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R E Hyatt

Publications and source records attributed to R E Hyatt.

114 records · Page 7Linked to original sources
PubMedDate not supplied

Evaluation of major airway lesions using the flow-volume loop.

The flow-volume (FV) loop is another way of representing spirometric data from combinations of forced expiratory and forced inspiratory vital capacity breaths. The FV loop is of use in identifying, and often localizing, lesions of the larynx and the trachea (down to the carina). Three general patterns have been recognized. When the lesion behaves in a fixed fashion (as might occur with an artificial orifice), maximal expiratory and inspiratory flows are almost equally compromised. This results in a rectangular FV loop, irrespective of whether the lesion is located intrathoracically or extrathoracically. When the lesion behaves in a variable fashion, two distinct patterns are seen, depending on the location of the lesion (intrathoracic or extrathoracic). The variable lesion acts as a fixed lesion during one phase of forced respiration only. The extrathoracic variable lesion results in a predominant reduction in forced inspiratory flow, with little effect on expiratory flow, whereas the intrathoracic variable lesion produces a characteristic reduction in expiratory flow. These patterns reflect the transmural forces existing at the site of the lesion.

Adult↗
PubMedDate not supplied

Nasopulmonary reflex: evaluation in the nonparalyzed and paralyzed anesthetized dog.

Changes in the pulmonary mechanics of various animal species have been observed after nasal stimulation. In reviewing the methods of these studies, we found that often the respiratory patterns were not controlled well enough to permit conclusions about changes in resistance and compliance. To further investigate the possibility of a nasopulmonary reflex, we first studied the effect of nasal stimulation on pulmonary mechanics in anesthetized, nonparalyzed dogs. In this group of 35 dogs, we found that nasal stimulation typically produced marked changes in breathing patterns, a large transient increase (150%) in pulmonary airflow resistance, but no change in compliance. This response to nasal stimulation could be abolished by interrupting either the trigeminal or the vagus nerves. In an additional group of 12 anesthetized, paralyzed dogs, we found no changes in resistance or compliance after nasal stimulation. From this observation, we concluded that nasal stimulation produced changes in breathing patterns that led to alterations in resistance without an actual change in the intrinsic behavior of the pulmonary airways.

Airway Resistance↗