The close proximity of the larynx to the entrance of the esophagus, and the common pathway through the pharynx that both air and a swallowed bolus must traverse, require that swallowing and respiration be well coordinated. Discoordination can result in the aspiration of food, liquid, or oral secretions consequent risk of severe respiratory complications. Despite its critical function, the coordination of respiration with swallowing is not well-understood either in healthy individuals or in persons, such as stroke patients, who are known to be at high risk for developing aspiration pneumonia. Using respirodeglutometry, this research will characterize the joint timing of respiration with the swallow and simultaneously record respiratory airflow, submental surface electromyography, and swallow-associated acoustic signals. Two hundred forty normal subjects (120 male, 120 female) in five groups ranging from 3 to 85 years-of-age, and sixty medically stable stroke patients, will be studied. Respirodeglutometric (RDT) output will be digitized at 1000 samples/sec/channel while subjects swallow pre-measured 5, 10, and 15 ml volumes of water and pudding. For all subjects and for each swallow, the direction of respiration preceding and following the swallow, the duration of deglutition apnea, and five additional RDT temporal measures will be obtained. All stroke patients will also be seen for videofluoroscopic assessment within 24 hours of the RDT evaluation in order to directly assess the oral and pharyngeal stages of their swallow and to identify various indicators of dysphagia, including the presence/absence of laryngeal penetration and aspiration. Analysis will address i) effects of size and viscosity of swallowed material on timing of RDT measured events within the swallow, ii) changes in the coordination of respiration with swallowing in healthy subjects across the lifespan, iii) age and gender adjusted effects of stroke on such coordination, iv) adaptations of coordination by healthy subjects and stroke patients to feeding by a caregiver relative to self-feeding, and v) the relationship in stroke patients of videofluoroscopically- observed oropharyngeal dysphasia and aspiration to aberrant respiratory-swallowing patterns. Findings from this research can have a profound effect on patient evaluation procedures as well as on behavioral management techniques, clinical outcome goals, and medical costs for stroke patients.
