An interventional study of Low Tidal Volume Ventilation During CPB in Perioperative Respiratory Function, Diaphragmatic Dysfunction and Low Tidal Volume Ventilation, sponsored by Konya City Hospital. Completed at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2026-09-15.
Sponsored by Konya City Hospital · Not applicable, Interventional, and Prevention
The goal of this clinical trial is to evaluate whether low tidal volume (LTV) ventilation during cardiopulmonary bypass (CPB) surgery helps preserve diaphragmatic excursion in adult patients undergoing coronary artery bypass grafting (CABG). The study will also assess the relationship between LTV ventilation and postoperative pulmonary complications, such as atelectasis, pleural effusion, and pneumonia.
The main questions this trial aims to answer are:
Does LTV ventilation better preserve diaphragmatic motion compared to apnea during CPB?
Are postoperative pulmonary complications less frequent in patients receiving LTV?
Does LTV contribute to shorter extubation times and ICU stays?
Researchers will compare LTV ventilation with apnea (standard care) during CPB to assess its effects on diaphragmatic excursion, measured via ultrasound, and postoperative respiratory outcomes.
Participants will:
Undergo elective CABG surgery under general anesthesia
Be randomly assigned to receive either LTV ventilation or apnea during CPB
Have diaphragmatic excursion measured by ultrasound before surgery, before extubation, and 24 hours after surgery
Be monitored for postoperative pulmonary complications (atelectasis, effusion, pneumonia), extubation time, and ICU length of stay
Ultrasound will be used to measure diaphragmatic excursion (DE) in quiet and deep breathing. DE below 10 mm will be considered as diaphragmatic paralysis. Postoperative respiratory assessments will include blood gas analysis (PaO₂/FiO₂ ratio), clinical respiratory parameters, and imaging findings.
This is a prospective, single-center, assessor-blinded randomized controlled trial. Patients and outcome assessors will be blinded to group allocation. The study will be conducted at the Anesthesiology Clinic of Konya City Hospital and is expected to enroll 60 patients.
oronary artery bypass grafting (CABG) surgery performed under cardiopulmonary bypass (CPB) is a complex procedure frequently associated with postoperative pulmonary complications (PPCs). During CPB, mechanical ventilation is usually paused (apnea), which leads to temporary diaphragmatic inactivity. The diaphragm, being a rhythmically contracting muscle under normal physiological conditions, may experience transient dysfunction or even paralysis due to this intraoperative inactivity. Several mechanisms, including loss of neuromechanical coupling, disrupted neuromuscular signaling, altered venous return, and impaired diaphragmatic oxygenation and metabolism, are thought to contribute to this process.
Reduced diaphragmatic motion can create a favorable condition for atelectasis, impair oxygenation, and increase the risk of infection in the postoperative period. The resulting transient diaphragmatic dysfunction is considered a potential contributor to the development of PPCs such as pneumonia, pleural effusion, and prolonged mechanical ventilation.
Recent research has focused on the protective effects of low tidal volume (LTV) ventilation in surgical and critical care settings. However, limited studies have evaluated its direct impact on diaphragmatic function during CPB, particularly in the context of CABG surgery. There is a need to investigate whether intraoperative application of LTV ventilation during CPB can help preserve diaphragmatic excursion (DE) and reduce PPCs.
Konya City Hospital is the lead sponsor of 76 studies on the registry; 21 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Age over 18 years
Male or female patients
American Society of Anesthesiologists (ASA) physical status class II or III
Scheduled for elective coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB)
Provided written informed consent to participate in the study -
Exclusion Criteria:
History of neuromuscular disease
History of thoracic surgery
History of pneumothorax or ascites
Chronic respiratory failure
Pulmonary hypertension or right ventricular failure
Emergency surgery
Inability to perform diaphragm ultrasonographic measurements
Refusal to participate in the study
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Low Tidal Volume Ventilation Group (LTV)
Other: Low Tidal Volume Ventilation During CPB
Apnea Group (Control Group)
Group Low: Patients in this group will receive low tidal volume mechanical ventilation during cardiopulmonary bypass (CPB). Ventilation settings will be: Tidal Volume: 3-4 mL/kg (ideal body weight) PEEP: 5-8 cmH₂O Respiratory Rate: adjusted to maintain normocapnia (PaCO₂ 35-45 mmHg)
Change in Diaphragmatic Excursion Measured by Ultrasound
Diaphragmatic excursion (DE) will be measured using M-mode ultrasonography with a 2-5 MHz convex probe placed in the right mid-clavicular subcostal view. Measurements will be performed during both quiet and deep breathing maneuvers. A DE value of ≤10 mm will be considered indicative of diaphragmatic paralysis. The average of three consecutive measurements will be recorded at each time point. The main comparison will assess postoperative DE values between groups receiving low tidal volume ventilation and apnea during CPB.
Time frame: Baseline (30 minutes before transfer to the operating room (Preoperative baseline) Postoperative ( Immediately Before Extubation) 24 Hours After Surgery (24 hours after the end of surgery)
Incidence of Postoperative Pulmonary Complications
Time frame: First 3 Days After Surgery and Prior to ICU Discharge
Time to Extubation
The time from ICU admission to successful extubation will be recorded in hours. Extubation will be performed based on predefined weaning criteria, including neurological status, respiratory stability, hemodynamic parameters, and oxygenation status. Patients not meeting criteria within 24 hours will be recorded accordingly.
Time frame: From ICU Admission to Extubation (Up to 24 Hours Postoperatively)
Plan to share: No — The plan to share individual participant data has not been determined. No data will be shared at this stage due to institutional policy and ethical concerns.
This study is completed, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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Konya City Hospital