en Nursing Orginal research <div style="text-align: justify;"><span style="line-height:2;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="color:#2980b9;"><b>Background: </b></span>Heat and moisture exchanger (HME) filters are essential for mechanically ventilated patients but can hinder aerosol delivery.<br> <span style="color:#2980b9;"><b>Objectives:</b></span> This study compared jet nebulizer placement positions relative to the HME filter on pulmonary parameters.<b> </b><br> <span style="color:#2980b9;"><b>Methods:</b></span> 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.<b> </b><br> <b><span style="color:#2980b9;">Results:</span> </b>Significant within-group time effects were found for mean airway pressure (MAP), SpO₂, lung compliance (Cst), and airway resistance (Raw) (P<0.05). Tidal volume (VT) and minute ventilation (MV) showed no significant temporal changes (P>0.05). The time&times;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).<b> </b><br> <b><span style="color:#2980b9;">Conclusion:</span> </b>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.</span></span></span><br> &nbsp;</div> Nebulizers, Heat and Moisture Exchangers, Airway Resistance, Lung Compliance, Mechanical Ventilation. 60 69 http://nmcjournal.zums.ac.ir/browse.php?a_code=A-10-1053-1&slc_lang=en&sid=1 Zahra Khezerlou Zahrakhezerloo8@gmail.com 100319475328460014798 100319475328460014798 No RN, PhD Student in Nursing, Nursing and Midwifery School, Zanjan University of Medical Sciences, Zanjan, Iran. Akram Khediri a.khediri@gmail.com 100319475328460014799 100319475328460014799 No MScN, Department of Critical Care and Emergency Nursing, School of Nursing and Midwifery, Zanjan University of Medical Sciences, Zanjan, Iran. Farhad Ramezani-Badr Ramezanibadr@gmail.com 100319475328460014800 100319475328460014800 Yes Associate ProfessorDepartment of Critical Care and Emergency Nursing, School of Nursing and Midwifery, Zanjan University of Medical Sciences, Zanjan, Iran. Mohammad Reza Din Mohammadi mdinmohammadi@zums.ac.ir 100319475328460014801 100319475328460014801 No Department of Nusing, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran. & Education Development Center (EDC), Zanjan University of Medical Sciences, Zanjan, Iran. Samad Ghodrati samad.ghodrati@zums.ac.ir 100319475328460014802 100319475328460014802 No Department of Pulmonology, Vali-e-Asr Hospital, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran 2 Internal Medicine Department, Zanjan University of Medical Sciences, Zanjan, Iran Mahtab Aligholipour aligholipourmahtab@gmail.com 100319475328460014803 100319475328460014803 No 1RN, PhD Student in Nursing, Nursing and Midwifery School, Zanjan University of Medical Sciences, Zanjan, Iran.