Bariatric Surgery (Sleeve Gastrectomy ), Mechanical Ventilation, Obesity, Morbid
Conditions
Keywords
Flow-controlled ventilation, Volume-controlled ventilation, Respiratory mechanics, Lung-protective ventilation, Bariatric surgery
Brief summary
The goal of this clinical trial is to compare the effects of flow-controlled ventilation (FCV) and volume-controlled ventilation (VCV) on hemodynamic and respiratory parameters in obese patients undergoing elective laparoscopic bariatric surgery. The main questions it aims to answer are: Does FCV provide better intraoperative hemodynamic and respiratory stability compared to VCV during laparoscopic bariatric surgery? Is FCV a safe and feasible ventilation strategy under high intraabdominal pressure and position changes required in bariatric surgery? Researchers will compare FCV group to VCV group to see if FCV improves intraoperative respiratory mechanics and hemodynamic parameters. Participants will: Undergo elective laparoscopic bariatric surgery with BMI \>40 kg/m² (ASA I-III) Receive either flow-controlled or volume-controlled ventilation with individualized PEEP and tidal volume of 6-8 ml/kg predicted body weight Have intraoperative hemodynamic and respiratory parameters monitored at regular intervals, including arterial blood gas analysis Be followed postoperatively for oxygen therapy requirement and intensive care need
Detailed description
Laparoscopic surgery is associated with significant physiological changes due to pneumoperitoneum, which adversely affects hemodynamic and respiratory parameters, thereby complicating intraoperative anesthetic management. These challenges are particularly pronounced in obese patients, who present with reduced functional residual capacity and other physiological alterations that impact both intraoperative and postoperative outcomes. Although bariatric surgery has conventionally been managed with volume-controlled ventilation (VCV), recent studies have highlighted the potential benefits of flow-controlled ventilation (FCV) in terms of safety and contribution to lung-protective ventilation strategies. This study primarily aims to compare the effects of FCV and VCV on intraoperative hemodynamic and respiratory function dynamics in patients undergoing bariatric surgery. Secondarily, the study evaluates the clinical feasibility and safety of FCV under the high intraabdominal pressures and position changes required during bariatric procedures. Study Design: This study includes 34 patients with BMI \>40 kg/m² classified as ASA I-III scheduled for elective laparoscopic bariatric surgery. Seventeen patients were prospectively managed with FCV, while data from 17 patients managed with VCV were retrospectively reviewed. All patients received standard monitoring plus intra-arterial blood pressure monitoring. Anesthesia induction and maintenance protocols were identical across both groups. Ventilation Protocol: In the FCV group, a tidal volume (VT) of 6-8 ml/kg predicted body weight was targeted, and positive end-expiratory pressure (PEEP) was individualized based on compliance following CO₂ insufflation. The same tidal volume strategy was applied in the VCV group with PEEP titration performed in eligible patients. Measurements: The following parameters were recorded after intubation, after insufflation, and at 30-minute intervals intraoperatively: mean arterial pressure (MAP), heart rate, peripheral oxygen saturation (SpO₂), plateau airway pressure (Pplat), peak airway pressure (Ppeak), driving pressure, end-tidal CO₂ (EtCO₂), minute volume, respiratory rate (RR), airway resistance (Raw), and static compliance (Cstatic) calculated as VT/(Pplat-PEEP). Arterial blood gas parameters including pH, PaCO₂, PaO₂, SaO₂, hemoglobin, and lactate were also recorded. Postoperative oxygen therapy requirement and intensive care unit admission were monitored.
Interventions
Patients were ventilated using flow-controlled ventilation with a tidal volume of 6-8 ml/kg predicted body weight. PEEP was individualized based on respiratory compliance following CO₂ insufflation.
Patients were ventilated using volume-controlled ventilation with a tidal volume of 6-8 ml/kg predicted body weight. PEEP titration was performed in eligible patients.
Sponsors
Ankara Training and Research Hospital
Study design
Observational model
COHORT
Time perspective
OTHER
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Age between 18 and 65 years * American Society of Anesthesiologists (ASA) physical status I, II, or III * Body Mass Index (BMI) ≥ 40 kg/m² * Scheduled for elective laparoscopic bariatric surgery * Willing to participate in the study
Exclusion criteria
* ASA physical status IV or V * Emergency surgical procedures * Pregnant patients * Patients requiring vasopressor support to maintain mean arterial pressure above 65 mmHg intraoperatively * Patients with advanced pulmonary disease * Patients who decline to participate in the study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Intraoperative Respiratory Mechanics | From intubation to end of surgery, measured after intubation, after insufflation, and at 30-minute intervals intraoperatively | Comparison of driving pressure between FCV and VCV groups at defined intraoperative time points. |
| Mean Arterial Pressure | From preoperative baseline to end of surgery, measured before surgery, after intubation, after insufflation, at 30-minute intervals intraoperatively, and at end of surgery | Comparison of mean arterial pressure (MAP) between FCV and VCV groups at defined intraoperative time points. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Pa02/Fi02 ratio | From intubation to end of surgery, measured after intubation, after insufflation, at 30-minute intervals intraoperatively and at the end of the surgery. | Comparison of Horowitz index between FCV and VCV groups. |
| Postoperative Oxygen Theraphy Need | Within 24 hours after surgery | Comparison of percentage of participants requiring postoperative oxygen therapy requirement between FCV and VCV groups. |
| Postoperative Intensive Unit Admission | Within 24 hours after surgery | Comparison of the number of patients requiring admission to the intensive care unit between the FCV and VCV groups. |
| Arterial Partial Pressure of Carbon Dioxide (PaCO2) | From intubation to the end of surgery, measured after intubation, after insufflation, and at 30-minute intervals intraoperatively and at the end of the operation | Comparison of arterial partial pressure of carbon dioxide (PaCO2) between the FCV and VCV groups to evaluate efficiency of carbon dioxide elimination at defined time points. |
Countries
Turkey (Türkiye)
Outcome results
None listed