Mitchell Jolyon P, Nagel Mark W, Wiersema Kimberly J, Doyle Cathy C, Migounov Vladimir A
Trudell Medical International, London, Ontario, Canada.
Respir Care. 2003 Nov;48(11):1025-32.
UNLABELLED: We describe a laboratory investigation comparing the delivery of chlorofluorocarbon (CFC)- and hydrofluoroalkane (HFA)-formulated beclomethasone dipropionate (BDP) by metered-dose inhaler and holding chamber (AeroChamber HC MV) in a simulation of a mechanically ventilated adult patient. METHODS: We equipped each HC MV (n = 5) with an 8.0 mm diameter endotracheal tube (ETT), locating the HC MV in the inspiratory limb of a breathing circuit linked to a mechanical ventilator set to simulate tidal breathing at tidal volume = 830 mL, respiratory rate = 15 breaths/min, inspiratory-expiratory ratio of 1:2.1, peak inspiratory pressure = 20 cm H(2)O. Temperature and humidity settings were 35+/-1 degrees C and 100% relative humidity (close to body conditions). We compared delivery of 5-actuations of CFC- and HFA-BDP (both 50 microg/actuation), measuring total emitted mass captured by a filter at the distal end of the ETT. In a separate study, we inserted the distal end of the ETT within the entry cone of a cascade impactor so that the aerosol particle size distribution could be determined with the circuit at similar environmental conditions as described previously. We made benchmark measurements with circuit temperature and humidity at room ambient conditions (21+/-1 degrees C and 54+/-5% RH respectively). RESULTS: Total emitted mass (5 measurements/device) was significantly greater for HFA-BDP (14.1+/-1.1 microg/actuation) compared with CFC-BDP (2.4+/-0.8 microg/actuation) (paired t test, p < 0.001). More HFA-BDP (2.7 +/- 0.2 microg/actuation) was lost from the delivery system during exhalation (0.9 +/- 0.4 microg/actuation for CFC-BDP) (p < 0.001). The mass median aerodynamic diameter (MMAD) increased from 1.2 microm (room ambient) to 2.8 microm (higher temperature and humidity conditions) for HFA-BDP. In contrast, MMAD for CFC-BDP remained close to 4.6 microm under either condition, but particles finer than about 4.0 microm increased in size when the circuit was saturated. CONCLUSIONS: Total emitted mass for HFA-BDP was increased by a factor of 5.8 compared with CFC-BDP, due largely to the finer particle size distribution of the HFA-based solution formulation. Additional water vapor required to operate the breathing circuit at close to body conditions resulted in fine particle growth with both formulations.
未标注：我们描述了一项实验室研究，该研究在模拟机械通气成年患者的情况下，比较了使用定量吸入器和储雾罐（AeroChamber HC MV）递送氯氟烃（CFC）和氢氟烷烃（HFA）配方的丙酸倍氯米松（BDP）的情况。 方法：我们为每个储雾罐（n = 5）配备了一根直径8.0毫米的气管内插管（ETT），将储雾罐置于与机械通气机相连的呼吸回路的吸气支中，该机械通气机设置为模拟潮气量 = 830毫升、呼吸频率 = 15次/分钟、吸呼比为1:2.1、吸气峰压 = 20厘米水柱的潮气呼吸。温度和湿度设置为35±1摄氏度和100%相对湿度（接近人体条件）。我们比较了CFC - BDP和HFA - BDP（均为50微克/揿）各5次揿压的递送情况，测量ETT末端过滤器捕获的总喷出质量。在另一项研究中，我们将ETT的末端插入多级冲击器的入口锥内，以便在与先前描述的类似环境条件下测定回路中的气溶胶粒径分布。我们在室温环境条件（分别为21±1摄氏度和54±5%相对湿度）下对回路温度和湿度进行了基准测量。 结果：与CFC - BDP（2.4±0.8微克/揿）相比，HFA - BDP的总喷出质量（每个装置5次测量）显著更高（14.1±1.1微克/揿）（配对t检验，p < 0.001）。呼气过程中，HFA - BDP从递送系统中损失的量更多（2.7±0.2微克/揿），而CFC - BDP为（0.9±0.4微克/揿）（p < 0.001）。HFA - BDP的质量中值空气动力学直径（MMAD）从（室温环境下的）1.2微米增加到（较高温度和湿度条件下的）2.8微米。相比之下，CFC - BDP的MMAD在两种条件下均保持接近4.6微米，但当回路饱和时，粒径小于约4.0微米的颗粒尺寸会增大。 结论：与CFC - BDP相比，HFA - BDP的总喷出质量增加了5.8倍，这主要归因于基于HFA的溶液制剂的粒径分布更细。在接近人体条件下操作呼吸回路所需额外的水蒸气导致两种制剂的细颗粒均生长。
Ann Allergy Asthma Immunol. 2001-5
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