Skip to main content
OpenTrials
Completed

NCT Number: NCT07073885

Effect of Ultra-Low Tidal Volume on Mechanical Power During Heart Bypass Surgery

The goal of this clinical trial is to evaluate whether ultra-low tidal volume (ULTV) ventilation during cardiopulmonary bypass (CPB) can reduce mechanical power (MP) and improve postoperative respiratory outcomes in adult patients undergoing elective coronary artery bypass graft (CABG) surgery.

The main questions it aims to answer are:

Does ULTV ventilation during CPB result in lower intraoperative mechanical power compared to apnea?

Can ULTV ventilation reduce extubation time and ICU (Intensive Care Unit) stay and improve the PaO₂/FiO₂ ratio (Partial Pressure of Arterial Oxygen / Fraction of Inspired Oxygen Ratio)?

Researchers will compare patients receiving ULTV ventilation to those undergoing apnea after aortic cross-clamping to assess the effects on mechanical power and postoperative outcomes.

Participants will:

Be randomized to either ULTV ventilation or apnea group

Undergo standard general anesthesia and CABG surgery

Have mechanical power measured at three time points (pre-CPB, post-CPB, and ICU pre-extubation)

Have arterial blood gases evaluated for PaO₂/FiO₂ ratios

Be monitored for extubation time and ICU length of stay

This study aims to generate evidence that could inform safer and more protective intraoperative ventilation strategies during cardiac surgery.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Coronary Artery Disease Arterial Occlusive Diseases Arteriosclerosis Cardiovascular Diseases Coronary Disease Heart Diseases Myocardial Ischemia Vascular Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Konya City Hospital

Konya, 42020, Turkey (Türkiye)

About this study

This is a prospective, randomized, assessor-blinded, single-center clinical trial designed to evaluate the effects of ultra-low tidal volume (ULTV) ventilation on intraoperative mechanical power (MP) and postoperative pulmonary outcomes in patients undergoing elective coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB).

After obtaining informed consent, eligible adult patients (ASA II-IV) scheduled for elective CABG will be randomly assigned to one of two groups:

ULTV Group: Ventilation will be continued after aortic cross-clamping using volume-controlled ventilation with a tidal volume of 3-4 mL/kg ideal body weight, 12-15 breaths per minute, 5 cm H₂O PEEP, and 50% FiO₂.

Apnea Group: Mechanical ventilation will be discontinued after aortic cross-clamping, and patients will remain apneic during CPB.

Mechanical power will be calculated using a validated surrogate formula and measured at three key time points: pre-CPB (baseline), post-CPB (before ICU transfer), and at the 2nd postoperative hour in the ICU (before extubation). Arterial blood gases will be obtained to determine PaO₂/FiO₂ ratios at these time points and 24 hours post-extubation.

Secondary outcomes include extubation time and length of ICU stay.

This study aims to generate evidence supporting the potential protective effects of continued low-volume ventilation during CPB, with a focus on reducing ventilator-induced lung injury by limiting mechanical power and preserving alveolar integrity.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients of either sex aged over 18 years
  • Patients classified as ASA II-IV
  • Patients scheduled for elective CABG

Exclusion criteria

  • Presence of severe COPD
  • Uncontrolled bronchial asthma
  • Decompensated heart failure (NYHA class III-IV)
  • Pulmonary hypertension
  • History of lung surgery
  • Morbid obesity (BMI >35)
  • Emergency surgery cases
  • Patients who decline to participate in the study

Treatment and study plan

Ultra-Low Tidal Volume Ventilation

Other

Ventilation continued during CPB using volume-controlled mode with ultra-low tidal volume (3-4 mL/kg IBW(Ideal Body Weight)), 12-15 breaths/min, 5 cm H₂O PEEP, and 50% FiO₂.

Apnea Group

Other

In this group, mechanical ventilation will be discontinued after aortic cross-clamping during CPB, and apnea will be maintained throughout the bypass period.

Primary outcomes

  1. Mechanical Power

    Time frame: MP Measurements (Mechanical Power)MP 1: Baseline (after intubation and before surgical incision)MP 2: At the end of surgery (prior to ICU admission)MP 3: Postoperative 2nd hour in ICU (prior to extubation)

    Primary Aim Measurements Calculation of Mechanical Power (MP)

    Several methods exist for measuring MP. In this study, a simplified and validated method will be employed. The formula is expressed as follows:

    MP (J/min) = 0.098 × RR × Vt × (PEEP + ½[Pplat - PEEP] + [Ppeak - Pplat]) (RR: Respiratory Rate, Vt : Tidal Volume, PEEP: Positive End-Expiratory Pressure, Pplat: Plateau Pressure, Ppeak: Peak Inspiratory Pressure).

    Thus, MP is calculated as the product of the work per individual breath (volume × pressure) multiplied by the respiratory rate. Primary evaluation parameters will be computed using ventilator settings, with three consecutive measurements taken and averaged for accuracy.

Secondary outcomes

  1. extubation time

    Time frame: From the end of surgery until the time of tracheal extubation, assessed up to 24 hours postoperatively.

    Extubation time is defined as the duration (in hours) from the end of surgery to the time of tracheal extubation.

  2. duration of intensive care unit (ICU) stay.

    Time frame: From ICU admission following surgery until ICU discharge, assessed up to 7 days postoperatively.

    Defined as the number of calendar days the patient remains in the intensive care unit (ICU) following surgery, until transfer to the general ward. Data will be collected daily during ICU stay.

  3. PaO₂/FiO₂ ratio.

    Time frame: 1. Baseline (after intubation, before surgical incision)2. At the end of surgery (prior to ICU admission)3. Postoperative 2nd hour in ICU (prior to extubation)4. 24 hours after extubation

    PaO₂/FiO₂ ratios will be calculated from arterial blood gas samples obtained at four predefined time points: after intubation and before surgical incision (preoperative baseline), at the end of surgery (prior to ICU admission), at the 2nd postoperative hour in the ICU (before extubation), and at the 24th hour following extubation.

Sponsors and collaborators

Lead sponsor

Konya City Hospital

Other

Registry information

Official study title

The Effect of Ultra-Low Tidal Volume Ventilation on Mechanical Power in Coronary Artery Bypass Graft Surgery

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Jul 18, 2025
Registry last updated
Mar 2, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.