School of Paediatrics and Child Health, University of Western Australia, Perth, Western Australia.
J Aerosol Med Pulm Drug Deliv. 2010 Oct;23(5):311-22. doi: 10.1089/jamp.2008.0733.
Output from spacers (or valved holding chambers) is sensitive to changes in breathing pattern. Different spacers have unique characteristics that may influence breathing. A method used for breathing simulation, where the simulated breathing can be recorded on subjects while they are using spacers, may allow for more accurate in vitro estimation of drug delivery in specific populations, using specific spacers.
A flow chamber was used to record breathing while salbutamol was administered to two adult subjects through different spacers. Each subject performed a series of breathing patterns over a range of different inhalation volumes and flows. Salbutamol "inhaled" by subjects was captured on inspiratory filters and quantified by ultraviolet spectrophotometry. Recorded breathing patterns were simulated and ex vivo drug delivery was compared to in vitro drug delivery. Three equipment configurations were used to validate different aspects of the methodology. Configuration 1: breathing recorded by pneumotachometer placed directly between a human subject and the spacer. Breathing simulation performed with an identical setup. Configuration 2: spacer enclosed within a flow-chamber while breathing was recorded. Breathing simulation performed with an identical setup. Configuration 3: spacer enclosed in flow chamber to record breathing, but not when simulating breathing. In each configuration, the ex vivo and in vitro (simulated) filter doses were compared.
Configuration 1: the median difference between ex vivo and in vitro filter doses was 0.4% (range: -12.2 to 6.9%). Configuration 2: the median difference was -2.3% (range: -9.0 to 5.0%). Configuration 3: the median difference was 1.7% (range: -11.5 to 3.9%).
Our results indicate that in vitro simulated drug delivery using this method of recording using a flow chamber, closely approximates ex vivo total drug delivery. This technique allows for recording of breathing on patients while they are using spacers, with minimum increase in dead space or resistance, and no physical alteration in the patient-device interface.
从储雾器（或带阀的储雾罐）输出的药物剂量对呼吸模式的变化非常敏感。不同的储雾器具有独特的特性，可能会影响呼吸。一种用于呼吸模拟的方法，即在患者使用储雾器时记录他们的模拟呼吸，可以使用特定的储雾器更准确地估计特定人群的药物输送体外。
使用流量室记录沙丁胺醇通过不同储雾器输送给两名成年受试者时的呼吸情况。每位受试者在不同的吸入量和流速范围内进行了一系列的呼吸模式。受试者吸入的沙丁胺醇被吸入过滤器捕获，并通过紫外分光光度法进行定量。记录呼吸模式并进行体外药物输送模拟，并将其与体外药物输送进行比较。使用三种设备配置来验证该方法的不同方面。配置 1： 通过直接放置在人体受试者和储雾器之间的气动计记录呼吸。使用相同的设置进行呼吸模拟。配置 2： 将储雾器封闭在流量室中，同时记录呼吸。使用相同的设置进行呼吸模拟。配置 3： 将储雾器封闭在流量室中以记录呼吸，但不进行呼吸模拟。在每种配置中，比较体外和体外（模拟）过滤器剂量。
配置 1： 体外和体外过滤器剂量的中位数差异为 0.4%（范围：-12.2 至 6.9%）。配置 2： 中位数差异为-2.3%（范围：-9.0 至 5.0%）。配置 3： 中位数差异为 1.7%（范围：-11.5 至 3.9%）。
我们的结果表明，使用这种记录方法和流量室进行体外模拟药物输送，非常接近体外总药物输送。该技术允许在患者使用储雾器时记录他们的呼吸，而对死腔或阻力的增加最小，并且对患者设备接口没有物理改变。
