Rehan V K, Nakashima J M, Gutman A, Rubin L P, McCool F D
Department of Pediatrics, Memorial Hospital of Rhode Island, Pawtucket, Rhode Island, USA.
Arch Dis Child. 2000 Sep;83(3):234-8. doi: 10.1136/adc.83.3.234.
The physiological basis underlying the decline in the incidence of sudden infant death syndrome (SIDS) associated with changing the sleep position from prone to supine remains unknown.
To evaluate diaphragm thickness (t(di)) and shortening in healthy term infants in the prone and supine positions in order to determine whether changes in body position would affect diaphragm resting length and the degree of diaphragm shortening during inspiration.
In 16 healthy term infants, diaphragm thickness at the level of the zone of apposition on the right side was measured using ultrasonography. Heart rate (HR), breathing frequency (f), and transcutaneous oxyhaemoglobin saturation (SaO(2)) were recorded simultaneously during diaphragm imaging with the infants in the supine and prone positions during quiet sleep.
At end expiratory (EEV) and at end inspiratory lung volumes (EIV), t(di) increased significantly in the prone position. The change in t(di) during tidal breathing was also greater when the infant was prone. SaO(2), HR, and f were not significantly different at EEV and at EIV in both positions.
In healthy term infants, placed in the prone position, the diaphragm is significantly thicker and, therefore, shorter, both at EEV and EIV. Diaphragm shortening during tidal breathing is greater when the infant is prone. In the prone position, the decreased diaphragm resting length would impair diaphragm strength, and the additional diaphragm shortening during tidal breathing represents added work performed by the diaphragm. This may compromise an infant's capacity to respond to stressful situations when placed in the prone position and may contribute to the association of SIDS with prone position.
与睡眠姿势从俯卧改为仰卧相关的婴儿猝死综合征（SIDS）发病率下降的生理基础尚不清楚。
评估健康足月儿在俯卧位和仰卧位时的膈肌厚度（t(di)）和缩短情况，以确定体位变化是否会影响膈肌静息长度以及吸气时膈肌缩短程度。
对16名健康足月儿，使用超声测量右侧附着区水平的膈肌厚度。在安静睡眠期间，当婴儿处于仰卧位和俯卧位时，在膈肌成像过程中同时记录心率（HR）、呼吸频率（f）和经皮氧合血红蛋白饱和度（SaO(2)）。
在呼气末（EEV）和吸气末肺容积（EIV）时，俯卧位时t(di)显著增加。当婴儿俯卧时，潮式呼吸期间t(di)的变化也更大。在两个体位的EEV和EIV时，SaO(2)、HR和f均无显著差异。
在健康足月儿中，处于俯卧位时，在EEV和EIV时膈肌明显更厚，因此更短。当婴儿俯卧时，潮式呼吸期间膈肌缩短更大。在俯卧位时，膈肌静息长度的减少会损害膈肌力量，潮式呼吸期间额外的膈肌缩短代表膈肌额外做的功。这可能会损害婴儿在俯卧位时应对压力情况的能力，并可能导致SIDS与俯卧位相关。
