CONTROL OF BREATHING--INFLUENCES OF UPPER AIRWAY ORIGINS

上呼吸道压力变化对呼吸控制的影响将是 学习。将特别强调呼吸计时和 横隔肌和上呼吸道肌肉的峰值活动，如 膝舌肌。在麻醉、气管切开、自主呼吸中 兔子，将上呼吸道隔离成一个封闭的系统，以便 压力变化可以随意进行。横隔肌和颧舌肌 肌电将用双极细电极记录。在 前两项研究，使用由颧舌肌触发的伺服呼吸器 肌肉活动、负压和正压脉冲(量值：5或10 厘米。水；持续200毫秒)将应用于隔离的上呼吸道 在吸气或呼气方面早或晚。高峰期变更 肌肉活动和呼吸持续时间的变化 (吸气和呼气持续时间) 与它们各自的控制值进行比较。在第三项研究中，角色 上呼吸道机械感受器在颧舌肌对颈部反应中的作用 屈曲度将被评估。颧舌肌肌活动的峰值 当动物通过鼻子呼吸时，脖子会弯曲 比起气管切开呼吸。同样，中国经济增长 在屈颈时的颧舌肌活动将与类似的 双侧喉上神经切断术在部分患者中的应用 动物和颈中迷走神经切断术后的其他动物。在第四协议中， 不同程度低氧高碳酸血症对反射的影响 将确定对上呼吸道压力变化的反应。这些 影响(大循环负压、颈屈、低氧和 高碳酸血症)通常出现在阻塞性呼吸暂停中。这样的呼吸暂停是可以看到的 临床状态多种多样：患有睡眠呼吸暂停的成人和儿童， 早产儿，可能是小岛屿发展中国家(婴儿猝死综合征)。 预计拟议的项目将提供对 在这种情况下维持上呼吸道通畅。

Influence of upper airway pressure changes on control of breathing will be studied. Special emphasis will be given to the respiratory timing and to the peak activity of diaphragm and upper airway muscles such as genioglossus. In anesthetized, tracheostomized, spontaneously breathing rabbits, the upper airway will be isolated into a closed system so that pressure changes can be made at will. Diaphragm and genioglossus muscle electromyograms will be recorded with bipolar fine electrodes. In the first two studies, using a servo respirator triggered by the genioglossus muscle activity, negative and positive pressure pulses (magnitude: 5 or 10 cm. water; duration 200 msec) will be applied to the isolated upper airway either early or late in inspiration or expiration. Alteration in peak muscle activity as well as the alterations in respiratory duration (inspiratory and expiratory durations) of the experimental breaths will be compared to their respective control values. In the third study, the role of upper airway mechanoreceptors in the genioglossus response to neck flexion will be evaluated. The peak genioglossus muscle activity during neck flexion when the animal is breathing throught the nose will be compared to tracheostomy breathing. Similarly, the increase in genioglossus activity during neck flexion will be compared to similar values obtained after bilateral superior laryngeal nerve section in some animals and after midcervical vagotomy in others. In the fourth protocol, the effect of various levels of hypoxia and hypercarbia on the reflex response to upper airway pressure changes will be determined. These influences (large cyclic negative pressure, neck flexion, hypoxia and hypercarbia) are usually present in obstructive apnea. Such apnea are seen in a variety of clinical states: adults and children with sleep apnea, premature infants and, possibly, in SIDS (sudden infant death syndrome). The proposed projects are anticipated to provide valuable insight into the maintenance of upper airway patency in such conditions.