J. W. Weiss

Dyspnea: A sensory experience

Dyspnea—an unpleasant or uncomfortable awareness of breathing or need to breathe—is a common symptom of patients with cardiopulmonary disease. Although often thought of as a single symptom, dyspnea probably subsumes many sensations. Experimental conditions used to induce dyspnea are characterized by discrete groups or clusters of descriptive phrases. Similarly, as the language of dyspnea is refined further, different disease states may be distinguishable by the nuances of breathlessness described by patients. Evidence is gathering that the sensations of dyspnea are modified by information from a variety of receptors throughout the respiratory system. The sense of effort, although still important in the breathlessness associated with mechanical loads, is insufficient to explain the dyspnea arising from a number of experimental and clinical conditions. As our understanding of the interactions between effort and afferent information from the respiratory system grows, new therapeutic interventions to alleviate dyspnea are likely to follow.

Weaning from Ventilatory Support

Weaning from mechanical ventilation — the process of preparing for and eventually carrying out the removal of external ventilatory support — may be a simple task in patients with readily reversible...

Low dose aminophylline selectively increases upper airway motor activity in normals

Because certain pharmacologic agents differentially influence upper airway and diaphragm motor activity, we postulated that the adenosine antagonist theophylline might preferentially increase alae nasi activity in human subjects. Using a double-blinded, randomized, placebo controlled design, we studied the effect of low dose aminophylline (1-2 mg/kg) on alae nasi and diaphragm surface electromyographic (EMG) activity. Seven healthy volunteers served as subjects for two trials on separate days. Subjects breathed from a close circuit while end tidal PCO2 was held constant in the eucapnic range. During each trial we recorded EMG signals from the alae nasi and diaphragm before and after intravenous infusion of either aminophylline or placebo. After the administration of aminophylline, the mean alae nasi EMG signal increased 87 +/- 31 (SD)% (P less than 0.005) while the mean diaphragmatic EMG signal did not change. There was no significant change in either the alae nasi or diaphragmatic EMG signal after placebo. There was no change in minute ventilation, tidal volume, or respiratory frequency after either aminophylline or placebo. We speculate that low dose aminophylline produces a selective increase in upper airway muscle activity through stimulation of the reticular activating system.

Normal pregnancy and delivery in a woman with severe underlying lung disease.

Little information is available about the impact of pulmonary insufficiency on the course and outcome of a normal pregnancy, since severe lung disease with functional impairment is unusual in women during childbearing years.1-5 We report here a patient with pulmonary insufficiency of combined restrictive and obstructive type who delivered a normal baby after a closely monitored but relatively uneventful pregnancy.