This single-center randomized controlled trial will evaluate whether real-time visual feedback from electrical impedance tomography (EIT) improves the immediate distribution of lung ventilation during incentive spirometry in adults with postoperative atelectasis. Approximately 60 participants will be randomized 1:1 to receive either EIT-guided visual feedback or standardized verbal guidance during one session of 30 incentive-spirometry breaths. The primary outcome is the change in dorsal ventilation fraction from before training to 5 minutes after training. Secondary outcomes include inspiratory capacity, ventilation homogeneity, dependent silent spaces, end-expiratory lung impedance, oxygenation, in-hospital intubation or reintubation, and intervention-related adverse events.
Age 18 years or older.
Admitted to an intensive care unit or postoperative monitoring unit after major thoracic or upper-abdominal surgery; tracheal tube removed; spontaneously breathing; and clinically stable.
Alert and able to understand and follow incentive-spirometry and EIT instructions.
Bedside lung ultrasound shows atelectasis or markedly reduced aeration in dorsal or posterolateral lung regions, with the lung-ultrasound assessment recorded.
Ongoing invasive mechanical ventilation or noninvasive ventilation, or high-flow nasal oxygen when study conditions cannot be maintained stably.
Hemodynamic instability or inability to tolerate a semi-recumbent position.
Inability to cooperate with training or impaired consciousness.
Unsuitable for EIT monitoring, including an implanted pacemaker or defibrillator incompatible with the device, severe skin disease at the electrode-belt site, or known relevant allergy.
Parallel
EIT-Guided Incentive Spirometry
BehavioralParticipants perform three sets of 10 incentive-spirometry breaths while viewing real-time electrical impedance tomography images. Trained staff provide standardized, target-directed feedback to increase ventilation in dependent dorsal lung regions.
Standardized Incentive Spirometry Guidance
BehavioralParticipants perform three sets of 10 incentive-spirometry breaths with the EIT screen concealed. Trained staff provide standardized verbal instructions on posture, slow sustained inspiration, a 2- to 3-second breath hold, and rest between breaths, without imaging feedback.
Change in Dorsal Ventilation Fraction
Dorsal ventilation fraction is the percentage of tidal ventilation occurring in the dorsal lung region during stable spontaneous breathing. The outcome is calculated as DVF at T1 minus DVF at T0 using 2-minute EIT recordings and a fixed offline analysis algorithm. Higher values indicate a greater shift of ventilation toward the dorsal region.
Mean Inspiratory Volume
Mean volume or device scale reached across the 30 incentive-spirometry breaths performed during the training session.
Change in Global Inhomogeneity Index
The EIT-derived global inhomogeneity index at T1 minus the value at T0. Lower values indicate improved ventilation homogeneity.
Change in End-Expiratory Lung Impedance
End-expiratory lung impedance at T1 minus the value at T0, derived from EIT. An increase generally indicates an increase in end-expiratory lung volume.
Change in Dependent Silent Spaces
Percentage of dependent silent spaces at T1 minus the percentage at T0, derived from EIT. A decrease indicates fewer dependent lung regions with little or no ventilation.
Intervention-Related Adverse Events
Number and proportion of participants with adverse events related to EIT monitoring or incentive-spirometry training, including skin irritation or pressure discomfort, worsened dyspnea, persistent oxygen desaturation, dizziness, hemodynamic instability, or increased incisional pain requiring the session to stop.
Change in PaO2/FiO2 Ratio
Change in PaO2/FiO2 from T0 to T1 when an arterial blood gas result is available from routine clinical care. No arterial blood sample is collected solely for this study.
ICU Length of Stay
Number of calendar days from ICU admission to ICU discharge, descriptively summarized.
Escalation of Respiratory Support
Number and proportion of participants requiring escalation of respiratory support after enrollment, including invasive ventilation or reintubation, noninvasive ventilation, or high-flow nasal oxygen.
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