Miller M J, Petrie T G, Difiore J M
Department of Pediatric and Medicine, Rainbow Babies and Childrens Hospital, Case Western Reserve University, Cleveland, Ohio 44106.
J Appl Physiol (1985). 1993 Aug;75(2):720-3. doi: 10.1152/jappl.1993.75.2.720.
To characterize the changes in respiratory mechanics and ventilatory timing that accompany apnea in premature infants, we evaluated 36 apneas in 13 premature infants (birth weight, 1,200 +/- 350 g, postconceptional age at study 34 +/- 3 wk). Apnea was defined as a ventilatory pause > or = 10s accompanied by a decrease in heart rate of 20 beats/min. Nasal airflow was recorded with a pneumotachometer, and esophageal, pharyngeal, and nasal mask pressures were continuously measured. Inspiratory time (TI), expiratory time (TE), tidal volume (VT), and VT/TI were determined over five breaths before and after apnea. In addition, total pulmonary resistance (RT) and supraglottic resistance (Rs) were measured over the same epochs in inspiration and expiration. Before apnea, TE and RT increased (P < 0.05 and < 0.01, respectively); however, Rs did not change. Immediately after apnea, prolongation of TI occurred and both RT and Rs were increased (P < 0.01), consistent with continued upper airway instability. However, within two breaths after resolution of the apnea, RT and Rs returned to normal, reflecting rapid recovery of upper airway and total pulmonary resistance. The ventilatory changes that precede and follow apnea closely resemble those occurring during periodic breathing.
为了描述早产儿呼吸暂停时呼吸力学和通气时间的变化，我们评估了13例早产儿（出生体重1200±350g，研究时孕龄34±3周）的36次呼吸暂停。呼吸暂停定义为通气暂停≥10秒，同时心率下降20次/分钟。用呼吸速度计记录鼻气流，并持续测量食管、咽部和鼻面罩压力。在呼吸暂停前后的五次呼吸中测定吸气时间（TI）、呼气时间（TE）、潮气量（VT）和VT/TI。此外，在相同的吸气和呼气时段测量总肺阻力（RT）和声门上阻力（Rs）。呼吸暂停前，TE和RT增加（分别为P<0.05和<0.01）；然而，Rs没有变化。呼吸暂停后立即出现TI延长，RT和Rs均增加（P<0.01），这与上气道持续不稳定一致。然而，在呼吸暂停缓解后的两次呼吸内，RT和Rs恢复正常，反映了上气道和总肺阻力的快速恢复。呼吸暂停前后的通气变化与周期性呼吸时发生的变化非常相似。
