We recently developed a model-based method for analyzing multiple breath nitrogen washout data that does not require identification of Phase-III. In the present study, we assessed the effect of irregular breathing patterns on the intra-subject variabilities of the model parameters. Nitrogen fraction at the mouth was measured in 18 healthy and 20 asthmatic subjects during triplicate performances of multiple breath nitrogen washout, during controlled (target tidal volume 1 L at 8–12 breaths per minute) and free (unrestricted) breathing. The parameters S_cond, S_acin and functional residual capacity (FRC) were obtained by conventional analysis of the slope of Phase-III. Fitting the model to the washout data provided functional residual capacity (FRC_M), dead space volume (V_D), the coefficient of variation of regional specific ventilation (\({\mathrm{C}}_{\mathrm{V}{,\dot{\mathrm{V}}}_{\mathrm{e}}}\)), and the model equivalent of S_acin (S_acin-M). Intra-participant coefficients of variation for the model parameters for both health and asthma were FRC_M < 5.2%, V_D < 5.4%, \({\mathrm{C}}_{\mathrm{V}{,\dot{\mathrm{V}}}_{\mathrm{e}}}\) < 9.0%, and S_acin-M < 45.6% for controlled breathing, and FRC_M < 4.6%, V_D < 5.3%, \({\mathrm{C}}_{\mathrm{V}{,\dot{\mathrm{V}}}_{\mathrm{e}}}\) < 13.2%, and S_acin-M < 103.2% for free breathing. The coefficients of variation limits for conventional parameters were FRC < 6.1%, with S_cond < 73.6% and S_acin < 49.2% for controlled breathing and S_cond < 35.0% and S_acin < 74.4% for free breathing. The model-fitting approach to multiple breath nitrogen washout analysis provides a measure of regional ventilation heterogeneity in \({\mathrm{C}}_{\mathrm{V}{,\dot{\mathrm{V}}}_{\mathrm{e}}}\) that is less affected by irregularities in the breathing pattern than its corresponding Phase-III slope analysis parameter S_cond.

我们最近开发了一种基于模型的方法来分析不需要识别 III 期的多​​次呼吸氮洗脱数据。在本研究中，我们评估了不规则呼吸模式对模型参数的受试者内变异性的影响。在多次呼吸氮冲洗、受控（目标潮气量 1 L，每分钟 8-12 次呼吸）和自由（无限制）呼吸期间，测量 18 名健康受试者和 20 名哮喘受试者的口腔氮分数。参数S _cond、S _acin和功能残气量(FRC)通过III期斜率的常规分析获得。将模型拟合到洗脱数据提供的功能残余容量（FRC _M), 死腔容积(V _D ), 区域比通风变异系数( \({\mathrm{C}}_{\mathrm{V}{,\dot{\mathrm{V}}}_{\ mathrm{e}}}\) ），以及 S _acin (S _acin-M )的等效模型。健康和哮喘模型参数的参与者内部变异系数为 FRC _M  < 5.2%，V _D  < 5.4%，\({\mathrm{C}}_{\mathrm{V}{,\dot{\ mathrm{V}}}_{\mathrm{e}}}\) < 9.0%，S _acin-M  < 45.6% 用于控制呼吸，FRC _M  < 4.6%，V _D  < 5.3%，\({\ mathrm{C}}_{\mathrm{V}{,\dot{\mathrm{V}}}_{\mathrm{e}}}\) < 13.2%, 和S_acin-M  < 103.2% 表示自由呼吸。常规参数的变异系数限制为 FRC < 6.1%， 控制呼吸的S _cond  < 73.6% 和 S _acin < 49.2%， 自由呼吸的S _cond  < 35.0% 和 S _{acin < 74.4%。}多次呼吸氮冲刷分析的模型拟合方法提供了\({\mathrm{C}}_{\mathrm{V}{,\dot{\mathrm{V}}}_{\ mathrm{e}}}\)比其相应的 Phase-III 斜率分析参数 S _cond受呼吸模式不规则性的影响更小。