Service d'explorations fonctionnelles pédiatriques, Hôpital d'Enfants, CHU de Nancy, France.
Respir Physiol Neurobiol. 2014 Jan 1;190:14-9. doi: 10.1016/j.resp.2013.09.002. Epub 2013 Sep 12.
Aspirative capnography may be of help to diagnose early childhood asthma, but clinical usefulness in young children is limited by the relatively high respiratory rate. This study aimed to characterize the [Formula: see text] time course during airway constriction in 8 anesthetized rabbits, artificially ventilated at 30, 60 and 80breaths/min. Methacholine was inhaled to double the respiratory resistance measured at 8Hz by the forced oscillation technique. The capnogram shape changed in response to both methacholine and ventilatory frequency. Slope of phase II, the peak of first-order time derivative and trough of the second-order time derivative of the [Formula: see text] signal, were significantly attenuated after methacholine compared with baseline at all breathing rates (p<0.02). Moreover, significant correlations between respiratory reactance and resistance were observed with the phase III slope and the angle described by phase II and phase III (p<0.01). It is concluded that capnography may be useful to identify acute airway changes related to bronchoconstriction, even at high breathing frequencies.
呼气末二氧化碳描记术可能有助于诊断儿童哮喘，但由于儿童的呼吸频率相对较高，其在幼儿中的临床应用受到限制。本研究旨在描述 8 只麻醉兔在气道收缩时[Formula: see text]时间过程，这些兔子以 30、60 和 80 次/分钟的频率人工通气。通过强迫振荡技术吸入乙酰甲胆碱使 8Hz 时呼吸阻力增加一倍。在所有呼吸频率下（p<0.02），与基线相比，[Formula: see text]信号的二阶时间导数的峰值和二阶时间导数的谷值的第二相斜率、一阶时间导数的峰值在吸入乙酰甲胆碱后均明显降低。此外，还观察到呼吸电抗与阻力之间存在显著相关性，其与第三相斜率以及第二相和第三相之间的角度有关（p<0.01）。因此，呼气末二氧化碳描记术可能有助于识别与支气管收缩相关的急性气道变化，即使在高呼吸频率下也是如此。
