Prospective Clinical Study of PCV and PCV-VG in Patients Undergoing Bariatric Surgery

Study Overview
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Brief Summary
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This study compares the two mechanical ventilation strategies in obese patients undergoing bariatric surgery: pressure-controlled ventilation(PCV) and pressure-controlled ventilation volume-guaranteed（PCV-VG). This is a randomized controlled trial with a sample size of 100 patients whose body mass index(BMI) is over 30kg/m².

Detailed Description
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With the development of economy and changing of life style, obesity is becoming a common phenomenon. More and more obese patients are undergoing bariatric surgery every year. Obesity results in a series of physiological changes particularly the respiratory system. The decrease of lung compliance and the limited total lung capacity, vital capacity, functional residual capacity are all contributed to intraoperative hypoxemia and postoperative lung complications. Presently study mainly discuss lung protective ventilation strategies from four aspects: tidal volume,ventilation modes,positive end-expiratory pressures and lung recruitment maneuvers. This prospective study will compare two ventilation modes in obese patients undergoing bariatric surgery:pressure-controlled ventilation(PCV) and pressure-controlled ventilation volume-guaranteed（PCV-VG). The total of 100 patients will be divided into two groups randomly. The patients will be ventilated with PCV or PCV-VG modes plus positive end expiratory pressure (PEEP) of 5cmH2O throughout the whole operation. The respiratory and hemodynamic parameters in six time points will be recorded, and the postoperative chest computerized tomography (CT) will be checked to identify the postoperative lung complications.

Official Title
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The Comparison of Pressure-controlled Ventilation and Pressure-controlled Ventilation Volume-guaranteed on Respiratory Dynamics and Clinical Outcome in Patients Undergoing Bariatric Surgery: Prospective Clinical Study

Conditions
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Bariatric Surgery, Mechanical Ventilation

Intervention / Treatment
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* Device: PCV-VG, PEEP5cmH₂O
* Device: PCV, PEEP5cmH₂O


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: BMI≥30kg/m² ASA classification II-III Bariatric surgery Exclusion Criteria: Patients combined restrictive or obstructive lung diseases,pneumonia, bullae of lung ; patients after pneumonectomy Patients combined with other severe internal medicine diseases duration of pregnancy or suckling

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: PCV-VG+PEEP5cmH₂O<br>Patients in this group are ventilated with pressure-controlled ventilation volume-guaranteed mode. And we use PEEP of 5cmH₂O to open the collapsed alveoli. | Device: PCV-VG, PEEP5cmH₂O<br>* This is an innovative ventilation mode developed in recent years. The preset tidal volume help the machine modify inspiratory pressures and compensate the decrease of lung compliance.<br>|
| Active Comparator: PCV+PEEP5cmH₂O<br>Patients in this group are ventilated with pressure-controlled ventilation mode. And we use PEEP of 5cmH₂O to open the collapsed alveoli. | Device: PCV, PEEP5cmH₂O<br>* This is a traditional ventilation mode used in obese patients in the past.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Dynamic lung compliance measure | Dynamic lung compliance can be calculated based on tidal volume,peak inspiratory pressure and PEEP. 10minutes after induction,10minutes after pneumoperitoneum,60minutes after pneumoperitoneum and 10minutes after pneumoperitoneum release will be recorded. | three hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Postoperative lung complications | Lung complications mainly contains pneumonia,atelectasis,pleural fluid. The investigator compare the preoperative chest CT with the postoperative chest CT and follow-up participants until participants leave hospital. | five days | 
| the risk factors of postoperative lung complications | risk factors may include age, gender, BMI, ventilation duration, etc | five days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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obesity, lung protective ventilation strategies