Jaspar N, Mazzarelli M, Tessier C, Milic-Emili J
J Appl Physiol Respir Environ Exerc Physiol. 1983 Sep;55(3):851-9. doi: 10.1152/jappl.1983.55.3.851.
We studied minute ventilation, breathing pattern, end-tidal CO2 partial pressure (PACO2), and tracheal occlusion pressure in cats anesthetized with ketamine (40 and 80 mg/kg) before and after CO2 inhalation. Before CO2 administration ventilation was reduced and PACO2 increased relative to unanesthetized cats at both ketamine doses. Breathing pattern was of the "apneustic" type, being characterized by 1) prolonged inspiratory duration and relatively short expiratory time and 2) markedly curvilinear (convex upward) inspiratory volume-time profile. The latter reflected a similar curvilinearity in the tracheal occlusion pressure waveform. During CO2 inhalation, the ventilatory response to CO2 was similar to that in unanesthetized cats in spite of a depressed tracheal occlusion pressure response. This discrepancy was due to the fact that in the presence of a convex upward inspiratory volume-time profile, the shortening of inspiratory duration with increasing CO2 results in a marked increase of mean inspiratory flow, and hence the ventilatory response to CO2 remains high.
我们研究了用氯胺酮（40和80毫克/千克）麻醉的猫在吸入二氧化碳前后的分钟通气量、呼吸模式、呼气末二氧化碳分压（PACO2）和气管阻塞压。在给予二氧化碳之前，与未麻醉的猫相比，两种氯胺酮剂量下的通气量均降低，PACO2升高。呼吸模式为“长吸式”，其特征为：1）吸气持续时间延长，呼气时间相对较短；2）吸气容积-时间曲线明显呈曲线状（向上凸起）。后者反映了气管阻塞压波形中类似的曲线特征。在吸入二氧化碳期间，尽管气管阻塞压反应降低，但对二氧化碳的通气反应与未麻醉的猫相似。这种差异是由于在吸气容积-时间曲线向上凸起的情况下，随着二氧化碳增加吸气持续时间缩短导致平均吸气流量显著增加，因此对二氧化碳的通气反应仍然很高。
