Effect of Intraoperative Dynamic Compliance Guided Individualized Positive End-expiratory Pressure on Postoperative Atelectasis After Laparoscopic Bariatric Surgery

Study Overview
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Brief Summary
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This study intends to explore the effect of dynamic compliance guided individualized positive end-expiratory pressure titration strategy on reducing the level of postoperative atelectasis in obese patient who have laparoscopic bariatric surgery.The results of the study are to assess the effects of this intervention on the incidence，duration of postoperative atelectasis and other complications including hypoxemia etc. after laparoscopic bariatric surgery.And reducing the burden of postoperative atelectasis on patients and their families, hospitals and public resources.

Official Title
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Effect of Intraoperative Dynamic Compliance Guided Individualized Positive End-expiratory Pressure on Postoperative Atelectasis After Laparoscopic Bariatric Surgery: a Single-center, Double-blind Randomized Controlled Trial

Conditions
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Postoperative Atelectasis

Intervention / Treatment
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* Procedure: Dynamic compliance guided individualized positive end-expiratory pressure titration strategy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Bmi ≥ 35 kg/ m2 over 18 years old elective laparoscopic bariatric surgery (gastric bypass or sleeve) Exclusion Criteria: ASA >IV Lung bullae thoracic surgery history quit smoking less than 1 week chronic obstructive pulmonary disease requiring oxygen congestive heart failure (New York Heart Association classification ≥ III) planned to be transferred to intensive care unit after surgery Patients participating in another interventional study Refuse to sign the informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: individualized PEEP<br>Basic ventilation: Volume-controlled ventilation mode with positive end-expiratory pressure（PEEP） of 8cm H2O after induction of anesthesia， Recruitment maneuver: Pressure-controlled ventilation mode increasing PEEP from 10 to 25cmH2O. PEEP-titration maneuver: At this PEEP level, a decremental PEEP-titration maneuver will be started in volume-controlled ventilation mode, decreasing PEEP to 5cmH2O to confirm the highest dynamic lung compliance. After titration: A new recruitment maneuver will be performed and the final PEEP will be the one related to the highest dynamic lung compliance plus 2cm H2O. Randomization: Subsequently patient was randomized, the PEEP was then maintained (individualized PEEP arm) until extubation. After discharged from post-anesthesia care unit (60 to 90 minutes after extubation)：A chest computerized tomography（CT） will be performed to assess the amount of atelectasis, expressed as the percentage of lung tissue in CT. | Procedure: Dynamic compliance guided individualized positive end-expiratory pressure titration strategy<br>* Basic ventilation: Volume-controlled ventilation (VCV) mode with positive end-expiratory pressure (PEEP) of 8cm H2O after induction of anesthesia， Recruitment maneuver (RM): Pressure-controlled ventilation (PCV) mode increasing PEEP from 10 to 25cmH2O in step of 5cmH2O per 30s. PEEP-titration maneuver: ventilation parameters reset as basic ventilation with PEEP still 25cmH2O.Decrease PEEP to 5cmH2O in step of 2cmH2O per 10 respiratory cycles to confirm the highest dynamic lung compliance (Cdy). After titration: A new RM will be performed and the final PEEP will be the one related to highest Cdy plus 2cm H2O. Randomized after the second RM. Individualized PEEP arm: maintain individualized PEEP; PEEP8 arm: maintain a fixed PEEP of 8cm H2O. VCV with other ventilation parameters the same as basic ventilation until extubation . After discharged from postoperative anesthesia care unit (60 to 90 minutes after extubation): chest CT .<br>|
| Active Comparator: PEEP 8<br>Bacis ventilation: Volume-controlled ventilation mode with positive end-expiratory pressure（PEEP） of 8cm H2O after induction of anesthesia， Recruitment maneuver: Pressure-controlled ventilation mode increasing PEEP from 10 to 25cmH2O. PEEP-titration maneuver: At this PEEP level, a decremental PEEP-titration maneuver will be started in volume-controlled ventilation mode, decreasing PEEP to 5cmH2O to confirm the highest dynamic lung compliance. After titration: A new recruitment maneuver will be performed and the final PEEP will be the one related to the highest dynamic lung compliance plus 2cm H2O. Randomization: Subsequently patient was randomized , the PEEP was then reduced to 8cm H2O (PEEP8 arm) until extubation. After discharged from post-anesthesia care unit (60 to 90 minutes after extubation)：A chest computerized tomography（CT） will be performed to assess the amount of atelectasis, expressed as the percentage of lung tissue in CT. | Procedure: Dynamic compliance guided individualized positive end-expiratory pressure titration strategy<br>* Basic ventilation: Volume-controlled ventilation (VCV) mode with positive end-expiratory pressure (PEEP) of 8cm H2O after induction of anesthesia， Recruitment maneuver (RM): Pressure-controlled ventilation (PCV) mode increasing PEEP from 10 to 25cmH2O in step of 5cmH2O per 30s. PEEP-titration maneuver: ventilation parameters reset as basic ventilation with PEEP still 25cmH2O.Decrease PEEP to 5cmH2O in step of 2cmH2O per 10 respiratory cycles to confirm the highest dynamic lung compliance (Cdy). After titration: A new RM will be performed and the final PEEP will be the one related to highest Cdy plus 2cm H2O. Randomized after the second RM. Individualized PEEP arm: maintain individualized PEEP; PEEP8 arm: maintain a fixed PEEP of 8cm H2O. VCV with other ventilation parameters the same as basic ventilation until extubation . After discharged from postoperative anesthesia care unit (60 to 90 minutes after extubation): chest CT .<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of postoperative atelectasis | The amount of postoperative atelectasis, expressed as the percentage of lung tissue in CT. | 60-90 minutes after extubation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| pulse oxygen | Continuous measurement of 24h pulse oxygen after surgery（%） | 24 hours after surgery | 
| PaO2/FiO2 ratio | PaO2/FiO2 ratio | 1 day before surgery(baseline)，5 minutes after anesthesia induction，1 hour after pneumoperitoneum，before extubation，30 minutes after extubation | 
| Quality of Recovery Score - 40 (QoR-40) | Quality of recovery will be evaluated by Quality of Recovery 40 (QoR40),which assesses five dimensions of recovery (physical comfort,emotional state, physical independence , physiological support and pain ). Each item is rated on a five-point Likert scale: none of the time, some of the time, usually, most of the time, and all the time. The total score on the QoR40 ranges from 40 (poorest quality of recovery) to 200 (best quality of recovery). | 1 day before surgery(baseline)，1，2，7，30 days after surgery | 
| Mini-Mental score examination (MMSE) | Mini-Mental score examination [MMSE] used for screening of dementia.The total score on the MMSE ranges from 0 (most severe dementia) to 24 (no dementia). | 1 day before surgery(baseline)，1，2 days after surgery | 
| Postoperative Complication | including pulmonary and other systematic postoperative complications | 1，2，7 days after surgery | 
| Mean arterial pressure | Mean arterial pressure = (systolic blood pressure + 2 × diastolic blood pressure) / 3（mmHg） | every 5minutes During Surgery；end of each step during RM and titration strategy | 
| systolic blood pressure | systolic blood pressure measured by invasive arterial blood pressure（mmHg） | every 5minutes During Surgery；end of each step during RM and titration strategy | 
| diastolic blood pressure | diastolic blood pressure measured by invasive arterial blood pressure（mmHg） | every 5minutes During Surgery；end of each step during RM and titration strategy | 
| heart rate | heart rate per minute | every 5minutes During Surgery；end of each step during RM and titration strategy | 
| pulse oxygen | pulse oxygen（%） | every 5minutes During Surgery；end of each step during RM and titration strategy | 
| dynamic compliance | tidal volume/(airway peak pressure - PEEP)（ml/cmH2O） | every 5minutes During Surgery；end of each step during RM and titration strategy | 
| airway plateau pressure | airway plateau pressure is directly showed in the screen of ventilator（cmH2O） | every 5minutes During Surgery；end of each step during RM and titration strategy | 
| airway peak pressure | airway peak pressure is directly showed in the screen of ventilator（cmH2O） | every 5minutes During Surgery；end of each step during RM and titration strategy | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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lung protective ventilation strategy, individualized positive end-expiratory pressure, Laparoscopic bariatric surgery, Mechanical ventilation, Anesthetic management, Lung dynamic compliance, Postoperative Atelectasis