Mitchell Jolyon P, Nagel Mark W, Bates Sara Lou, Doyle Cathy C
Trudell Medical International, London, Ontario, Canada.
Respir Care. 2003 Jan;48(1):46-51.
Current American Thoracic Society and American Association for Respiratory Care guidelines for the delivery of aerosol agents such as methacholine chloride (MC) for bronchoprovocation testing require the use of pneumatic jet nebulizers that have well-defined droplet size and mass output. A recently developed disposable, breath-actuated nebulizer (AeroEclipse) may offer bronchoprovocation testers an alternative to existing devices.
We studied the performance of 5 AeroEclipse nebulizers with regard to mass of MC delivered with various MC solution concentrations and numbers of inhalations, using a model of adult tidal breathing. Each nebulizer was operated with compressed air (8 L/min at 50 psig) and an initial fill of 2 mL. MC solutions with mass concentrations of 0.25, 0.98, 3.85, and 15.70 mg/mL were tested. The total mass of MC delivered was determined after 5, 10, and 15 complete breathing cycles, by assaying the MC collected on a filter placed at the nebulizer mouthpiece. The aerosol droplet size distribution, fine droplet fraction (FDF) (percentage of droplets < 4.8 microm diameter), and fine droplet mass (FDM) (mass of droplets < 4.8 microm diameter) were determined by laser diffractometry, using physiologically normal saline as a surrogate for MC solution.
The mean +/- SD FDM collected in 5 breathing cycles was 654 +/- 29 microg with the 15.70 mg/mL solution, 158 +/- 9 microg with the 3.85 mg/mL solution, 37 +/- 3 microg with the 0.98 mg/mL solution, and 7 +/- 2 microg with the 0.25 mg/mL solution. FDM showed a linear correlation (r(2) = 0.9999) with MC concentration, within the range studied. FDM also showed a linear correlation (r(2) = 0.999) with the number of breathing cycles. For instance, with the 15.70 mg/mL solution, FDM was 654 +/- 29 microg with 5 breathing cycles, 1,228 +/- 92 microg with 10 breathing cycles, and 1,876 +/- 132 microg with 15 breathing cycles.
Although the bronchoprovocation test procedure had to be slightly modified from the guidelines to accommodate the operation of the AeroEclipse's breath-actuation feature, our measurements indicate that a predictable dose of MC, within the useful range for bronchoprovocation testing, can be delivered to an adult patient breathing tidally. The green indicator on the AeroEclipse could be used to coach the patient to inhale for a specific period, thereby controlling MC delivery per breathing cycle.
美国胸科学会和美国呼吸护理协会目前关于用于支气管激发试验的雾化剂（如氯化乙酰甲胆碱）给药的指南要求使用具有明确液滴大小和质量输出的气动喷射雾化器。最近开发的一次性呼吸驱动雾化器（AeroEclipse）可能为支气管激发试验者提供现有设备的替代选择。
我们使用成人潮气呼吸模型，研究了5个AeroEclipse雾化器在不同氯化乙酰甲胆碱溶液浓度和吸入次数下的氯化乙酰甲胆碱输送量。每个雾化器使用压缩空气（50 psig下8 L/min）操作，初始填充量为2 mL。测试了质量浓度为0.25、0.98、3.85和15.70 mg/mL的氯化乙酰甲胆碱溶液。在5、10和15个完整呼吸周期后，通过分析放置在雾化器吸嘴处滤器上收集的氯化乙酰甲胆碱来确定输送的氯化乙酰甲胆碱总量。使用生理生理盐水替代氯化乙酰甲胆碱溶液，通过激光衍射法测定气溶胶液滴大小分布、细液滴分数（FDF）（直径<4.8微米的液滴百分比）和细液滴质量（FDM）（直径<4.8微米的液滴质量）。
在5个呼吸周期中收集的平均±标准差FDM，15.70 mg/mL溶液为654±29微克，3.85 mg/mL溶液为158±9微克，0.98 mg/mL溶液为37±3微克，0.25 mg/mL溶液为7±2微克。在所研究的范围内，FDM与氯化乙酰甲胆碱浓度呈线性相关（r² = 0.9999）。FDM与呼吸周期数也呈线性相关（r² = 0.999）。例如，对于15.70 mg/mL溶液，5个呼吸周期时FDM为654±29微克，10个呼吸周期时为1228±92微克，15个呼吸周期时为1876±132微克。
尽管支气管激发试验程序必须根据指南进行轻微修改以适应AeroEclipse的呼吸驱动功能的操作，但我们的测量表明，在支气管激发试验的有效范围内，可以向潮气呼吸的成年患者输送可预测剂量的氯化乙酰甲胆碱。AeroEclipse上的绿色指示灯可用于指导患者在特定时间段内吸气，从而控制每个呼吸周期的氯化乙酰甲胆碱输送量。
