Paydarfar D, Eldridge F L, Scott S C, Dowell R T, Wagner P G
Department of Medicine, University of North Carolina, Chapel Hill 27599.
Am J Physiol. 1991 May;260(5 Pt 2):R934-40. doi: 10.1152/ajpregu.1991.260.5.R934.
We studied the effects on breathing of seizures induced by focal injection of penicillin G into the parietal cortex in 13 anesthetized cats. Electrocorticograms, ventilation, end-tidal PCO2, and intrapleural and arterial pressures were monitored; changes of these variables were related to the stages of motor seizure. The first respiratory responses, tachypnea and hyperpnea, usually occurred before any peripheral muscular contractions developed. Progression of the seizure was always accompanied by further tachypnea and hyperpnea. The hyperpnea associated with all stages of seizure activity resulted in hypocapnia, which was sustained even during prolonged tonic-clonic motor convulsions that caused a threefold increase of metabolic rate. The extreme tachypnea of tonic generalized convulsions led to increased end-expiratory lung volume because of dynamic hyperinflation associated with very short expiratory durations in the tonic phase. We suggest that the profound effects of seizures on respiration are by feedforward mechanisms from the cortical focus itself and from subcortical circuits, such as hypothalamus, that become involved during seizure propagation and generalization. Peripheral respiratory feedback mechanisms are not important for the genesis of seizure-induced hyperpnea.
我们研究了向13只麻醉猫的顶叶皮质局部注射青霉素G诱发癫痫发作对呼吸的影响。监测了脑电图、通气、呼气末二氧化碳分压以及胸膜腔内压和动脉压；这些变量的变化与运动性癫痫发作的阶段相关。最初的呼吸反应，即呼吸急促和呼吸增强，通常在任何外周肌肉收缩出现之前就已发生。癫痫发作的进展总是伴随着进一步的呼吸急促和呼吸增强。与癫痫发作活动各阶段相关的呼吸增强导致低碳酸血症，即使在导致代谢率增加三倍的长时间强直阵挛性运动惊厥期间，这种低碳酸血症仍持续存在。强直全身性惊厥时的极度呼吸急促由于强直期呼气持续时间极短导致动态肺过度充气，从而使呼气末肺容积增加。我们认为，癫痫发作对呼吸的深远影响是通过来自皮质病灶本身以及来自下丘脑等在癫痫发作传播和泛化过程中涉及的皮质下回路的前馈机制实现的。外周呼吸反馈机制对癫痫诱发的呼吸增强的发生并不重要。
