Abstract：
Introduction: During mechanical ventilation (MV), inspired gases require heat and humidification. However, such conditions may be associated with reduced aerosol delivery efficiency. The practice of turning off heated humidification before nebulization and the impact of nebulization on humidity in a dry ventilator circuit remain topics of debate. This study aimed to assess the effect of turning off heated humidification on inhaled dose and humidity with nebulizer use during adult MV. Methods: A bronchodilator (albuterol) and two antibiotics (Colistimethate sodium and Amikacin sulfate) were nebulized with a vibrating mesh nebulizer placed at the humidifier inlet and in the inspiratory limb at the Y-piece. Additionally, albuterol was nebulized using a jet nebulizer in both placements. Aerosol particle size distribution was determined through a cascade impactor. Absolute humidity (AH) and temperature of inspired gases were determined with anemometer/hygrometers before, during, and after nebulization, before, during, and up to 60 minutes after interrupting active humidification. Aerosol collected on a filter distal to the endotracheal tube and on impactor stages were eluted and assayed by spectrophotometry. Results: The inhaled dose was greater when both nebulizers were placed at the humidifier inlet than the inspiratory limb at the Y-piece. Irrespective of the nebulizer types and placements, the inhaled dose either decreased or showed no significant change after the humidifier was turned off. The aerosol particle size ranged from 1.1 to 2.7 μm. With interruption of active humidification, humidity of inspired gas quickly dropped below recommended levels, and nebulization in dry ventilator circuit produced an AH between 10 and 20 mgH2O/L, lower than the recommended minimum of 30 mgH2O/L. Conclusion: Interrupting active humidification during MV before nebulization did not improve aerosol delivery efficiency for bronchodilator or antibiotics, but did reduce humidity below recommended levels.
摘要：
简介：在机械通气（MV）期间，吸入气体需要加热和加湿。然而,这样的条件可能与降低的气溶胶递送效率相关联。在雾化之前关闭加热加湿的做法以及雾化对干燥呼吸机回路中湿度的影响仍然是争论的话题。这项研究旨在评估在成人MV期间使用雾化器关闭加热加湿对吸入剂量和湿度的影响。方法：将支气管扩张剂（沙丁胺醇）和两种抗生素（大肠杆菌甲磺酸钠和硫酸阿米卡星）用振动网状雾化器雾化，该雾化器放置在加湿器入口处和Y形件的吸气肢体中。此外,沙丁胺醇在两个位置都使用喷射雾化器进行雾化。通过级联冲击器测定气溶胶粒度分布。之前用风速计/湿度计确定吸入气体的绝对湿度(AH)和温度，during,雾化后，之前，during,中断主动加湿后长达60分钟。将收集在气管内导管远端的过滤器上和冲击器级上的气溶胶洗脱并通过分光光度法测定。结果：当两个雾化器都放置在加湿器入口处时，吸入剂量大于Y形件处的吸气肢。无论雾化器类型和位置如何，加湿器关闭后，吸入剂量减少或无明显变化。气溶胶粒径为1.1至2.7μm。随着主动加湿的中断，吸入气体的湿度迅速下降到建议水平以下，在干燥的呼吸机回路中雾化产生的AH在10到20mgH2O/L之间，低于建议的最小值30mgH2O/L。结论：在雾化前中断MV期间的主动湿化并不能提高支气管扩张剂或抗生素的气雾剂递送效率。但确实将湿度降低到建议水平以下。
