Imai Tadashi, Satoh Katashi, Manabe Noriko, Miyoshi Makoto, Ichihara Naoto, Ozaki Risa, Kato Miho, Miki Arisa, Yokoo Tomoko, Kasai Miyoko, Hose Yoshie, Takagi Michiko, Kishimoto Nobuto
Department of Medical Technology, Graduate School of Kagawa Prefectural University of Health Sciences, Takamatsu, Japan.
Rinsho Byori. 2011 May;59(5):459-65.
The flow volume curve is an essential test method for diagnosis and treatment of the respiratory diseases. However, this curve depends on patient's continuous effort toward optimal expiration and it has been reported that differences in this effort may possibly result in error in flow speed. To overcome the potential error, we devised the "average flow" and the "acceleration wave" that comprehends the overall data of the expiration flow speed, and have done comparative analysis with the current parameters.
The average flow is derived by taking the integration from the beginning of the expiration to the end, and divides the integrated value by the number of data counts. Additionally, the acceleration wave is derived by taking the second degree derivative of the flow volume curve.
The average flow showed strong correlation among healthy male and healthy female V50, obstructive index and criteria for COPD severity patients. Also, we were able to obtain the maximum acceleration from the acceleration wave. Significantly, this value showed strong correlation with the COPD patient's peak flow and average flow/peak flow.
If the ratio of the average flow and the peak flow is below a fixed criterion, it is an obstructive lung disease, if it is above, it is possible to detect restrictive lung disease. Since the maximum acceleration rate of the acceleration wave is derived by the start of the expiration nearly up to 100 ml, it is especially possible to detect minute changes of the flow speed in large respiratory tract.
流量容积曲线是呼吸系统疾病诊断和治疗的重要检测方法。然而，该曲线依赖于患者持续进行最佳呼气努力，且有报道称这种努力的差异可能导致流速出现误差。为克服潜在误差，我们设计了“平均流量”和“加速波”，它们包含了呼气流速的整体数据，并与当前参数进行了对比分析。
平均流量通过对呼气开始到结束进行积分得出，然后将积分值除以数据点数。此外，加速波通过对流量容积曲线求二阶导数得出。
平均流量在健康男性和健康女性的V50、阻塞指数以及慢性阻塞性肺疾病（COPD）严重程度标准患者之间显示出强相关性。而且，我们能够从加速波中获得最大加速度。值得注意的是，该值与COPD患者的峰值流量以及平均流量/峰值流量显示出强相关性。
如果平均流量与峰值流量的比值低于固定标准，则为阻塞性肺疾病；如果高于该标准，则有可能检测出限制性肺疾病。由于加速波的最大加速度率是在呼气开始近100毫升时得出的，因此尤其能够检测到大呼吸道中流速的微小变化。
