The Effect of Jet Nebulizer Placement Relative to the Heat and Moisture Exchange (HME) Filter on Pulmonary Parameters in Mechanically Ventilated Adults: A Randomized, Double-Blind Controlled Clinical Trial

Background: Heat and moisture exchanger (HME) filters are essential for mechanically ventilated patients but can hinder aerosol delivery. Objectives: This study compared jet nebulizer placement positions relative to the HME filter on pulmonary parameters. Methods: This double-blind randomized controlled trial assessed ۸۶ patients for eligibility. After excluding ۱۳, ۷۳ were randomized into two groups: the intervention group (n=۳۶), where the nebulizer was placed between the patient and the HME filter, and the control group (n=۳۷), where it was placed between the ventilator and the HME. During the trial, ۳ patients died (intervention: ۱, control: ۲), resulting in a final analysis of ۷۰ patients (۳۵ per group). Parameters were measured at baseline and at ۹۰ minutes after each of four bronchodilator doses administered over ۲۴ hours. Data analysis included repeated measures ANOVA via SPSS v.۲۲. Results: Significant within-group time effects were found for mean airway pressure (MAP), SpO₂, lung compliance (Cst), and airway resistance (Raw) (P<۰.۰۵). Tidal volume (VT) and minute ventilation (MV) showed no significant temporal changes (P>۰.۰۵). The time×group interaction was significant only for Raw and SpO₂ (P<۰.۰۵). Between-group analysis revealed significant differences in VT, MAP, SpO₂, Raw, and MV (P<۰.۰۵), but not for Cst (P=۰.۲۲۲). Conclusion: Nebulizer placement relative to the HME filter affects temporal changes in Raw and SpO₂. Considering small-to-moderate effect sizes, differences are primarily physiological; thus, placement should be guided by clinical status and specific protocols.

کلیدواژه ها:

Nebulizers ، Heat and Moisture Exchangers ، Airway Resistance ، Lung Compliance ، Mechanical Ventilation.