in seven normal seated subjects during relaxed passive expiration from total lung capacity, during quiet breathing, rapid breathing at 60 breaths/min (RB), during exercise-induced hyperventilation(More)
To examine the relationship between expiratory effort, expiratory flow, and glottic aperture, we compared the effects of actively and passively produced changes in flow in six normal subjects. During flow transients of 1.08 +/- 0.08 l/s produced by voluntary expiratory effort, glottic width (dg) increased by 54 +/- 13% (mean +/- SE). In contrast transient(More)
We examined the effect of increasing work rate, without a corresponding increase in the pressure-time product, on energy cost and inspiratory muscle endurance (Tlim) in five normal subjects during inspiratory resistive breathing. Tidal volume, mean inspiratory mouth pressure, duty cycle, and hence the pressure-time product were kept constant, whereas work(More)
We measured the electromyographic activity of the posterior cricoarytenoid (PCA) muscle simultaneously with glottic width (dg) in five normal human subjects during hyperpnea induced by hypoxia (7% CO2 in N2) or hypercapnia (9% CO2 in 50% O2). The glottic aperture was measured during inspiration at the time corresponding to peak inspiratory PCA activity and(More)
In six normal male subjects we compared the O2 cost of resistive breathing (VO2 resp) between equivalent external inspiratory (IRL) and expiratory loads (ERL) studied separately. Each subject performed four pairs of runs matched for tidal volume, breathing frequency, flow rates, lung volume, pressure-time product, and work rate. Basal O2 uptake, measured(More)
We examined the electromyographic activity of the posterior cricoarytenoid (PCA) simultaneously with the alae nasi (AN) in response to increasing chemical drive in 5 normal, awake human subjects. During progressive isocapnic hypoxia the peak of the integrated PCA activity (EPCA) increased as a function of tidal volume (VT), and in 3 of the 5 subjects the(More)
We studied the effect of abdominal loading on exercise performance in 7 patients with severe chronic air-flow obstruction (CAO). The patients were exercised to exhaustion on a bicycle ergometer at a work rate equivalent to 80% of their maximal work rate. Three exercise studies were completed in the same afternoon. The first and third were control studies;(More)
We examined the effects of external mechanical loading on glottic dimensions in 13 normal subjects. When flow-resistive loads of 7, 27, and 48 cmH2O X l-1 X s, measured at 0.2 l/s, were applied during expiration, glottic width at the mid-tidal volume point in expiration (dge) was 2.3 +/- 12, 37.9 +/- 7.5, and 38.3 +/- 8.9% (means +/- SE) less than the(More)