Van den Aardweg Joost G, Karemaker John M
Department of Physiology, Academic Medical Center, Amsterdam, The Netherlands.
Am J Respir Crit Care Med. 2002 Apr 15;165(8):1041-7. doi: 10.1164/ajrccm.165.8.2104100.
The background of this study was the hypothesis that respiratory variability is influenced by chemoreflex regulation. In search for periodicities in the variability due to instability of the respiratory control system, spectral analysis was applied to breath-to-breath variables in 19 healthy subjects at rest. During room-air breathing, coherent oscillations in end-tidal CO2 (PET(CO2)) and mean inspiratory flow (VI/TI) were found in 15 subjects with frequencies mostly below 0.15 cycles per breath. Coherent oscillations in PET(CO2) and VI/TI were expressed by gain (0.13 to 0.34 L/second small middle dot kPa) and phase (-170 degrees to +8 degrees ). The oscillations in VI/TI were in phase with inspiratory volume (VI). A model that describes the effects of chemoreflex feedback to noise in the system could explain these gains and phases, whereas a model without chemoreflex could not. During 100% O2 breathing, only eight subjects had coherent oscillations in PET(CO2) and VI/TI. The coherent oscillations in PET(CO2) and VI/TI were interpreted as a manifestation of chemoreflex activity. We conclude that respiratory variability is not a random process but contains information on chemoreflex properties, such as the chemoreflex gain. The analysis of respiratory variability therefore provides a new tool to study the action of the chemoreflexes without application of external stimuli.
本研究的背景基于呼吸变异性受化学反射调节影响这一假设。为探寻因呼吸控制系统不稳定导致的变异性中的周期性，对19名静息状态下的健康受试者逐次呼吸变量进行了频谱分析。在室内空气呼吸期间，15名受试者的呼气末二氧化碳（PET(CO2)）和平均吸气流量（VI/TI）出现了相干振荡，频率大多低于每呼吸0.15次循环。PET(CO2)和VI/TI中的相干振荡通过增益（0.13至0.34升/秒·千帕）和相位（-170度至 +8度）来表示。VI/TI中的振荡与吸气量（VI）同相。一个描述化学反射反馈对系统噪声影响的模型能够解释这些增益和相位，而无化学反射的模型则无法解释。在100%氧气呼吸期间，只有8名受试者的PET(CO2)和VI/TI出现了相干振荡。PET(CO2)和VI/TI中的相干振荡被解释为化学反射活动的一种表现。我们得出结论，呼吸变异性并非随机过程，而是包含有关化学反射特性（如化学反射增益）的信息。因此，呼吸变异性分析为研究化学反射作用提供了一种无需施加外部刺激的新工具。
