Heldt G P, McIlroy M B
J Appl Physiol (1985). 1987 Jan;62(1):164-9. doi: 10.1152/jappl.1987.62.1.164.
Chest wall distortion is common in infants and is especially visible in preterm infants. It has been suggested that this distortion increases the volume displacement of the diaphragm during inspiration, which may be associated with muscular fatigue and apnea. We studied 10 preterm infants who had no evidence of lung disease, investigating the effect of chest wall distortion on the volume displacement and work of the diaphragm. The volume changes of the respiratory system were partitioned using an inductance plethysmograph. The minute volume displacement and the work of the diaphragm were calculated using the partitioned abdominal volume change and the gastric and esophageal pressures. The paradoxical movement of the chest wall lasted an average of 36% of inspiration. The minute volume displacement of the diaphragm ranged from 72 to 176% of the minute pulmonary ventilation, and diaphragmatic work ranged from 94 to 793% of that performed on the lungs. The amount of chest wall distortion, as reflected by the duration of the paradoxical chest wall movement, the minute volume excursion, or work of the diaphragm, was not related to the mechanical properties of the lungs. This estimated work load may represent a significant expenditure of calories in these infants and may contribute to the development of diaphragmatic fatigue, apnea, and a prolonged need for mechanical ventilation.
胸壁变形在婴儿中很常见，在早产儿中尤为明显。有人认为这种变形会增加吸气时膈肌的容积位移，这可能与肌肉疲劳和呼吸暂停有关。我们研究了10名无肺部疾病证据的早产儿，调查胸壁变形对膈肌容积位移和做功的影响。使用感应体积描记器对呼吸系统的容积变化进行划分。利用划分后的腹部容积变化以及胃和食管压力来计算每分钟的容积位移和膈肌的做功。胸壁的反常运动平均持续吸气时间的36%。膈肌每分钟的容积位移为每分钟肺通气量的72%至176%，膈肌做功为对肺部做功的94%至793%。由胸壁反常运动持续时间、每分钟容积偏移或膈肌做功所反映的胸壁变形程度，与肺部的力学特性无关。这种估计的工作量可能代表了这些婴儿大量的热量消耗，并可能导致膈肌疲劳、呼吸暂停以及对机械通气的长期需求。
