Cope Keary A, Watson Michael T, Foster W Michael, Sehnert Shelley S, Risby Terence H
Department of Environmental Health Sciences, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, MD 21205, USA.
J Appl Physiol (1985). 2004 Apr;96(4):1371-9. doi: 10.1152/japplphysiol.01034.2003. Epub 2003 Dec 12.
A computerized system has been developed to monitor tidal volume, respiration rate, mouth pressure, and carbon dioxide during breath collection. This system was used to investigate variability in the production of breath biomarkers over an 8-h period. Hyperventilation occurred when breath was collected from spontaneously breathing study subjects (n = 8). Therefore, breath samples were collected from study subjects whose breathing were paced at a respiration rate of 10 breaths/min and whose tidal volumes were gauged according to body mass. In this "paced breathing" group (n = 16), end-tidal concentrations of isoprene and ethane correlated with end-tidal carbon dioxide levels [Spearman's rank correlation test (r(s)) = 0.64, P = 0.008 and r(s) = 0.50, P = 0.05, respectively]. Ethane also correlated with heart rate (r(s) = 0.52, P < 0.05). There was an inverse correlation between transcutaneous pulse oximetry and exhaled carbon monoxide (r(s) = -0.64, P = 0.008). Significant differences were identified between men (n = 8) and women (n = 8) in the concentrations of carbon monoxide (4 parts per million in men vs. 3 parts per million in women; P = 0.01) and volatile sulfur-containing compounds (134 parts per billion in men vs. 95 parts per billion in women; P = 0.016). There was a peak in ethanol concentration directly after food consumption and a significant decrease in ethanol concentration 2 h later (P = 0.01; n = 16). Sulfur-containing molecules increased linearly throughout the study period (beta = 7.4, P < 0.003). Ventilation patterns strongly influence quantification of volatile analytes in exhaled breath and thus, accordingly, the breathing pattern should be controlled to ensure representative analyses.
已开发出一种计算机化系统，用于在收集呼气时监测潮气量、呼吸频率、口腔压力和二氧化碳。该系统用于研究8小时内呼气生物标志物产生的变异性。当从自主呼吸的研究对象（n = 8）收集呼气时，出现了过度通气。因此，从呼吸频率设定为每分钟10次呼吸且潮气量根据体重测量的研究对象中收集呼气样本。在这个“定频呼吸”组（n = 16）中，异戊二烯和乙烷的呼气末浓度与呼气末二氧化碳水平相关[Spearman等级相关检验（r(s)）= 0.64，P = 0.008；r(s) = 0.50，P = 0.05]。乙烷也与心率相关（r(s) = 0.52，P < 0.05）。经皮脉搏血氧饱和度与呼出一氧化碳之间存在负相关（r(s) = -0.64，P = 0.008）。在男性（n = 8）和女性（n = 8）中，一氧化碳浓度（男性为百万分之4，女性为百万分之3；P = 0.01）和挥发性含硫化合物浓度（男性为十亿分之134，女性为十亿分之95；P = 0.016）存在显著差异。进食后乙醇浓度立即出现峰值，2小时后乙醇浓度显著下降（P = 0.01；n = 16）。在整个研究期间，含硫分子呈线性增加（β = 7.4，P < 0.003）。通气模式强烈影响呼出气体中挥发性分析物的定量，因此，相应地，应控制呼吸模式以确保代表性分析。
