Deglutition and respiratory patterns during sleep in the aged

Conclusion: Deglutition was extremely infrequent and displayed unique patterns during sleep in the aged.

Objectives: The deglutition and respiratory phase patterns during sleep in the healthy aged were investigated in this study.

Methods: Ten aged adults (average age =?71 years) were examined via time-matched digital recordings of polysomnography and surface electromyography of the muscles (thyrohyoid and suprahyoid muscles) related to swallowing.

Results: During sleep, swallowing was extremely infrequent and absent for long periods in the aged. The median number of swallows per hour during total sleep time was 0.6, and the median longest deglutition-free period was 134.8?minutes. Most deglutition occurred in association with spontaneous electroencephalographic arousal both in REM and non-REM sleep. Deglutition was related to the sleep stage. The deeper the sleep stage, the lower the mean deglutition frequency. There was no deglutition during deep sleep. Overall muscle tone is inhibited during REM sleep. However, deglutition also occurred in association with spontaneous EEG arousal. The deeper the sleep stage, the lower the mean arousal frequency, and the lower the mean ratio of arousal with deglutition to arousal. Approximately one-third of swallows occurred after inspiration and were followed by inspiration.     

Discoordination of laryngeal and respiratory movements in aged rats

Voice and swallowing actions require the coordination of multiple motor systems, and this coordination may be impaired with aging. Although recent work has reported impairments in age-related laryngeal kinematics in rats, the temporal relationship of laryngeal excursions to the respiratory cycle is unknown. The goal of this study was to assess laryngeal-respiratory coordination by examining temporal interrelationships between change in laryngeal aperture and chest wall movement during quiet breathing in a rat model. Glottal images were recorded, digitized, and synchronized with respiratory signals, and temporal features were measured. In the young animals, glottal opening began before the onset of inspiration, and glottal and respiratory cycles were phasic and stereotypic. In old animals, however, inspiration often began during the glottal closing phase, and both respiratory signals were asymmetric. Discoordination of laryngeal and respiratory motor actions associated with aging may be caused by a generalized decline in sensorimotor cranial functions and may contribute to age-related swallowing and communication impairment.     

Physiopathology of the cochlear microcirculation

Normal blood supply to the cochlea is critically important for establishing the endocochlear potential and sustaining production of endolymph. Abnormal cochlear microcirculation has long been considered an etiologic factor in noise-induced hearing loss, age-related hearing loss (presbycusis), sudden hearing loss or vestibular function, and Meniere's disease. Knowledge of the mechanisms underlying the pathophysiology of cochlear microcirculation is of fundamental clinical importance. A better understanding of cochlear blood flow (CoBF) will enable more effective management of hearing disorders resulting from aberrant blood flow. This review focuses on recent discoveries and findings related to the physiopathology of the cochlear microvasculature.     

Predicting outcome in aged and severely ill patients with prolonged respiratory failure

OBJECTIVES: Consultations for tracheotomy are often sought on aged and severely ill patients with respiratory insufficiency. This patient population has high short-term mortality rates and is difficult to stratify on the basis of expected outcome. We examined whether APACHE III (Acute Physiology and Chronic Health Evaluation III) scores or neurologic status assessment (NSA) scores in sedated individuals are predictive of outcome. METHODS: We performed a retrospective study examining aged patients who underwent tracheotomy for respiratory insufficiency and prolonged intubation. The APACHE III scores (n = 30) and NSA (based on a modified Glasgow Coma Scale) scores (n = 37) were calculated before tracheotomy. All patients were mildly sedated. Using APACHE III and NSA scores as predictor variables and using death and ability to be weaned from the ventilator as outcome variables, we performed a Kaplan-Meier survival analysis and a Cox proportional hazard regression. RESULTS: The APACHE III was not significantly predictive of either outcome. Higher NSA scores were associated with increased survival rates (log rank = 19.7, p < .0001) and longer median survival (88 days versus 16 days for lower scorers). Higher NSA scores also predicted a higher rate of ventilator independence. CONCLUSIONS: Neurologic function in sedated patients (and not APACHE III scores) can be used to stratify aged individuals with respiratory insufficiency on the basis of expected outcome.     

Physiopathology of sleep-disordered breathing in children

Sleep-disordered breathing represents a broad spectrum of alterations, ranging from habitual snoring, through obstructive hypoventilation to obstructive sleep apnea-hypopnea syndrome, and produces breathing and architecture anomalies during sleep. There are some controversies on the physiopathological mechanisms of sleep-disordered breathing and its metabolic, neurocognitive and cardiovascular effects. The causes of comorbidity in obstructive sleep apnea-hypopnea syndrome in children are not yet well known and can include blood gasometric anomalies, fragmented sleep, and local and systemic inflammation, modulated by genetic, environmental and ethnic factors. The pathogenesis of pediatric sleep-disordered breathing undoubtedly involves complex interactions between anatomical or structural and functional factors, an airway prone to collapse and deficient neuromuscular compensation. Moreover, in children, sleep progresses in accordance with central nervous system development, which varies with age. This article reviews the role of the distinct anatomic, functional and inflammatory factors in the pathophysiology of pediatric sleep-disordered breathing.