EIT-Guided Visual Feedback During Incentive Spirometry for Postoperative Atelectasis

Effects of Electrical Impedance Tomography-Guided Visual Feedback During Incentive Spirometry on the Immediate Ventilation Distribution in Postoperative Patients With Atelectasis: A Prospective Randomized Controlled Trial

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Postoperative Atelectasis
• Intervention / Treatment: Behavioral: EIT-Guided Incentive Spirometry; Behavioral: Standardized Incentive Spirometry Guidance

Detailed Description

Eligible adults recovering from major thoracic or upper-abdominal surgery will be screened using bedside lung ultrasound and baseline EIT. Participants must be spontaneously breathing, clinically stable, able to follow instructions, and have a baseline dorsal ventilation fraction below 50%.

After a 2-minute baseline EIT recording in a 30- to 45-degree semi-recumbent position, participants will be randomized through a central randomization system using stratified variable blocks based on baseline dorsal ventilation fraction. Both groups will complete three sets of 10 incentive-spirometry breaths. In the experimental group, the EIT screen will be visible and trained staff will provide real-time, target-directed feedback intended to increase ventilation in dependent dorsal lung regions. In the control group, the EIT screen will be concealed and participants will receive standardized verbal instructions without imaging feedback.

After training, participants will rest for 5 minutes and undergo a second 2-minute EIT recording under stable oxygen-therapy conditions. EIT outcomes will be calculated offline by assessors blinded to group assignment. Respiratory-support outcomes will be recorded through hospital discharge. Intervention-related adverse events will be recorded from the start of the single intervention session through 24 hours after completion of the session.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Shanghai Municipality
    • Shanghai, Shanghai Municipality, China, 200032
      • Zhongshan Hospital, Fudan University
      • Contact: Kai Liu, BSc; Phone Number: +86-13512136346; Email: Liu.kai1@zs-hospital.sh.cn
      • Principal Investigator: Kai Liu, BSc

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Age 18 years or older.
2. 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.
3. Alert and able to understand and follow incentive-spirometry and EIT instructions.
4. Bedside lung ultrasound shows atelectasis or markedly reduced aeration in dorsal or posterolateral lung regions, with the lung-ultrasound assessment recorded.
5. Baseline EIT during quiet breathing in a semi-recumbent position shows insufficient dorsal ventilation with potential for improvement; dorsal ventilation fraction below 50%.
6. Written informed consent provided by the participant or legally authorized representative according to the ethics-approved process, with participant re-consent when decision-making capacity returns.

Exclusion Criteria:

1. Ongoing invasive mechanical ventilation or noninvasive ventilation, or high-flow nasal oxygen when study conditions cannot be maintained stably.
2. Hemodynamic instability or inability to tolerate a semi-recumbent position.
3. Inability to cooperate with training or impaired consciousness.
4. 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.
5. Severe underlying pulmonary disease likely to substantially affect ventilation distribution and obscure the intervention effect.
6. Chest-wall deformity or severe scoliosis affecting EIT image quality.
7. Body mass index greater than 35 kg/m2.
8. Pregnancy or breastfeeding.
9. Current participation in another interventional clinical trial that could interfere with study outcomes.
10. Any other condition that, in the investigator's judgment, makes participation inappropriate.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: EIT-Guided Visual Feedback; Participants complete one standardized session of incentive spirometry while viewing the real-time EIT screen. Trained staff provide target-directed feedback to increase ventilation in dependent dorsal lung regions.	Behavioral: EIT-Guided Incentive Spirometry; Participants 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.
Active Comparator: Standardized Verbal Guidance; Participants complete the same standardized session of incentive spirometry with the EIT screen concealed. Trained staff provide standardized verbal instructions without imaging feedback.	Behavioral: Standardized Incentive Spirometry Guidance; Participants 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	Baseline and 5 minutes after completion of the single intervention session

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Inspiratory Volume	Mean volume or device scale reached across the 30 incentive-spirometry breaths performed during the training session.	Day 1, during the single intervention session of 30 incentive-spirometry breaths
Change in Global Inhomogeneity Index	The EIT-derived global inhomogeneity index at T1 minus the value at T0. Lower values indicate improved ventilation homogeneity.	Baseline and 5 minutes after completion of the single intervention session
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.	Baseline and 5 minutes after completion of the single intervention session
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.	Baseline and 5 minutes after completion of the single intervention session
Change in Oxygen Saturation to Inspired Oxygen Ratio	The SpO2/FiO2 ratio at T1 minus the ratio at T0. SpO2 is averaged over a stable 30- to 60-second interval and FiO2 is determined from the concurrent oxygen-delivery settings.	Baseline and 5 minutes after completion of the single intervention session
In-Hospital Intubation or Reintubation	Proportion of participants who undergo tracheal intubation or reintubation after study enrollment.	From enrollment through hospital discharge, up to 30 days

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	From the start of the single intervention session through 24 hours after completion of the session
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.	Baseline and 5 minutes after completion of the single intervention session, when routine arterial blood gas data are available
ICU Length of Stay	Number of calendar days from ICU admission to ICU discharge, descriptively summarized.	From ICU admission through ICU discharge, up to 30 days
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.	From enrollment through hospital discharge, up to 30 days

Collaborators and Investigators

• Sponsor: Shanghai Zhongshan Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 31, 2027

Study Registration Dates

• First Submitted: June 9, 2026
• First Submitted That Met QC Criteria: June 26, 2026
• First Posted (Actual): July 2, 2026

Study Record Updates

• Last Update Posted (Actual): July 2, 2026
• Last Update Submitted That Met QC Criteria: June 26, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Pulmonary Rehabilitation; Electrical Impedance Tomography; Incentive Spirometry; Visual Feedback; Dorsal Ventilation
• Other Study ID Numbers: KY2026002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No