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 86 patients for eligibility. After excluding 13, 73 were randomized into two groups: the intervention group (n=36), where the nebulizer was placed between the patient and the HME filter, and the control group (n=37), where it was placed between the ventilator and the HME. During the trial, 3 patients died (intervention: 1, control: 2), resulting in a final analysis of 70 patients (35 per group). Parameters were measured at baseline and at 90 minutes after each of four bronchodilator doses administered over 24 hours. Data analysis included repeated measures ANOVA via SPSS v.22. Results: Significant within-group time effects were found for mean airway pressure (MAP), SpO₂, lung compliance (Cst), and airway resistance (Raw) (P0.05). The time×group interaction was significant only for Raw and SpO₂ (P<0.05). Between-group analysis revealed significant differences in VT, MAP, SpO₂, Raw, and MV (P<0.05), but not for Cst (P=0.222). 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.
Khezerlou et al. (Sat,) studied this question.