Gurses Burak K, Smaldone Gerald C
Pulmonary and Critical Care Division, State University of New York at Stony Brook, Stony Brook, New York 11794-8172, USA.
J Aerosol Med. 2003 Winter;16(4):387-94. doi: 10.1089/089426803772455640.
Aerosols produced by nebulizers are often characterized on the bench using cascade impactors. We studied the effects of connecting tubing, breathing pattern, and temperature on mass-weighted aerodynamic particle size aerosol distributions (APSD) measured by cascade impaction. Our experimental setup consisted of a piston ventilator, low-flow (1.0 L/min) cascade impactor, two commercially available nebulizers that produced large and small particles, and two "T"-shaped tubes called "Tconnector(cascade)" and "Tconnector(nebulizer)" placed above the impactor and the nebulizer, respectively. Radiolabeled normal saline was nebulized using an airtank at 50 PSIG; APSD, mass balance, and Tconnector(cascade) deposition were measured with a gamma camera and radioisotope calibrator. Flow through the circuit was defined by the air tank (standing cloud, 10 L/min) with or without a piston pump, which superimposed a sinusoidal flow on the flow from the air tank (tidal volume and frequency of breathing). Experiments were performed at room temperature and in a cooled environment. With increasing tidal volume and frequency, smaller particles entered the cascade impactor (decreasing MMAD; e.g., Misty-Neb, 4.2 +/- 0.9 microm at lowest ventilation and 2.7 +/- 0.1 microm at highest, p = 0.042). These effects were reduced in magnitude for the nebulizer that produced smaller particles (AeroTech II, MMAD 1.8 +/- 0.1 to 1.3 +/- 0.1 microm; p = 0.0044). Deposition on Tconnector(cascade) increased with ventilation but was independent of cascade impactor flow. Imaging of the Tconnector(cascade) revealed a pattern of deposition unaffected by cascade impactor flow. These measurements suggest that changes in MMAD with ventilation were not artifacts of tubing deposition in the Tconnector(cascade). At lower temperatures, APSD distributions were more polydisperse. Our data suggest that, during patient inhalation, changes in particle distribution occur that are related to conditions in the tubing and may reduce the diameters of particles entering the patient. This effect is more significant for nebulizers producing large particles. Changes in ambient temperature did not affect these observations.
雾化器产生的气溶胶通常在实验台上使用多级冲击器进行表征。我们研究了连接管路、呼吸模式和温度对通过多级冲击测量的质量加权空气动力学粒径气溶胶分布（APSD）的影响。我们的实验装置包括一个活塞呼吸机、低流量（1.0 L/min）多级冲击器、两个可产生大颗粒和小颗粒的市售雾化器，以及分别置于冲击器和雾化器上方的两个称为“T形连接器（冲击器）”和“T形连接器（雾化器）”的“T”形管。使用50 PSIG的储气罐雾化放射性标记的生理盐水；用γ相机和放射性同位素校准器测量APSD、质量平衡和T形连接器（冲击器）的沉积。通过回路的流量由储气罐（静置云雾，10 L/min）定义，有或没有活塞泵，活塞泵会在来自储气罐的气流上叠加正弦流（潮气量和呼吸频率）。实验在室温及冷却环境下进行。随着潮气量和频率增加，更小的颗粒进入多级冲击器（MMAD降低；例如，Misty-Neb在最低通气时为4.2±0.9微米，在最高通气时为2.7±0.1微米，p = 0.042）。对于产生较小颗粒的雾化器（AeroTech II，MMAD从1.8±0.1微米至1.3±0.1微米；p = 0.0044），这些影响的程度有所降低。T形连接器（冲击器）上的沉积随通气增加，但与多级冲击器流量无关。T形连接器（冲击器）的成像显示沉积模式不受多级冲击器流量影响。这些测量结果表明，通气时MMAD的变化不是T形连接器（冲击器）中管路沉积的假象。在较低温度下，APSD分布更具多分散性。我们的数据表明，在患者吸入期间，颗粒分布会发生变化，这与管路中的状况有关，并且可能会减小进入患者体内的颗粒直径。对于产生大颗粒的雾化器，这种影响更为显著。环境温度的变化并未影响这些观察结果。
