The Effect of Ultra-Low Tidal Volume Ventilation on Mechanical Power in Coronary Artery Bypass Graft Surgery
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- Enrollment
- 60
- Locations
- 2
- Primary Endpoint
- Mechanical Power
Study Overview
Brief Summary
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.
Detailed Description
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.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Prevention
- Masking
- Double (Participant, Outcomes Assessor)
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
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
Arms & Interventions
Group ULTV
Participants in this group will continue to receive mechanical ventilation after aortic cross-clamping during cardiopulmonary bypass (CPB). Ventilation will be provided in volume-controlled mode with a tidal volume of 3-4 mL/kg ideal body weight, respiratory rate of 12-15 breaths/min, 5 cm H₂O PEEP (Positive End-Expiratory Pressure), and 50% FiO₂.
.
Intervention: Ultra-Low Tidal Volume Ventilation (Other)
Apnea Group
After the application of the aortic cross-clamp, mechanical ventilation will be discontinued, and apnea will be maintained.
Intervention: Apnea Group (Other)
Outcomes
Primary Outcomes
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
- PaO₂/FiO₂ ratio.(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)
- extubation time(From the end of surgery until the time of tracheal extubation, assessed up to 24 hours postoperatively.)
- duration of intensive care unit (ICU) stay.(From ICU admission following surgery until ICU discharge, assessed up to 7 days postoperatively.)
Investigators
Esma Karaarslan
Medical Doctor (MD), Department of Anesthesiology and Reanimation, Konya City Hospital
Konya City Hospital