Walker D W, Harding R
J Dev Physiol. 1986 Apr;8(2):105-16.
Extra-dural or cerebroventricular intracranial pressure was measured in 7 unanaesthetized fetal sheep (123-137 days gestation). Basal intracranial pressure was 6.7 +/- 1.7 mmHg, but there were many transient increases of pressure in association with spontaneous changes of amniotic pressure, fetal intrathoracic pressure, and particularly when the fetal nuchal muscles were active. These spontaneous increases of intracranial pressure were often associated with cessation of breathing movements and change of the electrocorticogram from low to high voltage activity. To test whether increased intracranial pressure influenced breathing movements and electrocortical activity, intracranial pressure was raised either by occluding the superior vena cava for 1 min with an implanted extravascular cuff, or by extra-dural injection of 0.3-1.0 ml of 0.9% NaCl. Increasing the intracranial pressure 5-15 mmHg by either method during low voltage electrocortical activity caused cessation of breathing movements, electro-ocular activity, and change of the electrocorticogram from low to high voltage in a significant proportion of trials. We propose that natural fluctuations of intracranial pressure caused by compression of the fetal body or skull, by body movements or by uterine activity, may cause changes in electrocortical activity and breathing movements.
在7只未麻醉的胎羊（妊娠123 - 137天）中测量了硬膜外或脑室内颅内压。基础颅内压为6.7±1.7 mmHg，但与羊水压力、胎儿胸内压力的自发变化相关，尤其是当胎儿颈部肌肉活动时，会出现许多短暂的压力升高。这些颅内压的自发升高常与呼吸运动停止以及脑电图从低电压活动变为高电压活动有关。为了测试颅内压升高是否会影响呼吸运动和脑电活动，通过用植入的血管外袖带阻断上腔静脉1分钟，或通过硬膜外注射0.3 - 1.0 ml 0.9%氯化钠溶液来升高颅内压。在低电压脑电活动期间，通过这两种方法将颅内压升高5 - 15 mmHg，在相当比例的试验中会导致呼吸运动、眼电活动停止以及脑电图从低电压变为高电压。我们认为，由胎儿身体或颅骨受压、身体运动或子宫活动引起的颅内压自然波动，可能会导致脑电活动和呼吸运动的变化。
