Bisgaard H
Dept of Paediatrics, National University Hospital, Copenhagen, Denmark.
Eur Respir J. 1995 May;8(5):856-60.
The low tidal volume and flow in preschool children may reduce the efficiency of aerosol delivery from a pressurized metered-dose inhaler (pMDI) through a traditional holding chamber. A prototype small-volume steel holding chamber with two one-way valves was devised to prolong aerosol availability in the chamber and to ensure unidirectional airflow. Dead space between the valves was minimized to less than 2 ml. The dose-delivery and rate of passive disappearance of a budesonide pMDI aerosol were compared between this prototype and the large-volume, single-valved plastic Nebuhaler, in 164 asthmatic children less than 8 yrs of age. In vitro, the half life of aerosol disappearance in the steel prototype and the plastic Nebuhaler was > 30 s and 9 s, respectively. In vivo, the prototype delivered an age-independent mean dose of 38% of the nominal dose, and the Nebuhaler delivered an age-dependent mean dose, ranging from 42% of the nominal dose in children > or = 4 yrs to 19% of the nominal dose in infants. We conclude that the use of plastic for holding chambers may influence dose-delivery, and single-valve control may cause age-dependent dose-delivery. Reproducible age-independent drug-delivery may be achieved by pMDI aerosol inhaled through a small-volume metal holding chamber with separate inlet and outlet valves and minimized dead space. This holding chamber would improve the possibilities of aerosol therapy for young children.
学龄前儿童的低潮气量和低气流可能会降低通过传统储雾罐使用压力定量吸入器（pMDI）进行气溶胶给药的效率。设计了一种带有两个单向阀的小容量钢制储雾罐原型，以延长罐内气溶胶的存留时间，并确保气流单向流动。阀之间的死腔最小化至小于2毫升。在164名8岁以下的哮喘儿童中，比较了该原型与大容量单阀塑料储雾罐（Nebuhaler）对布地奈德pMDI气溶胶的给药剂量和被动消失率。在体外，钢制原型和塑料Nebuhaler中气溶胶消失的半衰期分别>30秒和9秒。在体内，原型输送的平均剂量与年龄无关，为标称剂量的38%，而Nebuhaler输送的平均剂量与年龄有关，范围从4岁及以上儿童的标称剂量的42%到婴儿的标称剂量的19%。我们得出结论，储雾罐使用塑料可能会影响给药剂量，单阀控制可能会导致剂量随年龄变化。通过pMDI气溶胶经带有独立进、出口阀且死腔最小化的小容量金属储雾罐吸入，可实现与年龄无关的可重复给药。这种储雾罐将改善幼儿气溶胶治疗的可能性。
